Studies on the constituents of Chenopodium quinoa seeds: Isolation and characterization of new triterpene saponins

Six triterpenoid saponins were isolated from the edible grain quinoa, which is seeds of Chenopodium quinoa (Chenopodiaceae). Following are their struc tures: phytolaccagenic acid 3-O-[alpha -L-arabinopyranosyl-(1 "-->3')-beta -D-glucuronopyranosyl] (1); phytolaccagenic acid 3-O-[beta -D-glucopyranosy l-(1 "-->3')-alpha -L-arabinopyranosyl]-28-O-beta -D-glucopyranoside (2); p hytolaccagenic acid 3-O-[beta -D-glucopyranosyl-(1'''-->3 ")-beta -D-xylopy ranosyl-(1 "-->2')-beta -D-glucopyranosyl]-28-O-beta -D-glucopyranoside (3) ; phytolaccagenic acid 3-O-[beta -D-glucopyranosyl-(1'''-->2 ")-beta -D-glu copyranosyl-(1 "-->3')-alpha -arabinopyranosyl]-28-O-beta -D-glucopyranosid e (4); oleanolic acid 3-O-[alpha -L-arabinopyranosyl-(1 "-->3')-beta -D-glu curonopyranosyl]-28-O-beta -D-glucopyranoside (5); and oleanolic acid 3-O-[ beta -D-glucopyranosyl-(1 "-->3')-alpha -L-arabinopyranosyl]-28-O-beta -D-g lucopyranoside (6). The oleanane-type saponins (5, 6) were isolated for the first time in this plant, two of the phytolaccagenane (1, 3) were new comp ounds and two (2, 4) were previously found in quinoa. The structures were c haracterized on the basis of hydrolysis and spectral evidence, including 1D - and 2-D NMR (HMQC and HMBC) and ESI-MS analyses.