不同方法提制的茶叶粗多糖的光谱分析

Spectral Analysis of Crude Tea Polysaccharides Extracted by Different Methods

以低档绿茶为原料采用煎煮法提制得茶叶粗多糖CTPS-Ⅰ,用复合酶法提制得CTPS-Ⅱ,采用复合酶法从茶树鲜叶中提制得茶叶粗多糖CTPS-Ⅲ。测定了各茶叶粗多糖的糖含量和蛋白质含量。用HPG-PC-ELSD法分析了各茶叶粗多糖中均一性组分分布及其质量比例,CTPS-Ⅰ,CTPS-Ⅱ和CTPS-Ⅲ各含有5,4和7种均一性组分;GC-MS法测得三种茶叶粗多糖均由鼠李糖、阿拉伯糖、木糖、甘露糖、葡萄糖和半乳糖六种单糖组成,并分析了其摩尔比例;紫外-可见吸收光谱显示CTPS-Ⅰ在257nm处有吸收峰,CTPS-Ⅱ在240～270nm区段有一吸收肩峰,CTPS-Ⅲ在250～360nm区段有微弱的"双波浪状"特征吸收,并分析了其游离蛋白质和核酸的含量关系,红外光谱研究了茶叶粗多糖的糖类复合物的特征;圆二色谱分析表明三种茶叶粗多糖在水溶液中呈现不同的构象。

Crude tea polysaccharides （CTPS） were extracted from low-grade green tea, separately named CTPS-Ⅰ by water-boiling extraction method and CTPS-Ⅱ by compound enzyme method, and CTPS-Ⅲ extracted from tea leaves by compound enzyme method. The content of saccharide and protein of them were determined. The homogeneity distribution and mass ratio of polysaccharides constituent were analyzed using HPGPC-ELSD, and there were 5, 4 and 7 kinds of homogeneous constituents accordingly in CTPS- Ⅰ , Ⅱ and Ⅲ. There were six kinds of monosaeeharide residues （rhamnose, arabinose, xylose, mannose, glucose and galatose） in CTPS confirmed by means of GC MS. UV spectra discovered that CTPS-Ⅰ had a distinctive peak absorption at 257 nm, while CTPS-Ⅱ showed a shoulder-shaped peak absorption in 240-270 nm, and CTPS-m exhibited a weak double wave-shaped absorption in 250-360 nm addition, the mass ratio of free protein and nucleic acid in CTPS was determined. IR revealed the characteristics of tea polysaccharides complex including related protein and nucleic acid. CD spectra showed that their conformations in water were different.