Research On Extraction Optimization,Purification And Structural Features Of Polysaccharides Isolated From Dendrobium Candidun Huoshanense

In order to extract the polysaccharides of dendrobium fully,the paper based on the material of fresh Dendrobium Candidum Huoshanense(HDCP),After removing the leaves and cleaning up the whole herb,green removing and drying,crushing skim,adopted traditional hot water extraction to extract the polysaccharides.Chose the three most important factors (temperature, time, liquid-raw ratio)to investigate the single factor,combined the Box-Behnken design of response surface,thus the hot water extraction of polysaccharide process was optimized.On the basis of this,used DEAE-52 anion exchange column to isolate crude polysaccharides of dendrobium.A serious of problems was discussed on the structural characters of each polysaccharide preparation,the results are following:1.The quadratic fitting equation of temperature(A),time (C),liquid-raw ratio(B) and polysaccharide yield was:Yield=16.98+1.26*A+2.14*B+1.05*C+1.23*A*B- 2.11*A2 - 3.75*B2 - 1.03*C2.The optimized process of polysaccharide hot water extraction is temperature 79 ℃,time 140minutes,liquid-raw ratio 1:30.And the polysaccharide yield is 17.45%,which is very closed to the predicted value.2.Through DEAE-52 chromatographic separation,the three fraction HDCP-W^ HDCP-1 and HDCP-3 was isolated from crude polysaccharides of HDCP. Analyzed the crude polysaccharides and each fraction with GC,the result showed that:HDCP consisted of arabinose,rhamnose,xylose,galactose,glucose and mannose in a ratio of 11.4:8:13.4:10.7:44.5:12.HDCP-W consisted of arabinose, galactose, glucose and mannose in a ratio of 38.9:21.3:24.2:15.6.HDCP-1 consisted of xylose,galactose and glucose in a ratio of 81.1:3.4:15.5.HDCP-3 consisted of arabinose, rhamnose, glucose and mannose in a ratio of 23.2:30:15.4:31.4.3.The infrared spectroscopy of HDCP-W, HDCP-1 and HDCP-3 showed that they both have the obvious characteristic absorption peak of carbohydrates at 3400, 2900cm-1.4.Detection by GPC-MALLS-RI conformed that HDCP-W does not contain impurities such as protein.The molecular weight of HDCP-W is 3.538×105g/mol and the molecular rotation radius is 51.9nm,dispersion coefficient is 1.139,molecular conformation tends to irregular line group.5.Observation by scanning electron microscope found that the molecular micromorphology of HDCP-W was mainly constituted by thin strips, fragments of different sizes and irregular network group.