| Porphyra haitanensis commonly known as wucai, is an important economic red alga whichis ditributed in southern China, mainly in Fujian, coastal region of southern Zhejiang. In thispaper, the extraction process, purification method, the physical and chemical characters ofPorphyra haitanensis polysaccharides were systematically studied, and the antioxidant activity invitro were also preliminarily explored.According to single factor and orthogonal test, the optimum conditions of extract processwere as follows: extracting temperature was100℃, extracting time was5h, the ratio of alga tosolvent was1:30. The maximum yield of Polysaccharidedede was14.5%under this optimalconditions; The ethanol concentration of80%was optimal for Polysaccharidedede precipitation.A large amount of protein will be settled down with Polysaccharide when it is extracted byhot water. Methods of Sevag, TCA, alkaline protease and papain were used to remove the protein.Four methods of removing protein were compared and their removal rates were59%,65%,94%and88%, respectively. It is clear to see that the protease method in deproteinization was much moreefficient and had less loss of polysaccharide.Polysaccharidedede was separated by DEAE Cellulose-52column. The elution wasperformed by step-wise process using the same buffer containing different concentrations ofNaCl: water,0.1mol/L,0.2mol/L,0.3mol/L,0.5mol/L and1mol/L, respectively. And threefractions were obtained under the concentrations of0.2mol/L,0.3mol/L and0.5mol/L, whichwere named SP1, SP2and SP3. The Sephadex G-100column was applied to further purification.The result showed that Sephadex G-100could effectively remove the protein from SP1, SP2andSP3.The three fractions of crude Polysaccharidedede were obtained, The composition of themwas analyzed by IR spectrum gas chromatography and the contents of SO42-,3,6-anhydrogalactose, uronic acid and galactose were meaured by chemical methods. The result ofgas chromatography indicated that SP1consisted of galactose, Rhamnose, fucose, arabinose andxylose. Their percentage were96.53%,1.225%,0.85%,1.37%and1.16%, respectively. SP2and SP3composed of galactose. The contents of SO42-of three fractions were measured to be8.54±0.44%,10.24±0.23%and12.357±0.58%, respectively; The contents of the uronic acid ofthree fractions were measured to be15.00±0.23%,10.46±0.55%and1.50±0.35%respectively;The contents of the3,6-anhydrogalactose of three fractions were measured to be6.84±0.43%,4.99±0.24%and4.56±0.36%, respectively. The results illustrated that ultrafilitration was effective to reduce the residue of metalelements. The effect of competitive chelators EDTA on depriving metals binding with Porphyrahaitanensis has been studied, as well as the effect of different acid concentration andultrafilitration on the regular of depriving metals. The results illustrated that it was effective toreduce the residue of metal elements, when acid was added, such as Mn, Zn, As, Cd and Pb.However, it was not very satisfied as to Mg, Hg, Fe, Ba. In addition, In the same acidicconditions, the effect of the competitive chelators EDTA removing the metal elements waseffective but not obvious.Antioxidant activity in vitro of Polysaccharidededede, SP1, SP2and SP3were determined,the results showed that the IC50on·OH were1.32mg/mL,1.05mg/mL,0.88mg/mL and0.80mg/mL, respectively. The IC50on DPPH were1.82mg/mL,1.90mg/mL,1.69mg/mL and0.88mg/mL, respectively. The IC50on liposome oxidation were2.01mg/mL,1.82mg/mL,1.59mg/mL and1.29mg/mL, respectively, but there was no significant effect on the inhibition of·O2-. |
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