库拉索芦荟多糖的分离、纯化及其理化性质

Isolation,Purification and Physicochemical Properties of Polysaccharides from Aloe vera

以库拉索芦荟鲜叶为原料,从其去皮后的凝胶中提取得到芦荟多糖(AGP),采用硫酸铵沉淀法进行分级纯化,得到一个主要级分AGP40。分别采用高效凝胶渗透色谱法、比色法和离子色谱法对AGP40的纯度及分子质量、化学成分和单糖组成进行分析。利用红外光谱技术表征AGP40的光学特性,用旋转流变仪测定其表观黏度。结果表明:AGP40为均一性高的中性多糖,相对分子质量为338 ku,几乎不含糖醛酸和蛋白质,主要由甘露糖组成,含少量的葡萄糖。红外光谱图显示:AGP40含有乙酰基团,其乙酰基含量达29.9%,推测该多糖为乙酰化的葡甘露聚糖。此外,流变学实验显示:该多糖溶液表观黏度随浓度增加而增加。当质量浓度达到4%以上时,呈假塑性流体性质。

In the study, crude polysaccharide(AGP) was extracted from fresh Aloe vera after peeling. A fraction named as AGP40 was isolated from AGP by ammonium sulfate precipitation method. The homogeneity and molecular weight(Mw) were determined by high performance gel permeation chromatography(HPGPC). The chemical components and monosaccharide composition of AGP40 were analyzed as well. Furthermore, spectroscopic and rheological properties were also studied. The results showed that AGP40 was neutral polysaccharide with high purity. Its relative molecular mass was338 ku. No uronic acid and protein were detected. AGP40 was mainly composed of mannose, containing a small amount of glucose and high content of acetyl groups(29.9%). The FT-IR spectrum confirmed that AGP40 was an acetylated glucomannan. The apparent viscosity of AGP40 solution increased with concentration increasing, and it behaved as pseudoplastic fluid when concentration was above 4%.