Separation, Purification, Structure Identification And In Vitro Activity Of Hericium Erinaceus Polysaccharide

Hericium erinaceus,which is a well-known edible and medicinal fungus,has been used as a tonic food,and also as a medicine for the prevention and treatment of chronic gastritis.Five Hericium erinaceus fruit bodies grown in different areas of China and a mycelium of Hericium erinaceus grown under liquid submerged fermentation were used as experiment objects.The main nutritional components,polysaccharide extraction conditions,chemical composition and antioxidant activities in vitro of the six polysaccharides were systematically compared.Also the purification,structural elucidation and anti-tumor activities were studied using the screened more active polysaccharide.The main nutrition constituent and mineral elements were determined.Analysis showed that Hericium erinaceus is a kind of food with high protein and low fat.The nutrition of the five fruit body samples was basically the same;difference of content percentage of same elements in fruit body samples was less than 20%.The content of protein and fat in mycelium were both higher than those in fruit body samples,there're also more beneficial elements in mycelium,such as calcium,magnesium,iron and manganese.Based on the single factor test,response surface method(RSM)was used for optimizing microwave-assisted cellulose extraction process to obtain the best polysaccharide extraction rate.The results showed that the optimal conditions for the extraction of Hericium erinaceus polysaccharide were as follows:microwave temperature 40°C,11 min extraction time,ratio of liquid to material 45:1,enzyme amount 1.3%.Under these conditions,the extraction yield reached 10.19%.The polysaccharide content of five fruit body samples were influenced by their origins greatly,the highest polysaccharide content researched 51.21±0.89%from Sichuan province sample.The yield rate of polysaccharides extracted from mycelium was 5.02%,which was significantly higher than the average yield rate of polysaccharides extracted from fruit body samples(2.15%).The results of GC showed that the components of monosaccharide in fruit body polysaccharide were D-mannose,D-galactose and D-glucose,in mycelium polysaccharide were L-Arabinose,L-Xylose,D-galactose and D-glucose.Their antioxidant activities were also investigated and compared.Five fruit body samples showed no significant difference in antioxidant activities.However,The mycelium exhibited excellent antioxidant activities and was significantly stronger than fruit body samples,and its ability to scavenge ABTS radical was close to ascorbic acid.The Hericium erinaceus mycelium polysaccharide(HEP)was purified using DEAE Sapharose Fast Flow and Sephadex series chromatographic column.One homogeneous polysaccharide HEP3-a was obtained.High performance liquid chromatography produced a single symmetrical peak,which indicated that it was homogeneous and the average molecular weight was 2.1×10~3 kDa.The anti-tumor activities were investigated and compared between crude polysaccharide extracted from Fujian Hericium erinaceus fruit body and mycelium and homogeneous polysaccharide HEP3-a.The inhibitory effects of crude mycelium polysaccharide against tumor cell BGC-823 were higher than the other two polysaccharides.The inhibitory rate reached55.96%with concentration of 15.80%after dosing polysaccharide for 72 h.Acetylation analysis by GC-MS indicated that HEP3-a was composed of L-Arabinose,L-Xylose,D-galactose and D-glucose with the rate of 0.80:0.39:1.00:2.25.The methylation analysis and NMR analysis showed that HEP3-a contained six sugar residues,the main chain was composed of(1?4)-?-D-Gal and(1?2)-?-D-Glc,a side chain composed of 1,3,4-Gal was linked at the C-4 position,it also contains(1?5)-?-L-Ara side-brunching unit and a minor of terminal glucosyl and galactosyl residues.