Extraction optimization of exopolysaccharide produced by Pleurotus cornucopiae SS-02 and its antioxidant activity

The extraction parameters for Pleurotus cornucopiae SS-02  exopolysaccharide (EPS) produced during submerged culture were  optimized using Plackett–Burman (PB) design and central composite  design (CCD). The optimum conditions for EPS extraction were ethanol  concentration of 86.97%, pH 8.99 and concentrated multiple 2.43, and the EPS production was estimated at 3.96 g/l. The actual yield of EPS under  these conditions was 3.75 g/l. The in vitro antioxidant activities of the EPS showed that the inhibition effects of EPS at a dosage of 4 g/l on  superoxide anion and hydroxyl radicals were 70.53 ± 3.27% and 40.59 ± 2.81%, respectively and the reducing power was 0.42 ± 0.02 (absorbance at 700 nm). The activities of superoxide dismutase (SOD), glutathione  peroxidase (GSH-Px) and catalase (CAT) in mice blood were 260.62 ±  22.18 U/ml, 187.66 ± 16.28 U/ml, and 403.75 ± 36.16 U/ml, respectively and the malondialdehyde (MDA) content was 5.01 ± 0.36 nmol/ml. The results provide a reference for large-scale extraction of EPS by P.  cornucopiae SS-02 in industrial fermentation, and the EPS can be used as a potential antioxidant which enhances adaptive immune responses. Key words : Exopolysaccharide, Pleurotus cornucopiae SS-02, antioxidant activity, in vitro, in vivo