本文以光果甘草叶为原料，提取得到水溶性多糖GC C，采用DEAE-Sepharose Fast Flow柱层析法对GC C进行分离纯化，得到一种中性多糖（GC I），两种酸性多糖（GC II和GC III），选择DPPH自由基清除能力、氧自由基吸收能力（ORAC）强的中性多糖GC I，对其进行结构特征分析。采用高效凝胶渗透色谱法（GPC）、红外光谱法（FT-IR）、PMP柱前衍生-高效液相色谱法（HPLC）、甲基化-气相色谱质谱法（GC-MS）测定GC I的分子量、单糖组成以及糖苷键连接方式。GC I含有两个分子量分布不同的多糖，它们的平均分子量分别为980 ku及20 ku；红外光谱中4000~500 cm-1波数范围内出现了多糖的特征峰；GC I由5种单糖组成，包括：甘露糖、鼠李糖、葡萄糖、半乳糖和阿拉伯糖；GC I中→2)-Araf-(1→、→6)-Galp-(1→和→6)-Glcp-(1→残基含量最高。

A crude water-soluble polysaccharide (GC C) was obtained from Glycyrrhiza glabra L. Leaf by water extraction. DEAE-Sepharose fast flow column chromatography was used to separate and purify GC C to obtain one neutral polysaccharide (GC I) and two acidic polysaccharides (GC II and GC III). The strongest 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and oxygen radical absorbance capacity (ORAC) were detected in GC I, which was therefore selected for structural characterization. The molecular weight, monosaccharide composition, and glycosidic linkages of GC I were determined by high performance gel permeation chromatography (GPC), infrared spectroscopy (FT-IR), 1-phenyl-3-methyl-5-pyrazolone (PMP) precolumn derivatization-high performance liquid chromatography (HPLC), and methylation-gas chromatography mass spectrometry (GC-MS). It was found that GC I consisted of two polysaccharides with average molecular weights of 980 kDa and 20 kDa. The FT-IR spectra showed the characteristic peaks of the polysaccharides were in the frequency range of 4000-500 cm-1. Monosaccharide composition analysis indicated that GC I contained mannose, rhamnose, glucose, galactose, and arabinose, The residues of →2)-Araf-(1→, →6)-Galp-(1→ and →6)-Glcp-(1→ showed thehighest amounts in GC I.

“十二五”国家科技支撑计划项目（2012BAD37B08-01）