@article{oai:nagasaki-u.repo.nii.ac.jp:00019943,
 author = {Kusano, Rie and Andou, Hisashi and Fujieda, Miho and Tanaka, Takashi and Matsuo, Yosuke and Kouno, Isao},
 issue = {3},
 journal = {Chemical & Pharmaceutical Bulletin},
 month = {Mar},
 note = {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., Chemical & Pharmaceutical Bulletin v.56(3) p.266-272, 2008},
 pages = {266--272},
 title = {Polymer-Like Polyphenols of Black Tea and Their Lipase and Amylase Inhibitory Activities},
 volume = {56},
 year = {2008}
}