金钗石斛免疫活性多糖DNP-W1B的结构特征

从金钗石斛茎中获得了1个均一多糖组分DNP-W1B, 采用化学与光谱学结合的手段对其一级结构进行了解析. 结果表明, DNP-W1B分子量为7.7×10⁵, 比旋度²⁰_D=+81.3°(c0.3, H₂O), 由葡萄糖、 阿拉伯糖和半乳糖3种单糖组成, 摩尔比为6.2:3.1:0.9. DNP-W1B主链由1,4-和1,6-连接的葡萄糖残基组成, 在主链1,6-连接葡萄糖残基的4位形成分支, 支链由末端半乳糖残基和阿拉伯糖残基组成. 初步的免疫活性实验结果表明, DNP-W1B在体外能促进免疫细胞的增殖.

Structural Characterization of an Immunoactive Polysaccharide DNP-W1B from Dendrobium nobile Lindl.

Dendrobium nobile Lindl.(Chinese name "Jin-Chai-Shi-Hu") is a species of Orchidaceae with distribution in Southeast Asia, southwest and south of China. In this work, a water-soluble heteropolysaccharide DNP-W1B with a molecular mass of 7.7×105 and specific rotation of 20D=+81.3°(c 0.3, H2O) was isolated from the stems of D. nobile Lindl. Monosaccharide composition analysis showed that DNP-W1B contained glucose, arabinose and galactose in a molar ratio of 6.2: 3.1: 0.9. The structural features of DNP-W1B were revealed by the combination of chemical and instrumental analysis, including IR, GC, methylation analysis and NMR. The results showed that DNP-W1B possessed a backbone of a disaccharide unit of with 33% branches at O-4 of (1→6)-linked β-D-glucopyranosyl residues. The side chains contained arabinosyl and galactosyl chains. Primary immunological tests in vitro indicated that it could stimulate LPS-induced B lymphocyte and Con A-induced T lymphocyte proliferation. Survey showed that DNP-W1B was a novel immunoactive polysaccharide compound from Dendrobium Sw.