响应面试验优化龙眼肉多糖乙酰化工艺及其抗氧化活性

对龙眼肉多糖进行乙酰化修饰最佳工艺研究，采用乙酸酐法制备乙酰化龙眼肉多糖，以取代度为指标，采用响应面法对工艺条件进行优化，并研究乙酰化龙眼肉多糖的体外抗氧化活性。结果显示，龙眼肉多糖的最佳乙酰化条件为：乙酸酐-多糖物质的量比（投料比）10.2∶1、反应温度42 ℃、反应时间30 min。该工艺条件下龙眼肉多糖乙酰化取代度达到0.443。乙酰化龙眼肉多糖能够清除羟自由基、抑制脂质过氧化以及H2O2诱导的红细胞溶血，半数抑制浓度（IC50）分别为702.41、646.04 μg/mL和380.11 μg/mL，表现出比未修饰龙眼肉多糖更强的抗氧化活性。

Optimization of Preparation of Acetylated Polysaccharides from Longan (Dimocarpus longan) Pulp by Response Surface Methodology and Its Antioxidant Ability

In this study, the synthesis of acetylated polysaccharides extracted from longan (Dimocarpus longan) pulp was
investigated using acetic anhydride. The influences of reaction time, reaction temperature and polysaccharides-to-acetic
anhydride ratio on the degree of substitution (DS) of the synthesized derivatives were examined to select and optimize
important reaction conditions by response surface methodology. The antioxidant activity of acetylated polysaccharides
in vitro was determined. The optimized conditions that provided the maximum DS of 0.443 were determined as follows:
reaction time, 30 min; polysaccharides-to-acetic anhydride ratio, 10.21:1; and reaction temperature, 42 ℃. The acetylated
derivatives could scavenge hydroxyl free radical, and inhibit lipid peroxidation and red cell hemolysis induced by H2O2, with
50% inhibition concentrations (IC50) of 702.41, 646.04 μg/mL and 380.11 μg/mL, respectively. The antioxidant ability of the
synthesized acetylated derivatives was improved as compared to the native polysaccharides.