中文摘要：

采用超声波辅助法从当归中提取水溶性当归粗多糖（ASP）,经过4种化学修饰分别得到硫酸化当归多糖（S-ASP）、磷酸化当归多糖（P-ASP）、乙酰化当归多糖（Ac-ASP）、羧甲基化当归多糖（C-ASP）。通过红外光谱对化学修饰前后ASP的结构进行表征,并进行抗氧化活性和清除自由基能力的测定,以获得一种抗氧化活性较强的当归多糖。结果显示：经化学修饰后的ASP分别具有相应的特征吸收峰,表明当归多糖的4种化学修饰均已成功;经化学修饰的4种当归多糖总还原能力均弱于未修饰多糖,且清除羟基自由基（·OH）的能力无明显变化,但清除1,1-二苯基-2-苦苯肼（DPPH·）自由基和抑制Fe^2＋诱发的脂质过氧化反应的能力有所增强,其中P-ASP清除超氧阴离子（O2^·-）自由基的能力最强;Ac-ASP抑制Fe^2＋诱发的脂质过氧化反应的能力最强,且均呈现出一定的量效关系。本实验结果为当归多糖的进一步研究与开发利用提供了一定的科学依据。

英文摘要：

Water soluble Angelica sinensis polysaccharide（ ASP） extracted from Angelica sinensis was obtained by ultrasonic extraction,and was chemically modified by sulfation,phosphorylation, acetylation and carboxymethylation. To obtain strong Angelica sinensis polysaccharide antioxidant activity,we used the infrared spectrum to characterize structure and study antioxidant activity. Results indicated that chemical modification of ASP had corresponding characteristic absorption peaks,namely the four kinds of chemical modification were successful. Different results were obtained by measuring antioxidant activity in vitro and the scavenging free radical capacity of the five kinds of polysaccharide. Total reducing power of the four modified polysaccharides was weaker than that of the unmodified ASP,and no obvious enhancement in scavenging hydroxyl radicals was observed in the modified polysaccharides,though the in vitro capacity of DPPH·radical scavenging and inhibition of Fe^2＋induced lipid peroxidation were enhanced. P-ASP was the strongest at scavenging the superoxide anion radical, Ac-ASP was the strongest at inhibiting Fe^2＋induced lipidperoxidation,and they all showed a certain dose-effect relationship. The results of this study provide a scientific basis for the further study and development of Angelica sinensis polysaccharides.