Triterpenoid saponins are triterpenes which belong to the group of saponin compounds. Triterpenes are a type of terpene containing 30 carbon atoms. Triterpenes are assembled from a five-carbon isoprene unit through the cytosolic mevalonate pathway to make a thirty-carbon compound. Some triterpenes are steroidal in nature. Cholesterol, phytosterols and phytoecdysteroids are triterpenes. The triterpenes are subdivided into some 20 groups, depending on their particular structures. Some triterpenoid compounds are found as saponin glycosides which refers to the attachment of various sugar molecules to the triterpene unit. These sugars can be cleaved off in the gut by bacteria, sometimes allowing the aglycone (triterpene) to be absorbed into the bloodstream or to insert into cell membranes.
Saponin glycosides reduce surface tension of water with foaming and will break down lipids. Usually triterpene saponins are designated as such by the suffix ending –side, such as ginsenoside or astragaloside, named for the plant genera they were first discovered in. Some, such as the ginsenosides and eleutherosides are designated Rx where the suffix x = a, a1, b2, is indicative of the relative position of the saponin spots from top to bottom of a thin layer chromatogram.
^ ab Robyn Klein Masters Thesis Paper, May 2004, Montana State University, Dept Plant Sciences & Plant Pathology: Phylogenetic and phytochemical characteristics of plant species with adaptogenic properties
^Attele, Anoja S., Wu, Ji An and Yuan, Chun-Su, 1999. Commentary: Ginseng pharmacology. Multiple constituents and multiple actions. Biochemical Pharmacology, 58, 1685-1693.