Cytotoxic Effects and Safety Profiles of Extracts of Active Medicinal Plants from South Africa

Plant derived antimicrobial compounds that have no or minimal toxicity to host cells are considered candidates for developing new antimicrobial drugs. Safety is therefore critical in the formulation of antimicrobials. The aim of this study was to investigate the cytotoxic effects of some South African medicinal plant extracts. The methanolic and aqueous extracts of nine South African medicinal plants were screened for cytotoxic activities against MAGI CC5+ cells using MTT assay.The nine plant extracts used in the MTT assayrevealed Herb 2 (Cyanthula inculata) as the most potent extract identified with activity of (1.4 Cc50values of 25.6 mg/ml) and induced over 50% of cell deaths, followed by herb 3 (Croton grattismus) and Herb 4 (Cassine trasvaalensis) with activity of (0.2 Cc50 values of3.7 mg/ml) each. The herbs that induced the least cell death, were herbs 5 (Capris tomentosa) and 7 (Hypoxis hemerocallidea), with the activity of (0.05 Cc50 values of 0.9 mg/ml) each. Of the nine plant extracts, Croton grattisimus and Lycium inerme 2(22%), exhibited minimal toxicity on MAGI cells and 7(77.8%) exhibited 50% toxicity. In a similar study 2(22%) of the methanolic extracts exhibited anti-HIV1 IIIB activities and against Mycobacterium tuberculosis (TB) only one medicinal plant extract (Lysium inerme) exhibited 29% activity. In this study, a systematic evaluation of cytotoxic activities of methanolic extracts made from tested medicinal plants showed minimal toxicity on cell lines. Therefore, such plants could serve as sources for natural antimicrobial therapeutic agents.