Cytotoxic effects Steroidal saponins

Many alkaloids are infamous for their strong toxicity towards animals and humans. Most of the deadly alkaloids fall into the class of neurotoxins (see above). The others have cytotoxic properties (Table 1.2). A cytotoxic effect can be generated when cell membranes are made leaky (as by saponins or steroidal alkaloids), or when elements of the cytoskeleton are inhibited. The spindle poisons vinblastine, vincristine, colchicine, and taxol are particularly famous. Actin filament formation is blocked by fungal poisons such as phalloidin from Amanita phalloides. 

Ghosh, P., Besra, S. E., Tripathi, G., Mitra, S., and Vedasiromoni, J. R. 2006. Cytotoxic and apoptogenic effect of tea (Camellia sinensis var. assamica) root extract (TRE) and two of its steroidal saponins TSl and TS2 on human leukemic cell lines K562 and U937 and on cells of CML and ALL patients. Leuk. Res. 30 459-68. 

Twenty nine steroidal saponins have been evaluated for their inhibitory effects on human spermatozoa motility in vitro according to a modified Sander-Cramer method [233]. Spirostane-type saponins have stronger inhibitory activities than those of furostane-type. The carbonyl group at C-12 and the double bond A (5,6) of the aglycone were important for the activity. The monodesmosidic saponin, diuranthoside B from Diuranthera major appeared the most active (motility of 45% at 0.1 mg/ml), almost equivalent to the commonly used spermicidal agent N-9. These results indicated the possibility of discovering natural spermicidal agents from steroidal saponins. Further work on the cytotoxic activity of these compounds are underway. 

---