Obtaining extracts rich in antioxidant polysaccharides from the edible mushroom Pleurotus ostreatus using binary system with hot water and supercritical CO2

•A new methodology was developed for the recovery of extract rich in antioxidant polysaccharide.•Box-Behnken design allowed the prediction of optimal conditions in H2O + CO2-SFE.•Temperature and pressure influence the obtainment of polysaccharide extract with H2O + CO2-SFE.•Anomeric bonds, identified in the FTIR and NMR spectrum, indicate that the extract is rich in polysaccharides.•The extract obtained with H2O + CO2-SFE showed high antioxidant activity in vitro and in a cell model. Pleurotus ostreatus is an edible mushroom with pharmacological potential, due to its metabolites, mainly polysaccharides. On here, the development of a new methodology for the recovery of extract rich in antioxidant polysaccharide was reported. The extracts were characterized, evaluated for antioxidant activity in vitro and in cell models and cytotoxicity. The best defined extraction condition was 25 MPa, 433.15 K, and 20% H2O, with 30.69% of the total yield and 0.921 mg of CHO3. The anomeric bonds, identified in the FTIR and NMR spectrum, indicate that the extracts are a mixture of heteropolysaccharides, β-glucans, α-glucans, and oligosaccharides. The best extraction condition has 80.83% of antioxidant activity, without cytotoxic effect in vitro. In addition to antioxidant activity in cell model, increasing protection against oxidative damage induced by H2O2. Finally, H2O + CO2-SFE technology can be used to obtain extracts rich in antioxidant polysaccharides with pharmacological and food potential.