沙棘果皮水溶性多糖H_n的结构研究

Structure investigation of water soluble polysaccharide H_n isolated from the fruits of Hippophae rhamnosides L

沙棘果皮水溶性多糖经酸性乙醇分级和DEAE -SephadexA - 2 5柱层析纯化 ,得到多糖Hn.经SepharoseCL - 4B柱层析、玻璃纤维纸电泳、比旋光度测定等方法鉴定Hn 为均一多糖 .经唾液淀粉酶解、部分酸水解、高碘酸氧化、Smith降解、甲基化分析及IR ,1 3C -NMR ,GC和GC -MS等方法 ,确定其基本结构中主链由 1→ 4Glc基、1→ 6Man基和 1→ 6Gal基构成 .三者摩尔比为nGlc∶nMan∶nGal=3∶1 .5∶1 ,分支点在 3—O处 ,分支率为 43% ,侧链由 1→ 6Gal基、1→ 4Glc基、末端Glc或末端Ara基构成 .

The crude polysaccharide isolated from the fruits of Hippophae rhamnosides L . Serveral fractions were got after fractionation. We have studied the structure of H n . Its homogeneity was confirmed by glass fiber electrophoresis,chromatography on sepharose CL-4B and optical rotation measurement. Its molecular weight estimated by gel filtration is approximately 100 000. By means of IR, GC, GC-MS, 13 C-NMR, periodate oxidation, Smith degradation, methylation analysis, partical hydrolysis with acid and amylase hydrolysis ect. The structure of H n was identified. Its basic structure is composed of (1→4)-linked glucose,(1→6)-linked mannose and (1→6)-linked galactose residues in main chain ;and (1→)-linked glucose,(1→)-linked arabinose, (1→6)-linked galactose and (1→4)-linked glucose in side chains. Side chains attached to O—3 of glucose, mannose and galactose. On average, among 11 main chain residues, there are 5 branches.