螺旋藻多糖及其硫酸酯清除羟自由基的活性

螺旋藻粗多糖经阳离子表面活性剂十六烷基三甲基溴化铵和乙醇分级，获得多糖级分Sl，S2，S3。通过硫酸化修饰，合成相应的硫酸酯化多糖SL1，SL2，SL3．并用BaCl2—明胶比浊法确定硫酸基的含量，红外光谱法确定硫酸酯健在1240，810和620cm^-1处存在强的特征吸收峰．通过Fenton反应产生羟自由基模型，对比研究不同级分螺旋藻多糖化学修饰前后体外清除羟自由基(OH)的能力．实验表明，由于多糖级分不同，组成、极性和酸碱性的差异，其清除羟自由基能力强弱的顺序为：Sl＞S3＞S2；螺旋藻多糖经硫酸酯化后，SL2，SL3清除羟自由基能力比酯化前多糖S2，S2的能力显著增强．

Activity of Spirulina Platensis Polysaccharides and Their Sulfated Ester for Scavenging Hydroxyl Radical

Different fractions S1 ,S2 and S3 of Spirulina platensis raw polysaccharides were got by fractionation with cetyltrimethylammonium bromide (CTMAB) and ethanol. The SL1 SL2 and SL3 of sulfated polysaccharides were synthesized by modification with sulfuryl chloride. Sulfuric group content was determined by means of BaCl2-glutin turbidimetry. Some strong characteristic absorption peaks of ester sulphate bonds were observed at 1 240 cm-1, 810 cm-1 and 620 cm-1 respectively by FTIR. Fenton reaction was used as a producing hydroxyl radical model and the capacities of different fractions of sulfated polysaccharides for scavenging OH were compared with those of the unsulfated. Results demonstrated that there was a great difference for the scavenging OH capacities due to the differences of fraction, composition, polarity and acidity of polysaccharides. The order of capacity for scavenging hydroxyl radical was as follows; S1 > S3 > S2. The capacities of sulfated fractions SL2 and SL3 for scavenging OH were much stronger than those of the unesterified Spirulina platensis polysaccharides S2 and S3.