Ultrasound Assisted Extraction of Polysaccharides from Auricularia cornea Ehrenb. and Its Antioxidant Activity Analysis

Optimization of the extraction of polysaccharide from Auricularia cornea Ehrenb. for higher polysaccharide yield was carried out using one-factor-at-a-time method and response surface methodology. Solvent-to-solid ratio,ultrasonic power,ultrasonic temperature and ultrasonic time were used as independent variables. FT-IR was used to preliminary characterize the polysaccharide structure. The in vitro antioxidant activity of Auricularia cornea Ehrenb. polysaccharides was investigated by measuring total reducing power and scavenging activities against 1,1-diphenyl-2-trinitrophenylhydrazine(DPPH),iron ion reduction ability(FRAP)and oxygen radical scavenging ability(ORAC). The results showed that the optimum extraction conditions were found to be extraction at 210 W,62 ℃ for 29 min with a solvent-to-solid ratio of 40∶1 (mL/g). Experiments conducted under these conditions gave a polysaccharide yield of 7.43%. Polysaccharides had the characteristic absorption peak of polysaccharide and proved to be β-pyranose. The IC₅₀ against the DPPH free radical of the Auricularia cornea Ehrenb. polysaccharides was 1.445,and the FRAP and ORAC values were 35.14±0.16 mmol Trolox g^-1and 0.627 mg Trolox mg^-1,which had good antioxidant capacity and could be used as natural antioxidants.