新疆医科大学学报

目的 探讨不同乙醇浓度醇沉法对库尔勒香梨多糖含量的影响,分析多糖红外表征及抗氧化活性。方法 采用水提取的库尔勒香梨提取物中加无水乙醇将乙醇浓度分别调为20%、40%、60%和80%沉淀得到四组库尔勒香梨总多糖组分,采用苯酚-硫酸法测定其含量,利用红外光谱法确定量高的多糖组分特定官能团结构。测定库尔勒香梨多糖清除1,1-二苯基-2-苦肼基(·DPPH)自由基、羟基自由基(·OH)及Cu²⁺还原能力,评价库尔勒香梨不同浓度乙醇沉淀的多糖组分的抗氧化活性。结果 当乙醇浓度为20%时多糖组分提取率为64.52%,乙醇体积分数为80%时多糖含量为62.93%。红外光谱结果显示,乙醇浓度80%时的库尔勒香梨多糖为吡喃糖;库尔勒香梨多糖对清除DPPH、·OH自由基能力和Cu²⁺还原能力随着多糖浓度的增加均逐渐增强。结论 水提、分级醇沉法操作简便,不同乙醇浓度醇沉对库尔勒香梨多糖含量、提取率和抗氧化活性有一定的影响。

Objective To investigate the effects of alcohol precipitation with different concentrations of ethanol on polysaccharide content of Pyrus sinkiangensis Yü, and to analyze its infrared characterization and antioxidant activity of polysaccharide. Methods Four groups of total polysaccharide components of Pyrus sinkiangensis Yü were precipitated by adding anhydrous ethanol to aqueous extract of Pyrus sinkiangensis Yü and adjusting ethanol concentration to 20%,40%, 60% and 80%; the content of polysaccharides was determined by phenol-sulfuric acid method, the structure of specific functional groups was predicted by infrared spectroscopy, and the antioxidant activity was evaluated by determining DPPH radical(·DPPH) scavenging ability, hydroxyl radical(·OH) scavenging ability and metal Cu²⁺reducing ability, and compared with the antioxidant ability of VC. Results When the volume fraction of ethanol was 20% with highest extraction yield, and the highest content was 80%. Infrared spectroscopy analysis showed that monosaccharide was pyranose. With increasing of polysaccharide concentration, the scavenging ability of ·DPPH and·OH radical and the reducing ability of Cu²⁺of Pyrus sinkiangensis Yü polysaccharide was increased gradually. Conclusion Fractional alcohol precipitation is easy to operate, and ethanol precipitation with different concentrations have certain effects on polysaccharide content, extraction rate and antioxidant activity.