Extraction optimization of Bruguiera gymnorrhiza polysaccharides with radical scavenging activities

Box–Behnken design including independent variables such as extraction temperature (60–80 °C), extraction time (20–40 min) and ratio of water to raw material (30–50 mL/g) was used to optimize the extraction process of Bruguiera gymnorrhiza polysaccharides (BGPs). The experimental data were fitted to a second-order polynomial equation using multiple regression analysis. The optimum conditions were predicted as follows: extraction temperature 71 °C, extracting time 31.4 min, and ratio of water to raw material 42. Under these conditions, the yield of BGPs obtained was (16.43 ± 0.08)%, which was in good agreement with the predicted value 16.47%. Additionally, characterization of BGPs was obtained by FT-IR analysis. The antioxidant activities of BGPs were evaluated in vitro. BGPs demonstrated appreciable antioxidant potential on superoxide anion radical, ABTS radical, and hydroxyl radical scavenging. These may provide theoretical basis for further system research and rational development and utilization of mangrove resources.