| Acaudina molpadioides is a kind of low-value sea cucumbers,its dried body walls were used as materials for this study.By comparing hot water extraction and enzymolysis,it determined the best extraction method for polysaccharides from Acaudina molpadioides,as well as the best method to remove protein and isolate,purify polysaccharides by using column chromatography.It also measured the chemical component and monosaccharide composition of polysaccharides from Acaudina molpadioides.Furthermore,a primary research was made to study the antioxidant activity of polysaccharides from Acaudina molpadioides.The result shows that:According to the study of the best method to extract polysaccharides,the ratio of hot water extraction was only?0.649±0.014?%.It selected neutral proteinase as the best proteinase for enzymolysis,and orthogonal experiment was used to control enzymatic hydrolysis conditions.The result showed that,the best optimum processing technology under the condition of material liquid than 1:40 was time 7 hours,enzyme concentration 7%,at 55?with pH value of 7.5.In this condition,total sugar?1.348±0.005?mg/mL was extracted in enzymatic hydrolysate,accounts for?13.475±0.464?%of extraction rate.In order to remove protein impurities,the rude polysaccharides solution were purified by TCA method,Sevage method,Potassium acetate method,TCA method was proved to be the best method among the three,but it only removed protein impurities at?30.14±0.17?%.Clearance rate of protein impurities increased to 79.55%when it added the technology of dialysis,extraction rate of polysaccharides was?4.16±0.12?%in this condition.After freezing drying,we got the rude polysaccharides as a kind of powder with brown color,its content of total sugar was?21.17±0.17?%,protein content was?31.67±0.42?%.It got two pure polysaccharides SCP-A and SCP-B by using Q-Sepharose-F-F ion-exchange column chromatography and Sephadex G-150 column chromatography to isolate and purify.A biggish absorption peak was always with the eluting peak of SCP-A,SCP-A might be a compound of carbohydrate and protein linked with a kind of stable glycosidic linkage.After freezing drying,we got the SCP-A as a kind of powder with pale brown color,the SCP-A as a kind of floccules with pale brown color.According to chemical component analysis,the content of total sugar,protein,uronic acid,hexosamine,sulfate,the fucose was?37.41±0.67?%,?34.31±0.26?%,?7.19±0.17?%,?8.91±0.12?%,?4.23±0.37?%,?7.07±0.36?%in SCP-A,was?51.75±0.59?%,?3.34±0.28?%,?5.52±0.21?%,?6.79±0.18?%,?25.21±0.45?%,?27.91±0.76?%in SCP-B.From the result of thin layer chromatography,it knew the monosaccharide composition of SCP-A was glucuronic acid,fucose,mannose and galactosamine after hydrolyzing by trifluoroacetic acid,the monosaccharide composition of SCP-B was galactosamine,glucuronic acid,fucose,and galactose.From the chemical component and monosaccharide composition,it can be speculated that SCP-A might be a compound of glycosaminoglycan and polypeptide,SCP-B might be a kind of sulfated fucoidans.The result of IR analysis further confirmed SCP-A was a compound of protein and polysaccharides,both SCP-A and SCP-B contained uronic acids and sulfate,the types of glycosidic bond in SCP-A and SCP-B were all?-pyran glucose type.The study on antioxidant activities of polysaccharides from Acaudina molpadioides was processed in vitro,the 1,1-diphenyl-2-picrylhydrazyl radical scavenging activities,hydroxyl radical scavenging activities and superoxide anion radical scavenging activities were detected and compared with that of ascorbic acid.The result showed that the DPPH·scavenging abilities of SCP-A and SCP-B were much weaker than Vc,SCP-A was stronger than SCP-B;SCP-A and SCP-B had strong·OH scavenging abilities,specifically,they were SCP-A>Vc>SCP-B;the O2-·scavenging abilities of SCP-A and SCP-B were weaker than Vc,SCP-A was stronger than SCP-B.The protein in polysaccharides from Acaudina molpadioides promoted the antioxidant activities. |
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