| Onchidium struma belongs to Mollusca,Gastropoda,Pulmonata,Systellommatophora,Onchidioidea,Onchidiidae.It is a subtropical shellless sea slug,has a soft body but with no shell inside.Its habit and nutrition is similar to the sea cucumber,so commonly known as soil sea cucumber.Studies have shown that the O.struma has a high nutritional value.It contains over twenty amino acids and a variety of trace elements,which are necessary for human being.It is a kind of high-protein and low-fat seafood.However,the current research on the O.struma mainly focus on ecological breeding,embryonic development,systematic classification,etc.,and the research on its bioactive peptide is relatively rare.Therefore,from the point of view of making full use of economic value of O.struma,combined with the current development situation of bioactive peptide of gastropod.This paper based on the O.struma as raw materials,extract natural active polypeptides and explore its activity.Firstly,using response surface method to optimize the extraction process of O.struma natural bioactive peptides and then separated and purified the crude protein of extraction and screened out the strongest antioxidant natural peptide component from them.Finally,make a study of the natural peptides with comprehensive screening antioxidant activity and stability,which provide theoretical basis for the development and utilization of natural active peptides.The main research results are as follows:(1)Take the maximum scavenging rate of hydroxyl radical as a response value,usingthe response surface method to optimize the extraction process of Onchidium struma bioactive peptides to get the optimal extracting conditions.NaCl concentration is 0.99%,liquid-solid rate is 56.71ml/g and the extraction time is 2.23 hour,considering the feasibility of practical operation,adjust optimization conditions as follows: 0.09% NaCl concentration,liquid-solid rate is 57ml/g,extraction is 2.5 hour,under the condition of the average scavenging rate of hydroxyl radical was 33.34%.And the value is close to the theoretical value and the relative error is only 0.76%,which proves that the optimized result is reasonable and feasible.Also it has a certain reference value.(2)After the optimized liquid of extracting polypeptides was freeze-drying,the first step is precipitated with ammonium sulfate,to remove most of the impure protein.Then,the components with strong antioxidant activity and good complex solution were selected by Sephadex G-100 gel filtration chromatography to obtain OBP-1,OBP-2 and OBP-3.OBP-3 and OBP-3b were obtained by DEAE-52 ion exchange chromatography,and the antioxidant activity of OBP-3b was 57.61%,and the scavenging rate of hydroxyl radical was 57.61%.(3)Using scavenging rate of hydroxyl radical and DPPH as well as superoxide anion,reducing power and chelating ferrous ion ability of five kinds of in vitro antioxidant activity evaluation index for tumor back stone sulfonated natural active polypeptide OBP-comprehensive evaluation on the antioxidant capacity of 3 b.The results showed that OBP-3b had the strongest scavenging ability of DPPH radicals up to 74.39%,followed by hydroxyl radical scavenging ability and reducing ability,reaching 65.34% and 0.82 respectively.Superoxide anion radical scavenging ability and ferrous ion chelating ability to be weak,respectively,51.31% and 48.25%.(4)The stability of OBP-3b was studied by measuring the antioxidant activity of OBP-3b under the conditions of light and in different temperature,different pH and adding two kinds of common food additives such as sodium chloride and glucose.The results showed that the antioxidant activity of OBP-3b under the environment of high temperature and glucose and NaCl was almost unaffected.However,under the light condition,the antioxidant activity of OBP-3b was obviously weakened.In the acid and alkali environment,its antioxidant properties have different degrees of decline,compared to alkaline environment,OBP-3b on the acidic environment tolerance better. |
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