Saponins in Food

Abstract

Saponins belong to the group of plant glycosides widely distributed in more than 100 families of both wild and cultivated plants and in some marine organisms. They consist of the steroidal or triterpene hydrophobic aglycone and one to three sugar chains (hydrophilic part) attached by ester or ether linkage. Based on number of chains attached to the aglycone, they can be categorized as monodesmosides, bidesmosides, or tridesmosides. To this group of compounds, the glycoalkaloids are also included. Some saponins may contain in their structures (in aglycone part or in sugar chain) glucuronic acid, what makes them acidic. A big number of structurally divergent compounds have been described. Their structures and concertation can be different even in the organs (roots, rhizomes, stems, bark, leaves, seeds, and fruits) of the same plant species. Depending on the structure, they express different biological activities. Triterpenoid saponins can be found in many legumes (alfalfa, soybean, chickpeas, beans, peanuts, broad beans, kidney beans, and lentils), ginseng roots, sunflower seeds, horse chestnut, liquorice roots, spinach leaves, tea leaves, quillaja bark, quinoa seeds, sugar beet, or alliums species. Steroidal saponins can be found in oats, Yucca, tomato seeds, yam, fenugreek seeds, ginseng roots, asparagus, aubergine, or capsicum peppers. Glycoalkaloids are characteristic compounds mostly for Soalanaceae species. In general these compounds show no or little toxicity and do not seem to be of hazard for consumers. Depending on the structure, they express different biological activities. In general, saponins have been related to immunostimulatory, hypocholesterolemic, antitumor, anti-inflammatory, antibacterial, antiviral, antifungal, and antiparasitic activities. The major feature of these compounds is their sterol affinity, which seem to be responsible for most of activities they express. When consumed they may provide different health benefits, out of which cholesterol reducing activity is most pronounced.

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