Extraction,Isolation,Purification And Structural Identification Of Polysaccharides From Alhagi Sparsifolia

Alhagi sparsifolia Shap.,is a plant of the family Leguminosae and the genus Alhagi.It is a commonly used medicinal plant in Xinjiang Uygur Autonomous Region and Inner Mongolia Autonomous Region,which is often used to treat rheumatic diseases and tumors.Seven homogeneous polysaccharides were isolated from the aerial parts of Alhagi sparsifolia in the early stage of our research group.Their structures had not been reported in literature,and they had certain osteogenic activity and anti-neuritis activity in vitro.Therefore,this thesis continued to separate and purify polysaccharides from the aerial parts of A.sparsifolia,and characterized the structures of the obtained homogeneous polysaccharides,which provide the basis of substances for subsequent studies on anti-osteoporosis or anti-neuritis activities.Firstly,four parts AP50,AP70,AP90,and APB were obtained by hot water/alkaline extraction and graded alcohol precipitation from the aerial parts of A.sparsifolia(30 kg).Four parts of crude polysaccharides APY50,APY70,APY90,and APYB were obtained by deproteinization and dialysis.Subsequently,eight purified polysaccharides,named APP90-1-1,APP90-1-2,APP90-2,APP90-3,APBP-1,APBP-2-1,APBP-2-2,and APBP-2-3 were systematically separated and purified by DEAE-52 anion exchange chromatography column and Sephacryl S-100 gel column in turn from the crude polysaccharides APY90 and APYB.The results of specific rotation analysis and HPGPC showed that these eight purified polysaccharides were all homogeneous polysaccharides,with the relative molecular weights of 5.0 kDa,4.8 kDa,5.9 kDa,7.5 kDa,40.2 kDa,41.0 kDa,31.9 kDa and 9.5 kDa,respectively.The primary structures of the eight homogeneous polysaccharides from A.sparsifolia were characterized by monosaccharide composition analysis,D/L absolute configuration analysis,FT-IR,methylation-linkage type analysis and NMR analysis.The results showed that APP90-3 was arabinan.APP90-1-1,APP90-1-2,APP90-2,APBP-1,APBP-2-1,APBP-2-2 and APBP-2-3 were all heteropolysaccharides,and the structures of them had not been reported.In addition,the Congo-red assay and the scanning electron microscopy analysis were used to analyze the advanced structures of these eight homogeneous polysaccharides,and the results showed that they did not contain triple helix structure and had different morphologies.At the same time,our research group also studied the osteogenic activity and anti-neuritis activity of the eight homogeneous polysaccharides from A.sparsifolia in vitro.The results showed that APP90-1-1,APP90-1-2,APP90-2,APBP-2-2 and APBP-2-3 had certain osteogenic activity in vitro.APP90-1-1,APP90-1-2,and APBP-2-1 had certain anti-neuritis activity,and the inhibitory effects of APP90-1-1 and APBP-2-1 on nitric oxide were equivalent to the 5 μM positive drug(minocycline).The above experimental results showed that the homogeneous polysaccharides of A.sparsifolia had certain osteogenic activity and anti-neuritis activity in vitro,which lays an experimental foundation for the subsequent study of its mechanism of action and structure-activity relationship,and is beneficial to the development and application of A.sparsifolia resources.