Optimization of extraction process and antioxidant activity of polysaccharides from leaves of Paris polyphylla

•Extraction process of polysaccharides from Paris polyphylla leaves was optimized.•The crude polysaccharides were purified.•The antioxidant activities of purified polysaccharide were evaluated.

Based on a single-factor test, a central composite design was used to optimize the extraction conditions of polysaccharides from leaves of Paris polyphylla Smith var. yunnanensis (Franch.) Hand.-Mazz. Three independent variables, including extraction temperature (°C), ratio of water to raw material, and extraction time (h), which significantly affected the yield of polysaccharides, were investigated. The experimental data were fitted to a quadratic polynomial equation using multiple regression analysis and also examined using appropriate statistical methods. The optimum conditions were as follows: extraction temperature, 90.8 °C; ratio of water to raw material, 21.3:1; and extraction time 4.8 h. Under these conditions, the experimental yield was 54.18%, which matched the predicted value well. Furthermore, the purified polysaccharide exerted strong antioxidant effects on DPPH, hydroxyl, and superoxide radicals in vitro.