|| Checking for direct PDF access through Ovid
The chemical structure of triterpenoid saponins is quite complicated, especially the glucuronide oleanane-type triterpene carboxylic acid 3,28-bidesmosides (GOTCAB) saponins. Moreover, triterpenoid saponins are numerous as a result of this complicated structure. This review tries to explain this diversity in terms of plant classification and phylogeny. The study focuses on the three main successive steps of the biosynthetic pathway of the triterpenoid saponins: cyclisation, oxidation and glycosylation showing the relationship between triterpenols and sterols in terms of cell membrane evolution and the importance of which metabolic intermediates involved as aglycones of the triterpenoid saponins, represented progressively less and less in the advanced groups of the plant kingdom as they are more and more oxidised. This oxidation seems to reflect a better adaptation to new environmental conditions of some of these groups. By their enormous chemical diversity, the triterpenoid saponins seem to be good candidates to study the phylogeny of the flowering plants. A first attempt is given using recent advances in botanical classification for the orders and families by the Angiosperm Phylogenic Group (APG). This study was simplified in the first step focusing only on the “gypsogenin group” of the GOTCAB saponins. For example, as a result, these compounds are mainly concentrated in advanced groups such as Caryophyllideae, primitive Rosideae and Asterideae.