A new flavonol glycoside and biological activities of Adenanthera pavonina L. leaves

Abstract

Adenanthera pavonina is a plant belonging to family Fabaceae. The 95% ethanol extract (EtOH) of the dried powdered leaves of the plant and successive extracts with solvents of increasing polarities were prepared. Fractionation of the successive aqueous EtOH extract on polyamide column and purification of the isolated compounds on Sephadex LH20 led to the isolation of a new methoxy flavonol glycoside named as quercetin 3-O-α-dirhamnopyranosyl-(1‴ → 2″,1″″ → 6″)-β-glucopyranoside-4′-methoxy (1), as well as kaempferol-3-O-α-dirhamnopyranosyl-(1‴ → 2″,1″″ → 6″)-β-glucopyranoside (2), isovitexin (3), quercetin-3-O-rhamnopyranosyl(1‴ → 4″)-β-glucopyranoside (4), quercetin-3-O-β-glucopranoside-4′-O-rhamnopyranoside (5), kaempferol-3-O-α-rhamnopyranosyl(1‴ → 2″)-β-glucopyranoside (6), quercetin-3-O-rhamnopyranosyl(1‴ → 2″)-β-glucopyranoside (7), quercetin-3-O-β-glucopyranoside (8), kaempferol (9) and quercetin (10). Structures of the isolated compounds were established by spectroscopic analysis. Antioxidant activities of EtOH extract, successive extracts and compounds 1 and 2 were evaluated. The ethyl acetate (EtOAc) extract and EtOH extract showed 62.67% and 49.30% free radical scavenging activity, respectively. Cytotoxic activities of the EtOH extract and compounds (1) and (2) were evaluated. The EtOH extract showed a significant cytotoxic activity against Hep G-2 (IC50 = 2.50 μg) as compared with cisplatin (IC50>10 μg).