Extraction And Antioxidant Activities Of Exopolysaccharide And Intracellular Germanium Polysaccharide By Cordyceps Militaris SU5-01

Cordyceps belongs to Ascomycotina, Pyrenomycetes, Sphaeriales, Claviciptiaceae, and Cordyceps militaris is one of the most representative model species. Comparing with Cordyceps sinensis, C. militaris also has the similar life history, bioactive substances and analogue functions. It contains many bioactive ingredients such as polysaccharides, cordycepin, trace elements, etc. Polysaccharide from C. militaris has significant effects on stimulating the immune system, anti-cancer and anti-oxidation. Studies indicate that the organic-germanium has lots of rewarding properties (anti-cancer, anti-phlogosis and sterilization). Intracellular germanium polysaccharide (IGPS) has the effects of organic-germanium and polysaccharide, and is easier to be absorpted and utilizated by organism. There are fewer reports about the organic combination of polysaccharide and germanium into germanium polysaccharide.In this paper, the single factors and orthogonal design were used to optimize the liquid culture conditions for producing IGPS by C. militaris SU5-01; The extraction conditions for exopolysaccharide (EPS) and IGPS of C. militaris SU5-01in submerged culture were optimized on the basis of Plackett-Burman (PB) design and response surface methodology (RSM), and the components of IGPS were separated in a preliminary way by Cellulose DEAE-52. The in vitro and in vivo antioxidant activities of EPS and IGPS were evaluated.By the single factor and orthogonal test, the optimum fermentation medium components for producing IGPS were glucose30g/L, yeast extract powder6g/L, germanium60mg/L, KH2PO41.5g/L, MgSO4-7H2O1.0g/L, pH6.5. Under the optimum conditions, the dry cell weight (DCW) of C. militaris SU5-01was19g/L, and the yield of IGPS was8.11%.On the basis of PB design and RSM, the optimum extraction conditions for EPS production were ethanol concentration94.43%, pH7.32, multiple3.57, the production was2.94g/L. The optimal conditions for extracting IGPS were extraction temperature89.92℃, ethanol concentration93.07%, extraction times2.92, while the maximum yield was5.09%. Through the Cellulose DEAE-52column, three components of IGPS named IGPS-1, IGPS-2, and IGPS-3were obtained, respectively.According to the antioxidant experiments in vitro, the EPS and IGPS had significantly scavenging effects on superoxide anion (O2-·), DPPH radicals and reducing power. At a dosage of2g/L, the reducing power of EPS (0.44) was higher than that of BHT (29.41%); the scavenging effects on O2"· and DPPH radicals was82.61%,50.52%, respectively. The EC50values of EPS scavenging O2-· and DPPH radicals were0.8g/L and2g/L. The EC50value of IGPS scavenging DPPH radicals was0.18g/L, and the reducing power of IGPS at a dosage of1.Og/L was36.89%higher than IPS.The antioxidation capacities of EPS and IGPS were observed by measuring the superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) activities and the content of malondialdehyde (MDA) in the blood, heart, liver, kidney and spleen of mice. Data indicate that EPS and IGPS can remarkably increase the activities of SOD, CAT and GSH-Px, and decrease the MDA content, respectively.The results suggest that the IGPS of C. militaris SU5-01had significantly antioxidant activity in vitro and in vivo, which could be used as the natural and potential antioxidants.