Study Of Polysaccharides Extracted From Isaria Farinosa B05

The selection of the optimal fermentation medium and conditions for polysaccharides production from Isaria farinosa B05, the extraction methods, characterization, components and bioactivities of polysaccharides are studied.(1) The medium components and fermentation conditions are optimized according to the one-at-a-time method, while the concentration of medium components is determined by orthogonal matrix method. The results show that the optimal fermentation medium is as follows: sucrose 3.5% (w/v), peptone 0.5%, yeast extract 0.2%, K₂HPO₄ 0.1% and MgSO₄ 0.05%. The suitable fermentation conditions are as follows: initial pH 7.0, temperature 25℃, medium volume 75mL/250mL, inoculum volume 5% (v/v), time 5d. In such optimal nutrition and environmental conditions, the maximal mycelial yield is 2.12g/100mL after 4 day's fermentation, while maximal water-soluble exo-polysaccharides production reaches 2.14g/L after 5 day's fermentation.(2) The suitable procedure for extraction exo-polysaccharides is determined as follows: the filtrate is concentrated to 1/7 volume at 70℃, adjusted to pH 7.0, and then precipitated by 3 volume of 95% ethanol. The suitable procedure for extraction intra-polysaccharides is determined as follows: the dried mycelium is added 30 multiple of water, and extracted 150min twice at 100℃. In such suitable procedure for extraction, the water-soluble intra-polysaccharides (IPS) and exo-polysaccharides (EPS) are obtained from the mycelium and filtrate.The active peaks of IPS1 and EPS1 are obtained when IPS and EPS are purified by anion-exchange chromatography on Q-Sepharose FF and gel chromatography on Sephacryl S-300HR, which was proved by Sephacryl S-300HR chromatography. The average molecular weight of IPS1 is determined to be 42kDa. IPS1 is composed ofmannose, galactose and glucose in molar ratio of 8.0: 4.8: 1.0, 90.3% carbohydrate, 8.00% uronic acid, hexosamine, 7.15% protein and 11 kinds of amino acid. The average molecular weight of EPS 1 is determined to be 208kDa. EPS1 is composed of mannose, galactose and glucose in molar ratio of 21.6: 4.7: 1.0, 93.4% carbohydrate, 8.06% uronic acid, hexosamine, 4.38% protein and 13 kinds of amino acid. The assay of dilute alkali suggests that the polysaccharide chain of IPS 1 and EPS1 is N-glucosidal bond. The infrared spectrum indicates that glucosidal linkage in IPS1 and EPS1 is (3-pyranose.(3) The bioactivities of polysaccharides are studied. Both IPS1 and EPS1 exhibit antitumor activities against SI80 solid-type tumor. The antitumor activity of IPS1 reaches maximum of 61.63% at a dose of 200mg/kg, while the one of EPS1 reaches maximum of 63.10% at a dose of 400mg/kg. IPS1 and EPS1 can improve the activities of antioxidase in tumor-bearing mice. Apparently the higher activities of SOD and CAT are, the higher the inhibition effects are obtained in the antitumor assay. The in vitro antioxidant activities are further investigated. The results show that WSIPS and WSEPS have effective antioxidant activities in various systems. WSIPS exhibits strong hydroxyl radical, superoxide radical and hydrogen peroxide scavenging activities; more over, it can chelate Fe2+, has great reductive ability and anti-lipid peroxidation ability. Although WSEPS can not scavenge hydroxyl radical as well as chelate Fe2+, it exactly shows similar effects with WSIPS in other antioxidation systems.The studies of this paper provide a theoretic foundation for further industrialization and clinic application.