Isolation,Purification,and Bioactivities Of Polysaccharides From Gelidium Amansii

Algal polysaccharides are important natural bioactive ingredients with many biological activities,such as anti-inflammatory,anticoagulant,antitumor and antiviral etc.In recent years,algal polysaccharides have gained much attention by many of researchers.Gelidium amansii is one of the most important economy marine algae in China,which has extremely high medicinal and nutritional value.At present,it is mainly used as raw material for extracting agar,the level of comprehensive utilization of this algae is low,and research reports about the polysaccharides from Gelidium amansii are also relatively few.In this paper,the research survey of polysaccharides from Gelidium amansii was summarized,and the process of extracting its polysaccharides were studied,and the physicochemical properties and preliminary structure of the purified components GAP1 were analyzed at the same time.Finally,its inhibitory effects against?-glucosidase and pancreatic lipase in vitro were assessed.The purpose of this study is to provide some experimental basis and theoretical reference for the functional development of polysaccharides from Gelidium amansii.The main research contents are given as follows.?1?Multi-enzymatic extraction was used to extract polysaccharides from Gelidium amansii.On the basis of single factor experiment,the Box-Benhnken design response surface method was used to optimize the extraction parameters of polysaccharides with the content of extraction yield as index,and the addition amount of multi-enzyme,enzymatic hydrolysis temperature,solid-liquid ratio and enzymatic hydrolysis time as the factors.The result indicates that enzymes addition of 2.30%,enzymatic hydrolysis temperature at 60.43?,ratio of material to water 1:32 g/m L was the best condition for the polysaccharides extraction.The extraction yield of polysaccharide was up to 15.98%after 120 min of enzymatic hydrolysis by this method.?2?Separation and purification of polysaccharides from Gelidium amansii.The crude polysaccharides were deproteinized by Sevag method,and then fractionated and further purified into homogeneity by ion exchange chromatography on DEAE-52column?eluted with 0,0.1,0.3,0.5,0.7,0.9 M sodium chloride?and Sephadex G-200gel column.The results showed that the major fraction eluted with 0.3 M sodium chloride was collected and named GAP1.After elution by Sephadex G-200 gel column,GAP1presented a single symmetrical elution peak,indicating that GAP1 was a single component polysaccharide with a recovery rate of 97.8%.?3?The monosaccharide composition and structural characteristics of GAP1 were analyzed.The total carbohydrates content,protein content,uronic acid content and sulfate radical content were analyzed by chemical methods,the monosaccharide composition was analyzed by High Performance Liquid Chromatography?HPLC?after PMP derivatization,infrared spectroscopy and nuclear magnetic resonance spectroscopy were also analyzed.The results showed that the total sugar content in GAP1 was 92.56%,the uronic acid content was 44.53%,and the sulfate radical content in GAP1 was 6.92%without protein;GAP1 was composed of rhamnose,glucuronic acid,glucose,galactose,xylose and L–fucose in different ratios,the molar ratio of monosaccharide was 1.00:1.00:4.45:27.31:2.27:1.88,and the weight average molecular weight of GAP1 is 62651Da,infrared spectroscopy and nuclear magnetic resonance spectroscopy confirmed that GAP1 was a kind of acidic polysaccharide.?4?The biological activities of GAP1 was studied.The inhibitory effects and inhibitory types of crude polysaccharide GAP and purified component GAP1 from Gelidium amansii on?-glucosidase and pancreatic lipase were investigated.Results showed that both GAP and GAP1 had certain?-glucosidase and pancreatic lipase inhibitory activities,of which GAP1 had significant inhibitory effects with IC₅₀ value of1.78 mg/m L and 1.44 mg/m L on?-glucosidase and pancreatic lipase,respectively.The kinetics analysis made by Lineweaver-Burk plots showed that the inhibition effects of GAP1 on both?-glucosidase and pancreatic lipase were of linear mixed-inhibition types.These results suggest that polysaccharides from Gelidium amansii could be used as natural source of?-glucosidase and pancreatic lipase inhibitors.