Composition and Structure of “Group A Saponin” in Soybean Seed

The composition of "group A saponin" in the seed hypocotyl of soybean was analyzed, and six kinds of "group A saponins," named Aa, Ab, Ac, Ad, Ae and Af according to their elution order from HPLC, were detected.On the basis of chemical and physicochemical evidence, Aa, Ab, Ae and Af are shown to be identical with the known saponins, acetyl-soyasaponins A4, Aj, A5 and A2, respectively, whilst Ac and Ad were novel saponins possessing different sugar chains.In all these saponins, the terminal sugar of the oligosaccharide chain attached to C-22 of an aglycone (soyasapogenol A) was acetylated in the soybean seed.Soybean seeds contain about 2% of glycosides, which are composed of several kinds of saponins and isoflavonoids.Recently, it has been reported that these glycosides had an undesirable, bitter and astringent taste to limit the wider exploitation soybean foods.1>2)In