Regioselective synthesis of sulfated guar gum: comparative studies of structure and antioxidant activities.
Regioselective synthesis of sulfated guar gum: comparative studies of structure and antioxidant activities.
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DOI：
10.1016/j.ijbiomac.2013.10.005
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发表时间：
2013-11
影响因子：
8.2
通讯作者：
Junlong Wang;Shengfan Niu;Baotang Zhao;Xiaofang Wang;Jian Yao;Ji Zhang;Weiwei Zhao;Yuting Zhao
中科院分区：
文献类型：
--
作者：
Junlong Wang;Shengfan Niu;Baotang Zhao;Xiaofang Wang;Jian Yao;Ji Zhang;Weiwei Zhao;Yuting Zhao
本文报道了以三苯基氯甲烷（TrCl）为保护前体合成低取代度（DSS）（0.58）的C-2和C-3硫酸化瓜尔胶（SRSGG）的新方法。三苯甲基化GG（GGTr）的产率和DSTr（以三苯基甲醇的重量计算）分别为165.6%和0.71。此外，由于保护基对酸的敏感性较低，硫酸化反应中选择了较低的氯磺酸与吡啶的比例（1：4）。FT-IR和~（13）C NMR结果表明，SRSGG中以C-2和C-3取代为主，但未完全硫酸化。体积排阻色谱结合多角度激光光度计（SEC-LLS）显示，在反应中的分子量下降。这可能是由于硫酸化和脱保护过程中的降解。最后，我们研究了结构特征对体外抗氧化活性的影响。体外抗氧化实验表明，该化合物在C-2和C-3位的区域选择性硫酸化，分子量小，具有较强的抗氧化活性，清除DPPH自由基和羟自由基的能力明显高于已知的C-6-硫酸化衍生物。硫酸多糖的抗氧化活性不是单一因素的作用，而是分子量、DSS和取代位置的综合作用。
We reported here a new synthesis of C-2 and C-3 sulfated guar gum (SRSGG) with low degree of substitution (DSS) of 0.58, employing triphenylchloromethane (TrCl) as a protected precursor. The yield and DSTr(calculated from the weight of triphenylmethanol) of triphenylmethylated GG (GGTr) was 165.6% and 0.71, respectively. In addition, low ratio (1:4) of chlorosulfuric acid to pyridine (1:4) was chosen in sulfation reaction since the protecting group was slightly sensitive to acid. Results of FT-IR and13C NMR spectroscopy indicated that C-2 and C-3 substitution was predominant but not fully sulfated in SRSGG. Size-exclusion chromatograph combined with multi-angle laser photometer (SEC-LLS) showed a decrease in molecular weight in the reaction. This might be due to the degradation in sulfation and deprotection process. Finally, we investigated the effect of structure features on the antioxidant activities in vitro. Vitro antioxidant experiments revealed that the regioselective sulfation at C-2 and C-3 and low molecular weight afforded strong antioxidant activities showing a much higher scavenging abilities of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radical than that by the known C-6-sulfated derivative. The antioxidant activities of sulfated polysaccharides were not a function of a single factor but a combination of molecular weight, DSSand substitution positions.