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目的考察金钗石斛水溶性多糖分子量分布并分析其单糖组成。方法金钗石斛水溶性粗多糖采用水提醇沉法获得,适量双蒸水复溶,再次醇沉,然后采用Savag法除去蛋白得到精制多糖。金钗石斛精制多糖的分子量分布采用高效凝胶渗透色谱(HPGPC)测得;多糖经水解、还原、乙酰化后采用气相色谱(GC)确定单糖组成。7种标准单糖(包括1种酮糖)同法处理。结果精制金钗石斛多糖主要由5部分组成,其保留时间分别为9.269、9.564、14.628、15.410和15.840 min,由面积归一化法计算各组分的百分含量依次是26.65%、32.36%、8.98%、20.70%和11.31%,其分子量则为9.2×104、8.1×104、4.5×102、1.2×102、6.1×10 Da。乙酰化标准单糖实现基线分离,精制金钗石斛多糖由鼠李糖、阿拉伯糖、木糖、甘露糖、葡萄糖和半乳糖6种酮糖组成,其摩尔比是:1.00:1.65:2.58:1.08:1.83:1.15。结论金钗石斛多糖主要由多糖及寡聚糖组成,其单糖组成为6种酮糖。
Objective To investigate the molecular weight distribution of water-soluble polysaccharides from Dendrobium nobile and analyze its monosaccharide composition. Methods The water-soluble crude polysaccharides of Dendrobium nobile were obtained by water-extraction and alcohol precipitation method, reconstituted with double distilled water, alcohol precipitation again, then the proteins were removed by Savag method to obtain refined polysaccharides. The molecular weight distribution of refined polysaccharides from Dendrobium nobile was determined by HPGPC. The polysaccharide was determined by gas chromatography (GC) after hydrolysis, reduction and acetylation. Seven kinds of standard monosaccharides (including a ketose) with the law. Results The polysaccharides of Dendrobium nobile were mainly composed of 5 parts with the retention times of 9.269, 9.564, 14.628, 15.410 and 15.840 min, respectively. The percentages of the components calculated by area normalization were 26.65%, 32.36% 8.98%, 20.70% and 11.31%, respectively, and the molecular weights are 9.2 × 104, 8.1 × 104, 4.5 × 102, 1.2 × 102 and 6.1 × 10 Da. Acetylated standard monosaccharides to achieve baseline separation, refined nobile dendrobium polysaccharides rhamnose, arabinose, xylose, mannose, glucose and galactose six kinds of ketose composition, the molar ratio is: 1.00: 1.65: 2.58: 1.08 : 1.83: 1.15. Conclusion The polysaccharides of Dendrobium nobile are mainly composed of polysaccharides and oligosaccharides, and their monosaccharides are composed of six kinds of ketoses.