Four flavonoid glycosides from the pulps of Elaeagnus angustifolia and their antioxidant activities

Four flavonoid glycosides were isolated from the pulps of Elaeagnus angustifolia and identified as Quercetin 3,4'-O-β-D-diglucoside (1), Isorhamnetin-3-O-β-D-galactopy -ranoside (2), Quercetin 3-O-β-D-Galactopyranoside-4'-Oβ-D-glucopyranoside (3) and Isorhamnetin 3-O-β-D-Galacto -pyranoside-4'-O-β-D-glucopyranoside (4).Among which, the compounds 1, 3 and 4 were isolated for the first time from this plant.The antioxidant activities of the four compounds were evaluated by measuring their reducing power and ability to scavenge the ABTS radical, DPPH radical and to inhibit superoxide anions.The results indicated that theses compounds exhibited antioxidant activities with a dose-dependent manner in all tested models, and had some structure-activity relationships.The order of potential antioxidant capacity was as follows:1>3>2>4.Considering related reports, the flavonoid might be responsible for antioxidant activity of pulps of E. angustifolia.