Study On The Properties Of Extracellular Polysaccharides From Cordyceps Sinensis Under Exogenous Phytohormones

In this paper, the effect of different exogenous plant hormones on biomass, extracellular polysaccharides (EPS) production of Cordyceps Sinensis were studied. The optimal exogenous plant hormone and the optimum concentration of hormone were determined by single factor experiment. Crud EPS obtained under the optimal exogenous plant hormone were separated and purified by DEAE-52 cellulose column chromatography and Sephadex G-100 glucan gel column chromatography successively, and two pure EPS were obtained. In addition, the antioxidant activity of EPS obtained under the optimal exogenous plant hormone were studied. The main research contents and results are as follows:1. the effect of different exogenous plant hormones on biomass and EPS production of Cordyceps Sinensis.the effect of different exogenous plant hormones on biomass and EPS production of Cordyceps Sinensis was investigated by adding different concentrations of different exogenous plant hormones in the liquid medium. IBA can improve the biomass of Cordyceps sinensis, while IAA can improve the EPS production of Cordyceps sinensis. So IAA was selected as the optimal exogenous plant hormone in the present work and the optimum concentration of hormone was 2.5μg/mL.2. Separation and purification of crude EPSThe crude EPS obtained under the optimal exogenous plant hormone was taken off protein by using Sevage method. Crud EPS were separated and purified by DEAE-52 cellulose column chromatography, and three polysaccharides were obtained: EPS-w, EPS-1s and EPS-2s. EPS-w was further separated and purified by Sephadex G-100 glucan gel column chromatography, and two pure EPS were obtained:EPS-1w and EPS-2w. Through the purity testing of UV spectrum, optical rotations and gel column, the results showed that both of EPS-lw and EPS-2w were pure polysaccharides.3. Physicochemical property of EPS-1w and EPS-2w.The physicochemical property of EPS-1w was similar to that of EPS-2w. Their lyophilized productions were white flocculent solid, soluble in water, dilute acid, but not soluble in methanol, acetone, chloroform, diethyl ether and dimethyl sulfoxide organic solvent. They did not contain protein, nucleic acid, phenols, amylum and free monosaccharide. Their molecular weights were 46.5kDa and 34.8kDa, respectively. They had the same monosaccharide composition, mainly composed of D- mannose, D-glucose and D-galactose, and contain a small amount of L- rhamnose, D- xylose and D- arabinose. However, their molar ratio of molecules are different:D- mannose:D-glucose:D- galactose=23.7:6.2:8.5 and 35:3.6:3.1, respectively.4. The antioxidant activity of EPSThe effect of IAA on antioxidant activity of crude EPS were measured by the methods of DPPH radical scavenging activity, ABTS·+scavenging activity and the ferric reducing antioxidant power (FRAP). Moreover, the antioxidant activity of EPS-w and EPS-1s, EPS-lw and EPS-2w were compared. The results showed that IAA could improve the antioxidant activity of crude EPS cmpared to that of crude EPS without adding IAA. The ICso of DPPH are 1.215mg/mL and 2.13mg/mL, the IC50 of ABTS·+ are 0.64mg/mL and 1.57mg/mL, and FRAP (C=10 mg/mL) are 0.56mmol/L,0.49mmol/L, respectively. The antioxidant activity of EPS-w was better than that of EPS-1s, the IC50 of DPPH are 1.13mg/mL and 2.49 mg/mL, the IC50 of ABTS·+ are 0.55mg/mL and 1.26mg/mL, FRAP (C=10 mg/mL) are 0.985mmol/L and 0.556mmol/L, respectively. In addition, the antioxidant activity of EPS-lw was better than that of EPS-2w. The IC50 of DPPH are 0.612mg/mL and 1.67 mg/mL, the IC50 of ABTS·+ are 0.818mg/mL, and 1.804 mg/mL, FRAP (C=10 mg/mL) are 0.989mmol/L and 0.507mmol/L, respectively.