Study On The Preparation,structure Analysis And Leucocyte Growth Activity Of Oligosaccharide From Astragalus

Astragalus,a kind of perennial herbaceous plant,grows in Shanxi,Gansu province.It contains several active ingredients such as saponins,flavonoids,polysaccharides.These ingredients showed plenty activities,such as the immune regulation,anti-tumor and antivirus activities and so on.The crude polysaccharides were extracted by water extract-alcohol precipitation method from Astragalus.The protein was removed by the method of Sevag and pigment was eliminated by ethyl alcohol,and then purified by Sephadex G-100,collected a kind of white power named APS.There was no absorption in UV spectrum showed that APS absent protein and nucleic acid.The content of soluble sugar is 83.86%.From HPLC,APS with the relative molecular weight 6.93×105 Da.The results of GC identified that APS consisted of rhamnose,arabinose,xylose,mannose and glucose with molar ratio for 1:5.71:1.47:1.86:175.19.On the basis of single factor test and the orthogonal test,the optimum preparation conditions of crude oligosaccharide were degradation temperature 80?,degradation time 2 h,the concentration of H2SO4 1 mol/L,the ratio of material to solvent 20(mg/mL).The qualitative and quantitative analyses were performed on crude oligosaccharides extracted from Astragalus by TLC and HPLC.The monosaccharide and oligosaccharide(AOS)were separated by Silica gel column chromatography.The purity of AOS was 91.9%.The molecular weight and structure of AOS were analysied by FR-IR,GC,ESI-MS,1H NMR?13C NMR,periodate oxidation and Smith degradation.Results showed that AOS was an oligosaccharide with a polymerization degree of 4.The molecular weight was 662,and it consisted of rhamnose,xylose and glucose with moar ratio of 1.4:1:1.9,and the backbone was 1?2 linked or 1?6 linked.Used the moded of mice induced by cyclophosphamide,the leucocyte growth activity of oligosaccharide from Astragalus was investigated.The results indicated that the AOS could significantly increase the number of white blood cells,red blood cells,hemoglobin and bone marrow mononuclear cells(p<0.05),comparing with the other groups,the thymus index and spleen index improve.At the same time it also greatly increased the GM-CSF levels in mice serum(p<0.05).It suggested that the AOS could obviously depress the effects of cyclophosphamide induced leukopenia and it had better effect than the crude polysaccharide.