New oleanane saponins in Chenopodium quinoa

Abstract

Six triterpenoid saponins were isolated from the seeds of Chenopodium quinoa (Chenopodiaceae). Their structures were as follows: phytolaccagenic acid 3-O-[α-L-arabinopyranosyl-(1″→3′)-β-D- glucuronopyranosyl]-28-O-β-D-glucopyranoside (1); spergulagenic acid 3-O- [β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl-(1→3)- α-L-arabinopyranosyl-28-O-β-D-glucopyranoside (2); hederagenin 3-O-[β-D-glucopyranosyl-(1→3)-α-L-arabinopyranosyl]-28-O- β-D-glucopyranoside (3); phytolaccagenic acid 3-O-[β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl-(1→4)- β-D-glucopyranosyl]-28-O-β-D-glucopyranoside (4); hederagenin 3-O-[β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl-(1→4)- β-D-glucopyranosyl]-28-O-β-D-glucopyranoside (5); and spergulagenic acid 3-O-[α-L-arabinopyranosyl-(1Prime;→3′)-β-D- glucuronopyranosyl]-28-O-β-D-glucopyranoside (6). Saponins 5 and 6 are new. The structures were characterized on the basis of hydrolysis and spectral evidence, including IR, UV, optical rotations, 1D- and 2D-NMR (HMQC and HMBC), ESIMS, and FABMS analyses.