sapogenins

Sapogenins are the aglycone (non-sugar) components of saponins, a diverse class of natural glycosides found in many plant species. Sapogenins are typically triterpenoid or steroidal in structure. In saponin molecules, a sugar moiety is linked to the sapogenin; hydrolysis cleaves the glycosidic bond, yielding the sapogenin.

They are classified into two broad groups: steroidal sapogenins and triterpenoid sapogenins. Steroidal sapogenins include diosgenin, tigogenin and related compounds. Triterpenoid sapogenins include hederagenin, sarsasapogenin and other oleanane- or ursane-type aglycones. Diosgenin is the best known due to its historical use as a starting material for steroid hormone synthesis. The sugar portion in saponins influences solubility and biological properties.

Sapogenins occur in many plant families, with notable concentrations in Dioscorea (yams) and Smilax (sarsaparilla). They originate from the plant isoprenoid biosynthesis pathway through cyclization of oxidosqualene into various skeletons, followed by oxidation and functionalization to form the aglycone structure. Plant saponins typically play roles in defense against herbivores and pathogens.

Uses include serving as precursors for steroid hormones and pharmaceutical intermediates; they are also valued in natural product research and cosmetics for surfactant properties. Analytical extraction from plant material often involves hydrolysis to liberate the sapogenin for identification and quantification.