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.
Kusano
Rie
R
Graduate School of Biomedical Sciences, Nagasaki University, 1-14 Bunkyo Machi, Nagasaki 852-8521, Japan.
Andou
Hisashi
H
Fujieda
Miho
M
Tanaka
Takashi
T
Matsuo
Yosuke
Y
Kouno
Isao
I
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*
D004791:Enzyme Inhibitors; D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols; D013662:Tea; D000431:Ethanol; D008049:Lipase; D000681:Amylases