桑叶中多糖的结构性质研究

Studies on Structural Features of Polysaccharide from Mulberry leaves

目的研究从桑叶中分离纯化获得的均一多糖SDC的结构。方法综合各种手段包括糖组成分析、甲基化分析、部分酸水解、NMR、IR等确定SDC的化学结构。结果该均一多糖相对分子质量为8.0×103,由鼠李糖、阿拉伯糖、木糖、半乳糖、半乳糖醛酸组成。主链由α-1,4-半乳糖醛酸残基相互连接而成。其中部分半乳糖醛酸形成甲基酯。侧链包括末端、1,5-、1,3,5-连接的阿拉伯糖;末端的木糖;末端、1,6-连接的半乳糖。结论该多糖为首次从桑叶中分离获得的酸性杂多糖。

OBJECTIVE To characterize the chemical structure of a homogenous polysaccharide SDC obtained from Mulberry leaves. METHODS Sugar component analysis, methylation analysis, partial acid hydrolysis, IR, ^1H-NMR, ^13C-NMR were applied to determine the structural features. RESULTS The molecular weight of SDC was 8.0×10^3 dalton by HPGFC. SDC consisted of rhammose （Rha）, arahinose （Ara）, xylose （Xyl）, galactose （Gal） and galacturonic acid units （GalA） in the molar ratio of 1.0 ： 1.6 ： 1.2 ： 2.0 ： 41.7. Part of galacturonic acid existed of methyl ester. SDC possessed an α-（1→4）-galacturonan backbone. The neutral side chains were attached to the O-3 , O-2 of GalA residues including terminal, 1, 5-linked, 1, 3, 5-linked Ara, terminal Xyl and terminal, 1, 6-linked Gal. CONCLUSION SDC was a new pectic polysaccharide for the first time obtained from Muberry leaves.