肠浒苔多糖的羧甲基化修饰及其抗氧化活性研究

Carboxymethylation modification and antioxidant activity of Enteromorpha intestinalis polysaccharides

关键词:  肠浒苔, 多糖, 羧甲基化修饰, 取代度, 抗氧化活性

Key words:  Enteromorpha intestinalis, polysaccharide, carboxymethyl modification, substituting degrees, antioxidant activity

摘要:

该研究采用氢氧化钠-氯乙酸的化学反应体系制备羧甲基化肠浒苔多糖,以获得不同取代度的羧甲基化肠浒苔多糖,取代度的大小受氢氧化钠浓度、反应温度和反应时间的影响。结果表明:(1)当氢氧化钠浓度20%、反应温度60 ℃、反应时间3 h时,得到羧甲基化的最大取代度为0.781。(2)通过体外抗氧化来评价不同羧甲基化肠浒苔多糖的抗氧化活性。(3)当羧甲基化肠浒苔多糖的浓度为1.6 mg·mL^-1时,羧甲基化肠浒苔多糖清除羟基自由基、超氧阴离子自由基的能力分别为44.45%、51.98%,其清除DPPH自由基清除率和还原能力分别为16.75%、0.457 6。(4)与修饰前的相比,羟基自由基、超氧阴离子的清除能力均有较大幅度提高,羧甲基化修饰对肠浒苔多糖的DPPH自由基和还原力有减弱作用。以上结果表明,羧甲基化修饰引起的肠浒苔多糖的结构变化可以提高其抗氧化活性。

Abstract:

Enteromorpha intestinalis polysaccharides carboxymethylation(EIPC)were made in the NaOH-chloroacetic acid chemical reaction system to obtain carboxymethylated gut polysaccharides with different degrees of substitution. The degree of substitution was affected by the sodium hydroxide concentration, the reaction temperature and the reaction time. The results were as follows:(1)When the sodium hydroxide concentration was 20%, the reaction temperature was 60 ℃, and the reaction time was 3 h, the maximum degree of substitution for carboxymethylation was 0.781.(2)The antioxidant activities of different polysaccharide carboxymethylations of Enteromorpha intesinalis were evaluated by in vitro antioxidant.(3)At the concentration of EPIC wsa 1.6 mg·mL^-1, the scavenging activity to hydroxyl free radical and superoxide anion free radical were 44.45% and 51.98%, the ability of scavenging DPPH free radical and reducing ability were 16.75% and 0.457 6.(4)Compared with the pre-modification, the scavenging abilities of hydroxyl radicals and superoxide anion were greatly improved, and the carboxymethylation modification had a weakening effect on DPPH free radicals and reducing power of polysaccharides. The above results indicate that the structural changes of the polysaccharides caused by carboxymethylation can increase its antioxidant activity.