A recent popular herbal medicine, Tribulus terrestris , also contains saponins that are thought to be similar in action to certain steroidal compounds used by athletes. The C 27 steroidal saponins of Dioscorea species serve as chemical precursors for the synthesis of anti-inflammatory compounds and contraceptive drugs. Cholesterol appears to be a usual precursor for steroidal saponins. Saponins have soap-like properties. They are toxic in large quantities to many animals, but are also found in small quantities in most of the plants eaten by herbivores.
Saponins cause changes in the microstructure of cell membranes and they lyse red blood cells.
Many saponins have molluscicidal activity. Those of Phytolacca species may have efficacy for control of snails that are intermediate hosts in the disease schistosomiasis. Pentacyclic triterpene glycosides have been shown to be phytoalexins in oats. Cardiac glycosides or cardenolides Cardiac glycosides are glycosides of mostly C 23 -steroidal compounds. They are called cardiac glycosides because they modify heart action.