Phenolic and antibacterial constituents of Vahlia capensis

Abstract

The n-butanol fraction of Vahlia capensis yielded kaempferol, quercetin, afzelin, astragalin, quercitrin, iso-quercitrin, rutin, gallic acid, chiro-inositol, dulcitol, and a novel biflavonoid, VC-15B (vahlia biflavone). The compounds were identified using ID and 2D NMR techniques and FABMS. Vahlia biflavone and gallic acid were isolated, using bioassay-guided procedure and identified as the antibacterial components. Both compounds showed activity against Gram positive Staphylococcus aureus and Bacillus subtilis. Vahlia biflavone gave MIC values of 15.3 µg/ml and 30.6 µg/ml against S. aureus and B. subtilis, respectively while gallic acid gave a value of 71.3 µg/ml for both organisms.