datasheet1_Structural Characterization and Immune Activity Screening of Polysaccharides With Different Molecular Weights From Astragali Radix.docx

Saccharides are the most abundant substance with the strongest immunological activity in Astragali Radix (AR). However, systematic structure study and immunoactivity screening of polysaccharides with different molecular weights (Mw) in AR have yet to be conducted. In this study, Astragalus polysaccharides (APSs) were divided into three fragments of different Mw values, >2,000 kDa (APS-Ⅰ), about 10 kDa (APS-Ⅱ), and about 300 Da (APS-Ⅲ), by using ultrafiltration for the first time. The structural differences of the three products were determined on the basis of monosaccharide composition, FT-IR spectrum, linkage analysis, and nuclear magnetic resonance analysis. Cellular immune activity experiments in vitro and cyclophosphamide immunosuppression animal model experiments in vivo for nonspecific and specific immunoactivity screening were applied to identify the most immunogenic fragment in APSs. Linkage analysis results showed that APS-Ⅰ, APS-Ⅱ, and APS-Ⅲ have different attachment sites of monosaccharide residues. Immune screening experiments indicated that the Mw of the APSs influenced their activity, and APS-Ⅱ had the strongest immunoenhancing activity among the products. This research may serve as a reference for further study on APSs with different structures and immune activities, and as a guidance for the quality control of APSs and the development of new APS products.

糖类是黄芪（Astragali Radix, AR）中含量最为丰富且免疫活性最强的物质。然而，目前针对黄芪中不同分子量（Mw）多糖的系统结构解析与免疫活性筛选仍有待推进。本研究首次采用超滤法，将黄芪多糖（Astragalus polysaccharides, APSs）划分为三个不同分子量区间的组分：大于2000 kDa的APS-Ⅰ、约10 kDa的APS-Ⅱ以及约300 Da的APS-Ⅲ。通过单糖组成、傅里叶变换红外光谱（FT-IR）、糖苷键连接分析以及核磁共振（NMR）分析，对三种组分的结构差异进行了系统表征。本研究依托体外细胞免疫活性实验，以及基于环磷酰胺免疫抑制动物模型的体内免疫活性筛选实验，针对非特异性与特异性免疫活性进行检测，以鉴定黄芪多糖中免疫原性最强的组分。糖苷键连接分析结果显示，APS-Ⅰ、APS-Ⅱ与APS-Ⅲ具有不同的单糖残基连接位点。免疫筛选实验表明，黄芪多糖的分子量会对其免疫活性产生显著影响，其中APS-Ⅱ的免疫增强活性在三种组分中最为突出。本研究可为不同结构与免疫活性的黄芪多糖的后续研究提供重要参考，同时可为黄芪多糖的质量控制以及新型黄芪多糖产品的开发提供科学指导。