Study On Dynamic Accumulation And Antioxidant Activity Of Polysaccharides Of Dendrobium Fimbriatum

Firstly to annual Dendrobium fimbriatum as material, using phenol-sulfuric acid method on different parts of the content of polysaccharide accumulation distribution was analyzed experimentally measured. In a year in each month were measured on the upper part of the stem of Dendrobium fimbriatum, stem end, the content of polysaccharide in leaves and stem and the bottom of. The experimental results show that the content of polysaccharide in Dendrobium fimbriatum stems are presented to first decreased and then increased trend, the content of polysaccharide in leaves first tends to be smooth and a significant rise in one of the largest peak and polysaccharides content of Dendrobium fimbriatum leaves higher than that of the stem.Through using different concentrations of ethanol alkali extraction and alcohol precipitation method to extract three kinds of different molecular weight polysaccharide from Dendrobium fimbriatum, the molecular weight of FP, SP and EP were 1.57×104Da?2.24×104Da?3.70×104Da that determined by HPGPC. The results on determination of three different molecular weight polysaccharides by FTIR shows that FP, EP polysaccharide sample contained a ?-configuration of the sugars, and SP sample contained a a-configuration of the sugars.This kind of structure has a effect on its antioxidant activity. We aslo go in on analyzing the physical and chemical properties, and testing the scavenging activity and reducing capacity of three samples to ABTS, DPPH and hydroxyl radical to study the correlation of Dendrobium fimbriatum polysaccharide functional groups and antioxidant activity in vitro. Using the different concentration of ethanol extracted three different molecular weight polysaccharides of Dendrobium fimbriatum,with Vc as positive control. The experimental results show that the content of uronic acid in the FP, SP and EP are 6.93%,0.51% and 0.49% respectively, the content of sulfate acid are 0.19%,0.49% and 0.97% respectively. Antioxidant experiment results show that the clearance rate of FP and SP to ABTS radical in the concentration of 3.2 mg/ml reached 95.26%, 98.51% respectively, IC50 were 0.740 mg/ml,0.478 mg/ml, and the clearance rate of EP to ABTS in the concentration of 0.4 mg/ml reached 98.60%, IC50 was 0.066 mg/ml. At the same time, the removal rate of EP to DPPH radical was 67.63%,IC50 was 0.58mg/ml, while the concentration of EP was 0.8mg/ml. Related studies have shown that the reducing power and the scavenging ability to ABTS?DPPH and hydroxyl radical of three kinds of Polysaccharides from Dendrobium fimbriatum have a strong correlation with the content of polysaccharide. Studies have shown that three polysaccharides of different molecular weight from Dendrobium fimbriatum has certain antioxidant activity, and has a certain correlation between the content of polysaccharide.