Extraction Process Optimization Enzymatic Hydrolysis And Structural Characteristics Of Laminaria Japonica

Laminaria japonica is a kind of natural macromolecules prossesses a number of biological activities. In this study extraction purification structural characteristiscs antioxidant capacities and enzymatic hydrolysis of polysaccharide from Laminaria japonica were investigated.Analysising the basic components of Laminaria japonica from different place of origin using extraction yield and cholate Adsorption rate as index the Laminaria japonica from Guangxi was found to be the best raw materials of polysaccharides. Its dry powder contains 64.22% carbohydrates 11.97% ash 1.81% crude fat 16.09% crude protein and 5.91% water.Aiming at optimization of the solvent of extraction different acids(water citric acid sulfuric acid hydrochloric acid and phosphoric acid) were investigated. Citric acid was proved to be the best solvent using extraction yield and cholate adsorption rate as index. The sample extracted by citric acid exhibited the lowest ABTS IC50 value as 1.06mg/m L and the highset ORAC value as 341.87μmol Trolox/g. The sample extracted by water exhibited ABTS IC50 value as 2.28mg/m L and ORAC value 123.14μmol Trolox/g which better than the sample extracted by other three kind of sovent.Basis on the Single factor experiment and orthogonal test using extraction yield and cholate adsorption rate as index it was proved that p H value exhibited the most important affection. The optimal conditions using extraction yield as index were determined to be p H as 2 extraction temperature as 100?C extraction time as 2h and solvent-material ratio as 25:1g/m L. LPA-C was prepared under this conditions and its extraction yield as 12.95% and cholate adsorption rate as 52.64%. The optimal conditions using cholate adsorption rate as index were determined to be p H as 2 extraction temperature as 120?C extraction time as 4h and solvent-material ratio as 30:1g/m L. LPA-Y was prepared under this conditions and its extraction yield as 11.22% and cholate adsorption rate as 58.85%.Trypsin and papain exhibit a stronge affect on LPA-C and LPA-Y. They lowered the ABTS IC50 value and reducing power A0.5 value(the concentration of polysaccharide when the absorbance value of reduecing power test was 0.500) of LPA-C and LPA-Y. The ABTS IC50 value of LPA-C decreased from 1.01mg/m L to 0.80mg/m L 0.89mg/m L and from 3.55mg/m L to 2.23mg/m L and 2.88mg/m L of LPA-Y.The reducing power A0.5 value of LPA-C decreased from 1.61mg/m L to 1.51 mg/m L and 1.53mg/m L and from 9.56mg/m L to 5.50mg/m L and 4.69mg/m L.After removing protein and salt LPA-P was prepared from LPA-C. LPA-P was purified by DEAE Sepharose fast flow chromatogram to botain LPA-P1 LPA-P2 and LPA-P3. All of them contain sulfated group. LPA-P3 contains the highest sulfated group as 5.36% and LPA-P1 the lowest as 1.22%.The main components of LPA-P LPA-P1 LPA-P2 and LPA-P3 were fucose mannose and galactose. LPA-P and LPA-P3 contain more galactose however LPA-P2 and LPA-P3 contain more mannose. LPA-P3 contained the highest rate of fucose and galactose.In the GPC test all of LPA-P and its purified fractions exhibit a single peak and the peak shape of three purified fractions were symmetric. The averange molecular weight of LPA-P LPA-P1 LPA-P2 and LPA-P3 were estimated to be 20.13 k Da, 17.55 k Da, 28.71 k Da, 17.14 k Da.LPA-P3 exhibited the strongest antioxidant capacities but LPA-P1 the weakest. The antioxidant capacitie of LPA-P was a little stronger than LPA-P2.