Tannins and Related Compounds. CV. Monomeric and Dimeric Hydrolyzable Tannins Having a Dehydrohyxahydroxydiphenoyl Group, Supinanin, Euphorscopin, Euphorhelin and Jolkianin, from Euphorbia Species

Abstract

A chemical investigation of tannins in three Euphorbia species (E. helioscopia, E. jolkini and E. supina) has led to the isolation and characterization of four new hydrolyzable tannins, named supinanin (15), euphorscopin (16), euphorhelin (17) and jolkianin (18), together with fourteen known compounds (1-14). On the basis of chemical and spectroscopic evidence, the structures of supinanin and euphorscopin were established as 1, 3, 6-tri-O-galloyl-2, 4-(S)-dehydrohexahydroxydiphenoyl-β-D-glucose (15) and 1, 3-(S)-dehydrohexahydroxydiphenoyl-2-O-galloyl-4, 6-(S)-hexahydroxydiphenoyl-β-D-glucose (16), respectively. Euphorhelin and jolkianin were characterized as dimeric hydrolyzable tannins (17 and 18, respectively), in which two glucopyranose units are linked via valoneoyl and dehydrodigalloyl groups, respectively, and each molecule possesses a dehydrohexahydroxydiphenoyl group.