Antimicrobial activity of Ugandan Medicinal Plants

Different methods of traditional medicine are still used by local healers in lots of developing countries. For the specific situation of Uganda, there is little to no information on medicinal plant use by Karamojong healers. Moreover, even though there are some reports on pharmacology of Ugandan medicinal plants [1, 2], their antimicrobial activities are still poorly documented [3]. Thus, we decided to investigate the antimicrobial activity of five Ugandan tree species selected based on the information on their use in traditional medicine as evidenced by ethnobotanical research.

Five ethanol extracts obtained by maceration of barks from Dregea rubicunda K.Schum., Trichilia prieureana A. Juss., Turraea floribunda Hochst., Warburgia ugandensis Sprague, and Zanthoxylum chalybeum Engl. were studied for potential antimicrobial activity against Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis, and Candida albicans using broth microdilution method [4].

With the exception of D. rubicunda, results show that all plant species possess antimicrobial activity against one or more micro-organisms tested in this study at concentrations of 16mg/ml or below. Among the plants tested, T. prieureana and T. floribunda showed the most promising antimicrobial properties, inhibiting both stains of Gram-positive bacteria with minimum inhibitory concentrations 0.25 and 0.5mg/ml, respectively. The extract from W. ugandensis exhibited the broadest spectrum of inhibitory activity against all microbial strains tested at concentrations of 8mg/ml or below.

References: [1] Katuura, E. et al. (2007) Afr J Ecol 45: 48–51. [2] Freiburghaus, F. et al. (1996) Trop Med Int Health 1(6):765–771. [3] Hamill, F.A. et al. (2003) J Ethnopharmacol 87 (1):15–19 2. [4] Jorgensen J.H. et al. (1999). In: Murray P.R. (ed.) Manual of Clinical Microbiology. ASM Press. Washington, DC.