Tannins and related compounds. LXXXIII. Isolation and structures of hydrolyzable tannins, phillyraeoidins A-E from Quercus phillyraeoides.

Abstract

A chemical examination of the leaves of Quercus phillyraeoides A. GRAY (Fagaceae) has led to the isolation of five new tannins, phillyraeoidins A-E (27-31), together with twenty-six structurally known tannins and related compounds including gallotannins (1, 2), ellagitannins (3-14), proanthocyanidins (15-17), complex tannins (18-21) and simple phenol glucoside gallates (22-26). On the basis of spectroscopic and chemical evidence, the structures of phillyraoidins A-D have been established as dimeric hydrolyzable tannins in which two glucose units are linked through a valoneayl ester bond, while phillyraeoidin E was characterized as 1, 2, 3, 6-tetra-O-galloyl-4-valoneayl(lactone)-β-D-glucose.