Extraction,Isolation,Purification,Characterization And Its Biological Activity Of Polysaccharide From Taraxacum Mongolicum

In this paper,the wild Taraxacum mongolicum was used as the main raw material,and the TMPs(Taraxacum mongolicum polysaccharides)was studied systematically,including optimization of extraction conditions,separation and purification,structural analysis and preliminary research of biological activity.The results are as follows:1.Extraction process optimization of polysaccharidesThe TMPs were extracted by ultrasonic extraction method,and the yield was taken as the response value.The single factors and response surface optimization experiments were carried out to determine the optimal extraction parameters.The results showed that the optimal extraction parameters were ultrasonic time 63 min,ultrasonic temperature 73 °C,ultrasonic power 120 W,liquid to material ratio 25:1 mL/g,the yield of polysaccharide was 14.27%.Compared with the traditional hot water extraction method,the extraction time was shorter,the temperature was lower,and the yield were higher.2.Separation and purification of TMPsThe polysaccharide loss rate and the decolorization rate as index,decolorization effects of activated carbon method,hydrogen peroxide method,chitosan method and macroporous resin method were compared.The deproteination effect of the sevag method,the sevag-enzyme method,trichloroacetic acid(TCA)method and salting out method were compared with polysaccharide loss rate and deproteination rate as index.The results indicated that the macroporous resin S-8 had the best decolorization effect,the decolorization rate was 86.45%,the polysaccharide loss rate was 18.9%,the salting out method deproteinization effect was the best,the deproteinization rate was 85.64%,and the polysaccharide loss rate was 20.51%.The initially purified polysaccharide was subjected to DEAE-Sepharose FF column chromatography to obtain two components,TMP-1 and TMP-2,which were then subjected to Sephadex G-75 and Sephadex G-150 column chromatography to obtain two polysaccharides TMP-1-1 and TMP-2-1.The purified components are pale yellow powder,and do not contain starch,polyphenols and reducing sugars;the purity of TMP-1-1 was 95.2% and does not contain uronic acid as a neutral polysaccharide;the purity of TMP-2-1 was 85.9% and contains uronic acid as an acidic polysaccharide.3.Structural characterization of TMP-1-1The structure of the TMP-1-1 was characterized,the results showed that TMP-1-1 consisted by mannose and glucose with a molar ratio of 45.41:52.39.The TMP-1-1 with triple helix structure composed mainly of ?-furanose glycans.The main chain is mainly composed by ?-D-Glc/Manp-1-and-1-?-DGlc/Manf-2-glycosyl groups with a molar ratio of 2:14 and its linkage mode is ?2-?-DFruf-1?2-?-D-Fruf-1?,there is also an ?-D-Glcp-1?glycosyl group attached to the non-reducing end of the polysaccharide and having an acetyl group attached to the hydroxyl group of C4.Scanning electron microscopy showed that TMPs had more impurities and irregular aggregation.The TMP-1-1 contained almost no impurities,and its surface morphology was relatively smooth and the edges showed irregular flaky morphology.4.Preliminary study on the biological activity of polysaccharideTMPs have strong reducing activity(0.6864,0.5 mg/mL),hydroxyl radical scavenging activity(65.30%,0.5 mg/mL),DPPH· free radical scavenging activity(80.14%,0.5 mg/mL)and superoxide anion scavenging activity(85.47%,0.5 mg/mL).It also has strong hypoglycemic activity,?-glucosidase inhibition ability(70.28%,1 mg/mL),and ?-amylase inhibition ability(79.26%,1 mg/mL).TMP-1-1 also has strong reducing activity(0.6819,0.5 mg/mL),hydroxyl radical scavenging activity(71.77%,0.5 mg/mL),DPPH· free radical scavenging activity(65.48%,0.5 mg/mL)and superoxide anion scavenging activity(80.02%,0.5 mg/mL).It also has strong hypoglycemic activity,?-glucosidase inhibition ability(75.47%,1 mg/mL),and ?-amylase inhibition ability(81.43%,1 mg/mL).Comparing the antioxidant activities of the two polysaccharides,it was found that TMPs had stronger free radical scavenging activity than TMP-1-1;the results of hypoglycemic activity showed that TMP-1-1 had stronger enzyme inhibitory activity than TMPs.It can be seen that dandelion polysaccharide is a promising and natural antioxidant and hypoglycemic drug.