Antioxidative flavonoid glycosides from quinoa seeds (Chenopodium quinoa Willd)

Six flavonol glycosides have been isolated from quinoa seeds (Chenopodium q uinoa Willd) via normal phase and reverse phase column chromatography. On t he basis of spectral data, their structures were established as kaempferol 3-O-[beta -D-apiofuranosyl(1'''-2 ")]-beta -D-galactopyranoside (a), kaempf erol 3-O-[alpha -L-rhamnopyranosyl (1'''-2 ")]-beta -D-galactopyranoside (2 ), kaempferol 3-O-[beta -D-apiofuranosyl(1'''-2 ")-alpha -L-rhamnopyranosyl (1''''-6 ")]-beta -D-galactopyranoside (3), kaempferol 3-O-(2,6,di-alpha -L -rhamnopyranosyl)-beta -D-galactopyranoside (4), quaercetin 3-O-[beta -D-ap iofuranosyl (1'''-2 ")-alpha -L-rhamnopyranosyl(1''''-6'')]-beta -D-galacto pyranoside (5) and quercetin 3-O-(2,6-di-alpha -L-rhamnopyranosyl)-beta -D- galactopyranoside (6). Among them, compounds 1, 4 and 6 were main flavonoid glycosides found in quinoa seeds and compounds 2, 5, and 6 were isolated f rom this plant for the first time. All six compounds exhibited antioxidant activity in DPPH test, and two quercetin 3-glycosides showed much stronger activity than the four kaempferol 3-glycosides presents.