酚酸结构对酚酸-g-聚甘露糖醛酸抗氧化性能的影响

以海藻酸钠水解产物聚甘露糖醛酸(PM)为原料,通过聚甘露糖醛酸-乙二胺(PM-EDA)中间体与酚酸接枝共聚,制备了8种PM的酚酸(PA)接枝共聚物酚酸-g-聚甘露糖醛酸(PA-g-PM),并探究了PA结构对8种PA-g-PM抗氧化活性的影响。在n_PM:n_EDA=1:1.5,PM与两种活化剂碳二亚胺(EDC)、N-羟基琥珀酰亚胺(NHS)的摩尔比1:2:1,活化0 h,pH 8.0条件下,反应24 h,获得最高取代度(17.27%)的PM-EDA。PM的PA-g-PM接枝率在4.171±0.16 ~ 8.880±0.32 mg GA/g之间。UV-vis、FT-IR、XRD表征证实酚酸已成功接枝到PM上获得PA-g-PM。相比PM,8种PA-g-PM的对DPPH的清除率和对铁的还原力均显著提升。PA-g-PM的抗氧化性能与其中的酚羟基个数呈正相关关系,对位酚羟基PA-g-PM的抗氧化性能优于邻位酚羟基PA-g-PM的抗氧化性能,PA-g-PM中的酚羟基被甲氧基取代其抗氧化性能减弱。以期本研究结果为海藻酸钠在食品、化妆品、医药等行业高值开发利用奠定理论基础。

Effect of phenolic acid structure on antioxidant activity of phenolic acid-g-polymanturonic acid

Eight kinds of phenolic acid (PA) graft copolymers phenolic acid-g-polymanturonic acid (PA-g-PM) were prepared by graft copolymerization of polymanturonic acid-ethylenediamine (PM-EDA) prepared from sodium alginate hydrolysate polymanturonic acid (PM) and phenolic acid. The effects of PA structure on the antioxidant activities of 8 PA-G-PM were investigated. At the condition of nPM:nEDA=1:1.5, molar ratio of PM : carbodiimide (EDC) : N-hydroxysuccinimide (NHS)=1:2:1, activation time 0 h, pH 8.0, the highest degree of substitution of PM-EDA was up to 17.27% after reacting for 24 h. The grafting rate of PA-g-PM ranged from 4.171±0.16 to 8.880±0.32 mg GA/g. Phenolic acids were confirmed successfully grafted onto PM.by Uv-vis, FT-IR and XRD characterization. Compared to PM, the DPPH scavenging rate and iron reducing power of 8 PA-g-PM all increased significantly. The antioxidant performance of PA-g-PM was positively correlated with the number of phenolic hydroxyl groups in PA-g-PM. The antioxidant performance of PA-g-PM prossessing para-phenolic hydroxyl group was superior to that prossessing o-phenolic hydroxyl group PA-g-PM. Moreover, the phenolic hydroxyl group in PA-g-PM was replaced by methoxy group, and its antioxidant performance was weakened. This study is expected to lay a theoretical foundation for the high-value