Study On The Structure And Activity Of Taraxacum Mongolicum Polysaccharide

Objective To study on the activity of Taraxacum mongolicum polysaccharide with different molecular weight,and continue to study its structural characteristics.Methods(1)Extraction,isolation and purification of TMP: The extraction process of TMP was optmized with orthogonal test.The crude polysaccharides were extracted from the dried whole grass of Taraxacum mongolicum polysaccharide by the method of water extract-alcohol precipitation.Then TMP was abtained by trichloroacetic acid(TCA)twice for to remove its protain.Seven groups TMP were isolated through membrane technology.(2)The activity screening of Taraxacum mongolicum polysaccharide: The anti-oxidant of Seven groups Taraxacum mongolicum polysaccharide were evaluated by three experiments that O2-scavenging ratio,.OH scavenging ratio and DPPH scavenging ratio;The Antibacterial activity of Seven groups TMP were evaluated by filter paper method and agar dilution method.(3)The TMP that have been selected were purified through DEAE Cellulose 52 and Sephadex G-100.(4)The structure analysis of homogenous TMP: The purity and molecular weight of homogenous TMP were detected by HPGPC-ELSD.The structure of homogenous TMP were analyzed by high performance liquid chromatography(HPLC),periodate oxidation,Smith degradation,methylation analusis,gas chromatography-mass spectrometer(GC-MS)and infrared spectroscopy(IR).Results(1)The optmized extraction condition is that extraction temperature is 90 ?,solid-liquid ratio is 1:30,extraction duration is 1 h and extraction times is three times.The extraction ratio of TMP is 10.32%.TMP was extracted under the optimum extraction process,and obtained by removing protain with TFA for twice,their protein content decreased by 0.9%,prop-ortions of 7 fractions of TMP(<6 kDa,6~10 kDa,10~20 kDa,20~50 kDa,50~100 kDa,100~150 kDa,and >150 kDa)in total polysaccharides are 41.6%,2.7%,2.4%,13.2%,3.0%,21.9%,15.2%.Content of 7 fractions of TMP are 38%,39%,30%,29%,23%,26%,9%.(2)Two groups of TMP were selected by activity screening about antioxidant and Antibacterial.(3)Two homogenous polysaccharides are isolated and purified through DEAE-Cellulose 52 and Sephadex G-100,named TMP-A0.a(<6 kDa)and TMP-D0.a(20~50 kDa).The molecular weights of two homogenous TMP are 5.21×103Da,and 4.97×104Da,respectively.Both of them are consist of Man,Rha,GlcA,GalA,Glc.However,their molar ratio are different.The structure of TMP-A0.a is mainly that main chain is(1?6)-linked-Glcp,terminal residues are Rhap and GlcpA.The structure of TMP-D0.a is mainly that main chain is consist of(1?2)-linked-Glcp and(1?4)-linked-Glcp,terminal residues are Rhap and GlcpA,and they also have two kinds of glycosidic bonds ? and ?.Conclusions(1)Taraxacum mongolicum polysaccharide has good antioxidant activity and antibacterial activity,and and different molecular weight of Taraxacum mongolicum polysaccharide has different activity.(2)Two homogenous polysaccharides,abtained from Taraxacum mongolicum,consist of the same type of monosaccharides,while the ratios and linkages of the monosaccharides are different in the homogenous polysaccharides.