title: Interaction mechanism between green tea extract and human α-amylase for reducing starch digestion.
abstract: This study evaluated the inhibitory effects of the green tea extract on human pancreatic α-amylase activity and its molecular mechanism. The green tea extract was composed of epicatechin (59.2%), epigallocatechin gallate (14.6%) and epicatechin gallate (26.2%) as determined by HPLC analysis. Enzyme activity measurement showed that % inhibition and IC50 of the green tea extract (10%, based on starch) were 63.5% and 2.07 mg/ml, respectively. The Michaelis-Menten constant remained unchanged but the maximal velocity decreased from 0.43 (control) to 0.07 mg/(ml × min) (4 mg/ml of the green tea extract), indicating that the green tea extract was an effective inhibitor against α-amylase with a non-competitive mode. The fluorescence data revealed that the green tea extract bound with α-amylase to form a new complex with static quenching mechanism. Docking study showed the epicatechin gallate in the green tea extract presented stronger affinity than epigallocatechin gallate, with more number of amino acid residues involved in amylase binding with hydrogen bonds and Van der Waals forces. Thus, the green tea extract could be used to manipulate starch digestion for potential health benefits.
authors.affiliation: State Key Laboratory of Food Science & Technology, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu 214122, PR China. Electronic address: miaoming@jiangnan.edu.cn.
authors.forename: Ming
authors.initials: M
authors.lastname: Miao
authors.affiliation: State Key Laboratory of Food Science & Technology, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu 214122, PR China.
authors.forename: Bo
authors.initials: B
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Food Science & Technology, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu 214122, PR China.
authors.forename: Huan
authors.initials: H
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Food Science & Technology, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu 214122, PR China.
authors.forename: Tao
authors.initials: T
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Food Science & Technology, Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, 1800 Lihu Avenue, Wuxi, Jiangsu 214122, PR China. Electronic address: xfli@hebust.edu.cn.
authors.forename: Xingfeng
authors.initials: X
authors.lastname: Li
mesh_terms: D000975:Antioxidants / Q000737:chemistry; D002392:Catechin / Q000031:analogs & derivatives* / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D004063:Digestion; D006801:Humans; D006860:Hydrogen Bonding; D020128:Inhibitory Concentration 50; D010179:Pancreas / Q000201:enzymology; D055292:Pancreatic alpha-Amylases / Q000037:antagonists & inhibitors* / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry; D013213:Starch / Q000378:metabolism*; D013662:Tea / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D010936:Plant Extracts; D013662:Tea; D002392:Catechin; D013213:Starch; C062669:epicatechin gallate; C045651:epigallocatechin gallate; D055292:Pancreatic alpha-Amylases
keywords: Green tea extract; Human pancreatic α-amylase; Interaction; Molecular docking