Abstract: The quantitative effects of extraction time (ETm), the ratio of sample to water (S/W), and extraction temperature (ETp) on polysaccharide extraction rate from Lygodium japonicum (Thumb.) Sw were investigated using response surface methodology, and the optimum extraction parameters were determined: ETm of 123.3 min, S/W of 1:20.9 (w/v) and ETp of 49.9 ℃. The predicted PS extraction rate reached 12.446%, and the result of verification experiment is 12.85±0.18% (n=3). The antioxidant activities of the purified PS in vitro were evaluated and compared to standard antioxidant as Vitamin C. The results indicated that the purified PS showed strong antioxidant activities against O₂^-• and •OH.

Key words: Lygodium japonicum (Thumb.) Sw, polysaccharide (PS), superoxide anion free radical, hydroxyl free radicals, oxygen free radicals (OFRs), response surface methodology (RSM)