ANTINEOPLASTIC AGENTS .2. 4 FUROSTANOL GLYCOSIDES FROM RHIZOMES OF DIOSCOREA-COLLETTII VAR HYPOGLAUCA

During activity-guided fractionations to screen for antineoplastic age nts, further studies by means of preparative HPLC led to the isolation of four known furostanol saponins: protoneodioscin, protodioscin, pro toneogracillin, protogracillin, along with their corresponding artifac ts: methyl protoneodioscin, methyl protodioscin, methyl protoneogracil lin, and methyl protogracillin, from the rhizomes of Dioscorea collett ii var. hypoglauca. Among them, protoneodioscin, protodioscin, and pro toneogracillin are first reported from the title plant. The structures of the compounds were established on the basis of chemical evidence a nd spectral analysis (H-1-NMR, C-13-NMR, H-1-H-1 COSY, HMQC, HMBC, and FAB-MS). These eight compounds all caused morphological abnormality o f Pyricularia oryzae mycelia. They also showed cytotoxic activities ag ainst the cancer cell line of K562 in vitro as antineoplastic agents.