Medicinal Foodstuffs. II. On the Bioactive Constituents of the Tuber of Sagittaria trifolia L. (Kuwai, Alismataceae) : Absolute Stereostructures of Trifoliones A, B, C, and D, Sagittariosides a and b, and Arabinothalictoside

Abstract

From the medicinal foodstuff "kuwai", the tuber of Sagittaria trifolia L., four bioactive diterpene ketones, trifoliones A, B, C, and D, two diterpene glucosides, sagittariosides a and b, and a nitroethylphenol glycoside, arabinothalictoside, were isolated, together with six known diterpenes. Their absolute stereostructures were determined on the basis of chemical and physicochemical evidence with included the application of a modified Mosher's method and an exciton chirality method. Among the diterpene consituents, trifoliones A, B, C, and D exhibited inhibitory effects on the histamine release from rat mast cells induced by compound 48/80 and calcium ionophore A-23187.