Preparation And Activity Study Of Collagen Peptides From The Skin Of Micropterus Salmoides

Micropterus salmoides also known as California perch,is now one of the major freshwater farming species in Zhejiang Province because of its rapid growth,wide temperature adaptability and strong disease resistance.In this project,the collagen peptide with high antioxidant activity was obtained from the skin of M.salmoides,and the effects of collagen peptide on immune enhancement and regulation of intestinal flora in immunocompromised mice were investigated to provide scientific basis for improving the high value utilization of M.salmoides.M.salmoides skin was used as raw material,from which collagen was extracted by acid-enzyme complex method.Alkaline,neutral,papain and pancreatic proteases were selected for enzymatic digestion of collagen,and alkaline protease enzymatic collagen peptide(APP),neutral protease enzymatic collagen peptide(NPP),papain enzymatic collagen peptide(PP)and pancreatic protease enzymatic collagen peptide(TP)were obtained,and their total antioxidant activity,reducing activity,ability to scavenge DPPH·,·OH and O₂^-·,lipid oxidation inhibiting activity and ferrous ion chelating ability as well as physicochemical properties were compared.Female Balb/c mice were arbitrarily divided into a blank control group,a model group,a positive control group,and a collagen peptide low,medium and high dose group.Seven days before the experiment,the blank control group was injected intraperitoneally with saline,and the remaining five groups of mice were injected intraperitoneally with 0.2 m L of 80 mg/kg cyclophosphamide to prepare a mouse immunosuppression model.From day 8,the blank control and model groups were gavaged with 0.2 m L of saline,and the dose groups were gavaged with 0.2m L of collagen peptide solution at concentrations of 50 mg/kg,100 mg/kg,and 200 mg/kg per day.The liver,kidney and ovary morphology were observed for 21 consecutive days by gavage,and the body mass,liver,kidney and ovary indices,cytokine and antioxidant levels,as well as intestinal flora and metabolic functions of the mice were measured.The main results were as follows.The collagen extracted from the skin of M.salmoides was analyzed by SDS-PAGE gel electrophoresis,UV and IR spectra,and could be identified as type I collagen.The moisture absorption rate of collagen peptide from M.salmoides skin was 15.85%,and the moisture retention rate could reach 93.45%;the oil absorption capacity reached the maximum value of 3.90m L/g at 40?,and the emulsification property had the maximum value of 88.50%when p H=8,and the emulsification stability could reach 66.00%.APP,NPP,PP and TP all had antioxidant activity,and the antioxidant capacity and the concentration of collagen peptide had a positive correlation,among which APP had the best antioxidant activity with total antioxidant activity and reducing activity of 1.725 and 0.958,respectively,and the maximum scavenging rate of DPPH·and O₂^-·radicals could reach 56.35%and 38.41%.Collagen peptide can reduce liver ALT,AST and kidney BUN and UA levels,and increase ovarian AMH and E₂levels,alleviate the toxicity of cyclophosphamide on liver,kidney and ovary;increase serum levels of cytokines TNF-?,IL₂and secretion of immunoglobulin Ig G;and increase antioxidant levels in mice.The morphological observation showed that collagen peptides could alleviate the damage of cyclophosphamide on liver,kidney and ovary.Collagen peptide mainly affects amino acid metabolism,purine metabolism and other pathways,and regulates the content of amino acids and fatty acids in the intestine of mice;collagen peptide can increase the relative abundance of Bacillus and Bacteriaceae in the intestine of mice.In summary,the collagen peptide of M.salmoides skin has good moisture absorption and moisturizing effect as well as stable emulsification.Among them,APP has better antioxidant activity.Collagen peptide can improve the immunosuppression caused by cyclophosphamide,improve the immunity of the body,and have a certain repair effect on the damage of liver,kidney and ovarian function.And it can regulate the intestinal flora of mice and affect the intestinal metabolic function,thus improving the immunity of mice.