RESUMO
Polysaccharides and free monosaccharides are important active components in Cistanches Herba, which have functions of anti-aging and immunological activity regulation. The study of monosaccharide composition in polysaccharide and free monosaccharide can lay a foundation for the study of primary structure, spatial structure of Cistanche polysaccharide and biological activity of Cistanches Herba. In this study, a method of water extraction and alcohol precipitation was used to extract Cistanche polysaccharide. Trifluoroacetic acid was selected as the hydrolytic acid for polysaccharide hydrolysis. An orthogonal experimental method is established. Three levels of acid concentration, hydrolysis temperature and hydrolysis time were selected to investigate the optimal hydrolysis condition. The optimal hydrolysis condition was 0.08 mol·L-1 trifluoroacetic acid hydrolysis at 100 ℃ for 3 h. The free monosaccharides of Cistanches Herba were extracted by water extraction. The established ion chromatogram integrated pulsed amperometry method can efficiently separate 11 monosaccharides in a short time. The method has good repeatability and high sensitivity, methodological experiment results meet the requirements of quantitative determination. It can accurately determine the monosaccharide composition of Cistanche polysaccharide and free monosaccharide content. Ion chromatography does not require derivatization operation and the pre-treatment steps are simple. This method can measure fructose, but PMP derivation-HPLC method can't. The monosaccharide composition of Cistanche polysaccharide include fucose, arabinose, rhamnose-galactose, glucose, xylose, mannose, fructose, ribose and glucuronic acid, among which the contents of glucose and fructose are relatively high. The free monosaccharides in the water extract of Cistanches Herba include glucose, fructose and mannose.