Saponins are a naturally occurring non-volatile glycosidic compound found in the majority of plants that can dissolve in water and latch itself to oils. ‘Saponins’ derived from the Latin word ‘Sapo’ which insinuates ‘soap’, are well known for their foaming properties. 

Sources and  Classification

They are present in the form of triterpenoid glycosides or steroids in plant-based foods. Untill now, around 60 kinds of different triterpenoid saponins have been extracted and characterized from different parts of the plant (seeds, leaves, flowers, and roots). 

Triterpenoid saponins can be found in legumes such as alfalfa, chickpeas, broad beans, soybean, lentils, kidney beans, peanuts, sunflower seeds, ginseng roots, horse chestnut, tea leaves, liquorice roots, quillaja bark, spinach leaves, quinoa seeds, tea leaves, sugar beets and other alliums species, whereas steroidal saponins are found in Yucca, tomato seeds, ginseng roots, yam, aubergine, fenugreek seeds, asparagus, capsicum peppers. ^[1]

Uses

Saponins are surface-active in nature as they contain hydrophilic sugar moieties covalently attached to a triterpene backbone or hydrophobic steroid. In this way, it seems to be a good alternative as a natural emulsifier, foaming, stabilizing, and drug delivery agent in the food and pharmaceutical industry. Owing to their foaming properties, they were extensively used in soaps and other detergents for cleaning purposes. 

Detection

The normal- and reverse-phase HPLCs are commonly used for separation, identification, and purification of saponins. But for the best separation of saponins, RP-HPLC is normally used. HPLC is increasingly used in the separation of various compounds including saponins. This technique is rapid, selective, and highly sensitive. Separation of saponins can be affected by HPLC using variety of stationary and mobile phases. And saponins in medicinal plants could be detected by the highly specific infrared absorption spectra of their sapogenins.^[2]

Reference

[1] Sharma, K., Kaur, R., Kumar, S., Saini, R. K., Sharma, S., Pawde, S. V., & Kumar, V. (2023). Saponins: A concise review on food related aspects, applications and health implications. Food Chemistry Advances, 2, Article 100191. https://doi.org/10.1016/j.focha.2023.100191
 [2] Negi, J. S., Singh, P., Pant, G. J. N., & Rawat, M. S. M. (2011). High-performance liquid chromatography analysis of plant saponins: An update 2005-2010. Pharmacognosy Reviews, 5 10, 155–158. https://doi.org/10.4103/0973-7847.91109