Pregnane glycoside multidrug-resistance modulators from Cynanchum wilfordii

The methanol-soluble extracts of the roots of Cynanchum wilfordii showed a significant multidrug-resistance-reversing activity, and four known pregnan e glycosides were isolated by bioassay-directed fractionation and separatio n. Their structures were identified as gagaminin 3-O-beta-D-cymaropyranosyl -(1-->4)-beta-D-oleandropyranosyl-(1-->4)-beta-D-cymaropyranosyl-(1-->4)-be ta-D-cymaropyranoside (1), wilfoside K1N (2), wilfoside C1N (3), and cynaur icuoside A (4). In particular, compound 1, at a concentration level of 1 mu M, was found to completely reverse the multidrug-resistance of KB-V1 and M CF7/ADR cells to adriamycin, vinblastine, and colchicine.