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[Objectives] This study was conducted to optimize the extraction process of Sipunculus nudus polysaccharide and study the antioxidant activity of S. nudus polysaccharide. [Methods] S. nudus polysaccharide was extracted by ultrasonic microwave assisted method, during which univariate factors including solid-liquid ratio, time, temperature, ultrasonic power, microwave power were investigated, to select optimal extracting conditions, which were also verified by an response surface optimization experiment (an four-factor three-level test); and the antioxidant activity of S. nudus polysaccharide was studied by determining its DP-PH radical scavenging capacity. [Results] Through univariate factor investigation and response surface optimization test, it was found that the response surface results were consistent with univariate results. The optimized conditions were as follows: solid-liquid ratio at 1:15, ultrasonic temperature at 60 °C, ultrasonic power of 360 W and microwave power of 200 W, and the predicted polysaccharide extracting amount was 4.35 mg/g. Under the optimized extracting conditions, the average extracting amount of S. nudus polysaccharide was 4.38 mg/g, which is close to the theoretical predicted value (4.35 mg/g). And the results of this study also showed that different concentrations of polysaccharide solutions have different scavenging effects on DPPH free radical. At the polysaccharide concentration of 0.16 mg/ml, the maximum value of DPPH radical scavenging rate was 7.22%, indicating that polysaccharide has certain antioxidant capacity. [Conclusions] This method is a new trial with satisfactory results. [ABSTRACT FROM AUTHOR]

[Objectives] This study was conducted to optimize experimental conditions for extraction of polysaccharides from Sipunculus nudus. % Methods] With the Sipunculus nudus from Sanya as the experimental material, S. nudus polysaccharide was extracted by ultrasonic microwave asisted method, during which univariate factors including solid-liquid ratio, time, temperature, ultrasonic power, microwave power were investigated, to select optimal extracting conditions, which were also demonstrated and optimized by variance and response surface analysis. The optimized conditions were adopted to carry out a test, in which the absorbance of S. nudus polysaccharide was measured with an ultraviolet and visible spectrophotometer, followed by the calculation of the extracting amount of polysaccharide, and precision test and recovery test were also carried out to verify the experimental method. [ Results] The standard solutions were determined at the maximum absorption wavelength of 486 nm, and the regression equation was A - 0. 267 7C + 0.001 8, R2 - 0. 999 8. Solid-liquid ratio, time, temperature, ultrasonic power and microwave power were investigated by univariate analysis and then optimized by response surface method as follows: solid-liquid ratio at 1:20 ( gmf), time of 35 min, temperature at 50 П, ultrasonic power at 420W and microwave power at 300 W, under which the measured extracting amount of S. nudus polysaccharide wa 1.37 mg g. The RSD was 0. 985 % in precision experiment. In the repeatability test, the extracting amounts of polysaccharide were 1.41, 1.43 and 1.38 mg g for three parallel tests, respectively, with a RSD of 1.140 %. The recovery test obtained following results: for group a ( added with glucose standard )$ the recovery of S. nudus polysaccharide was in the range of 100.3% -101.4%, RSD -0.03% ; and for group b ( not added with glucose standard) : the recovery of S. nudus polysaccharide was in the range of 99. 7% - 100. 3%, RSD - 0.02% . [ Conclusions] The research method is stable and reliable. This study provides data basis and reference for follow-up study on S. nudus. [ABSTRACT FROM AUTHOR]

[Objectives] rrhis study was conducted to optimize the extraction process of Sipunculus nudus polysaccharide. [Methods] 5. nudus polysaccharide was extracted by ultrasonic water extraction, with the marine S. nudus as a raw material from Sanya City, Hainan Province, by single factor variable method, to find the optimal extraction conditions including ultrasonic power, solid-liquid ratio, ultrasonic extraction temperature, ultrasonic extraction time, ultrasonic extraction times and lye concentration. The absorbance of the polysaccharide was determined by an ultraviolet spectrophotometer, and polysaccharide yield were calculated. The antioxidant activity of scavenging hydroxyl and DPPH radicals was measured at different concentrations. [Results] The optimal extraction conditions for S. nudus polysaccharide were as follows: solid-liquid ratio at 1:11 mg/ml, extraction temperature at 60 t, three times of ultrasonic extraction, ultrasonic power of 960 W, extraction time of 1.5 h, and lye concentration of 5 %, under which the polysaccharide yield was 3.21%. The scavenging rates of hydroxyl radical and DPPH radical were 12.58% at the concentration of 0.20 mg/ml. Moreover, the scavenging rates increased significantly with the increase of concentration. [Conclusions] This method is a new trial with satisfactory results. [ABSTRACT FROM AUTHOR]