Antibacterial activity of Marula (Sclerocarya birrea (A. rich.) Hochst. subsp caffra (Sond.) Kokwaro) (Anacardiaceae) bark and leaves

Marula bark is widely used for bacteria-related diseases by indigenous cult ures in Africa. This study was undertaken to investigate whether the ethnob otanical use can be validated by laboratory studies. Bark and leaves were e xtracted with acetone and MIC values were determined using a microplate ser ial dilution technique with Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Enterococcus faecalis as test organisms. All extracts were active with MIC values from 0.15 to 3 mg/ml. Based on minimum inhibito ry concentration values, inner bark extracts tended to be the most potent f ollowed by outer bark and leaf extracts, but the differences were not stati stically significant. There were two major bioactive components visible aft er bioautography of leaf extracts: one strongly polar and the other highly non-polar. The bioactive components could be separated from 92% of the non- active dry matter by solvent-solvent fractionation into the carbon tetrachl oride, chloroform and n-butanol fractions; these fractions, however, still contained many different compounds. Using bark may be detrimental to the pl ant, but leaf material can also be used for antibacterial application. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.