Antimicrobial and cytotoxic activities of fresh leaf extracts of Warburgia ugandensis

Abstract

Warburgia ugandensis Sprague (Canellaceae), is widely used by Traditional Health Practitioners in Eastern and Southern Africa for treatment of diseases and conditions associated with HIV/AIDS infections. The most commonly prescribed parts of the plant are usually barks and roots. The aim of this study was to investigate whether leaves of this plant have biological activities comparable to those of barks and roots. Fresh leaves of W. ugandensis were freeze-dried to complete dryness while another portion of the leaves from the same collection were air-dried under shade. Ethanolic extracts from the two differently dried leaves were tested for antimicrobial activity and for brine shrimp toxicity test. Ethanolic extract from the freeze-dried leaves exhibited both antibacterial activity against standard strains of Staphylococcus aureus, Escherichia coli, Vibrio cholerae, Bacillus cereus and antifungal activity against Candida albicans and Cryptococcus neoformans. The extract from the air-dried leaves showed similar antibacterial activity against the mentioned organisms but had no antifungal activity. However, both extracts exhibited comparable cytotoxic activity (95% CI), against brine shrimp larvae with reference to cyclophosphamide, a standard anticancer drug. Fresh leaves of W. ugandensis have shown to exhibit anticandida activity, a factor which substantiates their application as a traditional herbal remedy to complement treatment of fungal infections in HIV/AIDS patients. Further studies to establish constituents responsible for the exhibited antifungal activity are highly desirable.