STUDIES ON THE CONSTITUENTS FROM DIOSCOREA PLANTS Ⅱ. ISOLATION AND IDENTIFICATION OF STEROIDAL SAPONINS FROM DIOSCOREA COLLETTII HOOK.F.

Four steroidal saponins, collettinside Ⅰ, Ⅱ, Ⅲ and Ⅳ, were isolated from the rhizomes of Dioscorea collettii Hook. f. collected from Si Chuan Province. Their chemical structures have been elucidated by means of chemical and spectrometric analyses as 3-O-(β-D-glucopyranosyl)-yamogenin Ⅰ; 3-O-α-L-rhamno pyranosyl (1→4)-β-D-glucopyranosyl-yamogenin Ⅱ; 3-O-α-L-rhamnopyranosyl (1→4)-α-L-rhamnopyranosyl (1→2)-β-D-glucopranosyl-yamogenin Ⅲ; 3-O-(β-D-glucopyranosyl (1→3)-α-L-rhamnopyranosyl (1→2)-β-D-glucopyranosyl)-yamogenin Ⅳ. Colllettinside Ⅱ, Ⅲ and Ⅳ are new steroidal saponins.