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.

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).