Crude Drugs from Aquatic Plants. I. On the Constituents of Alismatis Rhizoma. (1). Absolute Stereostructures of Alisols E 23-Acetate, F, and G, Three New Protostane-Type Triterpenes from Chinese Alismatis Rhizoma

Abstract

From the less polar fraction of Chinese Alismatis Rhizoma [the dried rhizome of the aquatic plant Alisma orientale JUZEP. collected in Szechwan Province, China (Sentaku in Japanese)], three new protostane-type triterpenes named alisols E 23-acetate, F, and G were isolated together with four guaiane-type sesquiterpenes and several known triterpenes including 13, 17-epoxyalisol A. The absolute stereostructures of alisols E 23-acetate, F, and G have been determined on the basis of chemical and physicochemical evidence, which included the chemical correlations of alisols E 23-acetate, F, and G with the known triterpenes alisols A and A 24-acetate, and the application of the modified Mosher's method.