Tropical Journal of Pharmaceutical Research

Original Research Article | OPEN ACCESS

Effects of (-)-epigallocatechin gallate and quercetin on the activity and structure of ^5;-amylase

Jianhui Su, Zhe Tang

School of Marine and Bioengineering, Yancheng Institute of Technology, Yancheng 224051, PR China;

For correspondence:- Zhe Tang Email: tangzhe1983@163.com

Accepted: 18 February 2019 Published: 31 March 2019

Citation: Su J, Tang Z. Effects of (-)-epigallocatechin gallate and quercetin on the activity and structure of ^5;-amylase. Trop J Pharm Res 2019; 18(3):585-590 doi: 10.4314/tjpr.v18i3.20

© 2019 The authors.
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Abstract

Purpose: To investigate the effects of (-)-epigallocatechin gallate (EGCG) and quercetin on the activity and structure of α-amylase.

Methods: The inhibitory effects of 7 functional factors were compared by measuring half maximal inhibitory concentration (IC₅₀) values. Lineweaver-Burk plots were used to determine the type of inhibition exerted by EGCG and quercetin against α-amylase. The effect of EGCG and quercetin on the conformation of α-amylase was investigated using fluorescence spectroscopy.

Results: Quercetin and EGCG inhibited α-amylase with IC₅₀ values of 1.36 and 0.31 mg/mL, respectively, which were much lower than the IC₅₀ values of the other compounds (puerarin, paeonol, konjac glucomannan and polygonatum odoratum polysaccharide). The Lineweaver−Burk plots indicated that EGCG and quercetin inhibited α-amylase competitively, with ki values of 0.23 and 1.28 mg/mL, respectively. Fluorescence spectroscopy revealed that treatment with EGCG and quercetin led to formation of a loosely-structured hydrophobic hydration layer.

Conclusion: This study has unraveled the mechanism underlying the inhibition of α-amylase activity by EGCG and quercetin in vitro. This should make for better understanding of the mechanisms that underlie the antidiabetic effects of EGCG and quercetin in vivo.

Keywords: ^5;-Amylase, (-)-Epigallocatechin gallate, Quercetin; LineweaverW22;Burk plots, Antidiabetic, Fluorescence spectroscopy