Optimization of polysaccharides extraction from Trametes robiniophila and its antioxidant activities

Based on a single-factor experiment, Box–Behnken design was used to optimize the ultrasound-assisted extraction process of Trametes robiniophila (Huaier) polysaccharides (HPs). The optimum conditions were predicted as follows: ratio of water to raw material, 46.0 mL/g; extraction temperature, 68.9 °C; ultrasonic power, 51.3 W; and extraction time, 36.8 min. Under these conditions, the highest yield of HPs obtained was 36.8 ± 0.12%, which was in good agreement with the predicted value 36.6%. Additionally, chemical analysis of HPs showed a high content (85.3 ± 1.3%) of carbohydrates containing fucose, arabinose, xylose, mannose, galactose and glucose, with molar percentages 5.82%, 13.11%, 16.88%, 15.85%, 11.40% and 36.94%, respectively. Besides, HPs demonstrated appreciable antioxidant potential on ABTS, superoxide anion and hydroxyl radicals in vitro. These may further provide theoretical basis for the widely application of HPs in medicine and health care products.