Tannins and related compounds. Part 5. Isolation and characterization of polygalloylglucoses from Chinese gallotannin

Along with 1,2,3,4,6-penta-O-galloyl-β-D-glucose, the homologous series of hexa- and hepta-galloylglucoses have been isolated from Chinese gallotannin, and their structures established on the basis of 13C n.m.r. spectroscopic analysis, methanolysis, and partial hydrolysis. Octa–undeca-galloylglucoses have also been partially purified, and their structures characterized mainly by using 13C n.m.r. spectroscopy. From the isolation and structural studies of these galloylglucoses, Chinese gallotannin has been shown to be a mixture consisting mainly of penta–undeca-galloylglucoses which have depside galloyl group(s) randomly distributed at the C-2, C-3, and C-4 position(s) on a penta-O-galloyl-β-D-glucose core. The evidence for the occurrence of m- and p-depside linkages in a galloyl chain is also described.