Steroidal sapogenins and glycosides from the rhizomes of Dioscorea bulbifera

Four new steroidal sapogenins (1-4), named diosbulbisins A-D, two new spirostane glycosides, diosbulbisides A (5) and B (6), one new cholestane glycoside, diosbulbiside C (7), and the known compounds 8-10 were isolated from rhizomes of Dioscorea bulbifera. Their structures were elucidated by 1D and 2D NMR techniques, HRFTMS, and chemical methods. The unusual furospirostanol sapogenin skeletons, as found in compounds 3 and 4, are reported in the family Dioscoreaceae for the first time. Cytotoxicity of compounds 1-10 was evaluated using two human hepatocellular carcinoma cell lines (Bel-7402 and SMMC7721).