核桃多酚与蛋白质的作用方式及其抗氧化活性

以核桃为研究对象,将核桃碱提蛋白和酸提蛋白经溶剂作用后超滤,通过破坏核桃多酚-蛋白复合体间的作用力得到不同结合态多酚,测定多酚含量及其抗氧化活性,以期探究核桃酚类物质与核桃蛋白化学键结合机制。研究结果表明,在pH3.5和pH11条件下,游离态多酚含量分别为6.46、6.27 mg/g,占总酚含量的25.15%、29.77%,非共价结合态多酚含量分别为11.31、7.74 mg/g,占总酚含量的44.02%、36.75%,共价结合态含量7.92、7.05 mg/g,占总酚含量的30.83%、33.48%。由此可知,非共价结合为核桃多酚与核桃蛋白质的主要结合方式。在pH3.5和pH11条件下,游离态多酚对DPPH自由基的清除率分别为82.34%、43.68%,Fe2+螯合率分别为71.88%、49.96%,还原力吸光度值分别为1.157、0.857,脂质抗过氧化能力分别为47.71%、32.69%。在5种不同结合态多酚中,游离态多酚的抗氧化活性显著高于其他结合态多酚(p<0.05)。

Interaction between Walnut Polyphenols and Protein and Its Antioxidant Activity

The mechanism of chemical bonding between walnut phenolic compounds and walnut protein of the walnut were explored in this paper.The walnut protein solution was first treated by solvent under alkaline and acidic conditions,and then ultrafiltration was carried out,and different bound polyphenols were obtained by destroying the interaction force between walnut protein-polyphenol compounds.The content and antioxidant activity of polyphenols were determined.The results showed that the contents of free polyphenols were 6.46,6.27 mg /g respectively,accounting for 25.15% and 29.77% of the total phenols,the contents of non- covalent polyphenols were 11.31,7.74 mg /g respectively,accounting for 44.02% and 36.75% of the total phenols,and the contents of covalent polyphenols were 7.92,7.05 mg /g respectively,accounting for 30.83% and 33.48% of the total phenols.It was known that non covalent binding was the main form of interaction between polyphenols and protein complexes.Under pH3.5 and pH11 conditions,the scavenging rates of free polyphenols on DPPH free radicals were 82.34% and 43.68%,Fe2+chelating ability were 71.88% and 49.96%,reducing power absorbance value were 1.157 and 0.857,inhibition of lipid peroxidation ability were 47.71% and 32.69%,respectively.Among the five different bound polyphenols,the antioxidant capacity of free polyphenols was significantly higher than that of other bound polyphenols( p < 0.05).