【作者】 梁靖； 余强；

【Author】 Liang Jing;Yu Qiang;State Key Laboratory of Food Science and Resources,Nanchang University;

【机构】 南昌大学食品科学与资源挖掘全国重点实验室；

【摘要】 基于抑制动力学、荧光猝灭、圆二色谱及分子对接法系统研究了赤小豆皮膳食纤维里结合多酚（RBDF-BP）对α-葡萄糖苷酶的体外抑制机理。RBDF-BP对α-葡萄糖苷酶表现出可逆的混合型抑制作用并呈剂量依赖关系,半数抑制浓度(IC₅₀)为63.12±0.45 μg/ml,优于其三种主要成分（原儿茶酸、没食子酸、对羟基苯甲酸）及阿卡波糖。RBDF-BP的结合使α-葡萄糖苷酶发生静态荧光猝灭,同时使色氨酸（Trp）和酪氨酸（Tyr）残基微环境的极性降低、疏水性增加,导致酶构象发生改变,α-螺旋含量减少,β-折叠含量和无规则卷曲增加。通过分子对接模拟观察到氢键形成于多酚的羟基、羧基与酶的氨基、羧基之间,而疏水相互作用主要发生在酶的脂肪族、芳香族氨基酸与多酚的苯环之间。RBDF-BP主要与靠近Trp残基的活性口袋结合,或作用于非活性口袋,通过改变酶的构象和微环境抑制α-葡萄糖苷酶的催化活性。本研究为利用赤小豆皮膳食纤维中提取的结合多酚作为α-葡萄糖苷酶天然抑制剂的功能成分提供了理论依据。更多还原

【Abstract】 The inhibitory mechanisms of purified bound polyphenols extracted from red bean coat dietary fiber(RBDF-BP)on α-glucosidase were investigated through inhibition kinetics,fluorescence spec-troscopy,circular dichroism and molecular docking.It was shown that RBDF-BP exerted significant reversible inhibition on α-glucosidase in a mixed-type inhibition manner(IC50=63.12 ± 0.45 μg/ml),superior to its three main components(protocatechuic acid,gallic acid,phydroxybenzoic acid) and acarbose.The binding of RBDF-BP resulted in static fluorescence suppression of α-glucosidase,decreased polarity and increased hydrophobicity of Trp and Tyr residue microenvironment,resulting in conformational changes,decreased α-helix content,β-fold content and random crimp increase.Through molecular docking simulation,it was observed that hydrogen bonds formed between hydroxyl and carboxyl groups of polyphenols and amino and carboxyl groups of enzymes,while hydrophobic interactions mainly occurred between aliphatic and aromatic amino acids of enzymes and benzene rings of polyphenols.RBDF-BP mainly binds to active pockets close to Trp residues,or acts on inactive pockets,inhibiting the catalytic activity of α-glucosidase by changing the conformation and microenvironment of the enzyme.This study provided theoretical evidences for the utilization of bound polyphenols extracted from red bean coat dietary fiber as a functional component in natural inhibitors of α-glucosidase.更多还原