ANTIBACTERIAL ACTIVITIES OF COMPOUNDS ISOLATED FROM SELECTED MEDICINAL PLANTS FROM NANDI COUNTY, KENYA

Abstract

Microbial infections are becoming a major public health problem due to the emergence of multi-drug resistant bacterial strains. Traditional healers have long used plants to treat bacterial infections. Globally, 80% of the people depend on traditional medicine as primary health care to treat different human ailments. Hence, there is an increased interest in ethno pharmacological approaches to identify compounds from plants that can be used to treat bacterial infections. However, the efficacy of most of these plant extracts and their compounds have not been determined. Questionnaires were used to ascetain plants that are used to treat bacterial infections and disesases. Fresh plant parts were collected from the field, dried and the extracts obtained using methanol. The extracts were screened for antibacterial activities against selected strains of bacteria using disc diffusion and broth microdilution methods. Active plant extracts were further used for isolation of compounds and to determined the antibacterial activities of crude and isolated compounds. Bioguided fraction isolation using column chromatography was employed to isolate compounds. Antibacterial activities of the isolated compounds was determined as indicated above for plant extracts. Structural elucidation of the bioactive compoundsn was done using nuclear magnetic resonance (NMR). Thirty three (33) medicinal plants distributed within 24 botanical families were found to be used against bacterial infections. Majority of medicinal plants were used to treat pneumonia 11 (33.3%), wounds 10 (30.3%) and diarrhea10 (30.3%), followed by skin diseases 9 (27.3%). Other remedies used fewer plants species. Seventeen (17) medicinal plants were screened for antibacterial activities basing on the frequency of their use. The extracts from O. rochetiana, A. lahai, L. calastachys and C. myricoides were active against 60% of the test microorganisms and were considered for further tests. Ethyl acetate extracts (EAE) were the most active extracts from all the the plant extract selected except hexane (HE) extracts of L. calastachys. Antibacterial activities of fractions from active successive extracts were determined. Antibacterial activities of O. rochetiana and A. lahai were the most active against majority of bacteria with highest inhibition zone of 14 mm against MR. S. aureus.