Tannins and Related Compounds. LXXVI. : Isolation and Characterization of Cercidinins A and B and Cuspinin, Unusual 2, 3-(R)-Hexahydroxydiphenoyl Glucoses from Cercidiphyllum japonicum and Castanopsis cuspidata var. sieboldii

Abstract

Cercidinins A(1) and B(2) and cuspinin (3), unusual ellagitannins having an R-hexahydroxydiphenoyl ester group at the glucose 2, 3-positions, have been isolated from the bark of Cercidiphyllum japonicum (Cercidiphyllaceae) and the leaves of Castanopsis cuspidata var. sieboldii (Fagaceae). On the basis of chemical and spectroscopic evidence, their structures were established as 1, 4, 6-tri-O-galloyl-2, 3-(R)-hexahydroxydiphenoyl-β-D-glucose(1), 4, 6-di-O-gallolyl-2, 3-(R)-hexahydroxydiphenoyl-D-glucose (2) and 1-O-galloyl-2, 3-(R);4, 6-(S)-hexahydroxydiphenoyl-β-D-glucose (3). The co-occurrence of 3 with the atropisomeric S-hexahydroxydiphenoyl derivative suggests the non-specificity of the enzyme which converts gallic acid to hexahydroxydiphenoic acid.