Tannins and Related Compounds. XLI. : Isolation and Characterization of Novel Ellagitannins, Punicacorteins A, B, C, and D, and Punigluconin from the Bark of Punica granatum L.
A chemical examination of the bark of Punica granatum L. (Punicaceae) has led to the isolation of five new ellagitannins, punicacorteins A, B, C and D, and punigluconin, together with the known ellagitannins, casuariin (6) and casuarinin (7). Based on chemical and spectroscopic evidence, the structures of punicacorteins A, B, C and D were established as novel C-glycosideic ellagitannins, the former two possessing a unique tetraphenyl (gallagyl) ester group (1 and 2), and the latter two containing a galloyl group in place of the gallagyl group (3 and 4), while punigluconin was characterized as 2,3-di-O-galloyl-4,6-(S)-hexahydroxydiphenoylgluconic acid (5).