Three new saponins from Tribulus terrestris

Three new steroidal saponins 1-3, together with five known steroidal saponi ns, L-mannitol and an inorganic salt were isolated from Tribulus terrestris L. (Zygophyllaceae). The structures of the new steroidal saponins were elu cidated as hecogenin 3-O-beta-xylopyranosyl(1-->3)-beta-glucopyranosyl(1--> 4)-beta-galactopyranoside (1), hecogenin 3-O-beta-glucopyranosyl(1-->2)-bet a-glucopyranosyl(1-->4)-beta-galactopyranoside (2) and 3-O-[beta-xylopyrano syl(1-->2)-[beta-xylopyranosy[(1-->3)]-beta-glucopyranosyl(1-->4)-[alpha-rh amnopyranosyl(1-->2)]-beta-galactopyranosyl}-26-O-beta-glucopyranosyl-22-me thoxy-(3 beta,5 alpha,25R)-furostan-3,26-diol (3). Structure elucidation wa s accomplished by 1D and 2D NMR spectra (C-13-H-1 COSY, HMQC, HMBC, H-1-H-1 COSY, TOCSY, and NOESY), mass spectrometry (FABMS, ESIMS) and chemical met hods.