In vitro Activity of Selected Ethiopian Medicinal Plants against Mycobacterium bovis and Mycobacterium tuberculosis
Tuberculosis is a major global public health problem causing ill-health in millions of the world’s population. The emergence of drug resistant strains is a major challenge to the tuberculosis control programme. Hence, there is an urgent need for the development of new drugs. Herbs could be potential source of novel antituberculosis drugs due to their special attribute as a large source of therapeutic phytochemicals. The objective of this study was to investigate the in vitro antimycobacterial activity of the 80% methanol extracts of Erythrina brucei stem bark, Euphorbia candelabrum latex, Otostegia integrifolia leaf, Rumex abyssinicus root, and the chloroform extract of Vernonia amygdalina leaf on in vitro cultures of strains of Mycobactrium bovis and Mycobactrium tuberculosis. The extracts were obtained through cold maceration and soxhlet extraction, and essential oil was obtained by hydrodistillation. Macrodilution technique was used for determining the minimum inhibitory concentration (MIC) values. The MIC of the chloroform extract of V. amygdalina was 10 mg/ml against the mycobacterial strains tested. The 80% methanol extracts of E. brucei, O. integrifolia and R. abyssinicus were effective against M. bovis only with MIC ranging from 12.50 - 25.00 mg/ml. The oil from O. integrifolia was not active against the tested strains. E. candelabrum and oil from O. integrifolia failed to show antimycobacterial activity. In conclusion, the leaf extract of V. amygdalina is proven to be the most active plant that could be a potential source for antimycobacterial agents for human and bovine tuberculosis. Erythrina brucei, O. integrifolia and R. abyssinicus displayed good antimycobacterial activity against M. bovis suggesting their potential to be sources of new compounds for bovine tuberculosis.