胆木和裸花紫珠多糖的分子量测定

Molecular weight determination of polysaccharides from Nauclea officinalis and Callicarpa nudiflora Hook. ex Arn

目的:分离纯化出胆木和裸花紫珠药材中的水溶性多糖成分,并测定其分子量和分子量分布.方法:采用水提醇沉法分离纯化出胆木和裸花紫珠水溶性多糖,采用高效液相凝胶色谱法联合CAD检测器,以葡聚糖作为标准溶液,运用Chromeleon 7 Extension Pack GPC Templates软件作图分析,根据葡聚糖对照品标准曲线和方程测定胆木和裸花紫珠水溶性多糖的分子量和分子量分布.结果:本方法分到的水溶性胆木多糖数均分子量Mn为230 777,重均分子量Mw为261 646,分子量分散系数为1.13,分布带较窄;裸花紫珠水溶性多糖数均分子量Mn为167 885,重均分子量Mw为747 309,分子量分散系数为4.45,分布带较宽.结论:该法测定大分子物质的分子量和分子量分布准确可靠,适用于多种无紫外吸收的大分子物质的分子量测定.

Objective：To isolate and purify the water-soluble polysaccharides from Nauclea officinalis and Callicarpa nudiflora Hook. ex Arn and to determine the molecular weight and distribution.Methods： Polysaccharides were isolated and purified from the Nauclea officinalis and Callicarpa nudiflora Hook. ex Arn using water extraction followed by alcohol precipitation. The molecular weight（Mw） and distribution of polysaccharides was measured using size exclusion-high performance liquid chromatography（ SE-HPLC） combined with CAD detector. Dextran was used as the standard substance and mapping was analyzed by Chromeleon 7 Extension Pack GPC Templates software. Results： The number average molecule weight（ Mn） and weight-average molecule weight（ Mw） of polysaccharides isolated from Nauclea officinalis were 230 777 and 261 646,with a narrow Mw distribution from 360 000 to 1 020 000（ polydispersity index（ PDI） = 1. 13）; while Mn and Mw of polysaccharides from Callicarpa nudiflora Hook. ex Arn were 167 885 and 747 309 with a somewhat wide Mw distribution from108 000 to 1 310 000（ PDI = 4. 45）. Conclusion：The method used for molecular weight determination in this work is accurate and reliable, and it is suitable for measuring the molecular weight of macromolecular substances without ultraviolet absorption.