Phytochemical constituents of Vangueria infausta: their radical scavenging and antimicrobial activities

Abstract

A new biflavonoid, 5,7,3',5'',7'',4'''-hexahydroxy (4'-O-3''')-biflavone (1) and a polyketide derivative, methylcylohex-1-ene (3) [previously reported only as a synthetic compound] were isolated from aerial parts of Vangueria infausta.In addition, eight other known flavonoids viz.(-)-epicatechin, epiafzelechin, dihydrokaempferol, quercetin, luteolin (2), dihydroquercetin-3'-Oglucoside, daidzein and genistein were also isolated from this plant.Structures were identified using 1D-and 2D NMR experiments as well as ESI-MS, IR and UV spectra.The new biflavonoid 1 showed higher radical scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) reagent compared to ascorbic acid (standard) using a spectrophotometric method.Compound 1 was less sensitive to Gram-positive and Gram-negative bacterial strains and yeast (Candida mycoderma) compared to luteolin and quercetin on the Bioautographic Agar Overlay Assay.