目的 研究从细茎石斛Dendrobium moniliforme中得到的中性多糖DMP2-A的化学结构和在水溶液中的构象。方法 利用单糖组分分析、甲基化分析、红外光谱（IR）、尺寸排除色谱-激光光散射仪联用等方法分析其结构特征和溶液构象。结果 DMP2-A由阿拉伯糖、木糖、甘露糖、葡萄糖及半乳糖组成，其中木糖残基主要以1-链接的末端糖存在；葡萄糖残基链接方式为1，3-链接、1，4-链接和1，3，6-链接；半乳糖残基链接方式为1，3-链接、1，4-链接和1，3，6-链接；阿拉伯糖残基以1，3，5-链接；甘露糖残基以1，3，6-链接。该多糖在0.15 mol/L的NaNO₃水溶液中重均相对分子质量为1.07×10⁴，存在少量聚集体，聚集数约为38。结论 DMP2-A为多分枝、结构复杂的多糖，其化学结构及在水溶液中的聚集形态为首次报道。

Objective To study the chemical structure and the conformation in the aqueous solution for a novel neutral polysaccharide (DMP2-A) purified from Dendrobium moniliforme. Methods The chemical structural characterization was determined with sugar analyses, methylation analyses, and IR spectroscopic methods. Moreover, the molecular weight and conformation in the aqueous solution were analyzed by size-exclusion chromatography (SEC) combined with laser light scattering (LLS). Results The polysaccharide DMP2-A consisted of 1-linked terminal xylosyl residue, 1,3-, 1,4-, and 1,3,6-linked glucosyl residues, 1,3-, 1,4-, and 1,3,6-linked galactosyl residues, 1,3,5-linked arabinosyl residue and 1,3,6-linked mannosyl group. Moreover, the weight-average molecular (M_w) of polysaccharide DMP2-A was determined to be (1.07×10⁴). A small amount of aggregates were formed with the aggregation number of approximately 38 in the 0.15 mol/L NaNO₃ aqueous solution. Conclusion DMP2-A is a kind of polysaccharide with multi-branch and complicated structure. It's the first time that the polysaccharide DMP2-A was isolated and the chemical structure and conformation in aqueous solution were reported.

云南省应用基础研究面上项目（2014FB139）；云南省教育厅科学研究基金项目（2014Z046）