Purification,Structure Analysis And Bioactivity Of ?-glucan From Cell-wall Of Pleurotus Eryngii

Pleurotus eryngii(DC.exFr)Quel is an important edible mushroom with medicinal properties.It's native to Mediterranean regions of Europe,the Middle East,and North Africa,but also grown in many parts of Asia.It has generous amounts of nutrients including carbohydrates,proteins,vitamins,minerals and polysaccharide.It's proved that the polysaccharides from P.eryngii have activities of decreasing cholesterol,preventing arteriosclerosis and cardiovascular disease,improving immunity,promoting digestion,and even anti-virus.The molecular weight,monosaccharide composition and their structures of diverse polysaccharides distributed in cell,cell-wall,or extracell are related to different activities.The cell-wall of fungi accounts for 20%of dry cell weight.It contains abundant ?-glucan which has many bioactivities.However,there has not been any research on extraction of cell-wall ?-glucan from P.eryngii reported.In order to provide theoretical basis for industrialization development and enrich the database of polysaccharides structures of edible mushroom,the extraction,purification,physical and chemical properties,and bioactivities of ?-glucan from P.eryngii cell-wall were studied.The main conclusions are as follows:(1)The yield of crude cell wall polysaccharides from P.eryngii fruiting body through alkalin extraction and ethanol precipitation is 9.6%,which is 9.6 g crude polysaccharides can be extracted from 100 g P.eryngii dried fruiting body.And the polysaccharide content of crude polysaccharide is 84.6%.Crude polysaccharide from P.eryngii cell wall was subjected to CMC ion exchange chromatography and Sephadex G-75 gel column chromatography.Then a chromatographically pure gulcan(PEWP)was successfully isolated.The purity,molecular weight and structure of PEWP were measured through the high performance liquid chromatography(HPLC),infrared spectroscopy(IR)and chemistry analysis in the preliminary study.The results showed that molecular weight of PEWP was 41 kDa and the monosaccharide unit was identified as glucose.IR analysis illustrated that PEWP had absorption peak of ?-glucosidic bond,which belonged to the characteristic peak of polysaccharide.Periodate oxidation and smith degradation analysis showed that PEWP had 1?4 glucosidic bond(83.3%),1?6 glucosidic bond(12.8%),1?3 glucosidic bond(2.4%)and 1?2 glucosidic bond(1.5%).(2)The purified ?-glucan from P.eryngii cell wall was white-mica shaped solid,odorless,eas ily dissolved in water and easily moisture absorption.It couldn't be dissolved in ethanol or methan ol.The polysaccharides content determined by phenol-sulfuric acid method was 98.58%.The pH value of 1%P-glucan solution was 6.54.The transmittance of 3%solution was 63.92%un der 610 nm.The specific rotation was 223.52,and the viscosity of 10%solution was 2.14 mPa·s.(3)The protection effect of PEWP on gastric mucosa was studied.The gastric mucosa epithelial cells were treated by nutrient solutions with different concentration of PEWP.The rate of reproduction and migration was determined.Additionally,the cellular morphology was observed by inverted microscope.The results showed that low concentration of PEWP(0.08 mg/mL?0.4 mg/mL?2 mg/mL)protected the gastric mucosa by promoting the migration and proliferation of gastric mucosal cells in vitro,and accelerating the growth of epithelial cells in damage region.(4)The obesity prevention effect of PEWP on the rats fed with high fat diet was studied.The results showed that it inhibited the weight increase and fat accumulation;decreased the adipose fat of liver and heart,and the rate of fatty liver.Meanwhile PEWP reduced atherosclerosis by lowing the TG and TC but increasing HDL-C in the serum.It also could decrease the SOD activity and the content of MDA in liver of rat,and improve the antioxidant activity of the organism.These indicated PEWP had the potential activities of reducing the risks of obesity,hyperlipidemia and atherosclerosis.(5)On the basis of the experiment of obesity and hyperlipidemia prevention effect of PEWP,the further therapeutic efficacy was examined.The results revealed that PEWP had the functions of reducing the risks of obesity,hyperlipidemia and atherosclerosis.(6)The inhibitive activity assay of PEWP on a-glucosidase from the rabbit isolated small intestinal was performed with extracellular polysaccharides of P.eryngii(PEP)as control.The result showed that PEP had strong activity while the activity of PEWP was not obvious.This indicated that PEP was the key hypoglycemic component.