Evaluation of Antimicrobial activity of some plants used by traditional activity of some plants used by traditional healers for treatment of microbial infections in Kakamega District: Kenya
Makhatsa, Wenslaus Luvonga
MetadataShow full item record
Resistance to drugs especially antibiotics has become a major challenge facing the medical fraternity today. Most antibiotics that were once effective against pathogenic micro-organisms have now been rendered ineffective owing to resistance developed by these pathogens. This scenario has been complicated by the emergence of HIV/AIDS, which renders the victims immuno-compromised, and open to opportunistic infections. At the same time, most of the African population lives below the poverty line and cannot afford the expensive conventional medicines. These challenges call for renewed strategies on treatment, especially in the development of new antimicrobials. According to the World Health Organization (WHO), medicinal plants can provide the best alternative source to obtain a variety of drugs. Therefore there is need to investigate such plants in order to understand better their properties, safety and efficiency. Renewed interest in plant antimicrobials has also been prompted by the rapid rate of extinction of plant species owing to overharvesting and deforestation. In this study, some 18 plant species used as herbal medicine in Kakamega district were collected and authenticated at the East African Herbarium where voucher specimens are deposited. The plants were soxhlet extracted at the Kenya Medical Research Institute with petroleum ether, dichloromethane and methanol. Total extraction with water was also performed and all extracts screened at 1 g/ml against the organisms such as Escherischia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pneumoniae, Candida albicans, Candida parapsilosis, Microsporum gypseum and Trichophyton mentagrophyte by disc diffusion method. MIC tests by agar dilution method were performed on the active extracts at concentration range 0.5 - 0.004 g/ml. MBC and MFC tests were performed on the most active water extracts. Extracts of 6 plants with the highest activity were screened for phytochemicals using methods by Harborne. Of the 144 preliminary tests performed on all the water extracts, activity (inhibition zone >9 mm) was recorded in 44 cases as compared to 35 for methanol, 16 for dichloromethane and 4 for petroleum ether. Entada abyssinica water extract had the widest range of activity, with inhibitions against 7 of the 8 test organisms. However, the aqueous extract of Warbugia ugandensis was most inhibitory with MIC (≤ 12.5 X 103 μg/ml) against 7 (85%) of the 8 tested organisms. Entada abyssinica water extract had the broadest spectrum of bactericidal activity, with MBC (≤50 X 103 μg/ml) against 3 (75%) of the 4 tested bacteria. Only W. ugandensis water extract was fungicidal (MFC ≤50 X 103 μg/ml), with activities against C. parapsilosis and M. gypseum. These activities were not significantly different when compared with ketoconazole (P = 0.217). Phytochemical screening of E. abyssinica, W. ugandensis, N. macrocalyx, Albizia coriaria, Rhamnus prinoides and Albizia amara extracts revealed differences in the presence and abundance of alkaloids, phenolics, terpenoids, anthraquinones, flavonoids and saponins. Phenolics were most abundant and widespread, while anthraquinones were least abundant. Influence of these phytocompounds on the activities of the named plants varied. The ability by some of the plant extracts to inhibit microorganisms that have proved resistant to conventional medicine confirms the therapeutic potential that such plants hold, and the need to incorporate them into our healthcare systems, as well as conserving them.