Higher Plant Steroids
Further biosynthetic degradation of tetracyclic triterpenes leads to the plant sterols and steroids. The common plant sterols occur ubiquitously, and surprisingly one of the simplest, β -sitosterol (80), is known definitely to inhibit growth of the WA neoplasm. Presumably very few of the more highly hydroxylated sterols, such as those functioning as insect hormones and the plant steroids, have been evaluated for antineoplastic activity. This may account in part for the paucity of such substances now known to be antineoplastic agents. Some possible future prospects for the multihydroxylated sterols may be evidenced by the few steroidal saponins, such as digitonin and gitogenin galac-toside (81), active in the WA system. The latter saponin was found to be an antitumor constituent of Agave schottii Engelm. (Amaryllidaceae).29
KeywordsPlant Sterol Antineoplastic Agent Adenosine Triphosphatase Steroidal Saponin Amino Acid Accumulation
Unable to display preview. Download preview PDF.