Bioactive Saponins and Glycosides. III. Horse Chestnut. (1) : The Structures, Inhibitory Effects on Ethanol Absorption, and Hypoglycemic Activity of Escins Ia, Ib, IIa, IIb, and IIIa from the Seeds of Aesculus hippocastanum L.

Abstract

Five bioactive triterpene oligoglycosides named escins Ia, Ib, IIa, IIb, and IIIa were isolated from the seeds of horse chestnut tree, Aesculus hippocastanum L. (Hippocastanaceae). The chemical structures of escins Ia, Ib, IIa, IIb, and IIIa were determined on the basis of chemical and physicochemical evidence, which included selective cleavage of the glucuronide linkage using photochemical reaction and lead tetraacetate decarboxylation reaction. Escins Ia, Ib, IIa, and IIb were found to exhibit an ethanol absorption-inhibitory effect and hypoglycemic activity in the oral glucose tolerance test in rats. Some structure-activity relationships are reported.