东方伊萨酵母胞外多糖的单糖组成及抗氧化活性分析

Study on the Monosaccharide Composition of Exopolysaccharides from Issatchenkia orientalis and Its Antioxidant Activity

采用乙醇沉淀法从东方伊萨酵母的发酵液中得到胞外多糖。去蛋白、透析后,通过DEAE-Cellulose 52离子交换层析得到胞外多糖纯品EPS-I,紫外扫描该纯品无蛋白、核酸杂质。红外光谱鉴定表明该胞外多糖纯品含有—OH、—CH、—C O等多糖的特征吸收峰且不是以蛋白多糖的形式存在;气相色谱法测定了东方伊萨酵母胞外多糖水解后的单糖组分为L-鼠李糖、D-木糖和D-甘露糖,各糖残基的质量分数分别为3.62%、11.47%和84.91%。对EPS-I的体外抗氧化活性进行了研究,以胞外多糖的总抗氧化能力(TAC)和对DPPH.、羟基自由基、超氧阴离子的清除率4个方面来考察EPS-I的体外抗氧化能力,结果验证了EPS-I具有抗氧化活性,当EPS-I浓度为20 mg/mL时,对DPPH.和超氧阴离子的清除率均达到80%以上。

In this research we separated the exopolysaccharide from fermentation medium of Issatchenkia oriental by ethanol precipitation, and pure exopolysaccharide（EPS-I） was obtained by DEAE-cellulose52 chromatography after re- moving protein and dialyses. The structure of pure exopolysaccharide were determined by UV scanning. Identification of IR showed that the exopo- lysaccharide had polysaccharides specific function group such as --OH ,--CH ,--C -- O etc. but they were not proteoglycan. The hydrolyzate of pure exopolysaecharide was analyzed by Gas chromatography and the result indicated that the exopolysaccharide was mainly consisted of L-mannose, D-xylose and D-rhamnose, and their content were 3.62% , 11.47% and 84.91% , respectively. Preliminary research on the antioxidant activity in vitro of EPS-I was done. Total antioxidant capacity （TAC） , the scavenging rate of DPPH ~ , hydroxyl radical and superoxide anion were investigated in vitro. The results demonstrated that EPS-I had favorable antioxidant activity, at the concen- tration of 20mg/mL, the scavenging activities of DPPH ~ and O~ ~ radicals of EPS-I could reach to 80% above.