Studies On The Properties, Structure And Application Of Artemisia Sphaerocephala Krasch Gum

Artemisia sphaerocephala Krasch (ASK) classified as Artemisia L. of Compositae of Sympetalae of Dicotyledonea, is one of the important pioneer plants of the moving, semi-stable and stable sand dunes in the deserts of China. ASK is distributed in very wide regions and are abundant in northwest area. ASK seed rich in protein, oil and carbohydrate can be used as food and medicine. Artemisia sphaerocephala Krasch gum (ASKG) is suitable for a wide range of applications as a new food gum. At present, however, there are few reports about isolation, purification and structure determination of polysaccharides of ASKG. The purpose of this dissertation is to study the properties, structure and application of ASKG. The main results are as follows.ASKG was composed of xylose, arabinose, rhamnose, galactose, glucose and manna, in which glucose was the major monosaccharide. AG1 and AG2 were obtained from ASKG treated by a low concentration of alkali solution. AG1 was further fractionated by chromatography on a DEAE Sepharose CL-6B and Sepharose CL-6B column into two fractions (AG11and AG12), which were shown to be homogeneous by gel filtration chromatography.The two fractions (AG11, AG12) contained mainly arabinose, xylose, rhamnose, galactose and glucose, and also little uronic acids. Mw were estimated to be 863 kDa and 346 kDa, respectively. AG2 contained glucose and uronic acids. All of the three fractions (AG11, AG12, AG2) were free of nucleic acid and protein according to UV scanning. IR spectra showed the glycosidic structure is main characteristic of the main absorptions of the three fractions. AG11 and AG12 were characterized by bothα-linked andβ-linked glycosidic bonds, whereas AG2 was characterized byβ-linked glycosidic bonds.Structure of AG12 was studied using GC, partially hydrolysis, methylation analysis, GC/MS and NMR. The results showed the main chain of AG12 were mainly xylan fragments as"smooth regions"with 1,5-D-Xylf, 1,2,6-D-Galp and 1,4-D-GlcpA and other segments as"hairy regions"with 1,2,6-D-Galp and other monosaccharides through O-6. Some residues of GlupA in the main linear region were methoxylated and contained O-acetyl groups. 1,2,6-D-Galp, 1-D-GalpA, 1,3- D-Araf, 1,3,6- D-Glcp and 1,2-L-Phap were linked as gelose, galactoglucose and other glycans, which were the mainly constitution of the branch. The...