An assessment on anti-TB activity of the root extracts

Abstract

Boris Graf and Naftali Mboya

World Health Organization studies have demonstrated that 80% of the world’s population depends on medicinal plants for their primary health care. This has prompted increased efforts to the adoption and integration of herbal practices in health systems. This study soughts to answer the question whether Piliostigma thonningii has antitubercular, antibacterial, antifungal and cytotoxic activity. Antimicrobial activity was investigated by disc diffusion and micro dilution techniques. Antituberculous activity was investigated using the BACTEC MGIT 960 system while cytotoxicity was evaluated by 3-(4, 5- dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay on Vero cells. Phytochemicals were profiled using standard chemical procedures. A major output of our study is the methanolic fractions which yielded the best antituberculous activity (minimum inhibitory concentration [MIC] of 12.5 µg/ml), the highest antibacterial activity with zones of inhibition of 20.3 mm and MIC of 31.25 µg/ml (Staphylococcus aureus), 18.3 mm and MIC of 62.5 µg/ml (Methicillin Resistant S. Aureus, MRSA), 14 mm and MIC of 125 µg/ml (Escherichia coli), 13.3 mm and MIC of 31.25 (Shigella sonnei) and 13 mm against (Candida albicans), all within the acceptable toxicity limit (CC50 >500 µg/ml). The activity could be attributed to various phytochemicals that tested positive especially terpenoids. Important is its high activity against MRSA, S. aureus, E. coli, S. sonnei, C. albicans and Mycobacterium tuberculosis which are health challenge due to drug resistance and sources of community and nosocomial infections. To the best of our knowledge, this is the first report exploring the antituberculous activity of P. thonningii and thence a major addition in search of new safe antituberculous drug leads.