Tannins and related compounds. LXXIX. Isolation and characterization of novel dimeric and trimeric hydrolyzable tannins, nupharins C, D, E and F, from Nuphar japonicum DC.

Four novel dimeric and trimeric hydrolyzable tannins, nupharins C (1), D (13), E (15) and F (16), which possess a less favorable α-D-glucopyranose core with an atropisomeric (R)- or (S)-hexahydroxydiphenoyl group at the 3, 6-position, have been isolated from the rhizomes of Nuphar japonicum DC. (Nymphaeaceae). The structures of these compounds were established on the basis of spectroscopic and chemical evidence.