title: Polymer-like polyphenols of black tea and their lipase and amylase inhibitory activities.
abstract: 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.
authors.affiliation: Graduate School of Biomedical Sciences, Nagasaki University, 1-14 Bunkyo Machi, Nagasaki 852-8521, Japan.
authors.forename: Rie
authors.initials: R
authors.lastname: Kusano
authors.forename: Hisashi
authors.initials: H
authors.lastname: Andou
authors.forename: Miho
authors.initials: M
authors.lastname: Fujieda
authors.forename: Takashi
authors.initials: T
authors.lastname: Tanaka
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Matsuo
authors.forename: Isao
authors.initials: I
authors.lastname: Kouno
mesh_terms: D000681:Amylases / Q000037:antagonists & inhibitors*; D002851:Chromatography, High Pressure Liquid; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D000431:Ethanol / Q000737:chemistry; D005419:Flavonoids / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D008049:Lipase / Q000037:antagonists & inhibitors*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D010636:Phenols / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D059808:Polyphenols; D013056:Spectrophotometry, Ultraviolet; D013662:Tea / Q000737:chemistry*
chemical_list: D004791:Enzyme Inhibitors; D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols; D013662:Tea; D000431:Ethanol; D008049:Lipase; D000681:Amylases