In Vitro Antileishmanial Activities of Olea europaea, Kigelia africana, Terminalia mollis, Croton Macrostachyus and Bridella micrantha, Kenyan Medicinal Plants

Abstract

Leishmaniasis is a major public health problem globally. Visceral leishmaniasis is known to be fatal if left untreated, while cutaneous leishmaniasis is the most neglected. The first-line treatment of leishmaniasis is based on pentavalent antimonial drugs which are expensive, requiring inpatient treatment and toxic. The Plants containing active compounds against other protozoan diseases may offer alternatives against leishmania parasites. This study determined the in vitro antileishmanial activity of Olea europaea, Kigelia africana, Terminalia mollis, Croton macrostachyus and Bridella micrantha extracts. The plant samples were dried, pulverized into fine powders and extracted using ethanol at the Center for Traditional Medicine and Drugs Research, KEMRI. The in vitro assays were carried out at the Leishmania laboratory, Centre for Biotechnology Research and Development, KEMRI. In in- vitro assays the inhibitory concentrations (IC50) and Minimum Inhibition Concentration (MIC) on L. major promastigotes, percentage rates of macrophages infected by amastigotes and cytotoxicity on Vero cells were determined. For each parameter analyzed, differences among treatment groups exposed to different drugs were tested by logistic regression. Results showed that promastogote and amastigote growth inhibition was significantly affected by the crude extracts from the plants (P < 0.05) after 24 hours of exposure where the most effective drug was the standard drug (Amphotericin B) while among the crude extracts of the herbal drugs, T. mollis was the most effective against amastigote followed by C. macrostachyus while O. europaea was the least effective. Mammalian cell viability was significantly affected by the various test compounds (P < 0.05) after 24 hours exposure where % cell viability of herbal drugs, B. microstachyus, O. africana resulted to the most toxic effects by reducing the % cell viability to less than 50%. The study recommends the use of T. mollis in management of leishmaniasis in areas they occur. Further analysis of the active compounds that that affect efficacy of the plant extracts is advised.