Esterified Modified Of Fucoidan From Sea Cucumber And Its Antioxidant Activity Study

Acaudina molpadioides is a kind of low sea cucumber in China,and its body wall polysaccharide is a kind of active substances.Through the orthogonal experiment,it obtain the best enzyme hydrolysis conditions and combined with ultrafiltration method to extract polysaccharides from Acaudina molpadioides.By comparing Sulfuric acid method,Sulphur trioxide pyridine-pyridine,sulphur trioxide pyridine-DMF,chlorosulfonic acid-pyridine method and chlorosulfonic acid pyridine-DMF method for preliminary study sea cucumber fucoidan esterification modified.Furthermore,a primary research was made to study the antioxidant activity of sulphating polysaccharides from Acaudina molpadioides.The experimental results are as follows:By orthogonal experiment to optimize the hydrolysis conditions,the results show that when the solid-liquid ratio is 1:40,hydrolysis time is 8 hours,hydrolysis temperature is 50℃,enzyme dosage 10%,pH value is 7.0,the polysaccharide content is（1.0657±0.014）mg/mL,and the extraction ratio is（3.24±0.03）%.Then using of ultrafiltration of hydrolyzate with 200KDa ultrafiltration membrane,and operating ultrafiltration under pressure of 0.2MPa to hydrolyzate,the protein removal rate is（91.09±0.15）%.We carried out the esterification modification of sea cucumber fucoidan by using the concentrated sulfuric acid,sulfur trioxide pyridine-pyridine method,sulfur trioxide py ridine-DMF method,chlorosulfonic acid-pyridine method,chlorosulfonic acid pyridine-DMF method,respectively.By measuring its sulfate content to determine the optimal reaction condition s and it is carried out by infrared qualitative analysis.Single factor experiment results show that:concentrated sulfuric acid sulfated polysaccharides,when the reaction time is 0.5h,the best ratio of raw materials of esterifying agent is 1:30,sulfate content can reach（22.50±1.78）%.Sulfur trioxide pyridine-pyridine method:when the reaction time is 1 h,the best ratio of raw materials of esterifying agent is 1:6,sulfate content can reach（28.03±2.23）%.Sulfur trioxide pyridine-DMF method:when reaction time is 1h,reaction temperature is 60℃,ratio of raw materials of esterifying agent is 1:6,sulfate content can reach（28.52±1.82）%.Chlorosulfonic acid-pyridine method:when reaction time is 1h,the ratio of Chlorosulfonic acid and pyridine is 1:4.7,esterification effect is best and sulfate content can reach（52.17±1.84）%.Chlorosulfonic acid pyridine-DMF method:when ratio of raw materials of esterifying agent is1:1,reaction temperature is 30℃,the best reaction time is 2h,sulfate content can reach（59.49±2.05）%.The results show that sulfated polysaccharides have the best scavenging effect on DPPH·and have the inferior scavenging effect on O₂^-·and·OH by study of antixidant activity.Concentrated sulfuric acid sulfated polysaccharides:with the increase of sulfate radical content,sulfated polysaccharides have a remarkbale raise on clearance rate of O₂^-·and have a very slowly upward tendency on cavenging effect of DPPH·and·OH.Pyridine sulfur trioxide-pyridine method sulfated polysaccharides:sulfated polysaccharides have the same clearance rate trend on O₂^-·,·OH and DPPH·.It decreases after an increase and keep stable finally.Sulfur trioxide pyridine-DMF method sulfated polysaccharides:sulfated polysaccharides have an unfavorable effect on clearance rate of O₂^-·and·OH.Compared with sulfated polysaccharides,polysaccharide after esterification has more obvious clearance rate of DPPH·.With the increase of sulfate radical content,the clearance rate of DPPH·also have an upward tendency.Chlorosulfonic acid-pyridine method sulfated polysaccharide:with the increase on sulfate content,polysaccharide after esterification has an increasing scavenging effect on O₂^-·and·OH and it have a remarkable upward trend on DPPH·.Chlorosulfonic acid pyridine-DMF method sulfated polysaccharides:sulfated polysaccharides remains stable after the first increase on clearance rate of O₂^-·,·OH and DPPH·.