Separation And Purification Of The Polysaccharides From Bangia Fusco-purpure And Their Hpyerglycemic And Hypolipidemic Effects

Marine red alga Bangia fusco-purpure belongs to Bangia species,abundantly cultivated in Pu'tian sea area in Fujian province of China.B.fusco-purpure seems to contain certain polysaccharides.On this basis,we firstly extracted and purified the polysaccharide fraction from B.fusco-purpure,and subsequently analyzed its structrual characteristics,hpyerglycemic and hypolipidemic with the potential action mechanisms.The main results were as follows:?1?The crude polysaccharides from B.fusco-purpure were extracted by soaking in hot water and alcohol precipitation,and then the polysaccharide fraction F was obtained by using gel permeation chromatography Sephadex G75.The F fraction was further purified to obtain SF1,SF2 and SF3 fractions by DEAE Cellulose-52.?2?The monosaccharide composition analysis revealed that polysaccharide fraction F consisted of galactose,glucose and arabinose,the SF1 consisted of arabinose and glucose,the SF2 consisted of galactose and arabinose,the SF3 consisted of galactose and glucose.Based of calibration with standard dextrans,the apparent molecular mass of polysaccharide fractions F,SF1,SF2 and SF3 was estimated to be 43.16 kDa,2.07 kDa,32.07 kDa and 28.32 kDa respectively.The FTIR spectroscopy was conducted.Results showed F contains pyran structure and?-glucosidic bond and the possible presence of O-acetyl groups.The?-anomeric carbon structure was found in SF1 fraction.SF2 fraction indicated the presence of pyranose ring.The carboxy group was observed in both SF2 and SF3 fractions.?3?Enzyme inhibition assay revealed that polysaccharide fraction F showed significant inhibitory effects on the activities of both?-amylase and?-glucosidase in a concentraction dependent manner,the IC₅₀ value was 1.26 mg/m L and 1.34 mg/m L respectively.Furthermore,the Lineweaver-Burk curve showed the inhibitory mechanisms of?-amylase and?-glucosidase by fraction F were reversible inhibition.The results of kinetics analysis further revealed that the inhibition of fraction F against?-amylase was competitive different with that against?-glucosidase,which followed non-competitive inhibition.?4?The polysaccharide fractions SF1 SF2 and SF3 were showed significant inhibitory effects on the activities of?-lipase by enzyme inhibition assay,the IC₅₀ value was 0.69 mg/m L,0.60 mg/mL and 0.50 mg/mL respectively.The SF3 had the best inhibitory effect.Furthermore,the inhibtory mechanisms of?-lipase by SF3 was demonstrated to be reversible-competitive inhibition.The HepG2 cell model induced by oleic acid showed the inhibition effects of SF1,SF2 and SF3 on triglyceride synthesis,and SF3 had stronger inhibition effect than other fractions.The HepG2 cell model induced by 25-hydroxycholesterol showed the inhibition effects of SF3on cholesterol,triglyceride and free fatty acid synthesis.Caco-2 cell was cultured in Transwell chamber.The assay results indicated the SF1 SF2 and SF3 could control the FFA absorption in Caco-2 cell.To sum up,the composition and structure characteristic of polysaccharides from Bangia fusco-purpure were investigated in this study.It was illuminated preliminary that activity mechanism of hpyerglycemic and hypolipidemic.This study also provides a useful foundation for further investigating the relationship between the structure and bioactivity...