EVALUATION OF ANTIBACTERIAL ACTIVITY OF SEVERAL SOUTH AFRICAN TREES AND ISOLATION OF TWO BIFLAVONOIDS WITH ANTIBACTERIAL ACTIVITY FROM GARCINIA LIVIGSTONEI

The acetone leaf extracts of eleven South African plant species were screened for their antibacterial activity by determining the minimum inhibitory concentrations (MIC) against 4 nosocomial bacterial pathogens and bioautography. MIC screening was at concentrations of 0.02 to 1.25 mg/ml using two-fold serial microdilution against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa 1. The extracts of Macaranga capensis, Garcinia livingstonei, Diospyros rotundifolia and Dichrostachys cinerea had good antibacterial activity with minimum MIC values of 0.03, 0.04, 0.06 and 0.08 mg/ml, respectively. The average MIC values of the plant extracts against the tested pathogens ranged from 0.23-1.77 mg/ml. S. aureus was the most susceptible bacterial pathogen with average MIC of 0.36, the extract of Diospyros rotundifolia was the most active with an average MIC against all the organisms of 0.23 mg/ml. The extracts of Buxus natalensis, Dracaena mannii (natal), and Pittosporum viridiflorum, Acacia sibeiriana, Erythrina lattissima, Cassine papillosa and Pavetta schumanniana (savoti) had a low antibacterial activity. G. livingstonei was selected for further work and two biflavonoids with antibacterial activity was isolated from a leaf extract. Keywords: Garcinia livingstonei, biflavonoids, antibacteria, traditional medicine References: 1. Eloff JN, 1988 Planta Medica 64, 711-714