In Vitro Assessment of Antibacterial Activity of Crude Propolis Extracts from Different Regions 0f Ghana

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2017-07

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University of Ghana

Abstract

Background: Antimicrobial resistance has reached a global dimension and threatens the health and the economy of many nations including developing countries like Ghana. This realization led several researchers to anticipate the forthcoming “end of the antibiotic era”. Studies have shown that medicinal plants and their derivatives still play an important role to cover the basic health needs in resource poor settings. One of such natural products endowed with bioactive compounds used in traditional medicine to treat diseases is propolis. Aim: This study aimed at evaluating the antimicrobial activity of crude propolis extracts from different regions in Ghana against selected multidrug resistant clinical bacterial isolates. Methodology: About 100 g of propolis samples were collected from each selected commercial beekeepers across the (10) ten regions in Ghana. Samples were collected between December 2015 and March 2016. Crude propolis extracts were prepared using petroleum ether (PET), chloroform (CH) and ethyl acetate (EA). Extracts were evaporated using rotary evaporator and dried in a dessicator. A concentration of 64 mg/ml of each crude extract was dissolved in 5% dimethyl sulfoxide (DMSO). Clinical isolates including drug resistant S. aureus, E. coli, P. aeruginosa and their control strains MRSA NCTC 25923, P. aeruginosa ATCC 27853 and E. coli NCTC 13351 were used in the study. Screening for antimicrobial activity of the propolis extracts were carried out using agar well diffusion method. Active crude propolis extracts were fractionated using chloroform (CH), ethyl acetate (EA) and petroleum ether (PET). The active fractions, chloroform fraction of Northern (CHNR), chloroform fraction of Eastern (CHER), Ethyl acetate fraction of Ashanti (EAAS), ethyl acetate of Volta (EAVT) and ethyl acetate fraction of Northern region (EANR) were also tested. The minimum inhibitory (MIC) and the minimum bactericidal concentration (MBC) of the active fractions were determined using the broth macro dilution method. Screening for phytochemicals was done using standard procedures and HPLC was used to analyze the active fractions. Results: Varying degrees of antimicrobial susceptibility pattern were observed from the screening for antimicrobial activities of propolis collected from the ten (10) region in Ghana. Pseudomonas aeruginosa isolated from clinical samples and its control strain Pseudomonas aeruginosa ATCC 27853 were more susceptible to Northern (NR), Eastern (ER), Ashanti (AS) and Volta region (VT) crude propolis extract. The average zone of inhibition ranges from 10 to 13mm for Pseudomonas aeruginosa (clinical) and 20 to 31mm for Pseudomonas aeruginosa ATCC 27853. S. aureus (clinical) and its control strain, MRSA ATCC 25923 were also found to be susceptible to NR, ER, AS and VT region propolis extracts with average zone of inhibition ranging from 19 to 24mm and 20 to 25mm respectively. Among the twelve propolis fractions tested, CHNR, CHER, EAER, EAVT and EAAS were identified as the active fractions with the average zone of inhibitions ranging from 0 to 22mm and 9 to 31mm against P. aeruginosa (clinical isolate) and its control, P. aeruginosa (ATTC 27853) respectively, among twelve propolis fractions tested. At the concentration of 0.01 to 16 mg/ml of each propolis fraction, there were no MIC activities. Activity became evident at the concentration range of 24 to 100 mg/ml. S. aureus (clinical isolate) was found to be susceptible to two (2) of the fractions (CHNR and EAVT) with MICs (MBCs) of 56 (64) and 24 (32) mg/ml respectively whilst its control strain MRSA ATCC 25923 was susceptible to four (4) of the fractions (CHER, EAER and EAVT and EAAS) with MICs (MBCs) ranging from 24 to 64 mg/ml. EAVT exhibited broad spectrum inhibitory and bactericidal effect against all six (6) test isolates (S. aureus, MRSA ATCC 25923, E. coli, ESBL E. coli NCTC 13351, P. aeruginosa and P. aeruginosa ATTC 27853). The MIC (MBCs) ranges from 24 (24) to 40 (40). Qualitative phytochemical analysis of active fractions indicates that terpenoids, phenols, flavonoids, alkaloids and saponins were present in all fractions. Moreover, HPLC analysis revealed closely related chromatograms have their active fractions with major peaks and retention time ranging from 26 to 39 minutes. Conclusion: Propolis extracts have inhibitory and bactericidal effects on clinical S. aureus and P. aeruginosa isolates. The observed antimicrobial activities in fractions can be attributed to the qualitatively identified phytochemicals. The broad spectrum activities of EAVT could be due to the activity of major peaks observed at retention time 29 and 35.5 minute. The EAVT fraction demonstrated the highest antimicrobial activities S. aureus and P. aeruginosa. The observed antimicrobial activities may be due to the presence of alkaloids, phenols, tannins, saponins terpenoids and flavonoids.

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Antibacterial, Propolis, Medicinal Plants

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