银耳多糖的降解、磷酸酯化修饰及其抗氧化活性

目的:磷酸酯化修饰经氧化降解的银耳多糖,并测定修饰多糖的抗氧化活性。方法:采用双氧水-V_C体系降解银耳多糖,并测定其溶解度,以三氯氧磷和吡啶作为磷酸酯化试剂对降解的银耳多糖进行修饰;利用傅里叶红外光谱表征多糖的结构特征;采用磷钼蓝法测定取代度;以羟自由基和DPPH自由基的清除率为指标,比较修饰前后银耳多糖的抗氧化能力。结果:银耳多糖经降解、透析后获得一个单一组分,相对分子质量为7.82 kDa,红外光谱分析结果表明,修饰后的银耳多糖在1262.22、540.55 cm^-1处有磷酸酯键生成,磷酸酯化银耳多糖的取代度为0.021,水溶解度为42.71±1.67 mg/mL;修饰后的银耳多糖对羟自由基和DPPH自由基的清除作用具有明显的剂量效应,浓度为2.4 mg/mL时活性最高,对DPPH清除率达到73.77%,对羟自由基清除效率达到67.45%。结论:氧化降解提高了银耳多糖的水溶解度,磷酸酯化修饰增强了银耳多糖的抗氧化能力。

Degradation,Phosphate Modification of Tremella fuciformis Polysaccharide and Its Antioxidant Activity

Objective:To modify the oxidized degraded polysaccharides of Tremella fuciformis by phosphate esterification and determine the antioxidant activity of the modified polysaccharides.Methods:The polysaccharides of Tremella fuciformis were degraded by hydrogen peroxide-VC system and its solubility was determined.The degraded Tremella polysaccharides were modified by phosphorus oxychloride and pyridine as phosphorylating reagents.The structural characteristics of polysaccharides were characterized by Fourier transform infrared spectroscopy.The substitution was determined by phosphorus molybdenum blue method.The antioxidant activities of Tremella polysaccharides before and after modification were compared with the scavenging rate of hydroxyl radicals and DPPH free radicals.Results:The Tremella polysaccharides were degraded and dialyzed to obtain a single component with a relative molecular mass of 7.82 kDa.The results of infrared spectroscopy indicated that the modified Tremella polysaccharides had phosphate bond formation at 1262.22、540.55 cm^-1.The degree of substitution was 0.021.Water solubility was 42.71±1.67 mg/mL.The modified Tremella polysaccharide had a significant dose effect on the scavenging effects of hydroxyl radicals and DPPH free radicals.The activity was highest at the concentration of 2.4 mg/mL,and the DPPH clearance rate of the modified Tremella polysaccharides reached 73.77%.The scavenging efficiency of hydroxyl radicals reached 67.45%.Conclusion:Oxidative degradation enhanced the water solubility of Tremella polysaccharides,and the phosphorylation modification enhanced the antioxidant capacity of Tremella polysaccharides.