白子草多糖的分离、纯化及初步分析

Isolation,purification and identification of polysaccharides from Gynura divaricata

对白子草中的多糖进行分离纯化，并对得到的多糖组分的理化性质进行分析。将脱脂后的白子草药材经热水提取，乙醇沉淀，木瓜蛋白酶-Sevag法去蛋白后，再经DEAE-SepharoseFastFlow离子交换柱色谱分离，透析除盐纯化得白子草多糖，采用高效液相色谱法，红外光谱和。H-NMR对其进行组成研究和分析。白子草多糖中的GDPs-2的纯度为87．3％，相对分子质量为2．03×10^4Da；GDPs．3的纯度为90．9％，相对分子质量为4．29×10^4Da。红外光谱无法确定GDPs-2是否有α构型的呋喃糖苷，但提示GDPs-3可能有α构型的呋喃糖苷键，1H-NMR分析初步判断GDPs-2和GDPs-3的糖苷键连接方式均为α型。GDPs-2由葡萄糖醛酸和木糖组成，摩尔比为1．1：0．63；GDPs-3由鼠李糖、葡萄糖醛酸、半乳糖、木糖和半乳糖醛酸组成，摩尔比为0．32：6．0：0．21：1．75：4．3。

The purpose of this study was to isolate and purify polysaccharide from C, ynura divaricata and analyze its monosaccharide composition. A water-soluble crude polysaccharide was obtained by hot water extraction, ethanol precipitation and deproteinization after degreasing. The crude polysaccharide then purified with DEAE-Sepharose Fast Flow column chromatography and dialysis. The mono- saccharide composition and structure were analyzed by HPLC, UV spectrophotometer and 1H-NMR. The results showed that the purity and molecular weight of GDPS-2 and GDPS-3 were 87. 3% , 2. 03 × 10^4 Da and 90. 9%, 4. 29 ×10^4 Da, respectively. The UV spectro- photometer and 1 H-NMR data suggested that glycosidic bond of GDPS-2 and GDPS-3 were α type. Both GDPs-2 and GDPs-3 were hom- ogeneous polysaccharides, and GDPs-2 was mainly composed of glucuronic acid and xylose at a molar ratio of 1.1 ： 0. 63. GDPs-3 was mainly composed of rhamnose, glucuronic acid, galactose, xylose and galacturonic acid at a molar ratio of 0. 32： 6. 0： 0. 21： 1.75： 4. 3.