Optimization of Ultrasonic-assisted Extraction Technology of Sargassum fusiforme Polysaccharides and Evaluation of Their Antioxidant Activity

An ultrasonic-assisted extraction method was employed to get high quality bioactive polysaccharides from Sargassum fusiforme (SFP), with the technology optimized in light of an orthogonal test design L-9 (3(3)). Being the major factors that influence the yield of the extracts, the ultrasonic power, water/solid ratio, and extraction time were selected on the basis of a single-factor test. The extraction yield and the antioxidant activity of SFP were used as dependent variables in the analysis of the orthogonal test results. The antioxidant activity of SFP was evaluated using IC50 of scavenging 1,1-diphenyl-2-picrylhydrazyl (DPPH) as the activity monitoring parameter. The optimum extraction conditions were obtained when the ultrasonic power, the extraction time, and the ratio of water to solid were 800 W, 10 min and 20, respectively. Under the optimized conditions, the SFP extracted with the optimized ultrasonic-assisted method exhibited strongest DPPH radical scavenging activity (P < 0.05) compared with conventional hot water extracted SFP and other two antioxidants.