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目的研究红芪多糖HPS4-1A的化学结构特征,并初步分析其构象。方法红芪经水提醇沉法提取、Sevage法脱蛋白、H2O2脱色素、Sephadex G-200色谱柱分离纯化得到均一的红芪多糖HPS4-1A。以GC法、高效液相凝胶色谱(HPGC)法、凝胶渗透色谱-多角度激光散射仪联用(GPC-MALLS)法、元素分析、苯酚硫酸法、Bradford法研究其理化性质;以GPC-MALLS法对其构象进行初步分析。采用甲基化、部分酸水解、以及NMR研究其连接方式、主链和支链结构及分支点状况。结果 HPS4-1A的绝对分子质量为7.386×104,相对分子质量6.68×105以上;由鼠李糖、阿拉伯糖、葡萄糖、半乳糖组成,其摩尔比为1∶2∶1∶2,主链骨架由1,5、1,3,5连接的α-L-呋喃阿拉伯糖和1,6、1,2,6连接的α-D-吡喃半乳糖组成,侧链分支点位于阿拉伯糖的3位与半乳糖的2位。侧链分支由1,4、1,4,6-α-D-吡喃葡萄糖,1,2、1,2,4-α-L-呋喃鼠李糖组成。主链末端连接主要是阿拉伯糖,并且连接在1,5连接的阿拉伯糖的5位。侧链末端连接主要是葡萄糖,还有少量的阿拉伯糖。结论 HPS4-1A为一种新的中性红芪杂多糖,其构象为无规线团状,并且相对分子质量分布呈单分散性。
Objective To study the chemical structure of HPS4-1A of Radix Hedysari and to analyze its conformation. Methods Radix Hedysari extract by water extraction, Sevage deproteinization, H2O2 depigmenting, Sephadex G-200 column separation and purification to obtain a homogeneous HPS polysaccharide HPS4-1A. The physico-chemical properties were studied by GC, HPGC, GPC-MALLS, elemental analysis, phenol-sulfuric acid method and Bradford method. -MALLS method of its conformation for a preliminary analysis. Methylation, partial acid hydrolysis, and NMR were used to investigate the mode of attachment, backbone and branch structure, and branching conditions. Results The absolute molecular mass of HPS4-1A was 7.386 × 104, the relative molecular mass was above 6.68 × 105. The molecular weight of HPS4-1A was composed of rhamnose, arabinose, glucose and galactose, and the molar ratio was 1: 2: 1: 2. Α-L-arabinofuranose linked with 1,5,1,3,5 and 1,6,1,2,6 linked α-D-galactopyranose, the side chain branching point is located at 3 of arabinose Bit with galactose 2. The side chain branches consist of 1,4,1,4,6-alpha-D-glucopyranose, 1,2,1,2,4-alpha-L-furan rhamnose. The backbone end link is predominantly arabinose and attaches at position 5 of 1,5 linked arabinose. The end of the side chain is mainly connected to glucose, but also a small amount of arabinose. Conclusion HPS4-1A is a new neutral Hedysarum polysaccharide with a random coil shape and a monodisperse molecular weight distribution.