Tannins and Related Compounds. XLVIII. Rhubarb. (7). Isolation and Characterization of New Dimeric and Trimeric Procyanidins

Abstract

Together with the known flavan-3-ols and procyanidins, a new procyanidin dimer (11) and several new trimers (14, 15, 16, 20, 22, 24 and 26) have been isolated from high-quality rhubarb On the basis of chemical and spectroscopic data, the structures of these compounds were characterized as procyanidin B-5 3,3’-di~0-gallate (11), procyanidin C-l 3’,3”-di-O-gallate (14), procyanidin C-l 3,3’,3”-tri-O-gallate (15), 3-O-galloylepicatechin-(4β→6)-3-O-galloylepicatechin-(4β→8)-3-O-galloylepicatechin (20), 3-O-galloylepicatechin-(4β»6)-3-O-galloylepicatechin-(4β→6)-3-O-galloylepicatechin (22), 3-O-galloylepicatechin-(4β>6)-3-O-galloylepicatechin-(4β> 8)-catechin (26), 3-O-galloylepicatechin-(4β>8)-3-O-galloylepicatechin-(4β→8)-catechin (16) and 3~0-galloylepicatechin-(4β>-8)-3-O-galloylepicatechin-(4tf->6)-catechin (24). © 1986, The Pharmaceutical Society of Japan. All rights reserved.