Determination Of Histidine-Containing Dipeptides In Marine Organisms And Carnosine-related Metabolomes Analysis Of Mytilus Coruscus

Histidine-containing dipeptide(HCD)is a class of non-protein nitrogen-containing compounds with multiple physiological functions,mainly found in the excitable tissues of vertebrates.At present,carnosine has become an important class of nutritional supplements and prodrug molecules due to its better physiological activity.Carnosine supplementation has been proven to play an important role in skeletal muscle contraction and has anti-fatigue activity.Since β-alanine is a key substrate for carnosine synthesis in the body,β-alanine has also become a nutritional supplement for improving athletic ability and anti-fatigue,and is used to enhance the body’s athletic ability and performance.In addition,β-alanine supplementation can improve the growth traits of poultry and fish,tissue antioxidant capacity and meat quality.Therefore,β-alanine supplementation has important application prospects and research value in agricultural economic animal breeding.In order to understand the content of HCD in marine organisms and expand the understanding of the distribution characteristics of HCD in different species,this paper determined the HCD content in muscle tissues of nearly 40 species including fish,crustaceans and mollusks in the Zhoushan fishing grounds of the East China Sea.First,the o-phthalaldehyde(OPA)method was used to determine the HCD content in the muscle tissue and chicken breast of 39 aquatic economic species;the LC-MS/MS technology was further used to analyze the three types of carnosine,anserine,and homocarnosine in the HCD of the tested species.The results showed that among the tested species,the muscle tissues of most osteichthyes contained carnosine and anserine,and the content of anserine was significantly higher than carnosine(P < 0.05);only a few species,such as Trichiurus lepturus,Larimichthys polyactis,Harpadon nehereus,Conger myriaster and Scomber japonicus have been identified presence of high and low levels of carnopeptide in the muscle tissue;in addition,there are 14 species that have not been identified by the LC-MS method to identify HCD,including three species of fish,including Antennarius striatus,Boleophthalmus pectinirostris and Psenopsis anomala and 4 kinds of mollusks and 7 kinds of crustaceans.Further antioxidant activity test results showed that the HCD extracts of Pampus argenteus,Pennahia argentata and Mytilus coruscus have a higher DPPH clearance rate.The results of this study greatly expand the HCD species distribution data,provide clues for understanding the role of HCD in different animals and the nutritional assessment of marine aquatic species,and also lay a foundation for understanding the nutritional value of aquatic species in Zhoushan waters and the exploitation of Marine biological HCD resources.In addition,this thesis further uses an amino acid analyzer to find that M.coruscus also contain low concentrations of HCD.In order to explore the metabolic process of HCD in M.coruscus,ultra-high performance liquid chromatography-tandem mass spectrometry(UPLC-MS/ MS)technology was used to perform differential metabonomics analysis to explore the metabolic effects of β-alanine injection and carnosine injection on mussel tissues.The analysis results showed that the differential metabolites in the M.coruscus tissue after β-alanine injection were mainly enriched in the energy metabolism,lipid metabolism and amino acid metabolism pathways of the mussels.After carnosine injection,the differential metabolites in the M.coruscus tissue were enriched in arachidonic acid metabolism,steroid hormone metabolism and retinol metabolism pathways.In addition,this paper measured the antioxidant activity of small molecule extracts from whole mussel tissues before and after β-alanine and carnosine injections,and the activities of superoxide dismutase(SOD)and catalase(CAT)in whole tissues of mussels were significantly increased and the content of malondialdehyde(MDA)were significantly decreased after two treatments.Considering the positive effects of β-alanine injection on mussel metabolism,this study provides clues for the follow-up understanding of the potential application of β-alanine supplementation in mussel farming.