Microwave-Assisted Extraction and the Antioxidant Activity of Water-Soluble Polysaccharide from Palmaria palmata: Extraction Process and Antioxidant Activity of Polysaccharide from Palmaria palmate

An efficient microwave-assisted extraction (MAE) technique has been developed to recover polysaccharide from Palmaria palmata through an orthogonal experiment (L9(3)4). The content of polysaccharide was determined by phenol-sulphuric acid method and the antioxidant activities were evaluated by DPPH/ Hydroxyl radical-scavenging activity. Under the optimum parameters of microwave power of 500W, extraction temperature of 70°C, extraction time of 10 min and solid-to liquid ratio of 1:70, the yield of crude polysaccharides (CP) reached to 17.01%. The CP was further purified by DEAE52 cellulose ion-exchange chromatography to afford three fractions (Fl to F3). F12 with higher purity was isolated from Fl fraction using Sephadex G-75 gel chromatography. Using the vitamin C as the positive control, the antioxidant activities of CP and F12 were investigated. In the antioxidant tests, CP and F12 exhibited higher DPPH radical scavenging activity and hydroxyl radical scavenging activity than vitamin C in the concentrations ranges of 2.5 μg/mL to 25.0 μg/mL and 9.3 μg/mL to 93.0 μg/mL, respectively. The results demonstrated potential antioxidant activities effect of polysaccharide, providing scientific support for the empirical use of polysaccharide as an antioxidant for diseases caused by reactive oxygen species.