Abstract: Aim To investigate the water-soluble steroidal sapogenins from total sapogenins of Dioscorea nipponica Makino and to look for new active compounds. Methods The compounds were isolated with silica gel, PTLC and HPLC,and their structures were elucidated by acid hydrolysis, physical and chemical data and spectroscopic analyses (IR, NMR,MS, HMQC, HMBC) as well as chemical correlations. Results The two steroidal sapogenins (water-insoluble sapogenin and water-soluble sapogenin) were isolated from the total sapogenins of Dioscorea nipponica Makino. The structures were elucidated as diosgenin 3-O-{α-L-rhamnopyranosyl (1→2)-[β-D-glucopyranosyl (1→3)]}-β-D-glucopyranoside (I), diosgenin 3-O-[α-L-rhamnopyranosyl(1→3)-α-L-rhamnopyranosyl (1→4)-α-L-rhamnopyranosyl (1→4) ]-β-D-glucopyranoside (II). Conchusion Compound II is a new steroidal sapogenin and has been found in Dioscorea nipponica Makino for the first time . It was named dioscin Dc.

Key words: Total sapogenins of Dioscorea nipponica Makino, Total sapogenins of Dioscorea nipponica Makino, Steroidal sapogenins, Steroidal sapogenins, Dioscin Dc, Dioscin Dc