The soaps that are not soaps: the saponins
Saponins are glycosides present in many vegetable species and some invertebrates. Decoctions or pulverized parts of dried saponin-rich plants have been used for centuries around the world as washing aids and are still used for this purpose in emerging economies. With the advent of synthetic detergents, they have largely fallen into oblivion in industrialized countries. The toxicity of some extracts and the physical form of the “safe” saponins commercially supplied may be the principal reasons for the apparent disinterest, yet they probably represent an untapped opportunity in household and personal care formulations.
In these days of pervasive presence of “returning to nature” I thought it might be interesting to draw the attention to a class of surface active agents that in the recent years seem to have been neglected in favour of biosurfactants and bio-based surfactants: the saponins.
Saponins are glycosides that are found in an amazing number of vegetable species and also in some invertebrates. Difficult to think of something greener and more renewable and sustainable. The basic chemical structure is an aglycone (steroidal or triterpenoid) linked to one or more sugar chains (hexoses, pentoses). Properties generally shared by this group of natural products are pronounced surface activity, haemolytic action, steroid complexing ability, and biocidal capability (1).
Triterpene glycosides are the saponins most commonly found in nature and were extensively studied and characterized in the 1980ties (2-4).
The use as cleaning aids of decoctions or ...