Extraction Process Optimization and Antioxidant Activity Evaluation of Crude Polysaccharides from Lonicera japonica

The polysaccharides from Lonicera japonica were extracted by the hot water extraction method, and the effects of solid-liquid ratio, extraction time, extraction temperature and extraction times on the yield of polysaccharides were investigated by a single factor test. On this basis, the response surface method was used to optimize the extraction conditions. The antioxidant activity of crude polysaccharides from Lonicera japonica were evaluated by measuring DPPH free radical, ABTS⁺ free radical, hydroxyl free radical, superoxide anion free radical scavenging ability and total reducing power. The results showed that the optimal extraction process conditions of polysaccharides from Lonicera japonica were as follow: solid-liquid ratio of 1:30 (g/mL), extraction time of 120 min, and extraction temperature of 70 ℃. Under these conditions, the actual yield of polysaccharides from Lonicera japonica was 6.45%±0.15%, and the relative error with the predicted value was 1.2%. When the concentration of crude polysaccharides was 2 mg/mL, the maximum scavenging rates of DPPH free radical, ABTS⁺ free radical, hydroxyl free radical and superoxide anion free radical were 88.56%, 99.51%, 46.40% and 85.88%, respectively. Besides, the total reducing power was 1.04. The optimized crude polysaccharides had an excellent antioxidant activity, which provided a theoretical basis for further isolation, purification and characterization of active polysaccharides from Lonicera japonica.