糙米多酚对淀粉消化酶的抑制作用及机理

Inhibition and Mechanism of Brown Rice Polyphenols on Starch Digestive Enzymes

本研究将糙米多酚(brown rice polyphenols,BRP)经过提取和C18固相柱纯化后,研究了BRP对α-淀粉酶和α-葡萄糖苷酶的抑制作用及其机理。液相色谱-质谱联用技术(UPLC-DAD-ESI-Q-TOF-MS)分析结果表明,BRP中大部分多酚以糖苷的形式存在,包括1种酚醛、2种酚酸酰胺、4种酚酸糖苷、6种酚酸、6种酚酸酯和8种黄酮糖苷。BRP对α-葡萄糖苷酶显示出剂量依赖型酶抑制活性,当浓度为2 mg/mL时,抑制率最高可达到39.37%,而BRP对α-淀粉酶无明显抑制作用。此外,荧光光谱和热力学研究结果表明,BRP能与α-葡萄糖苷酶发生疏水相互作用,对α-葡萄糖苷酶的内源荧光具有动态猝灭作用。以上结果表明,BRP主要通过与α-葡萄糖苷酶发生疏水相互作用抑制α-葡萄糖苷酶的活性,从而延缓碳水化合物的水解。本文为改善餐后血糖提供一定的参考。

In this study,the brown rice polyphenols(BRP)were extracted and purified by C18 solid phase column. The inhibitory effect and of brown rice polyphenols on α-amylase and α-glucosidase were studied. Liquid chromatography-mass spectrometry(UPLC-DAD-ESI-Q-TOF-MS)analysis showed that most of the polyphenols in BRP existed in the form of glycosides,including 1 kind of phenolic aldehyde,2 kind of phenolic acid amides,and 4 kind of phenolic acids glycoside,6 kind of phenolic acids,6 kind of phenolic acid esters and 8 kind of flavonoid glycosides. BRP showed a dose-dependent enzyme inhibitory activity against α-glucosidase. When the concentrationof BRP was 2 mg/mL,the inhibition rate was up to 39.37%,and BRP had no significant inhibitory effect on α-amylase. In addition,fluorescence spectroscopy and thermodynamic studies showed that BRP could interact hydrophobically with α-glucosidase and had a dynamic quenching effect on the endogenous fluorescence of α-glucosidase. The above results indicated that BRP mainly inhibited the activity of α-glucosidase by hydrophobic interaction with α-glucosidase,thereby delaying the hydrolysis of carbohydrates,and providing a reference for improving postprandial blood glucose.