星点设计-效应面法优化白鲜皮多糖硫酸酯化工艺及抗氧化活性

Optimization for Sulfation Techniques of Dictamnus Dasycarpus Polysaccharide by Central Composite Design-response Surface Method and Study on Its Antioxidant Activity

关键词:  星点设计-效应面法  硫酸酯化  白鲜皮多糖  抗氧化  红外光谱  扫描电镜

Key words:  central composite design-response surface method  sulfation  Dictamnus dasycarpus polysaccharide  antioxidant activity  IR  SEM

摘要:

目的 利用星点设计-效应面法优化白鲜皮多糖（Dictamnus dasycarpus polysaccharide，DDP）硫酸酯化工艺，考察DDP修饰前后结构特征及抗氧化活性。方法 采用氯磺酸-吡啶法，以酯化试剂比例、酯化试剂与多糖溶液比例、反应温度、反应时间为自变量，硫酸根取代度（degree of substitution，DS）为因变量，对自变量各水平进行多元回归拟合，利用效应面法筛选最佳工艺并进行预测分析；采用红外光谱及扫描电镜观察其结构特点。测定硫酸酯化白鲜皮多糖（sulfated polysaccharides from Dictamnus dasycarpus，SDDP）对DPPH、OH·、O₂^-·清除能力，考察其抗氧化活性。结果 最佳工艺条件为酯化试剂比例1：4，酯化试剂与多糖溶液比例1：1，反应温度73℃，反应时间5 h。红外光谱显示SDDP在820 cm^-1和1 254 cm^-1附近出现C-O-S和S=O硫酸基特征吸收峰，表明DDP修饰成功；扫描电镜显示SDDP表面粗糙，排列紧密，且块状体积明显小于DDP；DDP和SDDP都有清除DPPH、OH·和O₂^-·能力，且SDDP对DPPH、OH·和O₂^-·清除率强于DDP。结论 星点设计-效应面法优化DDP硫酸酯化工艺方法简便且预测性良好，DDP经硫酸酯化后，抗氧化活性有所提高。

Abstract:

OBJECTIVE To optimize the sulfated process of Dictamnus dasycarpus polysaccharides(DDP) by central composite design-response surface methodology, compared with the polysaccharide structural feature without chemical modification and investigate its antioxidant activity. METHODS Chlorosulfonic acid-pyridine method processing technology was optimized by esterification reagent proportion, esterification reagent with polysaccharide solution proportion, reaction temperature, reaction time as independent variables and the degree of substitution as dependent variable, each level of independent variables were fitted by multiple regression fitting. Response surface methodology was used to select optimum processing technology; sulfated polysaccharides from Dictamnus dasycarpus(SDDP) were obtained after identified through IR and SEM. Antioxidant activity of SDDP was researched by setting the different concentration of the sample solution and adopting the free radical-scavenging(DPPH, OH·, O₂^-·) capacity of DDP and SDDP as the indicators. RESULTS The optimums were as follows:the esterification reagent proportion was 1:4, esterification reagent with polysaccharide solution proportion was 1:1, reaction temperature was 73℃, and reaction time was 5 h. The IR spectra exhibited that the characteristic peaks of sulfate at near 820 cm^-1 and 1 254 cm^-1 of SDDP. The results of IR revealed that DDP was modified successfully after sulfation. The SEM exhibited the surface of SDDP was roughly arranged and the bulk volume was obviously less than DDP. It was discovered that DDP and SDDP both had the strong free radical scavenging ability for DPPH, OH· and O₂^-·. Compared with the polysaccharides without chemical modification, the reducing power of SDDP was stronger. CONCLUSION This optimized processing technology of SDDP is simple and feasible with good predictability. After sulfation, the antioxidant activities of DDP have been improved.