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 removing 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,—CO etc.but they were not proteoglycan.The hydrolyzate of pure exopolysaccharide 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 concentration of 20mg/mL,the scavenging activities of DPPH· and O~-_2· radicals of EPS-I could reach to 80% above.