Hindawi
Journal of Chemistry
Volume 2020, Article ID 1608341, 8 pages
https://doi.org/10.1155/2020/1608341
Research Article
Vitamin Analysis, Trace Elements Content, and Their
Extractabilities in Tetrapleura tetraptera
Prince Oteng ,1,2 John K. Otchere,2 Stephen Adusei,2,3 Richard Q. Mensah,2,4
and Emmanuel Tei-Mensah2,5
1Department of Chemistry, University of Cape Coast, Cape Coast, Ghana
2Department of Laboratory Technology, University of Cape Coast, Cape Coast, Ghana
3Department of Environmental Science, University of Cape Coast, Cape Coast, Ghana
4Department of Biomedical Engineering, University of Ghana, Legon, Accra, Ghana
5Department of Food and Postharvest Technology, Koforidua Technical University, Koforidua, Ghana
Correspondence should be addressed to Prince Oteng; otengprince0508@gmail.com
Received 16 July 2019; Accepted 21 December 2019; Published 11 January 2020
Academic Editor: Isabel Mafra
Copyright © 2020 Prince Oteng et al. +is is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Tetrapleura tetraptera is widely cherished in African traditional homes because of its alleged therapeutic and nutritional
properties.+is present study aimed at determining the levels of vitamin A, C, E, and beta-carotene and trace element (Fe, Cu,Mn,
Co, Se, and Zn) concentrations and their extractabilities in the pulp, seeds, and whole fruit (mixture of pulp and seeds) of T.
tetraptera. +e total trace element concentration of Fe, Cu, Co, Mn, and Zn and their extractabilities (%) were determined using
flame atomic absorption spectrometer (FAAS), whereas UV-VIS spectrophotometer was used to determine selenium con-
centration. +e trace element content (mg/kg) based on dry weight in the pulp, seeds, and whole fruit was Fe (162.00± 7.14,
115.00± 12.00, and 154.00± 25.20, respectively), Zn (31.60± 4.77, 43.40± 5.29, and 41.50± 8.97, respectively), Cu (16.10± 4.98,
11.90± 8.40, and 17.20± 14.50, respectively), Mn (55.30± 2.41, 156.00± 10.20, and 122.00± 5.29, respectively), Co (38.10± 6.40,
21.10± 7.15, and 44.00± 14.90, respectively), and Se (1.49± 0.17, 2.43± 0.28, and 2.97± 0.27 μg/g, respectively). +e mineral
extractabilities (%) in the pulp, seeds, and whole fruit of T. tetraptera were established to be in the order
Co>Zn> Fe>Cu> Se>Mn. Also, the chromatographic method (HPLC) was used to evaluate vitamin E concentration, and
vitamin C and concentration of beta-carotene were calculated from the obtained concentration of vitamin A using a conversion
factor by the titrimetric method. From the results of vitamin analysis, a significant difference (p< 0.05) was observed among the
pulp, seeds, and whole fruit for vitamin C and E. However, no significant difference (p> 0.05) was perceived among these plant
parts for vitamin A and beta-carotene. +is study has therefore revealed that the pulp, seeds, and whole fruit of T. tetraptera
contain varying concentrations of vitamins and trace elements and has given many vital insights on which part of T. tetraptera to
consume, as concentrations of these nutrients differ in the discrete parts of the fruit.
1. Introduction particularly in Western African countries such as Ghana,
Nigeria, and Cameroon. +e dry powdered fruit is used in
Ghana is rich in many important tropical plants and one of soap making to increase the antimicrobial activity and
such plants is Tetrapleura tetraptera, locally known as improve the foaming ability of soaps [2]. +is has con-
“Prekese.” It is highly valued in Ghana and beyond for its tributed to the enormous use of the T. tetraptera fruits in
nutritional and medicinal properties. +e T. tetraptera plant many African homes.+e T. tetraptera fruits are also used in
is a leguminous multipurpose tree that belongs to the family the cooking of soup or porridge for nursing mothers to
Fabaceae, which can growth to a height of 20–35m with a eliminate postpartum contraction, aid in lactation, and
girth of 1.5–3m [1]. It is a deciduous plant which is usually manage convulsions, leprosy, inflammation, and rheuma-
located in the lowland rainforest of tropical Africa, tism [3, 4]. +e fruits have been reported to have strong
2 Journal of Chemistry
molluscidal, antimicrobial, anticonvulsant, and insecticidal Beta-carotene is also a form of natural substance that
activities [5] and are important compounds for the man- gives colour to plants (pigment). Yellow and orange fruits
agement of a collection of ailments including diabetes, ar- and vegetables get their rich hue from beta-carotene. Beta-
thritis, malaria, fever, and hypertension [6]. Tetrapleura carotene is the most abundant carotenoid that can be
tetraptera is believed to be nutritious. converted to vitamin A in the human body.+emain dietary
Trace elements are inorganic substances that are source of vitamin A, which is significant for normal growth,
present in all body tissues and fluids, and their presence is development, vision, and immune system function, is beta-
vital for the maintenance of certain physicochemical pro- carotene [15]. Studies have revealed the presence of vitamins
cesses that are essential to life. Although they do not and trace elements in the pulp and sometimes in the seeds of
provide energy, they have significant roles in many ac- T. tetraptera. However, less data has been provided on the
tivities in the body [7]. Generally, they are needed by the whole fruit (pulp and seeds). In this study, we determined
body for normal growth, development, and physiology. vitamins level, trace element concentrations, and their ex-
Some minerals such as Ca, Mg, Na, K, P, and S are needed tractabilities in the pulp, seeds, and whole fruit of T. tet-
in larger amounts to perform essential functions of life [8]. raptera. It is expected that this study will contribute to
However, other minerals are required in smaller amounts, further understanding of trace element extractability and
and these are referred to as trace elements, which include nutritional composition of T. tetraptera fruit.
Fe, Cu, Mn, Co, F, I, and Zn. Trace elements are very
important in the health and disease states of humans and 2. Materials and Methods
domestic animals. For example, one trace element of
crucial importance to people with HIV is selenium, which 2.1. Sample Collection. Matured Tetrapleura tetraptera pods
is an antioxidant that increases immune function [9]. In- were purchased randomly from different vendors at the
adequate intake of these trace elements or metals can lead Kotokroba market in Cape Coast, Ghana. +e samples were
to symptoms of nutritional deficiency. However, high in- kept in paper bags and transported to the laboratory for
take of trace elements beyond recommended limits may processing.
lead to metal poisoning, neurological disorders, and many
others [10].
Mineral extractability (%) is an index of bioavailability 2.2. Sample Preparation. +e samples were washed with
that represents the amount of minerals that would be distilled water and sun-dried. +e dried pods were cut open
available for absorption into the body. Mineral extractability to separate the seeds from the pulp. +e obtained pulp and
is complicated and dependent upon a number of factors seeds were milled into fine powders, while the whole fruit
related to mineral solubility and absorbability. +e fraction was obtained by milling the pulp and seeds together. +e
of an ingested trace mineral that can be used by the organism powdered samples were packaged into separate airtight
is of major importance, and several factors influence its ziploc bags for storage pending extraction and analysis.
availability: chemical state of the element, its release from the
food matrix, possible interaction with other trace elements,
presence of suppressors and cofactor formation of stable 2.3. Sample Extraction
compounds that are slowly metabolized, and so on [11]. 2.3.1. Extraction of Water-Soluble Vitamin (Vitamin C).
Absorption of one mineral can reduce the absorption of Vitamin C was extracted according to a modification of the
another mineral. For example, there are absorptive inter- method by [16]. Ten grams of T. tetraptera powder was
actions between iron, zinc, and copper and between calcium homogenized with an extraction solution containing 0.3M
and magnesium [12]. +ese interactions have therapeutic metaphosphoric acid and 1.4M acetic acid. +e mixture was
uses; oral zinc supplementation inhibits copper absorption transferred into a conical flask and agitated at 10,000 rev-
in patients with Wilson’s disease who have excessive tissue olutions per minute (rpm) for 15 minutes and then filtered
copper loads [12]. through a Whatman number 4 filter paper to get the extract.
Vitamins are organic compounds that are needed in Extraction was carried out in triplicate.
smaller amount for the normal growth and development of
an organism. Vitamins cannot be synthesized by organisms,
and thus they have to be obtained from ingested foods. 2.3.2. Extraction of Fat-Soluble Vitamins (Vitamin A, E, and
Ascorbic acid, also called vitamin C, plays a role in healing of Beta-Carotene). Vitamin A, E, and beta-carotene were
wounds in humans. Vitamin C is a water-soluble vitamin extracted by adding 10 g of homogenized T. tetraptera
that is available in many fruits, vegetables, and dietary powder to 1 g pyrogallic acid, 70mL of ethanol, and 30mL
supplements. Humans cannot synthesize vitamin C en- (50%) potassium hydroxide. +e mixture was stirred and
dogenously; therefore, it is an important food component refluxed for 40 minutes at 50°C with a water bath. +e
[13]. Vitamin E, on the other hand, is a collective name of a sample was extracted in triplicate using ether. +e extract
group of fat-soluble vitamins that has some distinctive obtained was neutralized using double-distilled water, which
antioxidant activities [14]. Naturally occurring vitamin E was then dehydrated using anhydrous sodium sulphate. +e
appears in eight chemical forms, viz, alpha-, beta-, gamma-, extract was further concentrated at 50°C using a water bath,
and delta-tocopherol and alpha-, beta-, gamma-, and delta- diluted to 10mL with methanol, and then filtered through a
tocotrienol [14]. 0.45 μm membrane [17, 18].
Journal of Chemistry 3
2.4. Vitamin A, C, E, and Beta-Carotene Determinations used eluent. +e wavelength for the UV detection of vitamin
E was 290 nm.+e separation of the vitamin was on the basis
2.4.1. Quantification of Vitamin A Using the Spectrophoto- of isocratic elution and maintenance of the solvent flow rate
metric Method. Two milliliters (2mL) of the extracted at 1.0mL/min. +e identification of vitamin E was achieved
sample were measured into a test tube with a tight stopper by comparing the retention times to that of authentic
and labelled as test tube 1. One milliliter of potassium standards [22].
hydroxide solution (1M solution of KOH in 90% ethanol)
was added to the liquid in the test tube 1 and shaken vig-
orously for 1 minute. +e test tube 1 was heated in a water 2.4.4. Quantification of Beta-Carotene Content. Based on the
bath at 60°C for 20 minutes and then cooled using cold knowledge that beta-carotene is a provitamin of vitamin A,
water. Two milliliters of xylene was added to the cooled the quantity of beta-carotene was determined from the ob-
solution and shaken for 1 minute and then centrifuged at tained concentration of vitamin A (retinol). +us, vitamin A
1500 rpm for 10 minutes. +e supernatant (upper layer) was was converted to beta-carotene by first converting the con-
collected and transferred into another test tube labelled test centration of vitamin A in the samples to mass of vitamin A
tube II. +e extract was analyzed by measuring the absor- using the equation: Mass� concentration× volume×molar
bance at a wavelength of 335 nm against xylene and named mass of retinol. +e mass of vitamin A obtained was in
A1. +e extract in the test tube labelled II was exposed to UV milligrams, which was converted to the international unit of
light for 30 minutes, and the absorbance was measured and retinol. +e values of retinol obtained in international units
named A2.+e concentration of vitamin A in the extract was were then converted to composition beta-carotene through
determined by applying the formula Cx � (A1 − A2)× 22.23, multiplication of the values by 0.6 μg beta-carotene. +e
where the value 22.23 was obtained from the absorbance of concentration of beta-carotene was then determined by the
the absorption coefficient of 1% solution of retinol in xylene relation: Concentration of beta-carotene�mass of beta-car-
at 335 nm in a measuring cuvette of about 1 cm thickness otene/volume of extract×molar mass of beta-carotene [23].
[19].
2.5. Trace Elements Analysis
2.4.2. Quantification of Vitamin CUsingModified Iodometric
Titration. Vitamin C in the extracts was quantified using the 2.5.1. Determination of Fe, Cu, Mn, Co, and Zn. All glass-
iodometric titration method. In the titrimetric method, a wares were washed neatly in a detergent, soaked in 10%
standard solution of sodium thiosulphate (Na S O ) of nitric acid for 4 hours and finally rinsed with deionized water2 2 3
concentration 0.05M and a starch indicator were used. A before use. Analytical reagent-grade chemicals and distilled
burette was filled with 0.05M sodium thiosulphate and ti- water were used for the preparation of all the solutions that
trated against the analyte (10mL of extract, 10mL of iodine were needed. Powdered samples of T. tetraptera pulp, seeds,
solution, and 3 drops of starch indicator) until the colour and whole fruit were digested according to a method de-
changed from blue-black to colourless. +e volume of the scribed by [24]. +ree powdered samples, 0.5 g each, were
thiosulphate that resulted in the colour change was observed weighed using the analytical balance and transferred into
and recorded. To know the concentration of the iodine clean well-labelled beakers. Five milliliters of 65%HNO3 was
solution and the amount of ascorbic acid in the sample that added to each of the beakers containing the samples, and the
reacted with the iodine, the thiosulphate solution was ti- solution mixtures were boiled gently for 30 minutes after
trated against a blank, which was composed of distilled which they were allowed to cool and 2.5mL of 70% HClO4
water, iodine solution, and starch indicator. With the help of was also added to the beakers. +e solution mixtures were
stoichiometry, the amount as well as the concentration of gently boiled until dense white fumes appeared.+e solution
ascorbic acid was determined [20]. mixtures were allowed to cool, and 10mL of distilled water
was added to each beaker, followed by further boiling until
IO−3 + 8I
−
+ 6H+⇌ 3I−3 + 3H2O (1) the fumes were totally released. +e prepared digest solu-
tions were diluted to the 50mL mark and transferred into
I−3 + 2S O
2−
2 3 ⇌ 3I
− 2−
+ S4O6 (2) clean plastic containers for the elemental analysis using the
flame atomic absorption spectrometer.
H O − − +2 + I3 + C6H8O6⇌C6H8O6 + 3I3 + 3H (3)
+e abovementioned equations show the preparation of 2.5.2. Determination of Selenium (Se). Analytical reagent-
triiodide and the reaction between triiodide and thio- grade chemicals and distilled water were used for the prep-
sulphate and triiodide and ascorbic acid, respectively [21]. aration of all the solutions that were needed. Selenium in the
powdered samples was determined using a spectrophotom-
eter according to a method described by [25]. One gram, each
2.4.3. Quantification of Vitamin E Using HPLC. +e reverse- of the pulp, seeds, and whole fruit, was weighed into clean
phase (RP) HPLC analysis of vitamin E was performed on an beakers and boiled gently with 10mL of 65% HNO3 for 20
Agilent 1100 series HPLC system with a diode array de- minutes. Half a milliliter (0.5mL) of 70% perchloric acid was
tector. In the quantification of vitamins E, the column used added to each of the sample solutions after cooling. Heating
was Agilent eclipse XDB-C18, with methanol as the only was continued for another 10 minutes and then allowed to
4 Journal of Chemistry
cool. Ten milliliters of distilled water and 5mL of 2M HCl 3. Results and Discussion
were added to each of the cooled residues, and this was boiled
for 10 minutes to convert Se (VI) to Se (IV). +e sample 3.1. VitaminA, C, E, andBeta-CaroteneContent. For normal
solutions were neutralized using dilute sodium hydroxide growth and development of the human body, vitamins are
solution and diluted to 25mL by addition of 5mL of 5% very important. Table 1 displays the various concentrations
EDTA. +ree milliliters each of these sample solutions were of vitamins (A, C, and E) and beta-carotene in the samples
analyzed for selenium using the spectrophotometer. (pulp, seeds, and whole fruit) after analysis. +ese results
obtained show that the concentrations of vitamin E and C
appear to be relatively high, whereas those of vitamin A and
2.6. Preparation of Selenium Standard Solution. One mg/mL beta-carotene were low. +e high levels of vitamin E and C
of standard selenium (IV) solution was prepared. Working recorded agree with the findings of Uyo et al. [4] in the same
standard solutions were prepared from dilutions of the plant species.
standard solution. +ionin (TN) solution (0.01%, w/v) was +e concentration of vitamin E was estimated to be in
prepared in 100mL of distilled water containing 1mL of 2M the order of seeds> pulp>whole fruit. +is finding implies
HCl. +ree milliliters each of the sample solutions were that vitamin E in the seeds and pulp, when mixed together,
pipetted into clean 10mL calibrated beakers. Two milliliters have an effect on the other. To support this assertion, the
of 1% potassium iodide solution and 1mL of 1M HCl were concentration of vitamin E in the whole fruit appeared to be
added to the pipetted sample solutions and gently shaken lower than that of the seeds or pulp only. +e concentration
until the appearance of yellow colour, indicating the lib- of vitamin C was also found to be higher in the seeds,
eration of iodine. Half a milliliter (0.5mL) of 0.01% TN followed by whole fruit and then the pulp. According to Lee
solution was added to the solution mixtures and shaken for 2 and Kader [27], long storage condition is a factor that
minutes. +e contents were then diluted to the 10mL mark contributes to the loss of vitamin C available in plants. Since
with distilled water and mixed well. +e absorbances of the the seeds of T. tetraptera are located in the fruits and are
resulting solutions were measured at 600 nm against a blank shielded from environmental and storage conditions that
solution that was prepared by replacing the analyte (sele- may result in vitamin C decrement, the seeds are less likely to
nium) solution with distilled water. +e absorbance corre- lose vitamin C than the pulp or whole fruit that are directly
sponding to the bleached colour, which in turn corresponds exposed to the environment, hence the abovementioned
to the analyte (selenium) concentration, was obtained by result for vitamin C.
subtracting the absorbance of the blank solution from that of +e composition of vitamin A was found to be higher in
the test solution. +e amount of the selenium present in the the seeds than in the pulp or whole fruit, as shown in
volume taken was calculated from the calibration graph [25]. Table 1, since oil is known to be present in large amounts in
the seeds and occasionally in the fleshy parts of fruits of
plants. Vitamin A is a fat-soluble vitamin; thus, its high
2.7. Trace Elements Extractabilities. +e extractabilities of the concentration in the seeds of T. tetraptera may be attrib-
trace elements were determined according to the method uted to the fact that vitamin A will readily be available in
described by [26]. Half a gram (0.5 g) each of the three the seeds because of the high amount of oil present in the
powdered samples (pulp, seeds and whole fruit) were weighed seeds than the pulp or whole fruit. +e concentration of
using the analytical balance and transferred into clean labelled beta-carotene was also established to be higher in the seeds
tubes with caps. +e weighed T. tetraptera samples were than the pulp or whole fruit. However, there was no sig-
extracted with 0.03M HCl (the approximate concentration of nificant difference between the three variables under study.
the acid found in the human stomach) by shaking at 37°C for +e insignificance among the values obtained for the seeds,
3 hours. +e clear extracts obtained after filtration with filter pulp, and whole fruit implies that there is no substantial
paper were oven-dried at 100°C and wet acid-digested using a effect of one concentration on the other of beta-carotene.
nitric/perchloric acid mixture. +e amounts of trace elements +us, whether the pulp or seeds are used separately or
Fe, Cu, Mn, Co, and Zn in the acid digest were determined mixed together, the concentration of beta-carotene ob-
using the flame atomic absorption spectrometer. +e ex- tained will be virtually the same. +e presence of these
tractability of Se in the powdered samples was determined vitamins and beta-carotene in the fruit of T. tetraptera
using a spectrophotometer. supports the use of the plant in many parts of Africa,
particularly in Ghana [28].
2.8. Statistical Analysis. +e data obtained after the exper-
iment were analyzed using GraphPad Prism version 5.01 3.2. Trace Elements Composition. +e pulp, seeds, and whole
statistical package. +e results were expressed as mean- fruit of T. tetraptera were found to contain varying amounts
± standard deviation and presented using tables. +e of trace elements that are essential in human nutrition.
resulting data from the study were subjected to Analysis of Table 2 shows the important variations of trace elements
Variance (ANOVA) using Tukey: compared all pairs of concentration in the fruit of T. tetraptera. +e mean con-
columns, at 95% confidence level. +e T-test statistical tool centrations of trace elements were estimated to be in the
was also used to compare the total trace elements and their order of Fe>Mn>Zn>Co>Cu> Se. +is indicates that T.
extractabilities at 95% confidence level. tetraptera has a high amount of Fe, Mn, Zn, Co, and Cu in
Journal of Chemistry 5
Table 1: Vitamin A, C, and E and beta-carotene composition in pulp, seeds, and whole fruit of T. tetraptera.
Attribute
Sample Vitamin A (mg/g) Vitamin C (mg/g) Vitamin E (mg/g) Beta-carotene (mg/g)
Pulp 0.00319± 0.0009a 0.242± 0.05b 0.923± 0.025b 0.0068± 0.002a
Seed 0.00848± 0.0030a 0.880± 0.18a 2.617± 0.201a 0.0168± 0.006a
W. fruit 0.00679± 0.0006a 0.411± 0.02b 0.013± 0.005c 0.0136± 0.001a
Sig. level 0.1814 ns 0.0027∗∗ <0.0001∗∗∗ 0.0851 ns
ns�not significant (i.e., p> 0.05); W. fruit�whole fruit; ∗∗ very significant (i.e., p< 0.01); ∗∗ extremely significant (i.e., p< 0.001); and Sig. Lev-
el� significance level. Means in a column with the same letter superscripts are not significantly different (p> 0.05), whereas means with different letter
superscripts are significantly different (p< 0.05).
the fruit, which is comparable with the data reported by source of Zn, supporting the native use of the fruit to treat
Akin-Idowu et al. [29]. diarrhoea and mental fatigue [34].
3.2.1. Iron (Fe) Concentration. +e iron concentration (mg/ 3.2.3. Copper (Cu) Concentration. +e copper content (mg/
kg) in the pulp, seeds, and whole fruit of T. tetraptera was kg) of T. tetraptera pulp, seeds, and whole fruit was also
determined to be 162.00± 7.14, 115.00± 12.00, and determined to be 16.10± 4.98, 11.90± 8.40, and
154.00± 25.20, respectively (Table 2), resulting in a mean of 17.20± 14.50, respectively, as shown in Table 2.+ere was no
143.67mg/kg. +e mean obtained was higher than that significant difference (p> 0.05) between the pulp, seeds, and
reported earlier by Abii and Amarachi [30] in T. tetraptera whole fruit. +e RDI for Cu is 2mg per day, and it is vital for
fruit. +e difference in concentrations may be as a result of iron metabolism, elastic tissue formation, skin and hair
the difference in iron content in the soil where the plants pigmentation, and other functions [8].
were located [31]. It was observed from Table 2 that there
was no significant difference (p> 0.05) between the pulp and
the whole fruit, as well as between the seeds and whole fruit. 3.2.4. Manganese (Mn) Concentration. From Table 2, the
However, there was a significant difference (p< 0.05) be- manganese concentration (mg/kg) in the pulp, seeds, and
tween the pulp and the seeds, which indicates a wide range of whole fruit of T. tetraptera was determined to be
iron content between the pulp and seeds as compared with 55.30± 2.41, 156.00± 10.20, and 122.00± 5.29, respectively.
the whole fruit. +ere was low iron content in the seeds Significant differences (p< 0.05) were observed between the
compared with the pulp because the plant has the ability to pulp, seeds, and whole fruit. +is may be due to the ability of
accumulate more iron in the pulp than in the seeds. Iron is a the plant to accumulate high manganese content in the fruit.
vital component of myoglobin, a protein that provides +e high manganese content in the seeds may be due to the
oxygen to the muscles. Fe is also important for growth, fact that manganese is required for the synthesis of chlo-
development, normal cellular functioning, and synthesis of rophyll and assimilation of nitrate and activates enzymes of
some hormones and connective tissue [32]. +e recom- fat biosynthesis [34]. +e mean concentration obtained was
mended daily intake (RDI) for Fe is 15mg per day, and the quite lower, but comparable with the Mn concentration
values obtained in this study indicate that T. tetraptera is a range in a study conducted by Akin-Idowu et al. [29], in
good source of iron. +is explains the use of the fruit by which Mn varied from 16.23mg/kg to 178.90mg/kg. +is
lactating mothers to regenerate lost blood [30]. may be attributed to the low concentration of manganese in
the soil, resulting in its low availability in the plant [32]. +e
RDI for Mn is 5mg per day [35], and it is essential for a
3.2.2. Zinc (Zn) Concentration. Zinc content (mg/kg) in the variety of metabolic processes, including those involved in
pulp, seeds, and whole fruit of T. tetraptera was determined energy metabolism, skeletal system development, and ner-
to be 31.60± 4.77, 43.40± 5.29, and 41.50± 8.97, respectively, vous system function and also serves as an antioxidant that
as presented in Table 2. Although there was no significant prevents cell damage due to free radicals [36].
difference (p> 0.05) between the pulp, seeds, and whole
fruit, as illustrated in Table 2, the values obtained were
observed to be higher as compared with a similar study by 3.2.5. Cobalt (Co) Concentration. Cobalt concentration
Akin-Idowu et al. [29], where a mean of 5.35mg/kg was (mg/kg) in the pulp, seeds, and whole fruit of T. tetraptera
recorded for the pulp and 5.45mg/kg for seeds. +e high samples was determined to be 38.10± 6.40, 21.10± 7.15, and
reported concentrations might be attributed to differences in 44.00± 14.90, respectively, as illustrated in Table 2. +ere
zinc content in the soil where the plants were situated. Zinc was no significant difference (p> 0.05) between the pulp,
is vital in wound healing, immune system function, pros- seeds, and whole fruit. Although there is no RDI for cobalt,
taglandin production, bone mineralization, proper thyroid an amount higher than 5mg per day is considered an
function, cognitive functions, fetal growth, blood clotting, overdose [37, 38]. Cobalt is an important cofactor of en-
and sperm production [33].+e RDI for Zn is 15mg per day, zymes involved in DNA biosynthesis, formation of neuro-
and the values obtained indicate that T. tetraptera is a good transmitters, and amino acid metabolism [39].
6 Journal of Chemistry
Table 2: Trace element composition in the fruit of Tetrapleura tetraptera.
Sample Fe (mg/kg) Zn (mg/kg) Cu (mg/kg) Mn (mg/kg) Co (mg/kg) Se (μg/g)
Pulp 162.00± 7.14a 31.60± 4.77a 16.10± 4.98a 55.30± 2.41a 38.10± 6.40a 1.49± 0.17a
Seeds 115.00± 12.00b 43.40± 5.29a 11.90± 8.40a 156.00± 10.20b 21.10± 7.15a 2.43± 0.28bc
W. fruit 154.00± 25.20ab 41.50± 8.97a 17.20± 14.50a 122.00± 5.29c 44.00± 14.90a 2.97± 0.27c
Mean 143.67 38.83 11.73 111.10 34.40 2.30
p value 0.0293 0.1396 0.7964 <0.0001 0.0766 0.0009
Note: W. fruit�whole fruit; values are means of triplicates± standard deviation. Means in a column with the same letter superscripts are not significantly
different (p> 0.05); means in a column with different letter superscripts are significantly different (p< 0.05).
Table 3: HCl-extractable trace elements composition in the fruit of Tetrapleura tetraptera.
Sample Fe (mg/kg) Zn (mg/kg) Cu (mg/kg) Mn (mg/kg) Co (mg/kg) Se (μg/g)
Pulp 101.00± 1.39a 22.60± 3.06a 10.30± 2.03a 40.80± 1.57a 27.70± 5.12a 1.00± 0.15a
Seeds 80.90± 2.45b 31.40± 1.52b 5.94± 3.05a 59.90± 4.97b 15.80± 2.45b 1.40± 0.12ab
W. fruit 95.30± 2.64c 31.70± 1.42bc 10.90± 7.02a 83.50± 3.10c 33.90± 3.57a 1.91± 0.42b
Mean 92.40 28.57 9.05 61.40 25.80 1.44
p value <0.0001 0.0031 0.4060 <0.0001 0.0034 0.0163
Note: W. fruit�whole fruit; values are means of triplicates± standard deviation. Means in a column with the same letter superscripts are not significantly
different (p> 0.05). Means in a column with different letter superscripts are significantly different (p< 0.05).
3.2.6. Selenium (Se) Concentration. Selenium concentration difference (p< 0.05) between the pulp, seeds, and whole fruit
(μg/g) in the pulp, seeds, and whole fruit of T. tetraptera for HCl-extractable trace elements, namely Fe and Mn.
samples was also determined to be 1.49± 0.17, 2.43± 0.28, Again, there was a significant difference (p< 0.05) between
and 2.97± 0.27, respectively, as displayed in Table 2. +ere the pulp and seeds, as well as pulp and whole fruit for HCl-
was a significant difference (p< 0.05) between the pulp and extractable Zn, but no significant difference (p> 0.05) was
seeds, as well as the whole fruit, but there was no significant noted between the seeds and whole fruit. +is may be as a
difference between the seeds and the whole fruit. +is is due result of absorptive interactions between iron, zinc, and
to the low concentration of selenium in the pulp as a result of copper. Zinc inhibits copper absorption [12]. +ere was also
the inability of the plant to accumulate selenium in the pulp. no significant difference (p> 0.05) between the pulp, seeds,
Selenium content was found to present the lowest levels of and whole fruit for the HCl-extractable Cu. +is indicated
the trace elements determined. However, it was higher than that the amounts of Cu extracted at the various sections of
the concentration obtained in a study conducted by Arinola the fruit were statistically similar. Trace element extract-
et al. [40], in which 50.0 μg/100 g of Se was reported. +e ability is complicated and dependent on a number of factors
high selenium concentration may be due to high availability related to mineral solubility and absorbability in the body.
of selenium in the soil where the plant was found. +e RDI +e poor mineral extractabilities may be as a result of the
for Se in children and adults is 20 μg/day and 55 μg/day, ability of some minerals to inhibit the absorption of others.
respectively [41]. Selenium is known to be involved in For example, there are absorptive interactions between
several major metabolic pathways, including thyroid hor- calcium and magnesium and also between iron, zinc, and
mone metabolism, antioxidant defense systems, and im- copper [45].
mune function [42].
In this study, higher trace element concentrations were
obtained as compared with earlier studies. +is is due to the 3.4. Extractabilities (%) of Trace Elements. +e extractabil-
dependence of the plant on the availability of elements in the ities of trace elements in the various sections of the fruit were
plant’s growth media (soil, nutrient solution, and water) also determined as displayed in Table 4. No significant
[32]. +us, higher trace element concentrations in a soil may difference (p> 0.05) was observed in the pulp, seeds, and
reflect in higher trace element accumulations in a plant. +e whole fruit for trace elements Fe, Zn, Cu, Co, and Se. +is
bioavailability of trace minerals in plants is also dependent indicates that the extractabilities of these trace elements in
on the plant’s ability to absorb trace minerals and the rate at the pulp, seeds, and whole fruit were statistically similar.
which the roots absorb them [43, 44]. However, there was a significant difference (p< 0.05) be-tween the pulp, seeds, and whole fruits for manganese. +is
was due to lower HCl-extractable Mn in the seeds, resulting
3.3. HCl-Extractable Trace Elements. +e HCl-extractable in low manganese extractability (38.30± 1.39) as compared
trace elements were determined according to a method with the high extractabilities in the pulp (73.70± 2.91) and
described by Suha and Babiker [26]. +e method was the whole fruit (68.70± 3.72). +e low manganese extract-
employed to determine how much of total trace element ability was as a result of absorptive interaction between Mn
would be absorbed into the body. Table 3 shows the HCl- and Fe. High iron contents suppress the extraction of
extractable trace elements composition in T. tetraptera fruit manganese [46, 47]. Mineral extractability in the body is
from which it can observed that there was a significant affected by inhibitory and/or accelerating factors such as
Journal of Chemistry 7
Table 4: Trace elements extractabilities (%) in the fruit of Tetrapleura tetraptera.
Sample Fe (mg/kg) Zn (mg/kg) Cu (mg/kg) Mn (mg/kg) Co (mg/kg) Se (μg/g)
Pulp 62.60± 3.75a 73.10± 17.80a 67.00± 23.00a 73.70± 2.91a 72.60± 1.37a 67.00± 3.99a
Seeds 70.80± 8.71a 72.80± 7.27a 56.80± 14.60a 38.30± 1.39b 79.50± 20.90a 58.00± 2.41a
W. fruit 62.90± 10.00a 78.90± 17.17a 71.10± 14.30a 68.70± 3.72c 80.70± 16.30a 63.70± 8.54a
Mean 65.43 74.93 64.97 60.23 77.60 62.90
p value 0.4102 0.8559 0.6206 <0.0001 0.7910 0.2170
Note: W. fruit�whole fruit; values are means of triplicates± standard deviation. Means in a column with the same letter superscripts are not significantly
different (p> 0.05). Means in a column with different letter superscripts are significantly different (p< 0.05).
phytates, fiber, ascorbic acid, and tannins as well as ab- [3] E. O. Nwaichi, “Effect of heat treatment on the antioxidant
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+e data used to support the findings of this study are artemissiadegatissina and rhayastrida and their relative me-
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+e authors declare that there are no conflicts of interest of thickening agents, based on soluble dietary fiber, on the
regarding the publication of this paper. availability of calcium, iron, and zinc from infant formulas,”
Nutrition, vol. 17, no. 7-8, pp. 614–618, 2001.
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