Saponins of Japanese Dioscoreaceae. VIII

Presence of steroidal Saponins in the rhizome of Dioscorea Tokoro MAKINO, other than dioscin, was examined. Diosgenin was chiefly obtained as the sapogenin and a small amount of tokorogenin was isolated, indicating the presence of a minute amount of several steroidal substances. Δ-Desoxytigogenin was obtained and it was assumed to have been formed secondarily during the hydolysis of diosgenin glycoside. Apart from dioscin, the saponins obtained were minute amounts of gracillin, a new diosgenin glycoside (A) with glucose and rhamnose as the sugars, and a substance (B) which was assumed to be a saponin with a new polar steroid and glucose and rhamnose as the sugars. It was considered that dioscorea-sapotoxin obtained by Tsukamoto and Ueno is a mixture of dioscin, gracillin, (A), and (B), from the manner of its isolation and purification and its apparent solubility in water is thought to be due to the formation of a colloidal solution by the presence of the mixture. (A) and (B) were tentatively named dioscorea-sapotoxin A and B.