Antibacterial activity and isolation of active compounds from fruit of the traditional African medicinal tree Kigelia africana

The fruits of Kigelia africana (Lam.) Benth. are a popular source of traditional medicine throughout Africa. The stembark has been widely analysed for pharmacological activity, yet knowledge of the fruits is limited, despite more extensive use in traditional remedies. Crude extracts of stembark and fruits were prepared with distilled water, ethanol or ethyl acetate. In the microtitre plate bioassay, stembark and fruit extracts showed similar antibacterial activity against Gram-negative and Gram-positive bacteria. A mixture of three fatty acids exhibiting antibacterial effects was isolated from the ethyl acetate extract of the fruits using bioassay-guided fractionation. Palmitic acid, already known to possess antibacterial activity, was the major compound in this mixture. These results confirm antibacterial activity of K. africana fruits and stembark, and support the traditional use of the plant in therapy of bacterial infections.