Cytotoxic activities of chemical constituents from rhizomes of Anemarrhena asphodeloides and their analogues

Seven steroidal saponins (1–7) and two xanthones (8, 9) were isolated from the rhizomes of Anemarrhena asphodeloides. Then in order to discover more analogues, which may possess good biological activity, the structural modifications of 2 and 9 were performed by acid hydrolysis and acetylation. Consequently, one novel steroidal saponin (2d, timosaponin BII-d), three compounds (2c, 2e and 2f) which were also the new products prepared by the diluted acid hydrolysis of 3 by our group previously, and four known compounds (2a, 2b, 9a and 9b) were obtained. The structures were elucidated by analyses of NMR and MS data. All the compounds were evaluated for their cytotoxicities against BEL-7402, HT-29, HeLa and MDA-MB-468 cell lines in vitro by Sulforhodamine protein coloration method. Compounds 1, 2, 2b, 4–6, 9a and 9b showed certain anti-proliferative activities against the four cell lines, in which compounds 2, 4 and 9b exhibited especially more potent activities. The structure–activity relationships of these compounds were simply discussed.