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

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 4.8h. 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.