Antioxidant flavonoids and phenolic acids from leaves of Leea guineense G.!Don (Leeaceae)

From leaves of Leea guineense (Leeaceae) three hydrophilic flavonoids were isolated and identified as quercetin-3'-sulphate-3-O-alpha-L-rhamnopyranoside, quercetin-3,3'-disulphate and a new flavonoid sulphate, quercetin-3,3',4'-trisulphate, together with kaempferol, quercetin, quercitrin, mearnsitrin, gallic acid and ethyl gallate. The structures were established by spectroscopic analysis (UV, MS,H-1-NMR, C-13-NMR and 2D-NMR). Their antioxidant effect on free radical scavenging was evaluated in the DPPH assay. Copyright (C) 2003 John Wiley Sons, Ltd.