Antibacterial activity of flavonoids from the stem bark of <i>Erythrina caffra</i> thunb.

Abstract

The antibacterial activity of the stem bark of Erythrina caffra Thunb. was investigated against different bacterial strains. The antibacterial activity was determined by a micro broth dilution assay. Antibacterial compounds were isolated and identified using a Bruker Avance III LPO NMR spectrometer. Four known flavonoids, abyssione-V 4'-O-methyl ether, 6,8-diprenylgenistein, alpinumisoflavone and burttinone, were isolated. All the compounds were active against both Gram-negative and Gram-positive bacteria. The minimum inhibitory concentration values obtained (MIC) ranged from 3.9 μg/mL to 125 μg/mL. This is the first report of antibacterial activity of burttinone and the isolation of these compounds from E. caffra.