裙带菜多糖的提取、羧甲基化修饰及抗氧化活性研究

Extraction,carboxymethylation and antioxidant activity of Undaria pinnatifida polysaccharide

目的研究裙带菜多糖及其羧甲基化衍生物的结构和抗氧化活性。方法通过碱提醇沉法提取出裙带菜中的多糖,并对其进行羧甲基化修饰,通过高效液相色谱仪、傅里叶红外光谱仪、尺寸排阻色谱-多角度激光光散射-示差折光联用仪对裙带菜多糖分别进行结构表征,并对裙带菜多糖和羧甲基化裙带菜多糖的抗氧化活性进行对比分析。结果裙带菜多糖中单糖主要由葡萄糖和甘露糖两种成分组成,分别占比为76.59%和21.12%。红外光谱证明裙带菜多糖的羧甲基化修饰成功。裙带菜多糖的重均分子量为6.935×10^(4)g/mol,多糖分散系数为7.218,均方根旋转半径为37.2nm,分析表明裙带菜多糖分子在溶液中呈现无规线团链构象。裙带菜多糖和羧甲基化裙带菜多糖都具有抗氧化活性,并且羧甲基化裙带菜多糖的抗氧化活性优于裙带菜多糖。结论羧甲基化修饰能够提高裙带菜多糖的抗氧化性能,为裙带菜多糖和羧甲基化裙带菜多糖在食品中的应用提供理论基础。

Objective To study the structure and antioxidant properties of Undaria pinnatifida polysaccharides and their carboxymethylated derivatives.Methods The polysaccharide from Undaria pinnatifida was extracted by alkali extraction and alcohol precipitation,then it was modified by carboxymethylation.The structure of the polysaccharides was determined by high performance liquid chromatograph,Fourier transform-infrared spectrometer,size exclusion chromatography-multi-angle laser light scattering-refractive index detector,and the antioxidant activities of Undaria pinnatifida polysaccharide and carboxymethylated Undaria pinnatifida polysaccharide were compared and analyzed.Results The monosaccharide of Undaria pinnatifida polysaccharide mainly consisted of glucose and mannose,accounting for 76.59%and 21.12%,respectively.The results of infrared spectroscopy showed that the carboxymethylation modification of Undaria pinnatifida polysaccharide was successful.The weight-average molecular weight of Undaria pinnatifida polysaccharide was 6.935×10^(4) g/mol,the polysaccharide dispersion coefficience was 7.218,and the root mean square rotation radius was 37.2 nm.The analysis indicated that the Undaria pinnatifida polysaccharide molecule exhibited a random coil chain conformation in solution.The Undaria pinnatifida polysaccharide and carboxymethylated Undaria pinnatifida polysaccharide had antioxidant activity,and carboxymethylated Undaria pinnatifida polysaccharide had better antioxidant activity than Undaria pinnatifida polysaccharide.Conclusion Carboxymethylation can improve the antioxidant properties of Undaria pinnatifida and provide a theoretical basis for the application of Undaria pinnatifida and carboxymethylated Undaria pinnatifida in food health care.