Evaluation of anti-microbial activity of some plants used by herbalists in central province, Kenya
Herbal medicine is the use of plants and plant-based products to treat or prevent diseases. The traditional use of plants as a source of medicine still plays a major role in primary health care in Kenya today. The information on the use of these plants is often passed on from one generation to another through folk knowledge. Many of the plants still in use have neither been documented nor tested so as to confirm their efficacy. Six plants from different families, selected on the basis of their traditional medicinal uses in Central Province to treat diseases of infectious nature, were evaluated for antimicrobial activity. The plants screened were Psidium guajava L., Persea americana Mill, Acacia mearnsh De Wild, Thunbergia alata Sims, Ocimum suave Willd and Periploca linearifolia Dill and Rich The aqueous, chloroform and methanol extracts of these plants were screened for their antifungal and antibacterial activities using the agar-well diffusion method. Four plants exhibited moderate activity against the tested microorganisms. Only one of the plants, Acacia mearnsii De Wild exhibited activity against the fungus. There was a significant difference in activity (p < 0.05) between the aqueous and the methanol extracts and between aqueous and chloroform extracts. There was however no significant difference in activity between the methanol and the chloroform extracts (p > 0.05). Extracts from A. mearnsii were the most active and exhibited moderate activity against ten out of the eleven microorganisms that were tested. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of the active extracts were determined using the micro-broth dilution method. The MICs of the methanol extracts ranged from 0.1953 to 100 mg/ml while those of the aqueous extracts ranged from 0.09 to 50 mg/mL The methanolic extract of P. linearifolia was fractionated using vacuum liquid chromatography and three active fractions obtained. Inhibition zones obtained on thin layer chromatogram (bioautoassay) revealed that the fractions obtained from this extract have more than one active component. These results are an important reference that confirms the use of the plants for treatment of bacterial and fungal diseases.
- MST-Zoological Sciences