Phytochemical screening of flavonoids with their antioxidant activities from rapeseed (Brassica napus L.)

Abstract Ten flavone compounds, including three new flavonoid glycosides, were isolated from defatted rapeseed, and their protective antioxidant effect on H 2 O 2 -induced oxidative damage in human umbilical vein endothelial cells (ECV-304) was investigated. Three new flavonoid glycosides were identified as kaempferol-3- O -[(6- O -sinapoyl)-β- d -glucopyranosyl-(1 → 2)-β- d -glucopyranoside]-7- O -β- d -glucopyranoside ( 8 ), kaempferol-3,7-di- O -β- d -glucopyranoside-4'-O-(6-O-sinapoyl)-β- d -glucopyranoside ( 9 ), and kaempferol-3- O -[(3- O -sinapoyl)-β- d -glucopyranosyl-(1 → 2)-β- d -glucopyranoside]-7- O -β- d -glucopyranoside ( 10 ). The protective effects of all of the isolated compounds on H 2 O 2 -induced oxidative damage were assessed, and the activities of superoxide dismutase (SOD) and lactate dehydrogenase (LDH) were measured. All of compounds had a protective effect on H 2 O 2 -induced oxidative damage in ECV-304 cells and the presence of a substituted sinapoyl group and its position in the structures were used to elucidate the activity differences.