Extraction,Purification,a Ctivity Study And Structural Analysis Of Polysaccharides From Sargassum Horneri

In this paper,the extraction,purification,antioxidant activity,anti-tumor activity and structural characterization of polysaccharides from Sargassum Horneri were systematic studied.The microwave-assisted extraction condition of polysaccharides from Sargassum Horneri was optimized by single factor experiment and response surface methodology(RSM).The optimal extraction conditions obtained by RSM were as follows:ratio of material to solvent 1:65(g/mL),extraction temperature 72?,extraction time 39 min.Under the optimal extraction conditions,the relative extraction rate of SHPS could reach 12.02%.(n=3).Three kinds of crude polysaccharides with different components(SHPS30,SHPS60,SHPS80)were obtained through stepwise ethanol precipitation.There three polysaccharides components were evaluated on their antioxidant activities in vitro systems including DPPH assay,superoxide radical assay,hydroxyl assay,ABTS assay and reducing capacity assay.The Antioxidant activities of Sargassum Horneri were determined by spectrophotometry.The results showed that SHPS30 showed high scavenging effect on OH· and O2-,SHPS60 showed high scavenging effect on DPPH·,and SHPS80 showed high scavenging effect on ABTS and high reducing power.So,polysaccharides from Sargassum horneri were promising for future use in natural antioxidant industry.SHPS60 was further purified by DEAE Sepharose Fast Flow anion-exchange chromatography and Sephadex G-25 gel-filtration chromatography,and a water-soluble polysaccharide SHPSA was obtained.Lack of absorption at 260 and 280nm by UV scanning indicated that there were no protein or nucleic acid elements in the SHPSA.The anti-tumor activity of SHPSA was evaluated based on the MTT assay,Annexin V/PI double staining and cell cycle analysis.SHPSA was observed to have the capacity to inhibit the growth of human colon cancer DLD cells in a dose-dependent manner by inducing the apoptosis of DLD cells and increasing the accumulation of cells in G2/M phase.The half inhibitory concentration(IC50)of SFPSA on the growth of DLD cells was about 1.0 mg/mL.The results indicated that SHPSA might be a promising natural antitumor agent in the future.The structural characterization of SHPSA was determined by a combination of chemical and instrumental analysis methods.IR spectra indicated that SHPSA was a neutral polysaccharide,the sugar rings of SHPSA were pyranose rings,and there were ?-type glycosidic linkages in SHPSA.The HPLC profile indicated that SHPSA was a homogeneous polysaccharide and its average molecular weight of 5.78×105 Da.Sugar composition analysis,methylation analysis and NMR spectroscopic methods showed that SHPSA was composed of T-D-Glcp,1,3-D-Glc/p,1,6-D-Glcp and 1,3,6-D-Glcp in a molar percentage of 1.00:4.17:1.17:0.89,respectively,and SHPSA was tentatively identified as a glucan with side chains linked to a ?-(1?3)backbone with relatively few branch points.The repeating unit of SHPSA was established as:...