Euscaphinin, a new ellagitannin dimer from Euscaphis japonica (THUNB.) KANITZ.

A new ellagitannin dimer named euscaphinin was isolated from the leaves of Euscaphis japonica (THUNB.) KANITZ. The structure of this dimer was determined on the basis of spectroscopic and chemical evidence. The resulting structure indicated that it was produced by intermolecular C-O oxidative coupling between the galloyl groups of molecules of 1(beta)-O-galloyl pedunculagin, the major ellagitannin of the leaves. The ellagitannins were not detected in the bark and wood part of the plant. This is the first example of the isolation of ellagitannins from Staphyleaceaeous plants

Polymer-Like Polyphenols of Black Tea and Their Lipase and Amylase Inhibitory Activities

Lipase and amylase inhibitory activities of black tea were examined. After solvent partitioning of a black tea extract with the ethyl acetate and n-butanol, the two soluble fractions showed comparable inhibitory activities. Activity in the ethyl acetate fraction was mainly attributable to polyphenols with low-molecular weights, such as theaflavin gallates. On the other hand, the active substance in the n-butanol layer was ascertained to be a polymer-like substance. 1H- and 13C-NMR spectra showed signals arising from the flavan A-ring and galloyl groups, although signals due to flavan B-rings were not detected, suggesting that the polymer-like substances were generated by oxidative condensation of flavan B-rings, a result which was previously deduced from our results of in vitro catechin oxidation experiments. Enzymatic oxidation of epicatechin 3-O-gallate produced a similar polymer-like substance and suggested that condensation between a B-ring and galloyl groups was involved in the polymerization reaction