Study On Extraction, Isolation, Purification And Antioxidant Activity Of Polysaccharide From Forsythia Suspensa Leaves

Polysaccharide is a kind of natural macromolecule compound,which widely exists in animals, plants and microbes. At present, thestudy of biological function of polysaccharide has gradually becomingthe hot of modern medicine research. In this study, the technologiesof extraction, separation and purification of the Forsythia suspensaLeaves Polysaccharide (FLP), its structure and antioxidant activity invitro have been systematically studied. The main results are shownas follows:(1)The method of sulfuric acid-anthrone was used to mensutatedof the content of FLP. The RSD in reproducibility test was2.07％（n=5）and the average recovery rate was97.95%with RSD of3.30%（n=5）.The content of FLP determined by this method was4.18%．(2)Based on the results of single-factors test, the ResponseSurface Methodology (RSM) was applied to optimize the extraction ofpolysaccharide from Forsythia suspensa Leaves. The results showedthe optimum conditions are: the ratio of water to material of23:1(mL/ g), extraction time of31min, extraction temperature of70℃, extract2times; Under the conditions, the yield of polysaccharide was7.87%.(3)The protein was removed by Sevag method. After repeat4time-s with Sevag method, the amount of protein removed rate was72.48％during the de-proteinization process. Effects of four kind of macrop-orous resins on decoloring were studied; The results showed that res-in X-5has a good effect. By he means of single factor and orthogonaltest, we can get the best parameters as follows: pH was6, dosage wa-s4g, time was1h, rotation speed was100r/min, and under the optimaldecoloring parameters, the decolored ratio was87.22％, and the rem-ain ratio of polysaccharide was86.31％.(4)After deproteinization and decoloration, the DEAE-52column c-hromatography was used to further separate FLP with the eluent of w-ater and different concentration of NaCl.Two components were obta-ined and respectively named FLP-1(distilled water eluting) and FLP-2(0.5mol/L NaCl solution eluting).(5)Characteristic reactions and spectra results showed that FLP-1and FLP-2did not contain starch, polyphenol material,reducing sugaror nucleic acid. FLP-1did not contain protein while FLP-2may be a s-ugar-protein. Two kinds of polysaccharide all had typical characteri-stic absorption peaks of polysaccharide by use of IR spectra.Intrar-ed spectroscopy analysis showed that the FLP-1was a furanoside w- ith mannose while FLP-2was a acidic sugar-protein complex.(6)Compared with antioxidant activity of Vc, four reaction system(hydroxyl radical, uperoxide anion radical, DPPH free radical and red-ucing power)were established. The results showed that FLP,FLP-1andFLP-2had antioxidative effect of scavenging hydroxyl radical, DPPH f-ree radical and reducing power in vitro and the scavenging activity in-creased with increasing concentration. FLP showed stronger antioxi-dant activities in vitro than FLP-l, FLP-2. The antioxidant activity of F-LP exist difference with Vc comparing.FLP, FLP-1and FLP-2had no a-ntioxidant effect of scavenging superoxide anion radical,but had pr-ooxidant activity.