Bioactive Saponins and Glycosides. I. Senegae Radix. (1): E-Senegasaponins a and b and Z-Senegasaponins a and b, Their Inhibitory Effect on Alcohol Absorption and Hypoglycemic Activity.

E-Senegasaponins a, b, and c were isolated from Senegae Radix, the root of Polygala senega L. var. latifolia TORREY et GRAY, together with their Z-isomers of the 4"-methoxycinnamoyl moiety, Z-senegasaponins a, b, and c. The structures of E-senegasaponins a and b and Z-senegasaponins a and b have been elucidated on the basis of chemical and physicochemical evidence, and the geometrical isomeric structure of the 4"-methoxycinnamoyl group in each saponin was found to show tautomer-like behavior in methanol solution or under irradiation with fluorescent lamps. E and Z-Senegasaponins a and b were found to exhibit potent inhibitory effects on alcohol absorption and hypoglycemic activity in the oral D-glucose tolerance tests in rats, and some structure-activity relationships of the acylated bisdesmoside-type saponins were clarified.