Saponins

Biological sources

Saponins have historically been plant-derived, but they have also been isolated from marine animals such as sea cucumber. They derive their name from the soapwort plant (genus Saponaria, family Caryophyllaceae), the root of which was used historically as a soap. In other representatives of this family, e.g. Agerostemma githago, Gypsophila spp., and Dianthus sp., saponins are also present in large quantities. Saponins are also found in the botanical family Sapindaceae, including its defining genus Sapindus (soapberry or soapnut) and the horse chestnut, and in the closely related families Aceraceae (maples) and Hippocastanaceae. It is also found heavily in Gynostemma pentaphyllum (Cucurbitaceae) in a form called gypenosides, and ginseng or red ginseng (Panax, Araliaceae) in a form called ginsenosides. Saponins are also found in the unripe fruit of Manilkara zapota (also known as sapodillas), resulting in highly astringent properties. Nerium oleander (Apocynaceae), also known as White Oleander, is a source of the potent cardiac toxin oleandrin. Within these families, this class of chemical compounds is found in various parts of the plant: leaves, stems, roots, bulbs, blossom and fruit. Commercial formulations of plant-derived saponins, e.g., from the soap bark tree, Quillaja saponaria, and those from other sources are available via controlled manufacturing processes, which make them of use as chemical and biomedical reagents. Soyasaponins are a group of structurally complex oleanane-type triterpenoid saponins that include soyasapogenol (aglycone) and oligosaccharide moieties biosynthesized on soybean tissues. Soyasaponins were previously associated to plant-microbe interactions from root exudates and abiotic stresses, as nutritional deficiency.