红景天多糖羧甲基化修饰及其抗氧化活性

Carboxymethylation and antioxidant activity of rhodiola polysaccharide

目的比较红景天多糖羧甲基化修饰前后抗氧化活性的变化。方法采用水提醇沉法提取红景天多糖,正交实验优选红景天多糖羧甲基化修饰条件,通过对2,2-联氮-二(3-乙基-苯并噻唑-6-磺酸)二铵盐(ABTS)自由基和超氧阴离子自由基清除能力的测定,比较修饰前后红景天多糖抗氧化活性的变化。结果红景天多糖羧甲基化修饰的最佳工艺条件为反应温度60℃、氯乙酸15 mg、反应时间3.5 h,得到羧甲基化的取代度为10.73。当浓度为5 mg/m L时,羧甲基化红景天多糖清除超氧阴离子自由基、ABTS自由基的能力分别为53.16%与45.64%,与红景天多糖比较,清除自由基能力明显提高。结论与修饰前比较,羧甲基化修饰后红景天多糖具有较强的抗氧化活性。

Objective To study the changes in antioxidant activity of rhodiola polysaccharide due to carboxymethylated modification. Methods Extraction of rhodiola polysaccharide was prepared with water extract-alcohol precipitation method. The conditions of carboxymethylated modification was optimized with orthogonal experiment. The elimination of 2,2 ＇-azinobis-（ 3-ethylbenzthiazoline-6-sulphonate （ABTS）-related free radicals and superoxide anion free radicals were detected before and after the modification of rhodiola polysaccharide to evaluate its antioxidant activity. Results The op- timal reaction temperature was 60 ~（2 for the carboxymethylated modification of rhodiola polysaccharide under the chloro- acetic acid dosage of 15 rag, the etherification reaction time of 3.5 hours, and the carboxymethyl substitution degree of 10. 73. At the concentration of 5 mg/mL,the carboxymethylated rhodiola polysaccharide-induced scavenging of superoxide anion radical and ABTS-related free radicals were was 53.16% and 45.64% ,which were obviously higher than the scav- enging activities of rhodiola polysaccharide. Conclusion Rhodiola polysaccharide is of strong antioxidant activity after being carboxymethylated.