Polysaccharides in Sipunculus nudus: Extraction Condition Optimization and Antioxidant Activities

Marine organisms constitute unlimited resource of bioactive substances due to their high biodiversity and represent a valuable source of new compounds. This study optimized the alkali-extraction conditions and antioxidant activities of soluble polysaccharides from the body wall of Sipunculus nudus. The effects of solid-liquid ratio, extraction duration, extraction temperature, and alkali concentration on the yield of S. nudus polysaccharides(SNP) were examined, according to which the optimal combination of extraction parameters was obtained by an orthogonal test. The relative influencing importance of different extraction parameters on the yield of SNP followed the order as solid-liquid ratio > extraction temperature > alkali concentration > extraction duration. The highest extraction yield, 1.98%, was achieved under an optimal extraction condition: temperature 60℃, solid-liquid ratio 1:6 g mL^(-1), duration 5 h, and alkali(Na OH) mass fraction 6%. The in vitro antioxidant activities examination showed that extracted SNP under this optimized condition had strong power in reducing certain hydroxyl and superoxide radical scavenging abilities. The promising results showed that extracted SNP could be a potent natural antioxidant.

The Optimization of Ultrasonic-assisted Extraction of Polysaccharide from Sipunculus nudus by Response Surface Methodology and Study on Antioxidant Activity

[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 solidliquid 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 DPPH 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 ℃,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 of0. 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.

Study on Extraction Process of Sipunculus nudus Polysaccharide and Its Antioxidant Activity

[Objectives] This study was conducted to optimize the extraction process of Sipunculus nudus polysaccharide. [Methods]S. 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 ℃,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.

Effects of Dietary Carbohydrate-lipid Ratio on Growth, Body Composition and Digestive Enzyme Activities of Juvenile Peanut Worm,Sipunculus nudus

[Objective] This study was conducted to investigate the effects of dietary carbohydrate-lipid( C / L) ratios on growth performance,body composition and digestive enzyme activities of juvenile peanut worm. [Methods]Juvenile peanut worm with average body weight of( 16. 77 ± 0. 40) mg were fed with five isonitrogenous and isoenergetic diets formulated to contain different carbohydrate / lipid( C / L) ratios( 0. 68,1. 02,1. 62,2. 61 or 4. 35) for 8 weeks. [Results] The dietary C / L ratios had no significant effects on survival of juvenile peanut worm( P 】 0. 05). With the increasing of dietary C / L ratios,weight growth rate( WGR)and specific growth rate( SGR) increased when dietary C / L ratios were between 0. 68 and 2. 61,and then decreased significantly with dietary C / L ratio further increased. When the dietary C / L ratio was 2. 61( carbohydrate level was 20. 64%,lipid level was 7. 92%) both WGR and SGR produced the maximum value,they were 451. 78 ± 16. 85% and 3. 41 ± 0. 06 % / d,respectively. The dietary C / L ratios had significant effects on body moisture,body protein content and body lipid content( P 【 0. 05),but no significant effects on body ash content of juvenile peanut worm( P 】 0. 05). Different C / L ratios had significant effects on amylase activity and lipases activity of juvenile peanut worm( P 【 0. 05),but no significant effects on protease activity( P 】 0. 05). [Conclusion]The regression model analysis showed that the most suitable dietary C / L ratio which can make juvenile peanut worm acquire the best weight growth rate is 2. 42.

Odor-Active Volatile Compounds from the Gonads of the Sea Urchin <i>Mesocentrotus nudus</i>in the Wild in Miyagi Prefecture, Tohoku, Japan

Background and Aims: Mesocentrotus nudus is commercially harvested from shallow rocky bottoms in northern Japan. The gonads are targeted as an edible product. The objective of this study was to identify odor-active volatile organic compounds (VOCs) from the gonads of adult M. nudus collected at a fishing ground in Miyagi Prefecture, Tohoku, Japan. Methods and Results: Gas chromatography-mass spectrometry analysis and gas chromatography-sniffing techniques identified 42 compounds categorized as alcohols, aldehydes, aromatic hydrocarbons, esters, halomethanes, hydrocarbons, ketones, sulfur-containing compounds, and nitrogen-containing compounds. GC-sniffing analysis characterized four compounds with preferable odors of sea urchin gonads;limonene, propyl acetate, acetone, dibromochloromethane. On the other hand, the analysis characterized three compounds with unpreferable odors;methyl mercaptane, dimethyl sulfide, and s-methyl thioacetate. Several VOCs from the gonads were derived from seaweeds, terrestrial plants, and fish flesh as food because M. nudus is omnivorous. Conclusion: This is the first study to identify VOCs from edible sea urchin gonads in the wild in Japan. These VOC data comprise a typical standard in order to evaluate a higher quality of sea urchin gonads.

Effects of Dietary Carbohydrate Sources on Daily Weight Gain and Digestive Enzyme Activities of Juvenile Peanut Worm(Sipunculus nudus)

In the study,glucose,sucrose,dextrin,tapioca starch,potato starch,corn starch and gelatinized corn starch were selected to make the diets with same nitrogen and lipid,and Juvenile peanut worms( Sipunculus nudus) were fed with the diets came from different carbohydrate sources,effects of diets with different carbohydrate sources on daily weight gain and digestive enzyme activities of S. nudus were studied. Results showed that diets with different carbohydrate sources had significant influences on daily weight gain and digestive enzyme activities of S. nudus( P < 0. 05). Daily weight gain in gelatinized corn starch group was significantly higher than that in other groups( P < 0. 05); daily weight gain in glucose group was significantly lower than that in other groups( P < 0. 05); daily weight gain in the three ungelatinized starch groups was significantly higher than that in glucose,sucrose and dextrin groups( P < 0. 05). Analysis of digestive enzyme activities showed that dietary carbohydrate sources had significant influences on digestive enzyme activities of S. nudus( P < 0. 05). Protease activities and amylase activities of S. nudus in sucrose group were the highest,which were significantly higher than that in the other groups( P < 0. 05); lipase activities of S. nudus in glucose group were the lowest,which were significantly lower than that in other groups( P < 0. 05). In conclusion,growth-promoting effects of macromolecules carbohydrates( starch) were better than that of disaccharide( sucrose) and monosaccharide( glucose),which of gelatinized starch were better than that of ungelatinized starch.

Ultrasonic Microwave Assisted Extraction of Polysaccharides from Sipunculus nudus

[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 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 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 = 0.2677 C + 0.001 8,R^2= 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( g/ml),time of 35 min,temperature at 50 ℃,ultrasonic power at 420 W and microwave power at 300 W,under which the measured extracting amount of S.nudus polysaccharide was1.37 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.

方格星虫胚胎与幼体发育的研究

研究了方格星虫Sipunculusnudus胚胎与幼体发育。实验用亲虫于1999—2001年每年的5—8月分别采自北海市白虎头、大冠沙及高德海区。用人工授精法获得胚胎,用自然受精法获得幼体并观察其发育状况。研究表明,在25℃水温下,从受精卵到孵化出海球幼体(Pelagosphericlar va),胚胎发育需50—52h;在水温28—29℃下,需38—40h。在水温28—29℃下,从初孵出的海球幼体到附着变态期幼体,需13—15d。附着幼体经过7—10d发育后才完成变态,成为稚虫。

裸体方格星虫消化道组织学研究

报道了裸体方格星虫(Sipunculus nudus Linnaeus,1766)消化道各部的形态、组织学结构。结果表明:裸体方格星虫消化道分为口、咽、食道、肠、盲肠、直肠和肛门。肠是消化道的主体,约为躯干长的4倍,通过固肠肌与体壁相连。肠由两个长短不一的肠环组成,肠环下降支和上升支相互盘绕,使肠呈双螺旋状。消化道管壁由黏膜、黏膜下层、肌层和外膜组成,消化道黏膜上皮主要由柱状细胞组成,但消化道的不同部位,柱状细胞的类型和分布不同。除盲肠外,黏膜均向腔面褶成皱襞。肠的各段中均有"V"字型纤毛沟的存在。此外,皱襞的形态、黏膜下层和肌层的厚度等在消化道各部也存在差异。研究表明裸体方格星虫消化道结构与其食性是相适应的。

沙虫及沙虫美拉德反应物的挥发性成分分析

采用固相微萃取-气相色谱-质谱法(SPME-GC-MS)对沙虫(Sipunculs nudus)及沙虫美拉德反应物的挥发性成分进行测定。结果表明,从沙虫和沙虫美拉德反应物中分别鉴定出34种和46种挥发性化合物,主要包括醇、醛、酮、烃、杂环类化合物等,通过比较,沙虫美拉德反应物比沙虫香气成分的种类增多,如(-)-4-萜品醇、α-松油醇、香叶基丙酮、(+)-柠檬烯、萜品烯等,苯甲醇和苯甲醛含量明显增加。

光裸方格星虫的研究进展

光裸方格星虫(Sipunculus nudus)具有丰富的食用和药用价值,为给光裸方格星虫的资源保护与利用以及进一步深入研究提供参考,综述了国内外有关光裸方格星虫在种质资源、营养价值、生理结构、人工养殖技术、营养需求与饲料及环境毒理学等方面的研究进展。

不同加工方式沙虫干品的脂肪酸组成比较

为研究不同加工方式下方格星虫(Sipunculus nudus)脂肪酸组成特征,采用气相色谱仪检测水煮烘干和暴晒干燥两种加工方式下方格星虫体壁脂肪酸种类和含量。结果显示,水煮干燥和暴晒加工方格星虫体壁中分别检测出21种、20种脂肪酸,分别包含12种、11种不饱和脂肪酸(UFA),两种加工方式具有相同的饱和脂肪酸(SFA)种类(9种)。水煮加工的饱和脂肪酸(SFA)、单不饱和脂肪酸(MUFA)和多不饱和脂肪酸(PUFA)含量分别为7.97、1.21和5.56 mg/kg,而暴晒加工的SFA、MUFA、PUFA分别为5.84、0.34和2.47 mg/kg。水煮加工方格星虫的体壁饱和脂肪酸含量显著高于暴晒加工(P<0.05)。两种加工方式方格星虫体壁中的不饱和脂肪酸占总脂肪酸的45.96%和32.98%,而SFA∶MUFA∶PUFA比值分别是1∶0.15∶0.7和1∶0.06∶0.42。两种加工方式样品中的十一碳酸、油酸和亚油酸分别是SFA、MUFA、PUFA含量最高的。在单不饱和脂肪酸中,水煮加工样品中的十八碳一烯酸的含量显著高于暴晒加工(P<0.05);在多不饱和脂肪酸中,水煮烘干样品中的9,12-十八碳二烯酸、6,9,12-十八碳三烯酸、8,11,14-二十碳三烯酸、5,8,11,14,17-二十碳五烯酸显著高于暴晒加工(P<0.05)。综合分析表明,不同加工方式会影响方格星虫干品中的脂肪酸含量,水煮干燥加工方式的脂肪酸保留率高于直接暴晒方式。