北沙参乙醇分级多糖的理化性质及抗氧化活性研究

采用水提醇沉法分级纯化得到4种北沙参多糖(GLP-30、GLP-50、GLP-70、GLP-剩余),采用傅里叶变换红外光谱、高效液相色谱、凝胶渗透色谱、扫描电镜以及差示扫描量热—热重分析等进行分析,并测定其抗氧化活性。结果表明:4种北沙参多糖均具有多糖的典型基团,但差示扫描量热结果相差较大;各多糖组分分子量随乙醇浓度的增加而降低;不同组分间的多糖得率及单糖含量有一定差异,其中GLP-50得率(5.43%)和半乳糖醛酸含量(2.03%)最高,蛋白含量(7.66%)较高,具有最高的保油性,在清除DPPH自由基和羟基自由基中表现出最高的抗氧化能力。乙醇分级沉淀的方法可用于分级纯化北沙参多糖组分,其中50%乙醇更适宜沉淀制备北沙参多糖,且所得多糖抗氧化性较强。

Ethanol fractional purification, physicochemical properties and antioxidant activity of polysaccharides from Glehnia Radix

To study the physicochemical properties and antioxidant activity of ethanol-graded polysaccharides of Glehnia Radix. Four kinds of polysaccharides of Glehnia Radix (GLP-30, GLP-50, GLP-70, GLP-residual) were fractionated and purified by water extraction and alcohol precipitation. Fourier transform infrared spectroscopy, high performance liquid chromatography, and gel permeation chromatography, scanning electron microscopy, and differential scanning calorimetry-thermogravimetric analysis were used to evaluate the physicochemical properties and structure characteristics of polysaccharides. The antioxidant activities were also studied. The four polysaccharides of Glehnia Radix have the typical groups of polysaccharides, but the results of differential scanning calorimetry are quite different, which may be due to the differences in the sugar chain spatial structure. The molecular weight of each polysaccharide were decreased with increasing ethanol concentration. The yield and monosaccharide content were different among different polysaccharides. The yield (5.43%) and the content of galacturonic acid (2.03%) of GLP-50 were the highest. It also has the highest oil-retaining property, and the highest antioxidant activities in DPPH and hydroxyl free radical scavenging. The ethanol fractionation method can be used to fractionate and purify the polysaccharides of Glehnia Radix. The final concentration 50% ethanol was more suitable for the preparation of Glehnia Radix polysaccharides for its stronger antioxidant activity.