Extraction of crude polysaccharides from Gomphidius rutilus and their antioxidant activities in vitro

Response surface methodology was used to optimize the extraction of crude polysaccharides from the fruiting bodies of Gomphidius rutilus. A central composite design was adopted to determine the combination of factors (extraction time, extraction temperature, extraction frequency, and ratio of water to raw material) that resulted in the maximum crude polysaccharide production. Results showed that the optimum extraction conditions were as follows: extraction temperature, 95 degrees C; ratio of water to raw material, 16; extraction time, 2.5 h; and extraction frequency, 4. Under these conditions, the experimental yield of crude polysaccharides was 8.02 +/- 0.15%, which well agreed with the predicted yield. Evaluation of the antioxidant activity in vitro suggested that the crude polysaccharides had high scavenging activity for superoxide anion, hydroxyl, and 1,1-diphenyl-2-picrylhydrazyl radicals. The crude polysaccharides also showed strong reducing power. Thus, they can be used as natural antioxidants in functional foods or medicine. (C) 2013 Elsevier Ltd. All rights reserved.