【摘要】 目的 研究不同梯度醇沉对红芪多糖提取含量的影响，及其抗氧化活性和红外谱图的分析。方法 采用水提分级醇沉（20%、40%、60%、80%乙醇浓度）法提取红芪多糖，采用苯酚-浓硫酸法测定红芪多糖的含量，并利用方法学考察该含量测定方法。测定不同梯度醇沉所得红芪多糖对金属Cu²⁺螯合能力、DPPH自由基清除率及羟基自由基清除率。通过近红外光谱分析确定抗氧化活性最强多糖组分的特定官能团结构。结果 当醇沉浓度为80%时，红芪多糖提取率为84.80%,含量为61.62%,抗氧化活性最强，红外光谱分析显示抗氧化活性最强的多糖组分中含有羟基（-OH）,次甲基（C-H）,羰基（C=O）,碳氧单键（C-O-C或C-O）等多个还原性基团。结论 红芪多糖的提取率和含量随着醇沉浓度增加明显增加，红芪多糖具有良好体外抗氧化活性，其抗氧化活性与富含羟基和次甲基等还原性官能团有关。更多还原

【Abstract】 Objective To study the effect of different gradient alcohol precipitation on the extraction content of polysaccharides from Astragalus membranaceus, as well as to analyze its antioxidant activity and infrared spectrum. Methods The method of water extraction and alcohol precipitation（20%, 40%, 60%, 80% ethanol concentration） was used to extract polysaccharides from Astragalus membranaceus. The content of polysaccharides was determined using the phenol concentrated sulfuric acid method, and the content determination method was investigated using methodology. The metal Cu²⁺ chelating ability, DPPH free radical scavenging rateand hydroxyl free radical scavenging rate of Astragalus polysaccharides were determinedby different gradient ofalcohol precipitation. The structure of specific functional groupsof polysaccharide with the strongest antioxidant activity was determinedby near-infrared spectroscopy. Results The concentration of alcohol precipitation was 80%, the extraction yield of Astragali polysaccharide was 84.80%, the content was 61.62%, and the antioxidant activity was the strongest. Infrared spectrum analysis showed that the polysaccharide components with the strongest antioxidant activity contained multiple reductions such as hydroxyl（-OH）, methine（C-H）, carbonyl（C=O）, and carbon-oxygen single bonds（C-O-C or C-O）. Conclusion The experimental results showed that the extraction rate and content of Radix Astragali polysaccharides increased significantly with the increase of alcohol precipitation concentration. And astragalus polysaccharide had good antioxidant activity in vitro, and its antioxidant activity wasrelated to the richreducing functional groups such as hydroxyl and methine.更多还原