Inhibition and Mechanism of Brown Rice Polyphenols on Starch Digestive Enzymes

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.