Cytotoxicity of triterpenoid saponins. Part 1: Activities against tumor cells in vitro and hemolytical index.

Genuine saponins from Solidago virgaurea L., Heteropappus altaicus (Willd.) Novopokr., H. biennis (Ldb.) Tamamsch., and Helianthus annuus L. (Asteraceae) as well as related carbohydrate modified glycosides of polygalacic acid and echinocystic acid were investigated in view of their structure related cytotoxicity in the YAC-1- and in the P-815-tumor cell model. The cytotoxic activities are influenced by both, the O-glycosylation pattern at carbon atom 3 and 28 of the sapogenin. The IC50-values of bisdesmosides of polygalacic acid are lower than those of the corresponding prosapogenins. The acylglycosidic carbohydrate sequence 1-fucose-2 <-- 1-rhamnose-4 <-- 1-xylose-3 <-- 1-rhamnose of these bisdesmosides showed the highest cytotoxic effect. One etherglycosidic linked glucose unit at C-3 of the aglycone is essential, a difference in activity to the disaccharide laminaribiose at the same position cannot be observed. In the case of echinocystic acid glycosides the acylglycosidic carbohydrate sequence 1-arabinose-2 <-- 1-rhamnose-4 <-- 1-glucose seems to influence the rate of the cytotoxic effects. By comparing the concentration of the saponins with the complete hemolysis time it is possible to determine the hemolytical index in a very short time. Cytotoxicity against tumor cells correlated with the basic structure of the saponins are in accordance with the hemolytical effect. Sugar moieties play an important role for the hemolytical index.