Tannins and Related Compounds. XLII. : Isolation and Characterization of Four New Hydrolyzable Tannins, Terflavins A and B, Tergallagin and Tercatain from the Leaves of Terminalia catappa L.

Abstract

A chemical examination of the leaves of Terminalia catappa L. (Combretaceae) has led to the isolation and characterization of four new hydrolyzable tannins named terflavins A (1) and B (2), tergallagin (3) and tercatain (4), together with eight known tannins : punicalin (5), punicalagin (6), chebulagic acid (7), geraniin (8), granatin B (9), 1-desgalloyleugeniin (10), corilagin (11) and 2, 3-[(S)-4, 4', 5, 5', 6, 6'-hexahydroxydiphenoyl]-D-glucose (12). Terflavins A (1) and B (2) possess novel structures in which a flavogallonyl (triphenyl) ester group is single bonded to the glucopyranose ring, and are presumed to be biosynthetic precursors of punicalagin (6) and punicalin (5), respectively, while tergallagin (3), which contains a gallagyl (tetraphenyl) group and a unique tergalloyl ester group attached to the glucose moiety, seems to be formed biosynthetically from punicalagin (6).