Study On Chemical Modification And Antioxidation Of Polysaccharides From

This paper selected Flos Farfarae polysaccharide which was left unnoticed before as the research object, and its carboxylmethylated and sulfated derivatives were synthesized successfully. In addition, antioxidant activity was tested in vitro. The important achievements and contents were showed below:(1) With isopropyl alcohol as solvent and chloroacetic acid as etherification agent, this paper successfully synthesized C-FFP which had the characteristics of high substitution degree (DS). The related parameters were optimized by orthogonal test method and the results were as follows:when the heating temperature was to60℃, dosage of CICH2COOH was5.0g, mass concentration of NaOH was20%, the DS of C-FFP will reach the maximum value of0.68(2) Because of the advantages of mild conditions and less degradation reactions, the method of ClSO3H-pyridine was chosen to synthesis S-FFP which used DMF as suspending agent of the crude polysaccharide, as a result, relatively good productive rate and DS were successfully achieved. What is more, the influential parameters of the synthetic process were optimized necessarily, and the results showed below:when the response time increased to2h, the heating temperature transferred to60℃, CISO3H:pyridine=2:1, DS will get the peak of1.75, meanwhile, with the better yield of62%.(3) The two polysaccharide derivatives were still a complex mixture of polysaccharide, therefore, a further separate operation was very necessary. By virtue of the diverse sizes of molecular weight and weak electro-chemical performance, SephadexG-200and DEAE-52chromatographic column were chosen to separate and purify C-FFP and S-FFP respectively, as a result, a single symmetrical peak appeared in the high performance liquid chromatography (HPLC), which showed the better separation effect. In the end, relatively narrow molecular weight distribution belonged to the two derivatives were got, noted respectively:C-FFP2and S-FFP2.(4) HPGPC and GC were adopted to analysis the molecular weight and monosaccharide composition of C-FFP2and S-FFP2. The measurement results of HPGPC as:for C-FFP2,Mw=27741, Mn=21379, molecular weight distribution width D=1.29; and for S-FFP2, Mw=29852, Mn=21508, molecular weight distribution width D=1.38. In addition, Measurement results of GC as:C-FFP2was mainly made up of mannose, glucose, as well as galactose, and their mole ratio was2.362:1.124:1.082; S-FFP2consisted mostly of mannose and glucose, and their mole ratio was1.802:1.214. (5) By vitro experiment method, this thesis inspected the antioxidant activity of C-FFP2and S-FFP2. Empirical data showed that chemical modification of FFP can enhance the inhibition effect of O2-·, OH·and DPPH· obviously, and within the concentration range, the scavenging effects was:S-FFP> C-FFP> FFP; C-FFP> S-FFP> FFP; S-FFP> C-FFP> FFP.