UNIVERSITY OF GHANA 
 
 
 
 
 
EVALUATION OF SOME NUTRACEUTICAL PROPERTIES OF 
LESSER KNOWN FUNCTIONAL FOODS IN GHANA 
 
 
 
 
 
 
 
BY 
 
 
 
ROSE YAA AMOAH MANTE  
 
   (10309213) 
 
 
 
 
 
 
 
THIS THESIS IS PRESENTED TO THE UNIVERSITY OF GHANA, 
LEGON IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR 
THE AWARD OF MPHIL FOOD SCIENCE DEGREE 
 
 
 
 
 
 
 
JULY 2019 
DECLARATION 
This is to certify that this thesis is the result of research undertaken by Rose Yaa Amoah 
Mante towards the award of the Master of Philosophy degree in Food Science from the 
Department of Nutrition and Food Science, University of Ghana, under the supervision of 
Prof. Agnes S. Budu and Prof. Firibu K. Saalia. All references made to other people‘s work 
have been duly acknowledged. 
 
 
 
 
…………………….                                                   ……………………. 
Rose Yaa Amoah Mante Date 
(Student) 
 
 
 
 
……………………                                                      …………………… 
Prof. Agnes S. Budu Date 
(Supervisor) 
 
 
 
 
……………………. ……………………….. 
Prof. F. K. Saalia Date 
(Co- Supervisor) 
 i 
ABSTRACT 
Functional foods are foods that possess other health benefits apart from their regular 
nutritional benefits. A functional food may contain nutraceutical properties, which have 
components, responsible for curing or preventing a disease or disorder. There are several 
indigenous foods in Ghana that have been purported to possess functional properties.  
The claim to functionality of some of these indigenous foods are based on folklore but the 
scientific backing to these claims may not be known. It is therefore important to find out 
foods that Ghanaians consider to be functional. Some of these may have their properties 
reported in literature. However, some may not be popular and so may not have been well 
studied. The aim of this study was to identify some of these lesser known foods and determine 
their nutraceutical properties. It also sought to find out, if there were correlations between the 
health claims of such foods with their nutraceutical properties. Since most of the local 
Ghanaian foods are cooked before eating, it is also necessary to know the effect of heat on 
their nutraceutical contents. 
A consumer survey was carried out in two major market centres in Accra to determine and 
select some indigenous functional foods. Analysis were carried out on selected samples to 
determine their total phenolic content, phytochemical profile (flavonoids, alkaloids, saponins) 
and antioxidant scavenging capacity. The samples were then blanched at different time 
regimes to determine the effect of heat on the physicochemical properties. 
The results revealed that foods such as turkey berries, cocoyam leaves, and fruit of 
Tetrapleura tetraptera, calabash nutmegs, bissap, water leaf, fermented African locust beans, 
cassava leaves, anise, orange leaves, soursop leaves, pawpaw leaves, and melon seeds were 
considered as functional foods. These foods were easily accessible in their communities. From 
those interviewed, 18% reported as having consumed some of these functional foods on a 
daily basis. Another 18% reported that they consumed some of them occasionally. About 
 ii 
16% consumed them on a monthly basis, 15% twice a week, and 9% three or more times a 
week.  
Seven indigenous food samples selected for nutraceutical analysis were bitter kola, Calabash 
nutmeg, alligator pepper, cloves, fruit of Tetrapleura tetraptera, anise and Ashanti black 
pepper. For antioxidant scavenging capacity, cloves recorded 0.933%, Ashanti black 
pepper, 0.798%, bitter kola, 0.877%, anise, 0.789%, fruit of tetrapleura tetraptera, 
0.867%, alligator pepper, 0.928% with calabash nutmeg having 0.709%. Bitter kola had a 
total phenolic content of 45.223mgGAE/g but Alligator pepper recorded levels of total 
phenolic content at 2.236 mg GAE/g. Total phenolic content and antioxidant scavenging 
capacity of the food samples were directly proportional to each other such that food samples 
that recorded high levels of phenolics also recorded a high level of free radical scavenging 
capacity. For phytochemicals, bitter kola recorded levels of alkaloids at 0.670. Cloves had on 
the other hand had alkaloid levels of 0.236. Ashanti black pepper had high flavonoid levels 
(8.250). Bitter kola recorded very high saponin content of 12.470, but low flavonoid levels of 
2.040. Cloves recorded low flavonoid contents (1.886).  
It can be concluded that the above indigenous foods have appreciable amounts of phenolic 
compounds, phytochemicals (alkaloids, saponins and flavonoids) and antioxidants which are 
bioactive compounds responsible for the functionality of foods.  The bioactive compounds 
identified are to be responsible for the various medicinal and pharmacological properties of 
the selected food samples. This supported the claim by those interviewed that those foods 
have medicinal or curative properties.  
There was a general decline in the levels of phytochemicals with respect to blanching time. 
The reduction occurred gradually but there was no significant difference in the values with 
heating time. Heating therefore had no effect on the levels of bioactive compounds present in 
the food. 
 iii 
DEDICATION 
This work is dedicated to the God, He who was, and is to come. Without him I couldn‘t have 
possibly completed this work. I also dedicate this work to my parents for being strong pillars 
in my life, both financially and spiritually. 
 iv 
ACKNOWLEDGEMENTS 
I am forever grateful to God Almighty for being faithful to me, even when I was not. Indeed 
without him, I am nothing. If the Lord had not been on our side Let Israel say! 
 
I also want to express my profound gratitude to my supervisors, Professors Agnes Simpson 
Budu and Firibu K. Saalia. You have worked tirelessly with me and offered your guidance and 
support throughout my thesis. God richly bless you. 
 
I also appreciate the encouragement of several individuals of the Department of Nutrition and 
Food Science. Notable among them are, Miss Farida Adam, Miss Sylvia Baah-Tuahene, Mr. 
Anthony Akwetey Mensah, Miss Genevieve Opoku and Miss Asantewaa Afia Wiafe. Their 
encouragement and advice went a long way. 
 
Special thanks go to friends and loved ones who kept me in their prayers. Namely, Miss 
Christiana Owiredua, Mr. Daniel Boateng Abankwa, Mr. Kwame Owusu-Sekyere, Mr and 
Mrs. Oguah and Mr. Obed Gyan. God has seen your labour of love and will surely reward 
you. 
 
To my course mates, especially Miss Loretta Darkwa, you made my experience very 
enjoyable. A big thank you to the lab technicians of the department of Nutrition and Food 
Science. Auntie Leo, Mama Flo and Mr. Quaye. You are amazing personalities. God bless you 
abundantly. 
 
 
 
 
 
 v 
TABLE OF CONTENTS 
DECLARATION ............................................................................................................................. i 
ABSTRACT ................................................................................................................................... ii 
DEDICATION............................................................................................................................... iv 
ACKNOWLEDGEMENTS ............................................................................................................ v 
LIST OF TABLES......................................................................................................................... ix 
LIST OF FIGURES ........................................................................................................................ x 
CHAPTER 1 ................................................................................................................................... 1 
INTRODUCTION .......................................................................................................................... 1 
1.1 Background information ........................................................................................................... 1 
1.2 Rationale ................................................................................................................................... 4 
1.3 Main objective .......................................................................................................................... 4 
1.4 Specific Objectives ................................................................................................................... 4 
CHAPTER 2 ................................................................................................................................... 5 
LITERATURE REVIEW ............................................................................................................... 5 
2.1 The era of Functional foods ...................................................................................................... 5 
2.2 Bioactive compounds and phytochemicals in food .................................................................. 6 
2.2.1 Probiotics and Prebiotics ..................................................................................................... 10 
2.2.2 Proteins and Peptides ........................................................................................................... 12 
2.2.3 Carbohydrates and Fibers .................................................................................................... 13 
2.2.4 Lipids and Fatty Acids ......................................................................................................... 15 
2.2.5 Isoprenoids........................................................................................................................... 16 
2.2.6 Phenolic compounds ............................................................................................................ 17 
2.2.7 Alkaloids .............................................................................................................................. 18 
2.2.8 Flavonoids ........................................................................................................................... 19 
2.2.9 Saponins............................................................................................................................... 22 
2.3 Free radicals and Antioxidant activity in foods ...................................................................... 23 
2.3.1 Antioxidant and nutraceutical properties of some green leafy vegetables........................... 25 
2.3.1.1 Bitter leaf (Vernonia amygdalina) .................................................................................... 25 
2.3.1.2 Water Leaf (Talinum triangulare) .................................................................................... 26 
2.3.1.3 Kale (Brassica oleraceae L. var. acephala DC.) ............................................................... 26 
2.3.1.4 Spinach (Spinacia oleracea) ............................................................................................. 27 
2.3.1.5 Dandelion greens (Taraxacum officinale) ........................................................................ 27 
2.3.1.6 Broccoli (Brassica oleracea) ............................................................................................ 28 
2.3.1.7 Cocoyam leaves (Colocasia esculenta) ............................................................................ 29 
2.3.1.8 Eggplant (Solanum macrocarpon) leaves ......................................................................... 31 
 vi 
2.3.1.9 Amaranthus leaves ............................................................................................................ 32 
2.3.2 Antioxidant and nutraceutical properties of some herbs ..................................................... 32 
2.3.2.1 Basil (Ocimum and Gratissimum) .................................................................................... 32 
2.3.2.2 Lemongrass (Cymbopogan citratus) ................................................................................. 33 
2.3.2.3 Rosemary (Rosmarinus Officinalis) ................................................................................. 34 
2.3.2.4 Bay Leaf (Laurus nobilis L.) ............................................................................................ 34 
2.3.3 Antioxidant and nutraceutical properties of some spices .................................................... 35 
2.3.3.1 Cloves (Eugenia caryophyllata) ....................................................................................... 35 
2.3.3.2 Alligator pepper (Aframomum melegueta) ....................................................................... 35 
2.3.3.3 Ashanti black pepper (Piper guineense) ........................................................................... 36 
2.3.3.4 Fruit of Tetrapleura tetraptera ........................................................................................... 36 
2.3.3.5 Calabash nutmeg (Monodora myristica) .......................................................................... 37 
2.3.3.6 Ginger (Zingiber officinale) ............................................................................................. 37 
2.3.3.7 Garlic (Allium sativum) .................................................................................................... 39 
2.3.3.8 Cumin (Cuminum cyminum L.) ....................................................................................... 41 
2.3.4 Antioxidant and nutraceutical properties of some fruits ...................................................... 42 
2.3.4.1 Pawpaw (Carica Papaya) ................................................................................................. 42 
2.3.4.2 Avocado (Persea americana) ............................................................................................ 43 
2.2.4.3 Bitter kola (Garcinia kola) ............................................................................................... 44 
2.3.4.4 Guava (Psidium guajava L.) ............................................................................................. 44 
2.3.4.5 Olives (Olea europaea L.) ................................................................................................ 45 
2.3.5 Antioxidant and nutraceutical properties of edible fungi .................................................... 46 
2.3.5.1 Mushrooms ....................................................................................................................... 46 
CHAPTER 3 ................................................................................................................................. 48 
MATERIALS AND METHODS .................................................................................................. 48 
3.1 Study design ........................................................................................................................... 48 
3.2 Consumer survey .................................................................................................................... 48 
3.2.1 Sample size calculation ....................................................................................................... 48 
3.3 Ethical Clearance for Data Collection .................................................................................... 48 
3.4 Materials ................................................................................................................................. 49 
3.4.1 Sample selection .................................................................................................................. 49 
3.4.2 Determination of Total Phenolic Content (TPC) ................................................................. 49 
3.4.3 Phytochemical profile determination (flavonoids, alkaloids, Saponins) ............................. 50 
3.4.3.1 Flavonoids ........................................................................................................................ 50 
3.4.3.2 Saponins............................................................................................................................ 50 
3.4.3.3 Alkaloids ........................................................................................................................... 50 
 vii 
3.4.3 Determination of Antioxidant potential using 2,2-diphenyl-1-picryhydrazyl (DPPH) ........ 51 
3.4.4 Determination of the effect of processing on the phytochemical profile of selected food 
samples ......................................................................................................................................... 52 
3.5 Analysis of results .................................................................................................................. 52 
CHAPTER 4 ................................................................................................................................. 53 
RESULTS AND DISCUSSION ................................................................................................... 53 
4.1 Consumer survey on indigenous foods Ghanaian considered to be functional foods ............ 53 
4.1.1 Consumer background characteristics ................................................................................. 53 
4.1.2 Indigenous foods listed by Ghanaian consumers to possess functional properties ............. 54 
4.1.3 Level of consumption of the stated foods ............................................................................ 57 
4.2 Chemical Analysis of selected food samples .......................................................................... 59 
4.2.1 Total Phenolic Content (TPC) ............................................................................................. 59 
4.2.2 Antioxidant scavenging capacity ......................................................................................... 62 
4.2.3 Phytochemical profile (Alkaloids, Saponins, Flavonoids) ................................................... 63 
4.3 Effect of heating on the TPC, Antioxidant scavenging capacity and phytochemical profile of 
selected food samples ................................................................................................................... 66 
4.3.1 Total Phenolic Content and Antioxidant scavenging capacity ............................................ 66 
4.3.2 Phytochemical profile .......................................................................................................... 68 
CHAPTER 5 ................................................................................................................................. 73 
CONCLUSION AND RECOMMENDATIONS ......................................................................... 73 
5.1 Conclusions ............................................................................................................................ 73 
5.2 Recommendations .................................................................................................................. 74 
REFRENCES ............................................................................................................................... 75 
APPENDICES .............................................................................................................................. 99 
APPENDIX 1: INFORMED CONSENT FORM ......................................................................... 99 
APPENDIX 2: CONSUMER SURVEY QUESTIONNAIRE ................................................... 102 
 
 
 
 
 
 
 
 
 viii 
LIST OF TABLES 
Table 2.1: Various nutraceuticals found in plants and their benefits ...................................................... 7 
Table 4.1: Background characteristics of consumers ............................................................................ 54 
Table 4.2: Indigenous foods perceived to possess functional properties .............................................. 55 
Table 4.3: Perceived medicinal properties of some indigenous food products as stated by respondents.
 .............................................................................................................................................................. 56 
Table 4.4: Total Phenolic Content (TPC) of selected food samples ..................................................... 60 
Table 4.5: Antioxidant scavenging capacity of selected food samples ................................................. 62 
Table 4.6: Phytochemical profile of selected food samples .................................................................. 64 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ix 
LIST OF FIGURES 
Figure 1a: Reported consumption of functional food patterns amongst consumers ............................. 58 
Figure 1b: Ease of availability of functional foods in communities ..................................................... 58 
Figure 2: Selected food samples. L-R top (Ashanti black pepper, cloves, bitter kola) ......................... 59 
Figure 3: Effect of blanching time on the antioxidant capacity of selected food samples .................... 66 
Figure 4: Effect of blanching time on Total phenolic content of selected foods .................................. 67 
Figure 5: Effect of blanching time on the phytochemical profile of Ashanti black pepper .................. 68 
Figure 6: Effect of blanching time on the phytochemical profile of cloves .......................................... 69 
Figure 7: Effect of blanching time on the phytochemical of Bitter kola ............................................... 69 
Figure 8: Effect of blanching time on the phytochemical profile of Anise ........................................... 70 
Figure 9: Effect of blanching time on the phytochemical profile of fruit of Tetrapleura tetraptera .... 70 
Figure 10: Effect of blanching time on the phytochemical profile of Alligator pepper ........................ 71 
Figure 11: Effect of blanching time on the phytochemical profile of calabash nutmeg ....................... 71 
 
 
 
 
 
 
 
 
 
 
 
 
 x 
CHAPTER 1 
INTRODUCTION 
 
1.1 Background information 
Functional foods can be defined simply as ‗Foods that are capable of providing additional 
health benefits beyond their basic nutrition‘ or ‗Foods that bear a resemblance to mainstream 
food meant to be eaten as part of everyday diet, but has been changed to function in other 
biological roles aside the provision of basic nutritional requirements‘ (Roberfroid, 2000). 
Diplock et al. (1999) also characterizes functional foods, to be foods that have been sufficiently 
shown to have a positive effect on some target functions of the body, beyond satisfactory 
nutritional benefits, in a manner that may enhance health and well-being and/or reduce risk of 
disease occurrence. Another definition of functional foods by the International Food 
Information Council (IFIC) (2007), is foods or dietary components that may provide a health 
benefit beyond basic nutrition. 
Functional foods have become one of the most fascinating fields of scientific study and 
innovation in the food industry. In Europe alone, the sale of functional foods have been raised 
significantly, with France, Germany, the United Kingdom, and the Netherlands representing 
the most important countries in the functional foods market (Jago, 2009). An annual growth 
rate of between 15% to 20% was recorded at the end of the 1990‘s in the functional food 
market and continued to increase exponentially at the end of 2009 (Hilliam, 2000; Bernal et 
al., 2011). Due to an increase in awareness of the benefit of functional foods to human health 
today, foods are eaten not only to satisfy hunger and to provide necessary nutrients for the 
body but also to prevent nutrition-related diseases and improve physical and mental well-
being (Menrad, 2003; Roberfroid, 2000). The growing excitement in the field of functional 
foods can be attributed to growing concerns regarding the diet‘s impact on health and diet-
 1 
related diseases such as diabetes, cardiovascular diseases, and cancer. Today, extensive 
studies into the curative abilities of a horde of bioactive compounds present in plant based 
edible and non-edible plant materials have resulted in a growth in medical and nutritional 
based research. According to Young, (2000); Mollet and Rowland, (2002), the benefits of 
functional foods have become so widely spread through research that, consumers now 
become knowledgeable in their benefits to their health. Research that has been carried out 
however, has not been focused much on indigenous African and for that matter Ghanaian 
foods.  
According to Mbhenyane, (2017), indigenous foods have a major role to play when it comes 
to enhancing the quality of diets and improving food and nutritional security. There is 
however little or no research carried out on indigenous foods due to the decline in usage as a 
result of its non-availability in commercialised and industrialised markets. Meanwhile, 
diverse avenues for the creation of never before seen dietary products have been made 
available. With all new fields of study come new terms. The terms "nutraceuticals" and 
"functional foods" are references given to foods that promote well-being in the human body, 
or their isolated components. Functional foods products are ingested as foods and not in 
regulated form (Hasler, 1998).  
Nutraceuticals are defined as foods or part of foods that provides health benefits including the 
intervention and treatment of a disease. The term "nutraceutical" was coined from "nutrition" and 
"pharmaceutical" in 1989 by Stephen De Felice, MD, founder and chairman of Foundation for 
Innovation in Medicine (De Felice, 2002). From the definition therefore, a functional food for 
instance, can play the role of a nutraceutical for a consumer. Nutraceuticals are also sometimes 
isolated or purified from foods and generally sold in medicinal forms such as pills and capsules which 
are not usually associated with foods. According to Swaroopa and Srinath (2017), a wide variety of 
nutraceutical foods are available in the market which falls in the category of traditional foods 
and non-traditional foods. Traditional nutraceuticals are food in which no changes are made 
 2 
so it the natural, whereas non-traditional nutraceuticals are the outcome from agricultural 
breeding or added nutrients or ingredients like calcium, vitamins or minerals to boost the 
nutritional content of the food. 
 Since the 1990s, functional foods have become very popular around the world. Its popularity 
amongst consumers has been identified as a deciding factor in the success of this industry, 
although little research has been conducted in this field. According to Menrad (2003), the 
functional foods market is increasingly growing worldwide, with new products being launched 
continuously, and competition becoming more intense.  
The therapeutic properties of these medicinal foods can be attributed to their phytochemical 
components especially the flavonoids, alkaloids, sterols, phenolic acids among others. 
Phytochemicals are not essential nutrients and are not required by the human body for 
sustaining life, but have important properties to prevent or fight some diseases. Because of 
this property, many studies have been undertaken to determine the health benefits of these 
phytochemicals.  
There has been considerable evidence gathered to implicate cellular damage as a result of the 
work of reactive oxygen species (ROS). The aetiology and pathophysiology of certain 
diseases such as Parkinson‘s disease, Alzheimer‘s, multiple sclerosis etc., can in part be 
attributed to the presence of reactive oxygen species (ROS) in the body. Free radicals are 
generated in living systems as part of the body‘s normal metabolic processes. Antioxidants 
are vital substances, which possess the ability to protect the body from damages resulting 
from free radical induced stress. They are inhibitors of the process of oxidation, even at 
relatively small concentration and thus have diverse physiological role in the body. 
Antioxidant constituents of the plant material act as radical scavengers, and helps in 
converting the radicals to less reactive species. A variety of free radical scavenging 
antioxidants is found in dietary sources like fruits, vegetables, tea, spices and herbs etc. (Hall, 
 3 
2001). 
1.2 Rationale 
Many Ghanaians consume indigenous foods which are purported to bear functional properties. 
The claim to functionality of some of these indigenous foods are based on folklore but the 
scientific backing to these claims may not be known. It is therefore important to find out 
foods that Ghanaians consider to be functional to the body and select the ones that may not be 
popular (lesser known food) so may not have been well studied or reported in literature. The 
nutraceutical properties of these foods will need to be identified so as to link them to the 
claimed health benefits. Since most of local Ghanaian foods are cooked before eating, it is 
also necessary to know the effect of heat on their nutraceutical contents. 
1.3 Main objective 
The main objective of this study was to identify some lesser known functional foods in 
Ghana, determine some nutraceutical properties to link to their claimed health benefits and to 
find the effect of cooking on such health benefits. 
 
1.4 Specific Objectives 
1. Determine what foods Ghanaian consumers perceive to be functional foods 
 
2. Determine the level of consumption of such foods. 
 
3. Determine some nutraceutical properties (the total phenolic contents, phytochemical 
profile; flavonoids, alkaloids and saponins and antioxidant potential) of identified 
functional foods 
4. Determine the effect of processing on the identified nutraceutical profiles of these foods. 
 4 
CHAPTER 2 
LITERATURE REVIEW 
 
 
2.1 The era of Functional foods 
The statement "Let food be thy medicine and medicine be thy food," stated by Hippocrates 
some two and a half millennia ago is being given a lot of attention today as it has dawned on 
food scientists and consumers alike that certain foods possess many overlooked health 
benefits. These foods contain certain components that aid and improve our general wellness. 
Food can be described in various ways. In the most basic sense, food is a fuel, thereby, a source 
of energy needed for the performance of day to day activities and the preservation of normal 
metabolic processes in the body. However, we are all aware that the function of food is much 
more than a substance that is responsible for the production of energy to the body since food 
also contains certain important nutrients needed in disease prevention. These key nutrients 
necessary for the prevention of particular ailments is one of the main concerns of nutritional 
studies over the last 100 years (Beecher, 1999). According to Wildman (2001), early 
civilizations including the Egyptians, Chinese and Sumerians, have provided evidence that 
suggests that, food can be effectively used as medicine, in the treatment and prevention of 
various diseases. These medicinal benefits have been explored for thousands of years. Novel 
research in Food industry has shown that, there is a lot more information out there concerning 
the science of food than what was known a few decades ago. Not too long ago, most food 
analysis was narrowed to sensory and nutritional tests. However, there is supporting proof that 
there are other compounds of food, which may be involved in a pivotal role in the association 
between food and health (Takayuki et al., 2008).  Compounds that are of a biological nature 
and are present in or isolated from a plant, animal or marine source and impart beneficial 
health or wellness are known as bioactive compounds. According to Hasler (1998), and Dixon 
 5 
et al. (1999), functional ingredients are the fractions or isolated parts of a food that bear 
bioactive compounds of that food in different degrees of purity.  
2.2 Bioactive compounds and phytochemicals in food 
Bioactive compounds are compounds found in foods that are capable of modulating mechanic 
processes and hence have exhibited potential beneficial impacts on human health. Examples 
include probiotics, prebiotics, proteins, peptides, carbohydrates, fibres, lipids and fatty acids 
Vijaya Kumar et al. (2015).  
Phytochemicals are the bioactive compounds found in plant foods like vegetables, fruits, 
cereal grains, tea and wine. They provide health benefits for humans as medicinal ingredients 
and nutrients as well as protect plant cells from environmental hazards such as pollution 
stress, drought, UV exposure and pathogenic attack (Ali and Alqurainy, 2006). Samrot et al. 
(2009) and Koche et al. (2010) have reported that a significant intake of phytochemicals play 
a role when it comes to protection of human health. Due to their medicinal properties, they 
can also be said to function as nutraceuticals. Examples of phytochemicals include 
polyphenols, carotenoids, glucosinolates, phytates, saponins, amines and alkaloids. 
Phytochemicals are grouped based on the foundation that they have different chemical 
constituents. They are mostly, naturally occurring foods which people have been eating for 
years. Table 2.1 outlines some phytochemicals (used as nutraceuticals), the foods in which 
they can be found, and the benefit they provide to the human body. Currently, about 8000 
phytochemicals have been identified; varying from simple phenolic acids to very complex 
polymerized compounds like tannins (Ibrić and Ćavar, 2014). 
 
 
 
 
 6 
Table 2.1: Various nutraceuticals found in plants and their benefits 
Chemical constitute Source Potential benefit 
1. Carotenoids   
(Isoprenoids) 
a. lycopene Tomatoes, pink grapefruit, Its antioxidative potential 
guava, pawpaw, watermelon protects the body from cancer 
formation. Mainly prostate, 
cervical, leukemia. 
b. lutin maize, avocado, egg yolk, Anti-cancerous properties(i.e. 
spinach colon cancer), protects the 
eyes against cataracts and 
development muscle 
degeneration due to 
ageing 
c. β-carotene Carrots, various fruits and Antioxidative properties and 
d. α-carotene vegetables protection of the cornea 
e. α-cryptoxanthin Carrots against UV light, 
f. zeaxanthin Oranges and tangerines Corn, anticarcinogenic properties 
avocado 
2. Dietary fibres   
a. Soluble fibre Black eyed peas, oats, Anticarcinogenic, preserves 
barley, certain fruits the GIT 
b. Insoluble fibre Whole grain foods, wheat corn Prevention of colon cancer, 
bran and nuts maintenance of the digestive 
tract 
3. Polyphenolic   
Compounds 
a. flavonones Citrus fruits Antioxidative and 
anticarcinogenic properties 
b. flavones Fruits, vegetables, soyabean Antioxidative and 
anticarcinogenic properties 
c. flavonols Onions, apples broccoli, tea Antioxidative properties 
d. anthocyanins Blueberries, blackberries, Antioxidative, offsets 
black raspberries inflammation in the body, 
lowers blood sugar levels in 
diabetic patients 
e. phenolic acids Berries, legumes Reduces the oxidation of LDL 
cholesterol , reduces 
cancer formation 
 
 7 
f. resveratrol Dark grapes, raisins, berries, reduces total serum 
peanuts cholesterol and elevates 
HDL cholesterol 
g. curcumin Turmeric root Strongly anti-inflammatory 
and strongly antioxidant , 
effective anti-clotting agent 
4. Fatty Acids   
a. Omega 3- fatty acids Salmon, flaxseed Controls inflammations and 
(PUFA) maintains the regular 
functioning of the brain 
b. MUFA Tree nuts Alleviates the occurrence of 
coronary heart disease 
5. Isothiocyanates   
a. sulporaphane Cauliflower, broccoli, May increase the rate of 
cabbage, kale, horseradish removal of toxins from the 
body and enhance 
antioxidative defences 
6. Phenols   
a. Caffeic acid Apples, pears, citrus fruits, May bolster cellular 
b. Ferulic acid some vegetables antioxidative defenses and 
may contribute to the 
preservation of vision and 
general health 
7. Plant stanols/sterols   
Stanol/sterol esters Fortified table spreads May lessen the occurrence 
of coronary heart disease 
occurrence 
8. Tocotrienol Rice, palm oil promotes cardiovascular 
(isoprenoids) health and prevents breast 
cancer occurrence 
9. Saponins Chick peas and soya beans Lowers cholesterol level and 
has anticarcinogenic 
properties 
10. Probiotics/prebiotics Yoghurt, cheese, milk May improve 
gastrointestinal health and 
systematic immunity 
11. Minerals (calcium, Food Essential component of a 
selenium, potassium, balanced diet 
zinc, copper) 
12. Polyols sugar Fruits Reduces the occurrence of 
alcohols (xylitol, dental caries 
sorbitol) 
 8 
13. Sulphides/thiols Cruciferous vegetables Anticarcinogenic 
Dithiothiones 
14. Glucosinolates Cruciferous vegetables, Anticarcinogenic 
cauliflower 
15. phytoestrogens   
a. isoflavanes Soy beans, cauliflower Reduces LDL cholesterol 
(genistein, daidzein) levels. antioxidative and 
anticarcinogenic properties 
b. lignans Flaxseed, rye, vegetables Inhibit the occurrence of 
breast cancer as well as colon 
cancer 
16. Alkaloids   
a. quinine Cinchona Fights malaria 
b. tropane alkaloids Deadly night shade, datura Alleviates cardiovascular 
conditions 
c. morphine Opium poppy Antidepressant and pain 
reliever 
d. ergot alkaloids Fungus: claviceps purpurea Abortifacients 
e. vincristine periwinkle Antineoplastic 
f. vinblastine periwinkle Antineoplastic 
g. coumarin fenugreek Hypoglaceamic 
h. scopoletin fenugreek Hypoglaceamic 
i. fenugreekine fenugreek Hypoglaceamic 
j. trigonelliine fenugreek Hypoglaceamic 
17. non- carotenoid   
terpenoids 
a. perillyl alcohol Cherries and mint Anticancer 
b. saponins Legumes (chicks, peas, Reduces cholesterol levels 
fenugreek) 
c. terpenol carrots Anticancer 
d. terpene limonoids Peels and membranes of Anticarcinogenic 
citrus fruits 
18. anthraquinones   
a. senna Legumes and pulses Purgative 
b. barbaloin Aloe Laxative anti-helminthic 
c. hypericin St. john‘s wort Analgesic 
d. capsaicin Capsicum (hot peppers) Anticancer, anti- 
inflammatory, anti-apoptotic 
e. piperine Black peppers (jalapeno Helps in digestion 
peppers) 
19. Terpenes   
a. Menthol Plants of mint family Topical pain reliever and 
(monoterpene) anti-pyretic 
 9 
b. Borneol Pine oil Disinfectant 
(monoterpene) 
c. Santonin wormwood Photosensitizer 
(sesquiterpene) 
d. Gossypol Cotton contraceptive 
(sesquiterpene) 
Source: Sarin Rajat et al. (2012) 
 
2.2.1 Probiotics and Prebiotics 
Probiotics and prebiotics restore a balance in the digestive tract of humans O‘Bryan et al., 
(2013). Probiotics are advantageous bacteria that are present in several foods. Common 
strains include the Lactobacillus and Bifidobacterium strains. Probiotics such as Lactobacilli 
are naturally found in fermented foods like yoghurt (Keswani and Cohen, 2005, Collins and 
Gibson, 1999). Probiotics were originally used to improve the health of both animals and 
humans through the modulation of the intestinal microbiota. At present, several well-
characterized strains of Lactobacilli and Bifidobacteria are available for human use to reduce 
the risk of gastrointestinal (GI) infections or treat such infections (Salminen et al., 2005). 
Some of the beneficial effects of probiotic consumption include improvement of intestinal 
health by the regulation of microbiota, and stimulation and development of the immune 
system, synthesizing and enhancing the bioavailability of nutrients, reducing symptoms of 
lactose intolerance, and reducing the risk of certain other diseases. The ability of probiotics to 
establish in the GI tract is enhanced by their ability to eliminate competitors. In different 
studies on humans and animals, beneficial microorganisms are used to improve the 
colonization resistance on body surfaces, such as GI, the urogenital, and the respiratory tract. 
Lactobacillus acidophilus and Lactobacillus casei produce lactic acid as the main end product 
of fermentation. In addition to lactic and acetic acids, probiotic organisms produce other 
acids, such as hippuric and citric acid. Lactic acid bacteria also produce hydrogen peroxide, 
diacetyl, and bacteriocin as antimicrobial sub-stances. These inhibitory substances create 
antagonistic environments for foodborne pathogens and spoilage organisms. Yoghurt bacteria 
 10 
are reported to produce bacteriocin against probiotic bacteria and vice versa (Dave &Shah, 
1997). 
Goldin & Gorbach (1980) reported that the introduction of L. acidophilus into the diet lowers 
the incidence of chemically induced colon tumors in rats. Later, the same authors also 
suggested that diet and antibiotics can lower the generation of carcinogens in the colon and 
reduce chemically induced tumors (Goldin & Gorbach, 1984).These effects appear to be 
mediated through the intestinal microbial communities. A possible mechanism for these 
anticancer effects relies on inhibiting intestinal bacterial enzymes that convert pro-
carcinogens to more proximal carcinogens (Kumar et al., 2015). 
Prebiotics on the other hand, are non-digestible foods such as fibre, which make their way 
through the digestive tract, and help good bacteria grow and thrive. Dietary fiber consists of 
non-digestible carbohydrates and lignin that are intrinsic and intact in plants. Functional fiber 
consists of isolated, non-digestible carbohydrates that have beneficial physiological effects in 
humans. Alternatively, Prebiotics are a source of food to the bacteria that reside in our 
gastrointestinal tract (GIT), and usually are in the form of carbohydrate fibres known as 
oligosaccharides. Sources of oligosaccharides include legumes, fruits and whole grains. An 
important mechanism of action for dietary fiber and prebiotics is fermentation in the colon 
and changes in gut micro-flora. The human large intestine is one of the most diversely 
colonized and metabolically active organs in the human body. The presence of prebiotics in 
the diet may lead to numerous health benefits. Studies on colorectal carcinoma demonstrated 
that the disease occurs less commonly in people who often eat vegetables and fruit. This 
effect is attributed mostly to inulin and oligofructose. Among the advantages of those 
prebiotics, one may also mention the reduction of the blood LDL (low-density lipoprotein) 
level, stimulation of the immunological system, increased absorbability of calcium, 
maintenance of correct intestinal pH value, low caloric value, and alleviation of symptoms of 
 11 
peptic ulcers and vaginal mycosis (Mojka, 2014). Other effects of inulin and oligofructose on 
human health are: the prevention of carcinogenesis, as well as the support of lactose 
intolerance or dental caries treatment (Jakubczyk and Kosikowska, 2000). Rat studies 
demonstrated that administration of inulin for five weeks caused a significant reduction of 
blood triacylglycerol levels (Socha et al., 2002). Epidemiologic studies suggest that adequate 
fiber intake consistently lowers the risk of CVD and coronary heart disease (CHD), primarily 
through a reduction in low density lipoprotein (LDL) levels. The results of randomized 
clinical trials are inconsistent, but suggest that fiber may play a beneficial role in reducing C-
reactive protein levels, apolipoprotein levels, and blood pressure, all of which are biomarkers 
for heart disease. Water-soluble fibres (specifically, beta-glucan, psyllium, pectin, and guar 
gum) were most effective for lowering serum LDL cholesterol concentrations, without 
affecting high density lipoprotein (HDL) concentrations. In the U.S., there are accepted 
health claims for the ability of oats and barley to lower blood lipids. Other soluble fibres, 
glucans and pectins, have recognized ability to lower blood lipids and the regulations in 
individual countries determine labelling and claims. 
2.2.2 Proteins and Peptides 
Proteins are made up of amino acids joined together in a long chain. Peptides refer to the much 
shorter forms of these amino acid chains. The proteins present in our diet can act as health 
promoters in two ways. Firstly, they can remain in our digestive tracts as indigestible 
substances, responsible for trapping and expelling through stool, toxins and bile. This results 
in a reduction of the possibility of cholesterol being taken up from the large intestine into the 
blood stream. Wheat and soybean proteins are recognized as foods that possess huge amounts 
of insoluble proteins and their continuous ingestion is needed for the maintenance of a clean 
and healthy gastrointestinal tract (GIT).  
Secondly, proteins have the ability to be converted into peptides during digestion from which 
 12 
it is absorbed into the circulatory system. Some of these bioactive peptides, especially those 
found in soybean, have exhibited a competence in the prevention of the production of 
cholesterol by cells of the liver, thereby lowering levels of cholesterol in the blood 
(Brannback et al., 2002). Most bioactive peptides derived from food have so far been isolated 
from dairy products. According to Walther and Sieber (2011), bioactive peptides have been 
reported to be involved in a large number of functions, consisting of antimicrobial and 
antifungal activities, reducing high blood pressures, reducing cholesterol levels, 
antithrombotic effects, and increment of mineral uptake, immunomodulatory effects and 
localized effects on the gastrointestinal tract. Even though much work is yet to be done in the 
field of peptides found in foods, it is evident that the production of bioactive peptides from 
proteins during the normal digestive process is of great importance. It will therefore be of 
importance when assessing the quality of dietary protein to take into consideration the 
potential effects of dormant bioactive peptides that are produced during of the protein 
breakdown in the gut (Inaba et al., 2002, Okamoto et al., 2003). 
2.2.3 Carbohydrates and Fibers 
Carbohydrates are grouped into sugars, oligosaccharides, starches and fibers and are one of the 
three major macro-nutrients, responsible for supplying the body with energy Slavin and 
Carlson (2014). There is now satisfactory proof that almost half of the energy we obtain from 
the foods we eat must be obtained from carbohydrates. Whereas it is crucial to preserve an 
appropriate equilibrium between the impact of carbohydrates on either blood glucose or 
adrenaline levels, and calorie intake and expenditure, research has indicated that a diet 
containing an optimum level of carbohydrates may help to prevent the accumulation of fat in 
the body.  
Starch and sugars provide readily available fuel for physical activity and dietary fibers help 
keep the bowel functioning correctly (Currell and Jeukendrup, 2008). Other than the direct 
 13 
benefits of carbohydrates for the body, they are found in a wide variety of foods which 
themselves contribute a large range of other important nutrients to the diet. For this reason it 
is recommended that carbohydrates be supplied from different food sources to ensure that the 
overall diet contains adequate nutrients WHO, (2002). Fructose oligosaccharide and galactose 
oligosaccharide fortified infant formulas are currently on the market; these are intended to 
support the developing immune systems of neonates (De Vrese and Schrezenmeir, 2008). 
According to Newell-McGloughlin, 2008, Fructans are an important ingredient in functional 
foods because evidence suggests that they promote a healthy colon (as a prebiotic agent) and 
help reduce the incidence of colon cancer.  
Fibre obtained from plant foods such as fruit, vegetables and whole grains is referred to as 
dietary fibre. They play a key role in the preservation of a fully functional digestive system. 
Fiber which is impossible to completely digest is commonly referred to as bulk or roughage. 
The fiber present in foods are of two different types. These consist of soluble and insoluble 
fibres (Sivam et al., 2011). Soluble fiber, which are the type of fibre with the ability to 
solubilize in water, is mostly present in foods like cowpea, fruits and wheat products and have 
the ability to decrease cholesterol in the circulatory system and regulate blood sugar. Insoluble 
fiber cannot dissolve in water, it therefore moves through the gut without being digested. 
Fiber rich foods take longer to digest, and this slow rate of digestion and its movement 
through the gastrointestinal tract regulates blood sugar and provides the feeling of prolonged 
fullness allowing people with obesity problems to control the rate at which they eat, ultimately 
helping them in weight loss and control. 
Fiber is important in the regulation of bowel movement. It also helps keep the gastrointestinal 
tract (GIT) clean and lowers the incidence of diverticulosis and constipation. A high fiber diet 
may reduce the incidence of the development of diabetes and cancers such as those that affect 
the colon and rectum (Dobbing, 1989). It is important to eat plant fibers due to their 
 14 
importance in the preservation of a healthy gastro intestinal tract and the reduction in the 
absorption of sugars mainly glucose into the blood, which can be of importance to diabetic 
patients. Foods containing insoluble fibers such as cellulose and hemicelluloses, include 
wheat, kale, orange fibre peaches and tangerines. They are a source of roughage which aids in 
the reduction of the caloric value of diets. This is very important in obese and diabetic 
patients (Mircea et al., 2009). Soluble fiber such as gums and pectin are abundant in whole 
grain wheat and oats, as well as in fruits such pineapples and lemons; this type of fiber forms 
a viscous insoluble mass in the gastro intestinal tract and helps trap digestive enzymes, 
cholesterol, starch, glucose and toxins that are then expelled through the stool. Because of 
their indigestibility, soluble fiber helps patients suffering from obesity, regulate the total 
amounts of calories they absorb from their food and help diabetics by reducing the rate of starch 
digestion and glucose absorption (F.A.C.S., 2006). Fibers and phytochemicals have for a very 
long time been recognized as the active nutrients responsible for health benefits of fruits and 
vegetables to humans. 
2.2.4 Lipids and Fatty Acids 
Oils obtained from fish have from time in memorial been accepted as a food with functional 
properties due to its capacity to lower high blood pressure and reduce the occurrence of other 
heart related disorders such as irregular heart beat and the obstruction of blood vessels by 
cholesterol. The health-promoting factors found in fish oil has been attributed to the family of 
omega-fatty acids, specifically omega 3 and omega 6 fatty acids. The predominant omega 3 
fatty acids found in fish oil are docosahexaenoic (DHA) and eicosapentaenoic acids (EPA) 
(Shearer et al., 2009). Studies have revealed that, DHA in particular is an important structural 
component of the brain and plays an important role in increased memory functions. Recently, 
increased incorporation of DHA into products such as margarines and baby foods has been 
encouraged to enhance brain memory development; a role in reducing the intensity of 
 15 
Alzheimer's disease. (Brenna, 2002). Linoleic and linolenic acids are other fatty acids which 
have the ability to provide elevated amounts of cardiovascular benefits. They are found in 
large quantities in products such as fish oils, vegetable oils and nuts such as groundnuts and 
cashew nuts. Nut consumption is highly encouraged because, they are loaded with elevated 
amounts of antioxidants that help preserve integrity of organs, blood vessels and genes (Eyres 
et al., 2001). 
2.2.5 Isoprenoids 
Isoprenoids form the largest single family of compounds found in nature with over 24000 
known examples and contain industrially useful compounds such as rubber, flavours, 
antibiotics and plant hormones. They are a large group of natural products, which contain 
tens of thousands of chemicals with diverse functional groups (Cuellar and van der Wielen, 
2015). Most of these compounds have been isolated from eukaryotes such as plants and 
fungi. In plants, isoprenoids range from essential and relatively universal primary 
metabolites, such as sterols, carotenoids, quinones, and hormones, to more unique and 
sometimes species-specific secondary metabolites that may serve roles such as plant defense 
and communication (Lange et al., 2000). Isoprenoids are classified according to the number 
of carbon atoms they contain. Major groups of interest include monoterpenes containing 10 
carbon atoms, sesquiterpenes with 5 carbon atoms, diterpenes with 20 carbon atoms and 
triterpenes with 30 carbon atoms. Many isoprenoids can be found on the global market as 
pharmaceuticals, nutrients, fragrances, flavouring substances, bulk chemicals, and fuels 
(Ajikumar et al., 2008). Several isoprenoids are vitally important in metabolic processes in 
animals. Tetraterpene carotenoid pigments are the source of vitamin A, which is essential for 
vision and is involved in growth, reproductive function, and neural development in animals. 
Other vitamins that are wholly or partly isoprenoid include vitamin E, important in 
reproduction, and vitamin K, necessary for blood- clotting process. The ubiquinones 
 16 
(coenzyme Q), which are involved in the derivation of energy by the oxidation of food, are 
also formed from isoprenoids.  
2.2.6 Phenolic compounds 
There are approximately 300,000 documented species of higher plants on the planet, which 
synthesize an enormous number of chemicals of diverse structure and class. These 
compounds can be further divided into primary and secondary metabolites. Primary 
metabolites include metabolites such as sugars, fatty acids, amino and nucleic acids, as well 
as chemicals considered ubiquitous to all plants for growth and development (Wu and 
Chappell, 2008). Secondary metabolites are structurally and chemically much more diverse 
than the primary metabolites and refer to compounds present in specialised cells that are not 
directly essential for basic photosynthetic or respiratory metabolism but are thought to be 
required for the survival of plants in the environment.  
Phenolic compounds are the most widely distributed secondary metabolites, ubiquitously 
present in the plant kingdom, even if the type of compound present varies according to the 
phylum under consideration. They are possibly the most explored natural compounds due to 
their potential health benefits as demonstrated in a number of studies (Del Rio et al., 2010). 
The generic terms phenolic compounds or polyphenolics refer to over 8000 compounds found 
in the plant kingdom and possessing at least an aromatic ring with one or more hydroxyl 
substituents, including functional derivatives like esters, methyl ethers, glycosides etc. (Ho, 
1992). Organoleptic properties of plant foods (such as fruits, legumes, vegetables and cereals) 
and beverages (such as beer, tea, wine) are all partially ascribed to phenolic compounds. 
Phenolic compounds have varied chemical structures ranging from simple molecules to more 
complex polymerized compounds (Galleano et al., 2010). Phenolics derived from various 
natural sources are linked to antioxidant, anti-inflammatory, anti-allergic, anti-carcinogenic 
anti-hypertensive, cardioprotective, anti-arthritic and antimicrobial activities (Dai and 
 17 
Mumper, 2010).  
Phenolics found in food products can be divided into 3 major groups; simple phenols and 
phenolic acids, hydroxycinnamic acid derivatives and flavonoids (Ho, 1992). Also based on 
the number of carbon atoms present, phenolic compounds commonly found in plants can be 
classified into several groups. Phenolic acids, flavonoids and tannins are considered as the 
main dietary phenolics (Balasundram et al., 2006). Flavonoids constitute the largest group of 
low-molecular weight plant phenolics and have been studied extensively. Phenolic acids are 
significant components of fruits and vegetables. These compounds play an important role in 
colour stability, aroma profile and antioxidant activity. Tannins are the third important group 
of polyphenolics which can further be divided into two subcategories: condensed and 
hydrolysable tannins. Fruits, grains and legumes consist of condensed tannins which are 
mainly polymers of catechins and epicatechins. Hydrolysable tannins are polymers of gallic 
or ellagic acids and are found in berries and nuts (King and Young, 1999). 
Numerous studies have been undertaken to determine the potential health benefits of plant 
polyphenolics. The potent antioxidative properties of plant phenols have been scientifically 
proven to prevent various oxidative stress-related chronic diseases such as cancer, 
cardiovascular and neurodegenerative diseases.  
2.2.7 Alkaloids 
Alkaloids are a highly diverse group of compounds that contain a ring structure and a 
nitrogen atom. In most cases, the nitrogen atom is located inside the heterocyclic ring 
structure.  Alkaloids are a group of naturally occurring chemical compounds that contains 
mostly basic nitrogen atoms. This group also includes some related compounds with neutral 
(McNaught and Wilkinson, 1997) and even weakly acidic properties. Alkaloids are produced 
by a large variety of organisms which includes bacteria, fungi, plants and animals.  
They rank among the most diverse, efficient and therapeutically significant plant substances. 
 18 
There are around 5,500 alkaloids known presently. The name alkaloids is derived from the 
word ―alkaline‖ and it was used to describe any nitrogen-containing base.  
The presence of alkaloids and other secondary metabolites in plants enhances plant 
reproductive rates, either by improving defenses against biotic and abiotic stresses or by 
affecting pollinators and seed/fruit disperser visitation. Defensive strategies include predator 
repellence by toxicity or bitterness taste or damage repair by antioxidant system (Vilariño and 
Ravetta 2008; Matsuura and Fett-Neto 2013). Alkaloids are known to have muscle relaxant 
property. D-tubocurarine is one such example that possesses the antiparalytic activity due to 
its ability to obstruct the acetycholine receptor spots which enable the muscles to unwind at 
neuromuscular intersections (Das et al., 1997). Alkaloids are known to possess antioxidant 
activities due to their ability to act as scavenger of free radicals, metal chelating activity or 
electron or hydrogen donation ability. 
2.2.8 Flavonoids 
Flavonoids are a diverse group of plant metabolites with over 10,000 compounds that have 
been identified until now. They have several important functions in plants, such as providing 
protection against harmful UV radiation or plant pigmentation. In addition, they have 
antioxidant, antiviral and antibacterial properties. They also regulate gene expression and 
modulate enzymatic action (Pollastri and Tattini, 2011). All naturally occurring flavonoids 
possess three hydroxyl groups, two of which are on the ring A at positions five and seven, 
and one is located on the ring B, position three. Biochemical actions of flavonoids depend on 
the presence and position of various substituent groups that affect metabolism of each 
compound. They can be found in free or bound forms: aglycones or β-glycosides (Majewska 
and Czeczot 2009). The flavonoid subclasses, based on types of chemical structure, include: 
flavonols, flavones, flavanones, flavanols, anthocyanins and isoflavones (Małolepsza and 
Urbanek, 2000).The major active nutraceutical ingredients in plants are flavonoids. As is 
 19 
typical for phenolic compounds, they can act as potent antioxidants and metal chelators. The 
flavones and catechins seem to be the most powerful flavonoids for protecting the body 
against reactive oxygen species (ROS). Body cells and tissues are continuously threatened by 
the damage caused by free radicals and ROS which are produced during normal oxygen 
metabolism or are induced by exogeneous damage (Duthie and Morrice, 2012). The 
scavenging activity of flavonoids has been reported to be in the order: Myrcetin > quercetin > 
rhamnetin > morin > diosmetin > naringenin > apigenin > catechin > 5,7-dihydroxy-3‘,4‘,5‘-
trimethoxy-flavone > robinin > kaempferol > flavone (Majewska and Czeczot, 2009). 
They also have long been recognized to possess anti-inflammatory, antiallergic, 
hepatoprotective, antithrombotic, antiviral, and anticarcinogenic activities. The well-
recognised anti-oxidant properties of flavonoids resulted in the interest about their potential 
role in prevention of cardiovascular diseases (Majewska-Wierzbicka and Czeczot, 2012). A 
recent study clearly showed health benefits of dietary flavonoids as there was a positive 
association between their intake and reduction of the risk of cardiovascular death in adult 
Americans (McCullough et al 2012). The study demonstrated that both male and female 
subjects who consume large amounts of flavonoids (the top quintile) had the 18% lower 
mortality risk of cardiovascular diseases (CVD) compared to those whose intake was in the 
lowest quintile. 
Antibacterial activity has been displayed by a number of flavonoids. Quercetin has been 
reported to completely inhibit the growth of Staphylococcus aureus. Most of the flavonones 
having no sugar moiety showed antimicrobial activities whereas none of the flavonols and 
flavonolignans tested showed inhibitory activity on microorganisms (Havasteen, 1983). A 
number of flavonoids isolated from the peelings of tangerine orange, when tested for 
fungistatic activity towards Deuterophoma tracheiphila were found to be active; nobiletin and 
langeritin exhibited strong and weak activities, respectively, while hesperidin could stimulate 
 20 
fungal growth slightly. Naturally occurring flavonoids with antiviral activity have been 
recognized since the 1940s but only recently have attempts been made to make synthetic 
modifications of natural compounds to improve antiviral activity. Quercetin, morin, rutin, 
dihydroquercetin (taxifolin), apigenin, catechin, and hesperidine have been reported to 
possess antiviral activity against some of the 11 types of viruses (Selway, 1986). The antiviral 
activity appears to be associated with the nonglycosidic compounds, and hydroxylation at the 
3-position is apparently a prerequisite for antiviral activity. 
Flavonoids, especially quercetin, has been reported to possess antidiabetic activity. Vessal et 
al (2003) reported that quercetin brings about the regeneration of pancreatic islets and 
proprably increases insulin release in strptozotocin-induced diabetic rats. Also in another 
2+
study, Hif and Howell reported that quercetin stimulate insulin release and enhanced Ca  
uptake from isolated islets cell which suggest a place for flavonoids in non-insulin-dependent 
diabetes (Hif and Howell , 1984, 1985). 
Effectiveness of flavonoids in prevention of age--related neurodegenerative diseases has been 
much investigated in the recent years. It concerns particularly dementia, Parkinson‘s and 
Alzheimer‘s diseases. It seems that flavonoids can modulate neuronal function (Macready et 
al., 2009, Prasain et al., 2010). Diets rich in these substances were shown to beneficially 
affect maintenance of human cognitive functions, probably through protection of neurons, 
enhancement of their function and regeneration (Youdim and Joseph, 2001). Reactive oxygen 
and nitrogen species are involved in the development of many neurodegenerative diseases, 
whilst dietary flavonoids have been shown to counteract effectively oxidative neuronal 
damage.  
Flavonoids are ubiquitous in plant foods and drinks and, therefore, a significant quantity is 
consumed in our daily diet. The toxicity of flavonoids is very low in animals. For rats, the 
LD50 is 2-10 g per animal for most flavonoids. Similar doses in humans are quite unrealistic. 
 21 
As a precaution, doses less than 1mg per adult per day have been recommended for humans 
(Starvic, 1984). Dunnick and Hailey (1992) reported that high doses of quercetin over several 
years might result in the formation of tumors in mice. However, in other long-term studies, 
no carcinogenicity was found. 
2.2.9 Saponins 
Saponins are bioactive compounds produced mainly by plants, but also by some marine 
organisms and insects. Chemically, they generally occur as glycosides of steroids or 
polycyclic triterpenes (Kensil, 1996).They are one of many secondary metabolites found in 
natural sources, with saponins found in particular abundance in various plant species. More 
specifically, they are amphipathic glycosides grouped in terms of phenomenology, by the 
soap-like foaming they produce when shaken in aqueous solutions, and, in terms of structure, 
by their composition of one or more hydrophilic glycoside moieties combined with a 
lipophilic triterpene derivative (Hanausek et al., 2001). Saponins have a range of properties 
due to their extensive structural diversity, which includes certain features, bitter sweeteners, 
detergents and emulsifying properties, in addition to the biological, medical and 
pharmacological properties, such as haemolytic activity, antimicrobial, insecticides and 
molluscicides. Also noteworthy are the applications in pharmaceutical industries as raw 
material for the synthesis of steroidal drugs such as birth control, besides the intense use in 
the cosmetic industry (Vincken et al., 2007). They have many medicinal uses including, 
microbial, anti-tumor, anti-insect (Hostettmann and Marston, 1995) hepatoprotective, 
haemolytic (Zhou et al., 2011), and anti-inflammatory activities. They also decrease blood 
cholesterol level and may be used as adjuvant in vaccines. Saponins are effective in 
maintaining liver function, lowering blood cholesterol, preventing peptic ulcer, osteoporosis 
as well as platelet agglutination (Liby et al., 2008). The beneficial effects of saponins have 
been applied commercially in drugs and medicines, emulsifiers, adjuvants, taste modifiers, 
 22 
sweeteners and precursors of hormone synthesis (Hanausek et al., 2001). 
Su et al. (2011), investigated antitumor activity of polysaccharides and saponin extracted 
from sea cucumber. These results indicated that the in vitro anti-tumor effect of saponins is 
more potent than polysaccharides (Liby et al., 2008). Several reports have demonstrated that 
plant saponins can reduce the risk of colorectal cancer. It has been reported that ingestion of 
saponin containing food decreases cholesterol levels in the bloodstream and as a result 
decreases the risk of cardiovascular diseases. It was also, reported that ginseng saponins 
decrease blood cholesterol levels in rabbits by increasing cholesterol excretion through bile 
acid formation (Kang et al., 2011) .Elekofehinti et al. in 2012 showed that consumption of 
saponin from Solanum anguivi fruit lead to reduction in the risk of hyperlipidemic symptoms 
and heart diseases (Liu et al., 1993 )   
2.3 Free radicals and Antioxidant activity in foods 
Plants are able to produce a large number of diverse bioactive compounds. High 
concentrations of phytochemicals, which may protect against free radical damage, 
accumulate in fruits and vegetables. These phytochemicals may act as natural antioxidants in 
the human body (Altemimi et al., 2017). Vast amounts of different foods such as vegetables, 
fruits, mushrooms and herbs, are usually eaten for their nutritional and or their therapeutic 
benefits. In recent times, examination of these foods have shown to bear important 
antioxidants of high nutritive and medicinal values. 
Antioxidants are substances which when examined with those of an oxidizable substrate 
prevents or delays to a large extent the oxidation of that substrate (Halliwell and Gutteridge, 
1989). Antioxidants possess the ability to prevent or reduce the impact of destruction such as 
lipid peroxidation, oxidative damage to cells, glycation of proteins and demobilization of 
enzymes caused by free radicals. Abundant evidence has revealed that oxidative stress that 
occurs as a result of the work of reactive oxygen species (ROS), which include free radicals 
 23 
are involved in important roles in the advancement of many medical conditions. These have 
been linked in the aetiology of medical conditions related to cardiovascular diseases, 
diabetes, inflammatory diseases, cancer, Alzheimer and Parkinson‘s disease, monogolism, 
ageing process and maybe dementia (Amin et.al., 2004). Although free radicals and other 
ROS are produced regularly within our cells during normal cell activity, examples of which 
includes energy synthesis in the mitochondria electron transport chain, ovulation, 
fertilization, and in xenobiotic metabolism (Halliwell and Gutteridge, 2007), free radicals can 
also be found outside the body in extraneous environments, examples of which include food 
products, medications, fumes from fires and cigarettes and many more environmental 
pollutants. Organisms have internal and external antioxidant defensive mechanisms that fight 
or resist reactions of free radicals. According to Ames et al., (1993), the body‘s production of 
free radicals beyond its antioxidant scavenging ability results in oxidative stress. A connection 
has been established between these free radicals and aetiology of several disease causing 
conditions such as lipid peroxidation, protein oxidation, and DNA destruction. As a result, a 
lot of attention is being placed on the use of antioxidants especially naturally occurring ones 
as a medium of inhibiting and protecting damage resulting from free radicals and reactive 
oxygen species. The interest in natural antioxidants has increased over that of artificial ones, 
due to the possibility that the activity of artificial antioxidants may act as boosters for the 
occurrence of cancers. Epidemiological studies have established that vegetables and fruits 
possess compounds that have the capacity to protect the human body from oxidative damage 
by inhibiting or assuaging the effects of free radicals and reactive oxygen species, when 
eaten. Many plants including fruits and vegetables are acknowledged as good sources of 
naturally occurring antioxidants that can protect the body from oxidative stress and thereby 
play a cardinal role in the chemoprevention of diseases that have their root and pathophysiology 
in reactive oxygen species (Odukoya et al., 2001, Atawodi 2005). These positive impacts are 
 24 
believed to be creditable to the antioxidants; especially the carotenoids, flavonoids, lycopene, 
phenolics and β-carotene present in these foods (Amin et al., 2004). 
2.3.1 Antioxidant and nutraceutical properties of some green leafy vegetables 
2.3.1.1 Bitter leaf (Vernonia amygdalina) 
Vernonia amygdalina is a green leafy vegetable belonging to the Asteraceae family. It is 
commonly referred to as bitter leaf in the English language. It is also known as ‗awonyono‘ 
in the Akan language, and ‗ewuro‘ in the Yoruba language. They have green leaves with a 
distinct odour and bitter taste (Akpaso et al., 2011). They are found mostly in tropical parts of 
Africa and Asia. They grow mostly around sewage systems and in forest areas or on farms. In 
most parts of the African continent, the bitter leaf is used in the preparation of soups after 
they have been thoroughly washed or boiled to get rid of their peculiar bitter taste. It is 
specifically used in the preparation of the popular Nigerian bitter leaf soup, ―onugbo‖ and used 
in the preparation of a Cameroonian dish known as ―Ndole‖. Bitter leaf has long been used in 
traditional folk medicine, particularly in sub Saharan Africa. This has required that a large 
amount of research be conducted to test the effectiveness of different parts of the plant in the 
management of a wide variety of disorders (Huffman and Seidu (1989), Yeap et al., (2010)). 
The entire plant for example, is used as a deworming agent, in the treatment of malaria, and 
in the prevention of constipation. Some people employ the use of the aqueous extract of the 
bitter leaf as a tonic to aid in digestion, an appetizer and also in the treatment of wounds. The 
leaf extract is also used to treat coughs in some parts of sub Saharan Africa (Ijeh et al., 2011). 
In Ethiopia, the leaf is used as hops in beer preparation. Traditional birth attendants in 
Malawi and Uganda use it as an aid for the removal of placenta after childbirth, assist in post-
partum uterine contraction, induce lactation and control postpartum bleeding. Different 
extracts of Vernonia amygdalina (bitter leaf) have been satisfactorily expressed to possess 
antioxidative characteristics both invitro and invivo. Ayoola et al., (2008) investigated the 
 25 
invitro antioxidative characteristics of the ethanolic leaf extract of bitter leaf using 2,2-
diphenyl-1- picrylhydrazyl (DPHH) radical. This plant contains naturally occurring 
antioxidants that fight against aqueous radicals and reactive species ions. Bitter leaf has been 
used in different parts of our continent in curing a diverse number of diseases including 
diabetes, malaria, and cancer. It also provides the body with general wellbeing. These folk 
remedies have in recent times been supported with scientific proof. 
2.3.1.2 Water Leaf (Talinum triangulare) 
Water leaf is an herbaceous annual plant which grows widely in tropical regions as a leafy 
vegetable. It is consumed mainly as a leafy vegetable and is used in the preparation of sauces 
and soups. It is a good source of several nutrients such as calcium, magnesium, vitamin C and 
pyridoxine (Oguntona, 1998). Research conducted by Ogodie-Oda and Oluowo (2009), 
revealed that extracts from the roots and leaves of water leaf is used to cure asthma. Another 
effective use of the plant is in the use as a diuretic (Mensah et al, 2008). Phytochemicals 
present in water leaf include carotenoids (Ogbonnaya and Chinnedum, 2013) and alkaloids, 
flavonoids, saponins and tannins which can found in the leaves (Aja et al., 2010).  Medically, 
water leaf has been linked to the regulation of cardiovascular diseases (Adewunmi and 
Sofowara, 1980). 
2.3.1.3 Kale (Brassica oleraceae L. var. acephala DC.) 
Kale are cabbage-like plants native to the eastern Mediterranean or to Asia Minor. Their wild 
forms have become widely distributed from their place of origin and are found on the coasts 
of northern Europe and Britain.  Kale is vegetable crop with high biological, nutritional and 
health values. Kale is considered as one of the highest-quality brassicas in terms of chemical 
composition. Younger and tenderer leaves of kale are used for human consumption and older 
leaves as fodder crop (Cartea et al., 2002). Kale has a long tradition of cultivation and has an 
important place in the diet of the population in the northern parts of Turkey (Ayaz et al., 
 26 
2006), on the Pyrenean Peninsula (Velasco et al., 2007), southeast of the USA (Olson and 
Freeman, 2007), and insular and coastal parts of Croatia (Batelja et al., 2009). Compared to 
other types of vegetables, kale has a higher content of beta carotene and lutein (USDA, 
2002). Kale leaves are rich in amino acids (Lisiewska et al., 2008). In recent years, kale has 
gained the attention of the scientific community due to its high content of bioactive 
compounds such as vitamin C, provitamin A, glucosinolates, phenolic antioxidants, dietary 
fiber, micronutrients (iron, zinc and manganese) and macronutrients (calcium and 
magnesium) (Ayaz et al., 2006). Likewise, in vitro and in vivo studies suggest that kale has a 
positive impact on the prevention of chronic diseases such as cardiovascular diseases 
(Kahlon, Chapman, & Smith, 2007; Kim et al., 2008).  
2.3.1.4 Spinach (Spinacia oleracea) 
Spinach is an edible flowering plant in the family Amaranthaceae. Spinach has a high 
nutritional value. It is a rich source of vitamin A, vitamin C, vitamin K, magnesium, 
manganese, folate and iron. The nutritional value of spinach indicates it to be a very nutrient-
dense food. It is low in calories yet very high in vitamins, minerals, and other phytonutrients. 
Spinach is also packed with a number of anti-oxidants like polyphenols, flavonoids and 
carotenoids, which are shown to possess anti-inflammatory effects, anti-mutagenic potential, 
anti-neoplastic effects as well as chemo-preventive activities (Boivin et al., 2009; Hait-
Darshan et al., 2009).  
2.3.1.5 Dandelion greens (Taraxacum officinale) 
Dandelion, a member of the Asteraceae family (Damylo et al.,1984) , commonly found in the 
temperate zone of the Northern hemisphere (Ali, 1989), is a herb that grows to a height of 
about 12 inches, producing spatula-like leaves and yellow flowers that bloom year round. 
Dandelion is used in many traditional and modern herbal medical systems, as particularly has 
been documented in Asia, Europe, and North America. Dandelion is grown commercially in 
 27 
the United States and Europe.The leaves and roots are used in herbal medicine. It is 
commonly used as a food.  It is used for treatment of jaundice and disorders of the liver, 
gallbladder and other various hepatic ailments (You et al., 2010; Ahmed et al., 2013). The 
folk medicines of China, India, and Russia have recognized dandelion‘s effect as a liver 
tonic. Traditional Chinese medicine combines dandelion with other herbs to treat hepatitis 
(Modaresi, 2012). It has been reported to be used for the treatment of various ailments, 
including liver and gallbladder disorders. It is used to enhance the immune response to upper 
respiratory tract infections, bronchitis and pneumonia, and as a topical compress to treat 
mastitis, anemia and inflammation (Blumental et al. 2000). Wolbis et al., 1993 carried out an 
analysis in which he mentioned and isolated various polyphenolic compounds from T. 
officinale plant extracts thereby showing that the plant is rich in various antioxidants and can 
have a direct effect of these phytochemicals on health of an organism. Cinnamic acid, 
coumarins and flavonoids and other phytochemicals bearing important medicinal and 
therapeutic importance have been isolated from different tissue of T. officinale plant by 
various analytical methods by Williams et al., (1996). Modern pharmacological research 
suggests this plant has broad-spectrum antibacterial (Woods-Panzaru et al., 2009), anti-fungal 
(Odintsova et al., 2010), antiviral, antidiabetic, choleretic, antirheumatic, anti-inflammatory 
(Koh et al., 2010), hepatoprotective, diuretic, and tumor apoptosis-inducing properties 
(Schutz et al., 2006). 
2.3.1.6 Broccoli (Brassica oleracea) 
Broccoli (Brassica oleracea) is a plant from the Brassicaceae family. It has been stated that 
plants from the Brassica genus have been cultivated for over 2,500 years, though the varieties 
of broccoli that we know today may have been developed from selections made in Italy in the 
last 2,000 years (Buck, 1956). Broccoli is an excellent source of bioactive compounds, and 
thus, it is considered a functional food. Phenolic compounds are among the nutraceuticals 
 28 
present in broccoli, mainly hydroxycinnamic acids and flavonoids (Vallejo et al., 2003). It 
has been shown that these compounds possess a great antioxidant activity and may play a role 
in the prevention of several diseases, such as diabetes (Balasubashini et al., 2004), 
cardiovascular diseases (Rodríguez-Cantú et al., 2004), and neurodegenerative diseases 
(Kanski et al., 2001; Kim et al., 2005). Additionally, broccoli contains high concentrations of 
vitamin C, an essential nutrient. Vitamin C is a hydrosoluble vitamin necessary for a normal 
development and it is used for wound healing, repairing of cartilage and bones, and collagen 
synthesis, an essential protein found on skin and ligaments (Iqbal et al., 2004). Moreover, 
vitamin C may act as a potent antioxidant, helping to prevent atherosclerosis and cancer 
(Padayatty et al. 2003). Carotenoids can also be found in broccoli (Villareal-Garcia et al. 
2015, Alanis- Garza 2015). Lutein, a carotenoid of the xanthophylls group, is one of the most 
abundant carotenoids present in broccoli. It is present throughout the retina, and it has been 
reported that it protects the eye by filtering hazardous light, preventing age-related macular 
degeneration and cataracts (Krinsky et al. 2003). Besides, previous studies have shown that 
lutein exhibits chemo protective activity against different types of cancer (Kim et al., 1998, 
González et al., 2003). 
2.3.1.7 Cocoyam leaves (Colocasia esculenta) 
Cocoyam is a starchy edible tuber and bears broad greenish leaves. It is grown in several 
places around the world. Its roots tubers or  leaves, locally called kontomire are the parts 
usually consumed. Both the root and leaves have many health benefits for the body because 
they are rich in nutrients. One cup of cocoyam leaves contains about 145mg of Vitamin C, 
about 86% of our body‘s daily requirement. This will help boost your immune system 
effectively. Cocoyam leaves are rich in vitamin C which acts as an antioxidant. This fights 
against free radicals that cause cancer. Cocoyam leaves are rich in vitamin A in addition to 
the vitamin C (Onwueme, 1994). The amount of vitamin A can be as high as 123% of our 
 29 
daily requirement. It is very good for eyes to stay healthy, maintain the visual acuity, and 
prevent the eyes diseases such as myopia, cataract and blindness. The high dietary fibre in 
cocoyam leaves helps in food digestion and absorption. Cocoyam leaves can prevent 
digestive problems such as indigestion, constipation, and diarrhoea. Cocoyam leaves have no 
cholesterol and only 1% of total fat, and so, is one of the best diets for reducing cholesterol. 
The dietary fibre and methionine contained in cocoyam leaves can reduce the cholesterol 
effectively. They bind and break down fat and cholesterol especially triglyceride. Cocoyam 
leaves are low in fat and high in protein as well as contain Omega 3 fatty acids which play a 
role in inflammation process and can inhibit the release of inflammatory substances. It can 
help to treat diseases like arthritis, gastritis, or lupus disease. 
The vitamin B complex including thiamin, riboflavin, niacin, and vitamin B6 in cocoyam 
leaves protect the nervous system. They also boost the immune system.The Omega 3, and 
essential fatty acid, help produce hormones to control the contraction and relaxation of 
arterial walls. Besides its rich nutrients content, the leaves also contain folate which is 
essential for the development of fetal brain and nervous system. It is, therefore, good for 
pregnant women to consume cocoyam leaves when pregnant. A cocoyam leaf diet is 
recommended in the prevention of anaemia. This is because they contain iron mineral which 
helps in red blood cell formation. The vitamin C content additionally helps in maximum 
absorption of the iron.  
The consumption cocoyam leaves help to prevent preeclampsia (a pregnancy complication 
characterised by high blood pressure and signs of damage to another organ system, often the 
kidneys) during pregnancy. The magnesium mineral helps in muscle relaxation and can be 
used to prevent preeclampsia. They contain the amino acid called threonine. The threonine 
helps in the formation of elastin and collagen which are good for the healthy skin. They 
prevent the skin from wrinkles and rejuvenate skin. 
 30 
Cocoyam leaves present one of the best energy sources for the body through its essential 
amino acid called isoleucine. This protein regulates the blood sugar and increases the muscle 
strength and energy levels. Cocoyam leaves release dopamine (a monoamine 
neurotransmitter found in the brain and essential for the normal functioning of the central 
nervous system) which acts in the brain and nervous system. Synthesized by phenylalanine, it 
enhances your brain memory and controls your mood. 
Cocoyam leaves contain tyrosine, a crucial amino acid in the human body. It becomes an 
adaptogen substance which helps to minimize the effect of nicotine, cocaine, and coffee 
addiction. Histidine, one of the essential amino acids is also contained in cocoyam leaves. It 
serves as a detoxification agent that helps to remove the heavy metals from the body and 
protect the body from damage from radiation. 
2.3.1.8 Eggplant (Solanum macrocarpon) leaves  
S. macrocarpon is a vegetable commonly called ―Gboma‖ in the local language of the Ewe 
people of Ghana. It is a plant of the family Solanaceae like tomato and pepper. The leaves 
and young fruits are prepared and eaten as a vegetable (Sodipo et al, 2012). The leaves 
constitute an important part of the diet because they are considered to be of high nutritional 
value and, therefore, used in the preparation of soups and stews. The leaves are rich in 
protein, fat, crude fibre, calcium, and zinc and are found to contain appreciable amounts of 
the sulphur-containing amino acid methionine (Sodipo et al, 2008). Several research results 
have revealed anti-inflammatory, antiasthmatic, antiglaucoma, hypoglycemic, hypolipidemic, 
and weight reduction effects of this green leafy vegetable (Dougnon et al 2012). These 
pharmacological properties have been attributed to the presence of certain chemical 
substances in the plants, such as polyphenols. Phytochemical studies of S. macrocarpon 
leaves showed that the leaves contained appreciable quantities of polyphenols, especially the 
flavonoids, which could contribute to strong antioxidant properties. 
 31 
2.3.1.9 Amaranthus leaves  
Amaranthus is highly nutritious. It is an annual, upright, tall and broad leafed plant. 
Amaranth species have huge number of varieties. The greens are edible leafy vegetables and 
nutritious. The leaves are utilized for human as well as for animal food (Tucker, 1986). The 
species vary slightly in their nutritional value and chemical composition. The nutritional 
value of amaranth has been extensively studied (Martirosyan, 2001 and 2003). It has been 
shown that amaranth leaves are excellent sources of protein, with its maximal accumulation 
in the blossoming phase (Kadoshnikov et al., 2005). They are regarded as storehouse of 
phytonutrients as well as antioxidants which assist to lower inflammation in the body and 
boost nutrition to maintain overall health. The leaves have adequate soluble and insoluble 
fiber that offers various health benefits. Its intake helps to lower weight and hinder heart 
disease as it reduces cholesterol in blood. Nutritionists recommend to intake high dose of 
amaranth leaves in diet for managing weight and high blood pressure. They possess a high 
content of vitamin C. A serving of 100 grams offers 70% of daily requirement of Vitamin C, 
a water soluble vitamin required to comb at infections and speeds up healing process. It also 
lowers the effect of free radicals in environment that results in aging and cancer. 
2.3.2 Antioxidant and nutraceutical properties of some herbs 
2.3.2.1 Basil (Ocimum and Gratissimum) 
There are about 50 different species of the genus ocimum on the continent of Africa alone. 
Ocimum basilicum and Ocimum gratissimum are the two species known on the African 
continent to be used in the management of several different ailments. They are in the family of 
the herbaceous plant, Lamiaceae. This herb is locally referred to as ‗nunum‘ among the Akan 
people of Ghana, ‗Efirin‘ in Yoruba and ‗ai-doya ta gida‘ in Hausa. They have a characteristic 
pleasant aroma due to the presence of volatile oils (Mindel et al., 1992). The leaf of Ocimum 
gratissimum, or the whole plant is popularly used in the treatment of diarrhea (Dalziel 1956). 
 32 
The plant is heavily imbued with volatile oils, containing about 75% of thymol, whose 
antimicrobial properties is widely known. In fact, evidence exists to prove that the 
antimicrobial properties of the water-saturated oil is proportionate to the amount of thymol 
present (Said et al., 1969). Ocimum gratissimum has shown an effectiveness in the treatment 
of infections occurring in the upper respiratory tract, headaches, diarrhea, skin diseases, fever, 
conjunctivitis and pneumonia, (Onajobi 1989). Ocimum basilicum is used in traditional folk 
medicine in the treatment of various ailments, such as headaches, coughs, diarrhea, warts, 
constipation, worms and kidney malfunction. It is used in chicken and meat dishes for 
seasoning and for flavouring soups and stews. It is also thought to be an antispasmodic, 
stomachicum, carminative, antimalarial, febrifuge and stimulant (Wome 1982). 
2.3.2.2 Lemongrass (Cymbopogan citratus) 
Commonly found in Asia, Africa, Australia and Tropical islands, is an aromatic perennial tall 
grass with rhizomes and densely tufted fibrous roots. Lemongrass is grown for its medicinal 
and culinary purposes due to their peculiar lemon-like smell hence their name. They are of 
the poaceae family. Lemongrass is an important herb with over 120 species which grows in 
tropical and subtropical regions all over the world (Dutta et al., (2014). According to 
Jagadish, (1975), of the 120 species of lemongrass, 45 species natively belong to India alone. 
Cymbopogan species contain an abundance of essential oils in monoterpenes such as citral, 
citronellal, citronellol, linalool, elemol, 1,8-cineolo,limonene, geraniol, methyl heptenone, 
geranyl acetate, and geranyl formate (Ganjewala et al., (2008). Studies conducted by 
Oloyede, (2009) and Preira et al., (2009), revealed that, lemongrass leaf extracts contained 
antioxidant, antifungal and antimicrobial compounds. In traditional folk medicine, 
lemongrass is mostly employed in the treatment problems related to the GIT and the nervous 
system. Lemongrass oil, has antispasmodic, analgesic, anti-inflammatory, anti-pyretic, 
diuretic and sedative properties (Santin et al., (2009). 
 33 
2.3.2.3 Rosemary (Rosmarinus Officinalis) 
This herb is one of the world‘s most popular cooking herb, found in most kitchens the world 
over. It is a perennial herb belonging to the Lamiaceae family. It can be used in both its fresh 
and dried states. Rosemary can be employed in a variety of ways. Some of these includes 
sauces and stews, as a marinade, as a tea in small amounts, and its extracts as an antioxidant 
to increase the shelf life of foods. It is employed in various traditional folk remedies. Among 
its pharmacological validated medicinal uses are, its use as an antibacterial, anticancer, 
antidiabetic, and anti-inflammatory agent (Bozin et al., (2007), Cheung and Tai (2007) and 
Yesil-Celiktas et al., (2010)). The ability of rosemary to play diverse roles in both culinary 
and medicinal uses is as a result of a vast number of plant secondary metabolites such as 
camphene, borneol, 1,8-cineole present in it (Atti-Santos et al., 2002). Another group of 
secondary metabolites present in rosemary are, polyphenolic compounds such flavonoids and 
phenolic acid derivatives like rosmarinic acid (Bai et al., (2010)).  
2.3.2.4 Bay Leaf (Laurus nobilis L.) 
Bay leaf belongs to the laureacea family. It is native to warm Mediterranean regions like 
France, Italy, Portugal and Spain. It‘s most common culinary uses include spicing and 
flavouring meat dishes, stews and rice (Camejo-Rodrigues et al., 2003). Folk medicine 
application of bay leaf include the use of its dry leaf infusions to combat gastric diseases and 
as carminative and stomachic remedies (Afifi et al., 1997; Dall‘Acqua et al., 2009). Its leaves 
and extracts are used to suppress high blood sugar, fungal and bacterial infections, to treat 
eructation, flatulence and gastrointestinal problems. It also exhibits anti-inflammatory, 
anticonvulsive, antiepileptic and antioxidant properties (Ferreira et al., 2006). Its ability to 
serve in this wide capacity of medicinal uses is as a result of the presence of compounds such 
as α-limonene, β-linanol, 3-carene, delta cadinene, quercetin, kaemferol and luteolin. 
 
 34 
2.3.3 Antioxidant and nutraceutical properties of some spices 
2.3.3.1 Cloves (Eugenia caryophyllata) 
Cloves have been scientifically proven to bear antibacterial agents and as such is seen to be 
widely used in various dental creams, toothpastes, mouth washes, and throat sprays to get rid 
of harmful and disease causing microorganisms. It is also used to alleviate pain that occurs in 
the gums and maximise overall dental health. They are sometimes used as an aphrodisiac and 
are also in other instances used as an anti-inflammatory agent. This property of cloves is due 
to their high flavonoid content. Their pure oils are used to cure the symptoms of chronic 
aches in the body and in joints. Cloves are employed as a carminatives to increase HCL 
content in the stomach and to improve movement of food in the GIT. Cloves possess strong 
antioxidative properties, which can be compared to the activities of synthetic BHA (butylated 
hydroxyl anisole) and Pyrogallol (Dorman et al., 2000). 
2.3.3.2 Alligator pepper (Aframomum melegueta) 
Aframomum melegueta (Alligator pepper) is a plant with both nutritive and medicinal values. 
It is commonly found in the rain forest region of tropical West African countries such as 
Ghana and Nigeria (Agoha 1974). Its seeds are commonly used in flavoring food in Eastern 
Nigeria (Okwu 2005). It is used in alcoholic beverages, medicine for intermittent fevers, 
dysentery and gastrointestinal problems (Agoha 1974; Okwu 2005). The seeds are used to 
spice up food and wine (Enwere 1998). The seeds have a spicy, hot and slightly bitter taste, 
due to the presence of a volatile oil. It contains hydroarylalkanone and acetone extracts 
(Okwu 2005). The constituents present in alligator pepper consist of essential oils, paradol, 
resin, and tannins (Gill 1992). Alligator pepper is extensively used as a common ingredient of 
traditional folk medicine. It is generally used as a stimulant and is usually used to lower body 
temperatures to alleviate fevers (Gill 1992). 
 
 35 
2.3.3.3 Ashanti black pepper (Piper guineense) 
Piper guineense commonly referred to as the Ashanti black pepper, grows as a climber. It is a 
slender climber with prominent nodes, common in forest areas. The fruits occur in clusters of 
small, reddish or reddish brown berries when ripe and blacken when dried (Agoha 1974). 
They are commonly found in the Southern part of Nigeria and the forest areas of Ghana and 
other sub Saharan African countries (Okwute 1992). The black berries are used as a spice in 
food and various local drinks. It was reported by Addae Mensah et al. (1977), Oliver (1986), 
Okwute (1992), and Okwu (2001) that the bioactive constituents comprising of piprine, amide 
alkaloids (terpenes) and dihydropiperine have effective physiological effects when 
administered to animals. The piprine and alkaloids phytoconstituents also have anti-microbial, 
anticonvulsant, antihypertensive, sedative, tranquilizing and insecticidal properties (Oliver 
1986; Okwute 1992; Okwu 2001). P. guineense seeds are used not only to relieve pain from 
gripping conditions of the stomach after childbirth but also to restore the uterus to its normal 
state (Ojimelukwe et al. 2000; Okwu (2001). P guineense is used extensively in foods meant 
for nursing mothers. The fruits are also used to spice up or flavour all kinds of foods such as 
soups, rice and stews. 
2.3.3.4 Fruit of Tetrapleura tetraptera 
T. tetraptera contains compounds like resins, carbohydrates, fats, colouring matter and fatty 
acids (Okwu 2001). A scientific study of the fruits of T. tetraptera showed the presence of 
oleanic acid, triglycoside and scoplatin, a coumarin (Okwu 2001, 2005). The presence of 
coumarin is most likely responsible for the unique aroma the fruits often impart in food and 
its ability to serve as a possible condiment in soups (Okwu 2001, 2006). In Nigeria, the fruits 
of T. tetraptera are used in traditional folk medicine for the treatment of infertility in women 
(Igoli et al., 2005). In some West African countries the infusion of fruits of T. tetraptera, is 
used to treat and reduce the risk of certain cardiovascular conditions such as hypertension. 
 36 
The fruit is often reduced to a powder and added to soups and sauces.  
2.3.3.5 Calabash nutmeg (Monodora myristica) 
Phytochemical screening of M. myristica revealed the presence of alkaloids, tannins, general 
glycosides, steroids, terpenoids and saponins (Firempong et al., 2016). Alkaloids have been 
reported to bear the most effective medicinally important phytochemical (Njoku and 
Akumfela 2007). Their pain relieving, antispasmodic and bacterial properties have been 
reported and are widely used as cancer chemotherapeutic agents. An analysis on 
phytochemical properties established that Monodora myristica has high levels of glycosides, 
flavonoids, saponins and steroids but showed very little cyanogenic glycosides, tannins, 
oxalates and phytates. Flavonoids, saponins and tannins are known to possess antimicrobial 
activity (Sofowara 1980, Evans 2005). This therefore is an indication that calabash nutmeg is 
a good source of antimicrobial properties. In fact, flavonoids which occur in calabash 
nutmeg, have a large number of biochemical and pharmacological activities occurring in 
mammals and in other biological systems. They also possess anti-inflammatory, anti-oxidant, 
anti-allergic, hepatoprotective, anti-thrombic, antiviral and anticarcinogenic activities 
(Middleton et al., 2000) 
2.3.3.6 Ginger (Zingiber officinale) 
It belongs to family ―Zingiberaceae‖ which is very famous due its medicinal herbal plants 
like, cardamom and turmeric (Park et al., 2006). It has been cultivated in South-East Asia 
from thousands of years.  After that it gains much popularity in European and African 
countries due to its therapeutic effects. Currently, ginger and its products are used in many 
traditional medicinal systems, due to its rich phytochemistry and diseases preventive 
properties (Shukla and Singh, 2007). Ginger is a magnificent pungent spice with a great 
history of cultivation. India is the largest producer of this herb and it is used in Indian and 
Chinese traditional medicines to treat many disorders over 5000 years. Many health claims of 
 37 
ginger were documented in many countries like China. It has been used to cure abdominal 
distensions, coughing, vomiting, diarrhoea, rheumatism, and toothaches for over 2500 years. 
In Nigeria and West Indies, it is used for the treatment of yellow fever, malaria and urinary 
tract infections. It was migrated to Europe during Roman and Greek times. It is one of the 
oldest spices used in Europe since the 9th century. Due to its carminative effects, the Greek 
people directly incorporated it into bread and generated the idea of ginger incorporation in 
food products. In India, people still prepare the cough syrup from ginger and honey to get 
relief from common cold (Grant and Lutz, 2000). Ginger is very excellent source of a variety 
of biologically active components, which shows remarkable pharmacological and 
physiological benefits. The well reputed and most pungent bioactive molecule of ginger is 6-
gingerol.  The  use  of  ginger  and  ginger  products  is commonly considered  as safe but still  
more researches  are needed  to  understand  the  complete  mechanism  behind  its 
therapeutic  effects  (Tapsell  et  al.,  2006).  Due  to  the phytochemical  profile  and  
pharmacological  properties, ginger  and  ginger  products  are  widely  administrated  into 
human  diet to  diminish different  kinds of  ailments, such as  hypertension (Ali et al., 2008; 
Nicoll and Henein 2009).  Fresh ginger rhizome is composed of fat (1.0%), minerals (1.2%), 
protein (2.3%), fiber (2.4%), carbohydrate (12.3%) and water (80.8%). The minerals present 
in ginger are sodium, potassium, calcium, magnesium iron, and phosphorous (Odebunmi et 
al., 2009). The distinct aroma of fresh ginger comes from volatile oils ranging from 1-3% 
(Evans, 2002). The bioactive components which possess pharmacological activities are of 
two types discussed below due to rich phytochemistry ginger is considered  as remedy  for 
many  health complications  from cold to cancer, from thousands of years. It is a good source 
of many functional and nutraceutical components gingerols, shogaols and paradolsetc (Ali et 
al., 2008). All these components have been shown strong antioxidant potential and helpful in 
scavenging the free radicals. The administration of ginger in the in vivo studies on rats 
 38 
claimed many therapeutic effects such as the improvement of antioxidant status, prevention 
from lipid peroxidation, carcinogens, glucose and LDL lowering effects and many others 
(Nirmala et al., 2010). The evidence for the effectiveness of ginger as an antioxidant, 
hypocholesterolemic, hypoglycemic, anti-inflammatory, anti-nausea, and anticancer agent as 
well as the protective effect of ginger against other disease conditions are claimed. 
2.3.3.7 Garlic (Allium sativum) 
Garlic, Allium sativum L. is a member of the Alliaceae family, has been widely recognized as 
avaluable spice and a popular remedy for various ailments and physiological disorders. The 
name garlic may have originated from the Celtic word 'all' meaning pungent. Cultivated 
practically throughout the world, garlic appears to have originated in central Asia and then 
spread to China, the Near East, and the Mediterranean region before moving west to Central 
and Southern Europe, Northern Africa (Egypt) and Mexico (Lutomski, 1987). Garlic is 
considered to be rich in medicinal properties. The undamaged bulbs contain allin which will 
be enzymatically converted to allicin during cutting. Allicin, is the major bioactive compound 
found in garlic followed by other organosulfur compounds. Garlic is claimed to be effective 
against diseases due to its scavenging property for oxygen free radicals. High pressure liquid 
chromatography method was used to investigate the ability of allicin which is the active 
ingredient in garlic to scavenge the hydroxyl radicals. The decrease in hydroxyl radicals has 
shown the effectiveness of the antioxidant property of allicin by preventing lipid peroxidation 
(Prasad et al., 1995). Due to its biological active component allicin and its derivative, garlic 
has been used as a medicine to cure a wide range of diseases and conditions related the heart 
and blood system including high blood pressure, high cholesterol, coronary heart disease, 
heart attack, and ―hardening of the arteries‖ (atherosclerosis) (Mikaili et al. 2013). Amagase 
(2006), noticed garlic is used to prevent various types of cancer comprising colon cancer, 
rectal cancer, stomach cancer, breast cancer, prostate cancer, prostate cancer and bladder 
 39 
cancer, and lung cancer. It is also used to treat Cardiovascular disease including: Antilipemic, 
antihypertensive, anti-atherosclerotic, an enlarged prostate (benign prostatic hyperplasia; 
BPH), diabetes, osteoarthritis, hayfever (allergic rhinitis), traveler's diarrhea, high blood 
pressure late in pregnancy (pre-eclampsia), cold and flu. It is also used for building the 
immune system, preventing tick bites, and preventing and treating bacterial and fungal 
infections. Garlic is a broad spectrum antibiotic, killing a wide variety of bacteria. Garlic 
appears to have antibiotic activity whether taken internally or applied topically. Researchers 
found that the urine and blood serum of human subjects taking garlic had activity against 
fungi (Caporaso et al. 1983). Ajoene is an active compound found in garlic which plays a 
great role as topical antifungal agent (Ledezma and ApitzCastro, 2006). Garlic has been 
shown to inhibit growth of fungal diseases as equally as the drug ketoconazole, when tested 
on the fungi Malassezia furfur, Candida albicans, Aspergillus, Cryptococcus and other 
Candida species (Shams Ghahfarokhi et al., 2006). A report from a Chinese medical journal 
delineates the use of intravenous garlic to treat a potentially fatal and rare fungal infection of 
the brain called Cryptococcus meningitis. In the report, the Chinese compared the 
effectiveness of the garlic with standard medical treatment which involved a very toxic 
antibiotic called Amphotericin-B. The study revealed that, intravenous garlic was more 
effective than the drug and was not toxic regardless of its dosage (Lemar et al., 2007). A 
study found that Candida colonies were substantially reduced in mice that had been treated 
using liquid garlic extract. The study also revealed that garlic stimulated phagocytic activity. 
This implies that infections such as Candida may be controlled because garlic stimulates the 
body‘s own defenses. Garlic oil can be used to treat ringworm, skin parasites and warts if it is 
applied externally. Lesions that were caused by skin fungi in rabbits and guinea pigs were 
treated with external applications of garlic extract and began to heal after seven days. 
 
 40 
2.3.3.8 Cumin (Cuminum cyminum L.) 
Cuminum cyminum L., belonging to the family Apaiaceae, is one of the old cultivated 
medicinal food herbs in Asia, Africa and Europe. Its seeds have been commonly used for 
culinary and flavouring purposes as well as folklore therapy. In various countries dried ripe 
seeds of C. cyminum are usually used for medicinal or culinary purposes. In Iranian 
traditional medicine, Cumin seeds were used for their therapeutic effects on gastrointestinal, 
gynaecological and respiratory disorders, and also for the treatment of toothache, diarrhoea 
and epilepsy. The seeds were also documented as stimulant, carminative and astringent. 
(Zargari, 2001). It has been recently reported that medicinal usage of Cumin seeds has also 
been widespread in diverse ethnomedical systems from Northern Europe to the 
Mediterranean regions, Russia, Iran, Indonesia and North America, where these have 
remained as an integral part of their folk medicines. (Johri 2011). Antimicrobial activity has 
been reported from the volatile oils and aqueous extract of Cumin. Cumin seed oil and 
alcoholic extract inhibited the growth of Klebsiella pneumoniae and its clinical isolates by 
improving cell morphology, capsule expression and decreasing urease activity. 
Cuminaldehyde is the main active compound of Cumin for this property (Derakhshan et al., 
2008). Limonene, eugenol, α- and β-pinenes and some other minor constituents have been 
found in cumin oil and suggested as the active antimicrobial agents (Derakhshan et al., 2008). 
The Cumin oil is reported as a high antioxidant mainly due to the presence of monoterpene 
alcohols (De Martino, 2009). The presence of phytoestrogens in Cumin has been reported 
which related to its anti-osteoporotic effects. Methanol extract of Cumin showed a significant 
reduction in urinary calcium excretion and augmentation of calcium content and mechanical 
strength of bones in animals (Shirke et al., 2008). Furthermore, the aqueous extract of Cumin 
seeds indicated the protective effect against gentamycin-induced nephrotoxicity, which 
decreased the gentamycin-induced elevated levels of serum urea and enhanced the clearance 
 41 
of the drug (Mahesh et al., 2010). 
2.3.4 Antioxidant and nutraceutical properties of some fruits 
There is epidemiological evidence that shows a correlation between consumers whose diets are 
rich in fresh fruits and vegetables and a marked reduction in the risk of cardiovascular diseases 
and certain types of cancers. These plants often exhibit wide ranges of biological and 
pharmacological activities, such as anti-inflammatory, anti-fungal and anti-bacterial properties. 
2.3.4.1 Pawpaw (Carica Papaya) 
Pawpaw (Carica papaya) belonging to the Carica genus in the myrtle family (Caricaceae). 
Pawpaw is indigenous to Central American countries but has been introduced and become 
wide spread throughout tropical Africa. It is popularly known as pawpaw in most English 
speaking West African countries. Papaya is one of the most nutritious fruits grown and eaten 
over the world. Carica papaya is not only an edible and tasty fruit, but it has also been used 
in most African countries for its healing properties. The pawpaw fruits as well as other plant 
parts have been known to be used in treatment of a wide variety of medical conditions, from 
stomach problems to bronchial disorders and even STD‘s. C. papaya is best known for its use 
as a deworming agent. Its leaves are usually boiled with other herbs with the aim to getting rid 
of worms when ingested (Neuwinger, 2000). A resultant extraction of the powdered seeds of 
the pawpaw has been employed in similar ways. Its leaves are regularly incorporated in the 
treatment of harmful organisms that reside in the gut (Iwu 1993). In Madagascar, the entire 
fruit is also sometimes cooked in water and the resulting tea ingested to treat stomach ulcers. 
Its leaves are sometimes brewed into a tea and the infusion used in the treatment of stomach 
ulcers as well as general stomach aches (Novy 1997). Among the Congolese people, a solution 
made from boiling the milled ripe seeds have evidently proven to be very adequate in curing 
dysentery (Tona et al., 1998). Pawpaw is also believed to be effective in malaria treatment. 
Several research findings revealed that pawpaw fruits and their leaves exhibited elevated 
 42 
antioxidative activities as a result of their high vitamin B levels which were present in the 
leaves, vitamin C and E, present in fruits, as well as carotenoids (Tona et al., 1998). 
2.3.4.2 Avocado (Persea americana) 
Persea americana is of the family Lauraceaea. The same family to which cinnamon, and 
camphor belong. Avocado has been proven to possess certain phytochemicals which have 
many valuable curative properties. These phytochemicals may be divided into alkanols, 
terpenoids, glycosides, several furan ring-containing derivatives, flavonoids, and coumarin 
(Kashman et al., 1969). Avocados are a rich source of nutrients such as Vitamin K, dietary 
fiber, pyridoxine, ascorbic acid, folate and copper, carbohydrates, soluble fibres, insoluble 
fibres and potassium. They are a rich source of oils, mainly containing monounsaturated fatty 
acids. However, oil contents of avocados are dependent on factors such as difference in 
variety and the stage at which the extraction of oil by the cold-press method was conducted. 
The existence of the afore mentioned phytochemicals and vitamins make this fruit an 
excellent source of antioxidants, making them very competent in the combating and 
prevention of a sizeable number of ailments which are usually the result of an unreasonable 
amount of free radicals in the biological system. Avocados possess the ability through their 
bioactive compounds to lessen and inhibit the occurrence of mouth and skin cancers, as well 
as prostate cancers. This study was conducted at a primary stage by medical researchers, 
mostly using cancerous cells or conducting laboratory experiments that involved nonhuman 
subjects and their ingestion of avocado extracts. Although this anti-cancer research is not yet 
extended to human subjects, the impression is that the initial results are spectacular enough. 
The anti-cancerous activities of this fruit is most likely related to its eclectic mixture of anti-
inflammatory and antioxidative nutrients (Donnarumma et al., 2010). The link between its 
anti - inflammatory factors and antioxidative factors is understandable due to the fact that 
cancer risk factors almost always include excessive inflammation and oxidative stress. The 
 43 
story of the avocado gets especially interesting when we come to the realization that in sound 
cells, avocado performs the function of alleviating inflammatory and oxidative stress levels, 
whereas in cancer ridden cells, bioactive components in the avocado increases oxidative 
stress and shift the cancer cells over into a scheduled cell death cycle (apoptosis), reducing 
the cancer cell numbers (Ding et al., 2009). This therefore means that, avocado seems to 
selectively tip cancerous cells "over the edge" when it comes to the area of strains which are 
as a result of reactive oxygen species and heightens their probability of expiration. In the same 
instance, avocados are involved actively in assisting the health of cancer free cells by 
elevating their reservoir of antioxidative and anti- inflammatory nutrients. 
2.2.4.3 Bitter kola (Garcinia kola) 
Garcinia kola is to a very large extent used in traditional herbal medicines and as a food. It is 
highly valued in many sub Saharan African countries because of its diverse medicinal uses. 
Bitter kola seeds are also chewed in some countries because of its possible aphrodisiac 
properties, it is also used in the cure of coughs, dysentery, and chest colds (Farombi et al., 
2005). In addition, it possesses hepatoprotective, analgesic and hypoglycaemic activities 
(Braide, 1991; Akintonwa and Essien 1990). A study conducted by Ogunmoyole et al., 
(2005), showed that, G. kola seeds were high in phenolic acids, and other bioactive 
compounds such as flavonoids and ascorbic acid. 
2.3.4.4 Guava (Psidium guajava L.) 
Psidium guajava L belonging to the myrtle family (Myrtaceae), is commonly referred to as 
guava in the English language. Guava is an excellent source of minerals such as iron, calcium, 
and phosphorus and also many nutrients such as vitamin A, pantothenic acid, carotenoids such 
as B- carotene, lycopene, and niacin (Mercandante et al., 1999). The guava fruit has about four 
times the concentration of vitamin C as an orange will contain (Misra et al., 1968). Analysis 
on its fruit has also revealed them to possess saponins along with oleanolic acid (Misra et al., 
 44 
1968). Studies conducted on the fruit have revealed the presence of flavonoids and phenolic 
compounds such as ellagic acid, anthocyanin, guaijavarin, and quercetin. Anti-microbial 
compounds have also been isolated in the fruit. A study conducted by Lim et al., (2002) 
aimed at comparing the antioxidative activities of a large number of fruits found in the 
tropics revealed that guava possesses principal antioxidative properties. This was determined 
using methods of DPPH radical scavenging and iron (III) reducing assays (Lim et al., 2002). 
This gives the guava fruit the ability to be used in either preventive or protective roles, 
against diseases arising from oxidative stress. 
2.3.4.5 Olives (Olea europaea L.) 
The Olive tree belongs to the family Oleaceae and is native to tropical and warm temperate 
regions of the world. According to an estimate of Food and Agriculture Organization (FAO), 
in 2009, 9.9 million hectares were planted with olive trees with production of oil about 2.9 
million tonnes worldwide. Olive oil has been used as a nutritious food, drug and as cosmetics 
for centuries by the Mediterranean people. During last few decades‘ olive has been a subject 
of much scientific interest for approving its multiple biological, therapeutic and functional 
food applications. Numerous epidemiological and clinical studies acknowledged olive oil as a 
source of food and medicine. The most important functional properties of olive oil are 
antioxidant, anti-microbial, anti-inflammatory and anti-cancer as evident from a variety of 
studies. These biological activities and individual taste are due to the presence of unique 
bioactive compounds in the olives, namely phenolics (e.g., oleuropein, hydroxytyrosol, 
verbascoside and derivatives), tocopherols and carotenoids, amongst others (Rahele et al., 
2012). Olive fruit contains both lipophilic and hydrophilic phenolics. Among the lipophilic 
phenols the most important are cresols while the major hydrophilic phenols include phenolic 
acids, phenolic alcohols, flavonoids and secoiridoids (Rahele et al., 2012). Flavonoids are 
abundantly present in fruit tissues at the early stages of growth and development. 
 45 
Accumulation of polyphenols in fruit tissue at the early stages of development of olive and 
many other fruits has been a common biosynthetic pathway (Bendini et al., 2007). The 
distribution and structure of the chemical constituents of olive fruit is complex and dependent 
on parameters including variety, cultivation practices, geographical origin, and the level of 
maturation. The therapeutic utilities of O. europaea have been indicated in traditional 
medicine. It has been known to reduce blood sugar, cholesterol, and uric acid. It has also been 
used to treat diabetes, hypertension, inflammation, diarrhoea, respiratory and urinary tract 
infections, stomach and intestinal diseases, asthma, haemorrhoids, rheumatism, laxative, 
mouth cleanser, and as a vasodilator. Many phenolic compounds, especially secoiridoids and 
iridoids (Bendini et al., 2007), and their pharmacological activities have been the focus of 
attraction for scientists in the last decade (Ryan and Robards, 1998; Ghisalberti, 1998). 
Oleuropein, a major constituent of olives, has got much attention and a lot of work has been 
done on its pharmacological properties (Soler-Rivas et al 2000; Omar, 2000). Olive has 
widely been explored as a functional food (Erbay and Icier, 2010; Galanakis, 2011) with 
various biophenols and other bioactive constituents (Obied et al, 2005; Saija and Uccella, 
2000). Volatile constituents from olive oil and their applications in flavour development have 
also been a hot area of the current research.  
2.3.5 Antioxidant and nutraceutical properties of edible fungi 
2.3.5.1 Mushrooms 
Mushrooms for many generations have been eaten because of their high nutritional content, 
and used as seasoning products as well as for their health benefits (Tel et al., 2012). Because 
of their unique flavours and aromas, mushrooms are held in high regard in various countries. 
Chang and Miles (2004), have defined mushrooms as ‗a macrofungus with a peculiar fruiting 
body, which can be hypogeous or epigeous, large enough to be visible to the naked eye and to 
be harvested by hand‘. There are several thousands of known mushroom species in the world. 
 46 
Of this large amount of mushroom species, only about 10% have been identified (Lindequist 
et al., 2005). Research conducted have indicated that mushrooms have potential antiviral, 
antimicrobial, anticancer, anti-hyperglycemic, cardio protective, and anti-inflammatory, 
activities (Kumar, 2015). Bioactive compounds identified in mushrooms consisting of 
antitumor substances, have been isolated in a large number of mushroom species over the last 
few years. Polysaccharides are the predominant and most potent compounds found in and 
derived from mushrooms. Fresh mushrooms have been proven to possess both soluble and 
insoluble fibres. The soluble fibre is mainly made up of beta-glucan polysaccharides and 
chitosans which are components found in the cell walls (Sadler 2003). Soluble fibre present in 
mushrooms prevents and manages cardiovascular diseases that occur in the human system 
(Chandalia et al., 2000). The antioxidant properties of mushrooms have been scientifically 
established. They are considered to be organisms which possess naturally occurring 
antioxidants. There is also a correlation between their phenolic and polysaccharide 
compounds. 
 
 
 
 
 
 
 
 
 
 
 
 47 
CHAPTER 3 
MATERIALS AND METHODS 
 
 
3.1 Study design 
The study was conducted in two parts. A study was carried out using a questionnaire in four 
market centres, namely Madina, Makola, Adenta and Dome markets to find out what foods 
Ghanaian consumers perceive to be functional in nature and how easily accessible it was in 
their communities. The second part of the study, involved chemical analysis conducted on 
selected foods that respondents considered to possess nutraceutical properties, for 
identification and quantification of bioactive compounds. 
3.2 Consumer survey 
The survey was a cross sectional one, conducted in 4 markets centres in the Greater Accra 
region. Market centres were used in this study because, they are places where people from all 
walks of life, social classes, different religious and ethnic backgrounds converge. As such, it 
was a good place to sample views of a wide range of people. 
3.2.1 Sample size calculation 
The sample size used was 283 consumers. It was calculated using the formula given by Charan 
2 2
and Biswas (2013).          (Z - 2 1 α/2 SD ) ÷ d  
  
Z 1-α/2 = standard normal variate SD = standard deviation variable d = Absolute error or 
precision 
The inclusion criteria was willingness of participants to partake in the study, without any 
coercion. 
 
3.3 Ethical Clearance for Data Collection 
Ethical clearance was obtained from the Ethical committee of the College of Basic and Applied 
Sciences. Verbal consent as well as a signed consent form, was obtained from participants, 
taking part in the survey. 
 
 48 
3.4 Materials 
Samples were obtained from Madina and Makola market centres. The criteria for sample 
selection was based on lesser known functional foods in Ghana, identified from the earlier 
consumer survey, conducted as part of this study. 
3.4.1 Sample selection 
The selected samples, were a part of a list of indigenous foods that participants perceived to 
have functional properties. In total, ninety-six (96) different food commodities were 
identified by respondents to possess nutraceutical properties. The most frequently mentioned 
foods included abeduru (solanum torvum), bitter leaf, dawadawa (fermented Parkia 
biglobosa), kontomire (cocoyam leaves), basil, orange leaves and bitter kola. Of the ninety-
six (96) mentioned foods, seven (7) were selected to determine their nutraceutical properties. 
They include, Ashanti black pepper, cloves, bitter kola, anise, and fruit of Tetrapleura 
tetraptera, alligator pepper and calabash nutmeg. The Seven (7) selected for analysis was 
because, they are indigenous to Ghana, and research conducted on them is limited. 
3.4.2 Determination of Total Phenolic Content (TPC) 
Total phenolic content was estimated using Folin Ciocalteu‘s reagent, and the protocol as 
outlined by Singleton and Rossi, (1965). A volume of 0.04ml of each sample‘s extract was 
mixed with 0.2ml Folin Ciocalteu‘s reagent in a 100ml test tube. The mixture was allowed to sit 
for 5 mins, before addition of 0.5ml of 20% sodium carbonate. The volume was adjusted to 5 
ml with distilled water and vortexed for approximately 10 secs. The mixture was then 
incubated at 45˚C for 30 mins and allowed to cool to room temperature. Reading was then 
taken at 750nm using a UV spectrophotometer. The total phenolic content were quantified 
and expressed as Gallic Acid Equivalent (GAE) mg/g. 
 
Calculation of Total phenolic content in percent is based on gallic acid standard. 
 
Total phenols % = [(A sample × W sample × 50) ÷ (A standard × W sample × 50)] × 100%    
 49 
Where A is absorbance at 760nm and W is the volume 
3.4.3 Phytochemical profile determination (flavonoids, alkaloids, Saponins) 
3.4.3.1 Flavonoids 
To determine the flavonoid content of food samples, 10g of each sample was extracted 
repeatedly with 100 ml of 80% aqueous methanol at room temperature. The resultant 
solutions were filtered through whatman no. 4 filter paper. The filtrates were then transferred 
into a crucible and evaporated into dryness over a water bath and weighed to a constant 
weight. Obadoni and Ochuko (2001). 
3.4.3.2 Saponins 
In the test for saponins, the protocol as outlined by Obadoni and Ochuko (2001) was employed. 
The samples were first reduced to powder using a mill and 20 g of each weighed sample put 
into a conical flask and 100ml of 20% aqueous ethanol added. The extracts were heated over a 
hot water bath at a temperature of 55°C for 4h. The samples were stirred continuously during 
the heating period. The mixture was filtered and the residue re-extracted with another 200 ml 
of 20% ethanol. The combined extracts were reduced to 40 ml over water bath at about 90°C. 
The concentrate was transferred into a 250 ml separatory funnel and 20 ml of diethyl ether was 
added with vigorous shaking. The aqueous layer was then separated from the ether layer, which 
was then discarded. The purification process was repeated once more. 60 ml of n-butanol was 
added. The combined n-butanol extracts were washed twice with 10 ml of 5% aqueous sodium 
chloride. The remaining solution was heated in a water bath until most of the aqueous layer 
had evaporated. The samples were dried in the oven to a constant weight; the saponin content 
was calculated as percentage. 
 3.4.3.3 Alkaloids 
An amount 5 grams of each selected food product was measured into a 250 ml beaker. 200 ml 
of 10% acetic acid in ethanol was then measured and added to the samples. The solution was 
 50 
covered and allowed to sit for 4 hours. The solution was then separated using Whatman no. 4 
filter paper. The resulting extract was then heated on a water bath, until it was concentrated to 
a quarter of its initial volume. The extract was then added to in a dropwise manner to a 
concentrated solution of ammonium hydroxide until complete precipitation was achieved. The 
precipitated solution was then allowed to settle, after which the precipitate was collected and 
washed using dilute ammonium hydroxide and afterwards filtered. The residue remaining was 
the alkaloid, which was then dried to a constant weight (Harbone, 1998). 
3.4.3 Determination of Antioxidant potential using 2,2-diphenyl-1-picryhydrazyl (DPPH) 
The Antioxidant potential of the extracts using the DPPH radical was determined using the 
method according to Brand-Williams et al., (1995). DPPH radicals have an absorption 
maximum wavelength of 515 nm, which disappears with reduction by an antioxidant 
compound. The DPPH solution in methanol (6 × 10-5M) was prepared, and 3 mL of this 
solution was mixed with 100μL of methanolic solutions of plant extracts. The extracts of the 
samples were incubated for up to 20 minutes at 37 °C in a water bath. After that, absorbance 
was measured at 515 nm. This reading was the absorbance of the plant extract (AE). A blank sample 
containing100 μL of methanol in the DPPH solution was prepared, and its absorbance was 
measured also at 515nm. This reading was the absorbance of the blank (AB). The analysis was 
conducted in triplicate, and averages recorded. The radical scavenging activity was calculated 
using the following formula: 
 
% inhibition = [(AB – AE)/AB] × 100 
 
Where AB = absorbance of the blank sample, and AE = absorbance of the plant extract. 
 
 
 
 
 
 
 
 
 
 51 
3.4.4 Determination of the effect of processing on the phytochemical profile of selected 
food samples 
The determination of the effect of processing on phytochemical contents of the selected 
samples was carried out by steam cooking, using the method of blanching. Blanching was 
conducted on each of the samples at 5 minutes intervals for up to 1 hour. The physicochemical 
analysis stated in section 3.5 was repeated on all the food samples after each blanching time 
to establish the effect of heating on the phytochemical contents of the samples. 
3.5 Analysis of results 
Analysis of results from the consumer survey were tabulated and frequencies and percentages 
calculated using Microsoft Excel. The physicochemical values were analysed using one way 
ANOVA. The software used were SPSS and STAT Graphics.  
 52 
CHAPTER 4 
RESULTS AND DISCUSSION 
 
This section presents results obtained from both the consumer survey, and laboratory analysis 
of the selected samples used in the study. 
4.1 Consumer survey on indigenous foods Ghanaian considered to be functional foods 
4.1.1 Consumer background characteristics 
Table 4.1 outlines the background characteristics of respondents who took part in the survey. 
Characteristics of consumer markets is based on demographics which include differences in 
gender, age, ethnic background, income, occupation, education, household size, religion, 
generation, nationality and even social class. Most of these demographic categories are 
further defined by a certain range. The total number of respondents interviewed in this survey 
was 283. Of this number, 201 (71%) were females and the remaining 82 (29%) were males. 
This is due to the fact that more trading in market centres is carried out by women than men 
.The respondents fell between the ages of 15-65, with the highest percentage of  27.6%, 
falling within the age bracket of 15-25, and the least (11.7%) in the 56-65 age bracket. In 
terms of marital status, the highest percentage (48.1%) were single with the 4.9% being 
widowed. The highest percentage being single can be attributed to the fact that most of the 
respondents were between 15-25 years. For their religious affiliations, 91.5% of respondents 
asserted to be Christians, 7.1% Moslems, and 1.1% traditionalists, with the remaining 0.4% 
being Rastafarians. Ghana being a predominantly Christian country with the next largest religious 
group being Islam can account for this. In terms of ethnicity, 60.7% of respondents were Akans 
which constituted the largest group.  
 
 
 
 53 
Table 4.1: Background characteristics of consumers  
Variables  Total (n=283) Percentage (%) 
Gender   
males 82 29 
females 201 71 
   
Age   
15-25 78 27.6 
26-35 59 20.8 
36-45 68 24.0 
46-55 45 15.9 
56-65 33 11.7 
   
Marital status    
Single  136 48.1 
Married  108 38.2 
Divorced  25 8.8 
Widowed  14 4.9 
   
Religion    
Christianity 259 91.5 
Islam 20 7.1 
traditionalist 3 1.1 
Rastafarian 1 0.4 
   
Ethnicity    
Akan 170 60.7 
Ga/Adangbe 40 14.1 
Ewe 47 16.6 
Northern 18 6.3 
ethnicity  
Krobo 8 2.8 
 
4.1.2 Indigenous foods listed by Ghanaian consumers to possess functional properties 
Indigenous foods can be described as foods that people have eaten for ages. These foods have 
become part of traditions and cultures. The data from the survey as shown in Table 4.2 indicated 
that, the indigenous foods mostly perceived to possess functional properties were Solanum torvum, 
locally as Abeduru or kantose. Cocoyam leaves (kontomire), ginger, cassava leaves, bitter leaves 
(awonyono), and fruit of Tetrapleura tetraptera (prekese), fermented Parkia biglobosa 
 54 
(dawadawa) and Talinum triangulare (bokorbokor).  
Table 4.2: Indigenous foods perceived to possess functional properties 
Food product  Frequency  Percentage (%) 
Turkey berries (Abeduru/Kantose) 276 97.5 
Cocoyam leaves (kontomire) 276 97.5 
Bitter leaves (awonyono) 206 72.7 
Solanum macrocarpon (gboma) 156 55.1 
Amaranthus species (alefu) 156 55.1 
Moringa oleifera 136 48.0 
Talinum triangulare (bokorbokor) 129 45.5 
Dandelion  125 44.1 
Cassava leaves  123 43.4 
Fruit of Tetrapleura tetraptera (prekese) 94 33.2 
Bissap (sobolo) 71 25.1 
Garcinia kola (michi goro) 69 24.4 
Fermented parkia biglobosa (dawadawa) 43 15.2 
Garlic  41 14.5 
Ginger  36 12.7 
Ashanti black pepper (soro wisa) 35 12.4 
Calabash nutmeg (widie aba) 28 9.9 
Alligator pepper (efom wisa) 16 5.6 
Anise (nkitinkiti) 12 4.2 
Cloves (pepre) 12 4.2 
 
Indigenous foods are generally perceived as foods with beneficial properties due to 
genuineness, local production, propagation and minimal or no industrial processing. 
According to FAO (2008), traditional food products represent an expression of culture and 
lifestyle resulting from the local climatic, agricultural and economic conditions that 
determine production and processing practices. The foods listed by consumers as frequently 
consumed such as cocoyam leaves (kontomire), turkey berries, cloves, dandelion etc. are 
 55 
easily and readily available on the local markets and sometimes can even be found growing 
wild in homes and neighbourhoods.  
The perceived curative or preventive properties of the foods as reported by consumers are 
presented on Table 4.3.  
Table 4.3: Perceived medicinal properties of some indigenous food products as 
stated by respondents.  
Food product  Perceived medicinal  properties  
Turkey Berries (Abedru/Kantose) Anaemia prevention , treatment of 
intestinal worms  
Cocoyam leaves (kontomire)  Anaemia prevention, immune system 
booster             
Bitter leaves (awonyono) Reduces high blood pressure, fever 
treatment, prevents anaemia  
Solanum macrocarpon (gboma) Improves vision, prevents anaemia, lowers 
high blood pressure 
Amaranthus species (alefu) Improves vision, prevents anaemia, lowers 
high blood pressure  
Moringa  Lowers blood sugar and cholesterol, 
prevents cancer and stroke  
Talinum triangulare (bokorboko) Prevents anaemia, regulation of blood 
sugar levels 
Dandelion  Lowers blood pressure, immune system 
booster,  reducing blood sugar 
Cassava leaves  Relieves constipation, prevents anaemia, 
 56 
treatment of diarrhoea  
Fruit of Tetrapleura tetraptera (prekese) Lowers blood pressure, fever reduction, 
reducing blood sugar  
Bissap (sobolo) Lowers blood pressure, promotes weight 
loss  
Garcinia kola (michi goro) Aids digestion, improves sexual function, 
lowers high blood pressure   
Fermented Parkia biglobosa (dawadawa) Promotes good eye sight, lowers high 
blood pressure, immune system booster  
Garlic  Lowers high blood pressure, colds, 
detoxification, improves digestion  
Ginger  Nausea, colds, coughs, indigestion, lowers 
high blood pressure  
Ashanti black pepper (soro wisa) Coughs, colds, intestinal worms, joint 
pains, immune system booster  
Calabash nutmeg (widie aba) Colds, coughs, nausea, high blood pressure  
Alligator pepper (efom wisa) Asthma, indigestion, period cramps, 
malaria, stomach pain 
Anise (nkitinkiti) Stomach aches, asthma, indigestion, colds 
Cloves (pepre) Treatment of tooth aches, coughs and colds 
 
4.1.3 Level of consumption of the stated foods 
The consumption levels amongst consumers were 24% for those who consumed them daily, 
23% for those who consumed them occasionally, 22% for monthly consumers and 20% for 
those who consumed it twice a week. 11% of consumers reported consuming the foods three 
 57 
or more times a week (Figure 1a). In terms of ease of availability of these foods in communities, 223 
respondents reported that it was easy to find these foods in their communities whilst 19 said it was 
not easy to access them in their communities (Figure 1b). The easy accessibility of these foods can be 
attributed to the fact that Accra is a cosmopolitan city with inhabitants coming from all over 
the country so traders bring a lot of these to Accra, making these foods available in markets 
and communities in Accra. For those who said they foods are not accessible to them, one 
main reason given was that, those particular functional foods were peculiar to their ethnic 
groups and were not easily accessible in areas outside their hometowns. 
24% 23% daily
twice a week
3 or more times a week
monthly
22% 20% 
occassionally
11% 
 
 
Figure 1a: Reported consumption of functional food patterns amongst consumers 
 
250
223 
200
150
100
50
19 
0
yes no
 
 
Figure 1b: Ease of availability of functional foods in communities 
 58 
 
 
4.2 Chemical Analysis of selected food samples 
For the purposes of this study, seven (7) indigenous Ghanaian foods were selected 
from those stated by the respondents.  
 
 
 
Figure 2: Selected food samples. L-R top (Ashanti black pepper, cloves, bitter kola) 
 L-R bottom (Anise, fruit of Tetrapleura tetraptera, Alligator pepper and Calabash 
nutmeg) 
 
These were Ashanti black pepper, cloves, bitter kola, Anise, fruit of Tetrapleura 
tetraptera, Alligator pepper and Calabash nutmeg (figure 2). They were analysed for 
their Total Phenolic Content (TPC), Antioxidant scavenging capacity and 
phytochemical profile. 
4.2.1 Total Phenolic Content (TPC) 
There were significantly differences (p ˃ 0.05) among the foods for the levels of total 
phenolics (Table 4.4). 
 59 
Table 4.4: Total Phenolic Content (TPC) of selected food samples 
Sample Total Phenolic Content (mg GAE/g) 
  (mean ± S.D) 
Ashanti black pepper 15.523 ±0.083b 
 
Cloves 12.256 ±0.081c 
 
Bitter kola 45.233 ±0.351a 
 
Anise 2.960 ±0.000d 
 
Fruit of Tetrapleura tetraptera  15.503 ±0.351b 
 
Alligator pepper 2.236 ±0.045e 
 
Calabash nutmeg 3.306 ±0.089d 
 
Figures within the same column bearing the same superscript are statistically the same at p<0.05 
 
 
Bitter kola had a total phenolic content of 45.233mg GAE/g which is comparable with levels of 
45.2mg GAE/g obtained by Ogunmoyole et al. (2012). The values obtained in this study for cloves 
(12.256mg GAE/g) was in close proximity to those obtained by Seranthinata et al. (2012) who 
had 11.78mg GAE/g. They stated that such amount of polyphenols are high enough to exhibit 
curative properties such as anti-cancer, anti-microbial and anti-diabetic. Nwoba (2015) 
reported a TPC of 0.373mg GAE/g for Tetrapleura tetraptera and concluded that the fruit 
contains appreciable levels of TPC making them a good source for promotion of good health. 
Values recorded in this study (15.803mg GAE/g) was even much higher. As demonstrated by 
Thomas et al. (2018), the variations in the total phenolic content might be due to several 
factors such as genetic variability, environmental pressure, cultivation techniques, age, 
maturity of the plants and postharvest treatments. The TPC of calabash nutmeg (3.306mg 
GAE/g) and anise (2.96mg GAE/g) were in close proximity to those reported by Womeni et 
al. (2013). TPC of Alligator pepper was 2.236mg GAE/g.  
 60 
Phenolics are secondary aromatic compounds (Abdelaaty et al., 2014). They have been 
reported to be associated with functions such as nutritional and antioxidant properties 
(Robbins, 2003). The presence of phenols in cloves can be attributed to their ability to act as 
pain relievers for tooth aches and a cure for coughs and colds. Antibacterial activity of clove 
essential oil has been reported against Staphylococcus aureus (Mishra and Sharma 2014). 
Eugenol a type of phenolic compound present in cloves is a routine analgesic agent widely 
used in dental clinics due to its ability to alleviate tooth pain. The effects have been attributed 
to its capability to suppress prostaglandins and other inflammatory mediators such as 
leukotriene. It is also believed to depress the sensory receptors involved in pain perception 
(Raghavenra et al., 2006). These support claims made by consumers of its ability to treat 
tooth aches, coughs and colds.  
Phenolic content of calabash nutmeg has been reported to be potent in killing Staphylococcus 
aureus, Bacillus subtilis and Canadidia albicans (Nwaiwu and Imo, 1999, Nwankwo, 2015) 
Also Oluwafemi and Taiwo reported on the reversal of toxigenic effects of aflatoxin by 
alcoholic extracts of Monodora myristica. 
 The total phenolic content in a food sample is a determinant of its curative ability for several 
diseases. Total phenolic content has a direct relationship to antioxidant activities. The higher 
the total phenolic content, the higher the antioxidant activity (Al-Mamary et al., 2002).  
The levels of TPC recorded in the different food samples, are an indication that these foods 
possess the ability to cure or prevent disease as stated by consumers. The presence of phenols 
at different levels in the foods further indicates that could act as anti-inflammatory, 
anticlotting and immune enhancers. Phenols have been the subjects of extensive research as 
disease preventatives (Duke, 1992). Phenols have been responsible in having the ability to 
block specific enzymes that causes inflammation. This could justify the health claims made 
by consumers concerning these foods.  
 61 
4.2.2 Antioxidant scavenging capacity 
Results of this is recorded in Table 4.5. There was a marked reducing activity of the extracts. 
According to Nataraj et al., (2013) the marked reducing activity of the extracts may be as a 
result of the presence of polyphenols, which may act as reductants by donating the electrons 
and reacting with free radicals to convert them to more stable products and terminate radical 
chain reaction.  The activities of natural antioxidants in influencing diseases are closely 
related to their ability to reduce DNA damage, mutagenesis, carcinogenesis, and inhibition of 
pathogenic bacterial growth (Roginsky and Lissi (2005). 
 Table 4.5: Antioxidant scavenging capacity of selected food samples 
Sample Antioxidant scavenging capacity (%)                       (mean ±S.D) 
Ashanti black pepper 0.798 ± 0.0004e 
 
Cloves 0.933 ±0.0000a 
 
Bitter kola 0.877 ±0.0004c 
 
Anise 0.789 ±0.0004f 
 
Fruit of Tetrapleura tetraptera  0.867 ±0.0013d 
 
Alligator pepper 0.928 ±0.0000b 
 
Calabash nutmeg 0.709 ± 0.0000g 
 
 Figures within the same column bearing the superscript are significantly the same at p< 0.05 
 
 
Food samples which recorded high total phenolic contents therefore, equally recorded 
relatively high antioxidant capacities. High levels of antioxidant scavenging potential is a 
sign that a particular food is able to remove free radicals that may be present in the body, and 
are usually the cause of many diseases that occur in the body. A positive correlation can 
therefore be made between these food samples, and claims made as to their curative 
 62 
properties. Bitter kola for example has been purported to bear preventive properties in terms 
of cancer. Its relatively high level of antioxidant scavenging capacity (0.877%) could be the 
reason for such claims. However, Vasco et al. (2008) analysed fruits such strawberries, 
passion fruit and bananas reported that an antioxidant capacity of between 4 to 17% obtained 
were low for fruits. The samples analysed in the current study were mostly spices and hence 
will not provide an appreciable level of antioxidant capacity unless used in high amounts. 
Low values could also be due to extraction methods and storage conditions of the commodity 
(Vasco et al., 2008). 
 Cloves had an antioxidant scavenging capacity of 0.933%. A study conducted by Ou et al 
(2006), showed that Eugenol, a major phenolic component from clove oil (Eugenia 
caryophyllata), has demonstrated several biological activities, such as anti-inflammatory 
activity by inhibiting the enzyme cyclooxygenase-II, analgesic activity due to selective 
binding at the capsaicin receptor, anti-oxidation activity, and antibacterial activity against 
both gram-positive and gram-negative microorganisms. In a research conducted by Onoja et 
al (2014) extracts of alligator pepper revealed that it has a potent antioxidant activity 
comparable to vitamin C which was used as a reference standard. They concluded that the 
demonstrated antioxidant and antilipid peroxidation effects of the extract of A. melegueta 
may be the rationale behind some of its folkloric uses and also may be responsible for some 
of its pharmacological effects.  
4.2.3 Phytochemical profile (Alkaloids, Saponins, Flavonoids) 
Table 4.6 shows results regarding the levels of some individual phytochemical constituents in 
the selected food samples 
 
 
 
 63 
Table 4.6: Phytochemical profile of selected food samples 
Sample Alkaloids Flavonoids Saponins  
                                                 (mean ±S.D) (mean ±S.D)  (mean ±S.D) 
Ashanti black pepper 0.343 ±0.0351c 8.250 ± 0.0794a 4.376 ±0.0057f 
  
Cloves 0.236 ±0.0115c 3.130 ± 0.0265a 1.886 ± 0.0057f 
 
Bitter Kola 0.670 ±0.0173c 2.040 ± 0.0000d 12.470 ±0.0200g 
 
Anise 0.380 ±0.0173c 1.340 ± 0.0000d 7.790 ±0.0265g 
 
Fruit of Tetrapleura tetraptera  0.300 ±0.0100c 2.120 ± 0.0173d 9.013 ±0.0152g 
 
Alligator pepper 0.290 ± 0.0173c 6.10 ± 0.0000a 1.220 ±0.0451f 
 
Calabash nutmeg 0.493 ± 0.0152b 0.220 ± 0.0152e 9.790 ± 0.0265g 
 
Figures within the same column bearing the same superscript are statistically the same at p<0.05 
 
The phytochemical content of ashanti black pepper showed it having a high content of 
flavonoid followed by its saponin content and then its alkaloid content. Alkaloids possess 
anti-malarial, antihypertensive, antiarrhythmic and anticancer properties (Heikens et al 1995). 
The flavonoids present are also responsible for the antioxidant, anti-inflammatory, and their 
anti-allergic properties (Okoye and Ebeledike 2013). The anti-inflammatory properties of 
flavonoids present in ashanti black pepper is responsible for its ability to relieve joint pains as 
stated by consumers. According to Mba (1994), it is used as an adjuvant in the treatment of 
rheumatic pains and as an anti-asthmatic. Saponins also have anti-carcinogenic properties. 
Alkaloids are bioactive compounds that contain elements such as nitrogen, and are 
biologically active, bearing sedative and analgesic properties for relieving pains, anxiety and 
depression (Jisika et al., 1992). They are a cluster of biological compounds found in various 
plant parts. Alkaloids can act in either a beneficial or destructive medium. Some alkaloids 
stimulate the nervous systems; others can cause paralysis, raise blood pressure or lower it this 
 64 
explains why certain alkaloids alleviate pain, while others serve as tranquilizers. Others have 
also been noted to contain antimicrobial properties (Adesuyi et al., 2011). Flavonoids have 
also been reported to possess protective effects including anti- inflammatory, anti-oxidant, 
antiviral, and anticarcinogenic properties. (Middleton et al., 2000). The high saponin content 
of a food has been linked to that food, possessing high cholesterol binding abilities.  
Some traditional remedies, prescribe foods made with or from fruit of Tetrapleura tetraptera 
and calabash nutmeg for people who suffer from high blood pressures and this can be 
attributed to the presence of the phytochemicals in the commodities. Work done by Adesina, 
(2016) showed that the extracts of tetrapleura tetraptera and some of the isolated compounds 
showed sedative, hypotensive, molluscicidal, CNS depressant, anti-inflammatory, 
antimicrobial, wound-healing, contraceptive, analgesic, hypoglycemic, antioxidant, 
hypolipidemic, antimalarial, muscle-relaxant, anticonvulsant, hypothermic, and anxiolytic 
effects in experimental animals. This is as a result of the presence of phytochemicals like 
alkaloids, glycoside, saponins, and flavonoids. This supports claims made by consumers 
concerning the ability of tetrapleura tetraptera to reduce blood sugar as well as blood 
pressure. Flavonoid content present in calabash nutmeg was 0.220. As compared to research 
conducted by Ekeanyanwu and Nwachuku (2010) and Effiong et al (2005) showed large 
amounts of flavonoids present in calabash nutmeg. This variation could be attributed to many 
factors, such as climatic, edaphic and time of exposure to dryness. Such differences may arise 
from variations in soil micronutrients. It could also be partly attributed to the method of 
analysis (Bimakr, 2010).  
Research carried out by Naiho and Ugwu (2009), on bitter kola showed that it is rich in 
phytochemicals such as flavonoids, tanins, saponins, biflavonoids and resins. The research 
further revealed Garcinia kola is capable of lowering blood pressure due to the presence of 
these phytochemicals. This provides scientific proof to claims made by consumers 
 65 
concerning the ability of consumption of bitter kola to reducing high blood pressure.  
4.3 Effect of heating on the TPC, Antioxidant scavenging capacity and phytochemical 
profile of selected food samples 
4.3.1 Total Phenolic Content and Antioxidant scavenging capacity 
The technique used in processing the food samples was blanching. Blanching is the process by 
which food is exposed to mild heating in water for short periods of time (Patras et al., 2011). 
Blanching is typically carried out by treating food products for 1-10 min at 75-95˚C. The 
time-temperature combination used, is usually dependent on the type of vegetable being 
processed (Cano, 1996). The process of blanching has been recorded to either reduce or give 
rise to antioxidant activity of agricultural products (Pujimulyani et al., 2012). From Figure 3, 
the antioxidant scavenging capacities of all the food samples showed a gradual decline during 
blanching. In alligator pepper for example, after about 20 minutes of blanching time, 
antioxidative capacity was stable over a period of 25 minutes, before another marked change 
was seen. A similar trend is seen in all the other samples. The effect of blanching on the total 
phenolic content also showed a gradual decline, with the TPC holding steady after some time of 
blanching, just as was seen with the antioxidant activity.  
 
ashanti black cloves bitter kola
anise Prekese Alligator pepper  
c.Nutmeg  
100
 
80
60  
40  
20
 
0
0 10 20 30 40 50 60 70  
BLANCHING TIME/SEC 
 
 Figure 3: Effect of blanching time on the antioxidant capacity of selected food samples 
 66 
% ANTIOXIDANT ACTIVITY 
According to Goncalves et al. (2010), high intensity heat treatment leads to the maximum 
loss of phenolic content which may be due to several reasons like thermal degradation and 
leaching or diffusion of component into water. Similar results were reported by Jaiswal et al. 
(2012) during blanching of cabbage. These results can be compared to work done by Sharma 
et al. (2014). Phytochemicals are heat sensitive and so when exposed to heat over a period of 
time, they will break down. In some studies however, total phenolic content and antioxidant 
capacities increased with heating time as reported by Sinha et al., (2015). These variations can 
be attributed to the different types of heating techniques used. For example, samples that were 
treated with dry heat methods such as microwave heating, both antioxidant capacity and total 
phenolic content increased. However, those treated with wet heat methods showed a decrease 
in total phenolic content as well as antioxidant capacity. 
 
ashanti black cloves bitter kola
anise prekese alligator pepper
c.nutmeg
50
45
40
35
30
25
20
15
10
5
0
0 10 20 30 40 50 60 70
BLANCHING TIME/SEC 
 
 
Figure 4: Effect of blanching time on Total phenolic content of selected foods  
 
 
 
 
 67 
TOTAL PHENOLIC CONTENT  
4.3.2 Phytochemical profile 
Most vegetables are cooked either by boiling, steaming or microwaving before being 
consumed (NG et al, 2011). Several studies have reported that these heating processes cause 
many changes in the chemical composition of vegetables. For example, the antioxidant 
capacity and total phenolic content of pepper (Capsicum spp.), green bean (Phaseolus 
vulgaris), broccoli (Brassica oleracea), spinach (Spinacia oleracea), and sweet corn (Zea 
mays) increase after boiling, steaming, or microwaving (Dewanto et al, 2002, Turkment et at 
2005).  
The effects of heating on the phytochemical profile of the selected food samples are shown 
on Figures 4 to 10.  
ALKALOIDS SAPONINS FLAVONOIDS
9
8
7
6
5
4
3
2
1
0
0 10 20 30 40 50 60 70
BLANCHING TIME/SEC 
 
 
Figure 5: Effect of blanching time on the phytochemical profile of Ashanti black pepper 
 
 68 
PHYTOCHEMICAL PROFILE 
alkaloids flavonoids saponins
3.5
3
2.5
2
1.5
1
0.5
0
0 10 20 30 40 50 60 70
BLANCHING TIME/SEC 
 
 
Figure 6: Effect of blanching time on the phytochemical profile of cloves 
 
 
alkaloids flavonoids saponins
14
12
10
8
6
4
2
0
0 10 20 30 40 50 60 70
BLANCHING TIME/SEC 
 
 
 
Figure 7: Effect of blanching time on the phytochemical of Bitter kola 
 69 
PHYTOCHEMICAL PROFILE 
PHYTOCHEMICAL PROFILE 
alkaloids flavonoids saponins
9
8
7
6
5
4
3
2
1
0
0 10 20 30 40 50 60 70
BLANCHING TIME/SEC 
 
Figure 8: Effect of blanching time on the phytochemical profile of Anise 
 
 
 
alkaloids flavonoids saponins
10
9
8
7
6
5
4
3
2
1
0
0 10 20 30 40 50 60 70
BLANCHING TIME/SEC 
 
 
 
Figure 9: Effect of blanching time on the phytochemical profile of fruit of Tetrapleura 
tetraptera 
 
 
 70 
PHYTOCHEMICL PROFILE PHYTOCHEMICAL  PROFILE 
alkaloids flavonoids saponins
7
6
5
4
3
2
1
0
0 10 20 30 40 50 60 70
BLANCHING TIME/SEC 
 
 
Figure 10: Effect of blanching time on the phytochemical profile of Alligator pepper 
 
 
alkloids flavonoids saponins
12
10
8
6
4
2
0
0 10 20 30 40 50 60 70
BLANCHING TIME/SEC 
 
 
Figure 11: Effect of blanching time on the phytochemical profile of calabash nutmeg 
 
 
There is a general trend of reduction of the levels of phytochemicals with time after blanching. 
However, in Figure 9, which is the fruit of Tetrapleura tetraptera, for its alkaloid content, after an 
initial decline, there was an increase in alkaloid levels, higher than the initial. Other reports have 
 71 
PHYTOCHEMICAL PROFILE PHYTOCHEMICAL PROFILE 
shown that the bound phenolic compounds might be more easily released upon heating as recorded for 
fruit of Tetrapleura tetraptera plant (Choi et al, 2006). It held steady until blanching time ended. 
These results are in line with the study conducted by Babalola and Opeyemi (2015). They reported a 
decrease in alkaloid, flavonoid and saponin contents between fresh product and blanched product.  
  
 72 
CHAPTER 5 
CONCLUSION AND RECOMMENDATIONS 
 
5.1 Conclusions 
The consumers interviewed mentioned certain indigenous foods that were considered by 
them to be functional foods. The foods considered to have nutraceutical properties included 
alligator pepper, calabash nutmeg, kola nut, fermented parkia biglobosa, anise, fruit of 
Tetrapleura tetraptera (prekese) and ashanti black pepper. 
 
Analysis of the above indigenous foods revealed appreciable amounts of phenolic 
compounds, phytochemicals (alkaloids, saponins and flavonoids) and antioxidants which are 
bioactive compounds responsible for the functionality of foods. The claim by those 
interviewed as having medicinal or curative properties is therefore justified, as these bioactive 
compounds isolated have been reported to be responsible for the prevention and curing of 
many diseases. 
 
Blanching showed that heating reduces the level of their bioactive compounds, that is, the 
phytochemicals, the total phenols, and the antioxidant scavenging potential. This provides the 
necessary knowledge about the harmful effect of heating on the nutraceutical properties of 
such foods. However, for some samples like fruit of Tetrapleura tetraptera (prekese), there 
was an increase in their alkaloid content after blanching. This could infer that to obtain the 
optimum benefits from the fruit of Tetrapleura tetraptera, it should be heated to activate the 
alkaloid levels. 
The study provided knowledge of these lesser known foods. This could encourage their 
consumption by consumers. 
 
 
 73 
5.2 Recommendations 
Based on the finding in this study further work is being recommended on the following: 
 
 Further studies should be carried out using a larger sample size and carried out in 
different parts of the country to be able to identify other lesser known indigenous 
functional foods.  
 Survey should be carried out in other institutions like schools, hospitals and churches 
where people are given education talks on some of these medicinal foods to know their 
level of knowledge on more lesser known foods. 
 Detailed chemical analysis of the selected food commodities to find other phytochemicals 
in them should be carried out to determine the specific nutraceuticals in those functional 
foods and the specific roles they play in disease prevention or cure. 
 The effect of cooking on other local functional foods should be determined since most 
local foods are cooked before eating. 
 There be should sensitization and education of the benefits of functional foods to promote 
consumption. 
                                   
 74 
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APPENDICES 
 
APPENDIX 1: INFORMED CONSENT FORM 
 
UNIVERSITY OF GHANA 
 
Protocol number 
OFFICE OF RESEARCH, INNOVATION AND DEVELOPMENT 
Ethics Committee for Basic and Applied Science (ECBAS) 
 
PROTOCOL CONSENT FORM 
 
Section A- BACKGROUND INFORMATION 
 
Title of Study: Evaluation of lesser known functional foods in Ghana, for their nutraceutical 
properties. 
Principal Investigator: Rose Yaa Amoah Mante 
Certified Protocol  
Number 
 
 
 
Section B– CONSENT TO PARTICIPATE IN RESEARCH 
 
General Information about Research 
 
 
You are invited to participate in a research study conducted by Ms. Rose Yaa Amoah Mante, 
who is a Masters student from the Nutrition and Food Science Department, University of 
Ghana, Legon. Ms. Rose Yaa Amoah Mante is conducting this study for her Masters 
dissertation. 
 
Your participation in this study is entirely voluntary. You should read the information below 
and ask questions about anything you do not understand, before deciding whether or not to 
participate. 
 
Purpose of the study 
The purpose of this study is to determine the phytochemical properties of some lesser known 
functional foods in Ghana, and evaluate them for their nutraceutical properties. It also seeks 
to find out, if there is a correlation between claims made about such foods in regards to their 
health benefits, and their nutraceutical properties. 
 
Procedures 
If you volunteer to participate in this study, we will ask you the following: 
Questions on what you know about functional foods 
Questions about these foods and what health benefits you derive from them 
 99 
Questions about how accessible these foods are to you and how often you eat them 
 
Benefits/Risk of the study 
There are no risks involved in participating in this study. 
Your participation will indirectly benefit your community and the nation as a whole by 
helping us to gather information that will be useful in assessing the health benefits of lesser 
known indigenous foods through their nutraceutical properties. 
 
Confidentiality 
We will not tell anybody what you say or give out any information about you. Only the 
people involved in this research will have access to your information. You will not be named 
in any oral or written reports and no individual reference will be made that could be linked to 
your information. 
 
 
Compensation 
There is no compensation and there is no cost to you for participating in this study. However, 
a small gift of a napkin, will be given to you in appreciation of your time. 
 
 Withdrawal from Study 
You can choose whether or not to be in this study. If you volunteer to be in this study, you 
may withdraw at any time without consequences of any kind. You may also refuse to answer 
any questions you do not want to answer. There is no penalty if you withdraw from the study 
and you will not lose any benefits to which you are otherwise entitled. 
 
 
Contact for Additional Information 
This statement should indicate whom to contact for answers to any questions about the 
research and whom to contact in case of research-related injury. 
Names, addresses and telephone numbers (including mobile numbers) should be made 
accessible to all participants. 
 
 
Section C- VOLUNTEER 
AGREEMENT 
 
"I have read or have had someone read all of the above, asked questions, received answers 
regarding participation in this study, and am willing to give consent for me, my child/ward to 
participate in this study. I will not have waived any of my rights by signing this consent form. 
Upon signing this consent form, I will receive a copy for my personal records." 
 
 
 
Name of Volunteer 
 
 
 
 
 
Signature or mark of volunteer Date 
 
 100 
If volunteers cannot read the form themselves, a witness must sign here: 
I was present while the benefits, risks and procedures were read to the volunteer. All 
questions were answered and the volunteer has agreed to take part in the research. 
 
 
Name of witness 
 
 
 
 
 
Signature of witness Date 
 
 
 
 
I certify that the nature and purpose, the potential benefits, and possible risks associated with 
participating in this research have been explained to the above individual. 
 
 
 
 
Name of Person who obtained Consent 
 
 
 
 
 
Signature of Person who obtained Consent Date 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 101 
APPENDIX 2: CONSUMER SURVEY QUESTIONNAIRE 
 
UNIVERSITY OF GHANA 
NUTRITION AND FOOD SCIENCE DEPARTMENT 
 
QUESTIONNAIRE ON THE CONSUMER PERCEPTION ON LESSER KNOWN 
FUNCTIONAL FOODS IN GHANA, THEIR LEVEL OF CONSUMPTION AND 
EASE AVAILABILITY 
 
 
Questionnaire No: …………………Contact: ………………………………  
Name of community……………………………………………………………………. 
 
This survey is being conducted on consumers‘ perception of functional foods, and their 
knowledge on their nutraceutical properties. Your participation in this survey is voluntary. 
Any personal information gathered from this survey will not be published. 
 
 
BACKGROUND INFORMATION 
 
1) SEX: 
2) Male 2) Female 
 
2) AGE: 
1) 15-25 2) 26-35 3) 36-45 4) 46-55 5) 56-65 
 
3) MARITAL STATUS: 
1) Single 2) Married 3) Divorced 4) Widowed 
 
4) RELIGION: 
1) Christianity 2) Islam        3) Traditionalist      4) Other please specify ……….......... 
 
5. ETHNICITY ………………………………………………… 
 
6. HOMETOWN (REGION): ………………………………………………………….... 
 
 
7) Have you heard of any local foods that have any medicinal properties? If yes, please list 
them. 
……………………………………………………………………………………… 
…………………………………………………………………………………….. 
 
8) Do you use such foods?  YES NO 
 102 
9. Why do you use these foods? ...................................................................................... 
……………………………………………………………………………………….. 
 
 
10) If yes, how long have you been using these foods? 
Daily 2) Twice a week   3) 3 or more times a week 4) Monthly 5) Occasionally 
 
11) Are these foods easily accessible to you in your community?   YES NO 
 
 
12) What are some of the health benefits you derive from these foods? 
Name of food Health benefits 
  
  
  
  
  
 
13) Are there any special conditions, for which you consume such foods?   YES NO  
 
14) If YES, what are they? …………………………………………………………….. 
………………………………………………………………………………………. 
 
15) Are there any possible side effects to these foods?  YES  NO 
 103