Isolation,purification,structure identification and biological activity of low relative molecular weight Sargassum polysaccharides
Objective To isolate and purify a low molecular weight Sargassum polysaccharides(LMSP)from Sargassum of traditional Chinese medicine,and preliminarily analyze its structural characteristics and study its antioxidant,hypoglycemic and anti-tumor effects.Methods The seaweed polysaccharides were extracted by water extraction and ethanol precipitation,and then degraded by H2O2NC method.They were purified by DEAE-52 anion exchange column and Sephadex G-100 gel filtration column.The total sugar content was determined by phenol-sulfuric acid method,the sugarfarn acid content was determined by p-hydroxybenzaldehyde method,the sulfate content was determined by BaCl2-gelatin turbidimetry method,and the protein content was determined by Coomassie brilliant blue method.The relative molecular mass was determined by high-performance gel permeation chromatography,the infrared spectrum was analyzed,and the composition of monosaccharides was determined by high-performance liquid chromatography.The type of glycosidic bond was detected by gas chromatography-mass spectrometry.The morphological features were analyzed by scanning electron microscopy.The antioxidant activity of LMSP was determined by 1,1-diphenyl-2-picrylhydrazyl(DPPH)free radical scavenging rate experiment,hydroxyl radical scavenging rate experiment,and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS)free radical scavenging rate experiment.The hypoglycemic activity of LMSP was determined by α-amylase inhibition experiment and α-glucosidase inhibition experiment.The antitumor activity of LMSP against A549,Hela,and Hep-G2 cells was determined.Results The relative molecular mass of LMSP is 4 635,with a total sugar content of(83.85±2.12)%and a sugar aldonic acid content of(29.73±3.57)%.The sulfate content is(24.44±1.97)%,the protein content is(1.35±0.63)%,and it is mainly composed of galactose,xylose,and fucose.Infrared spectroscopy and gas chromatography-mass spectrometry were used to analyze its structure,and it was inferred that LMSP may be a pyransulfonic polysaccharide containing pyransulfonic glycosides,mainly containing 2-Rhap,T-Galp,3-Galp,and 4-Glcp fragments.Under scanning electron microscope,LMSP presents a porous network structure,tightly stacked.The half maximal inhibitory concentration(IC50)for DPPH radical scavenging,hydroxyl radical scavenging,and ABTS radical scavenging were 1.35,0.61,and 1.31 mg·mL-1,respectively.The IC50 values for α-amylase and α-glucosidase inhibition were 0.82 and 1.27 mg·mL-1,respectively.The IC50 values for A549,HeLa,and Hep-G2 cell inhibition were 2.31,3.41,and 3.10 mg·mL-1,respectively,and the effects of all indicators were stronger than those of seaweed crude polysaccharides.Conclusion The LMSP prepared by the H2O2/V C method is homogeneous and has good antioxidant,glucose-lowering,and anti-tumor effects.
Sargassum polysaccharideslow relative molecular weightH2O2/V C degradationisolation and purificationstructural characterizationbiological activityantioxidanthypoglycemicanti-tumor