超声波辅助过氧化氢法降解坛紫菜多糖及其抗氧化活性的研究

Degradation of Porphyra haitanensis polysaccharide by ultrasonic assisted hydrogen peroxide method and its antioxidant activity analysis

该试验比较了超声波法、过氧化氢法、超声波辅助过氧化氢法降解坛紫菜(Porphyra haitanensis)多糖的效果,最后以1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基清除率为指标,通过单因素和正交试验优化了超声波辅助过氧化氢法降解坛紫菜多糖的工艺。对比了降解前后多糖的抗氧化活性,并分析了其与分子量、结构特征及理化性质等的相关性。结果表明,在过氧化氢体积分数10%、温度65℃、超声波辅助2.5 h条件下,该多糖降解前后DPPH自由基清除率的半抑制浓度(Half maximal inhibitory concentration,IC50)由9.37 mg·mL^-1降为1.71 mg·mL^-1;凝胶渗透色谱结果显示分子量由大于670 kD降为235835 D;傅里叶红外光谱表明多糖特征吸收峰依旧存在;高效液相色谱分析发现单糖组成大致相同,糖醛酸质量分数有所降低;理化性质显示硫酸基质量分数增高,3,6-内醚半乳糖质量分数明显降低。因而超声波辅助过氧化氢法可较好地降解坛紫菜多糖,并可改善理化性质及结构特征进而增强抗氧化活性,为低分子量多糖的制备及构效关系分析提供依据。

We have compared the degradation effects of ultrasonic method,hydrogen peroxide method and ultrasound-assisted hydrogen peroxide method on Porphyra haitanensis polysaccharide,and finally optimized ultrasonic assisted hydrogen peroxide degradation of polysaccharides by single factor and orthogonal test,using DPPH scavenging rate as the index.Meanwhile,we compared the antioxidant activity of polysaccharides and analyzed its correlation with molecular mass,structural characteristics and physicochemical properties.The results show that the IC50(Half maximal inhibitory concentration)of DPPH scavenging reduced from 9.37 mg·mL^-1 to 1.71 mg·mL^-1 under the conditions of 10%hydrogen peroxide,65℃and 2.5 h.Gel permeation chromatography shows that the molecular mass of polysaccharide decreased from more than 670 kD to 235835 D before and after degradation.FT-IR shows that the absorption peaks of the polysaccharide did not change.The monosaccharide composition was almost the same with PMP column derivatization according to HPLC analysis,while the content of uronic acid decreased.Moreover,the Sulfate-group content increased but the 3,6-endogalactose content decreased obviously.Therefore,the ultrasonic assisted hydrogen peroxide method can degrade P.haitanensis polysaccharides and improve the antioxidant activity.The results provide references for the preparation of low molecular mass polysaccharides and analysis of structure-activity relationship.