ANTIMICROBIAL CONSTITUENTS OF RHUS-GLABRA

The antimicrobial activity of the methanol extract and isolated consti tuents of Rhus glabra (Anacardiaceae), a species used in folk medicine by North American native people, was evaluated against 11 microorgani sms, including grampositive and gram-negative bacteria. The extract wa s subsequently fractionated and monitored by bioassays leading to the isolation of three antibacterial compounds, the methyl ester of 3,4,5- trihydroxybenzoic acid (methyl gallate) (minimal inhibition concentrat ion (MIC) 12.5 mu g/ml), 4-methoxy-3,5-dihydroxybenzoic acid (MIC 25 m u g/ml) and gallic acid (MIC > 1000 mu g/ml). The first two compounds are reported here for the first time from Rhus glabra. Their structure s were established using spectroscopic and chemical methods.