Abstract: The extraction of water-soluble polysaccharides (WSP) from Cordyceps cicadae was optimized using one-factor-at-a-time method and response surface methodology. Solvent-to-solid ratio, extraction time and temperature were used as independent variables while polysaccharide yield was taken as response variable. The in vitro antioxidant activity of WSP was investigated by measuring total reducing power and scavenging activities against 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH), hydroxyl and superoxide anion radicals. The optimum extraction conditions were found to be extraction at 80 ℃ for 130 min with a solvent-to-solid ratio of 50:1 (mL/g). Experiments conducted under these conditions gave a polysaccharide yield of 26.14 mg/g. WSP possessed strong antioxidant activity with half inhibitory concentration (IC50) for scavenging of DPPH, hydroxyl and superoxide anion radicals 28.99 μg/mL, 0.19 mg/mL and 0.30 mg/mL, respectively.

Key words: Cordyceps cicadae polysaccharides, extraction process, response surface methodology, antioxidant activity