Physical chemical and biological properties of saponins
Answers
Chemical and Physical Properties of Saponins
Saponins consist of an aglycone unit linked to one or more carbohydrate chains (Figure 1). The aglycone or sapogenin unit consists of either a sterol or the more common triterpene unit. In both the steroid and triterpenoid saponins, the carbohydrate side-chain is usually attached to the 3 carbon of the sapogenin.
Saponins possess surface-active or detergent properties because the carbohydrate portion of the molecule is water-soluble, whereas the sapogenin is fat-soluble. The stability and strength of forage saponin foams are affected by pH, and this may have an effect on the development of bloat in ruminants. Saponins are remarkably stable to heat processing, and their biological activity is not reduced by normal cooking.
Isolation of saponins from plant material involves extraction with a polar solvent after removal of lipids, with petroleum ether or chloroform, followed by various purification techniques. A number of chromatographic procedures have been used to separate individual saponins.
Saponins are steroid or triterpenoid glycosides, common in a large number of plants and plant products that are important in human and animal nutrition. Several biological effects have been ascribed to saponins. Extensive research has been carried out in the membrane-permeabitising, immunostimulant, hypocholesterolaemic and anticarcinogenic properties of saponins and they have also been found to significantly affect reproduction in animals. These structurally diverse compounds have also been observed to kill protozoans and molluscs, to have an effect on cold blooded animals, also to have the analgesic, anti-nociceptive, antioxidant activity, to impair the digestion of protein, to cause hypoglycemia and to act as antifungal and antiviral agents.