期刊
JOURNAL OF FUNCTIONAL FOODS
卷 26, 期 -, 页码 144-156出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.jff.2016.07.012
关键词
Tea polyphenols; alpha-Amylase; Inhibition; Kinetics; Galloyl moiety
资金
- Australian Research Council Centre of Excellence in Plant Cell Walls [CE110001007]
- BBSRC [BBS/E/F/00044425] Funding Source: UKRI
The inhibitory activities of three tea extracts (TEs) and individual phenolic compounds in TEs against porcine pancreatic alpha-amylase (PPA) were studied by measuring their half inhibitory (IC50) concentrations. The kinetics of inhibition by these extracts and compounds were investigated through Dixon, Cornish-Bowden, and Lineweaver-Burk plots. The results showed that green, oolong and black tea extracts, epigallocatechin gallate, theaflavin-3, 3'-digallate and tannic acid were competitive inhibitors of PPA, whereas epicatechin gallate, theaflavin-3'-gallate and theaflavin were mixed-type inhibitors with both competitive and uncompetitive inhibitory characteristics. Only catechins with a galloyl substituent at the 3-position showed measurable inhibition. The competitive inhibition constants (Ku) were lower for theaflavins than catechins, with the lowest value for theaflavin-3, 3'-digallate. The lower than the uncompetitive inhibition constant for the mixed-type inhibitors suggests that they bind more tightly with free PPA than with the PPA-starch complex. A 3 and/or 3'-galloyl moiety in catechin and theaflavin structures was consistently found to increase inhibition of PPA through enhanced association with the enzyme active site. (C) 2016 Elsevier Ltd. All rights reserved.
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