Study On Uric Acid-reducing Peptide Of Tilapia Skin Collagen

Collagen contains a variety of biologically active peptides,which are naturally non-toxic and have no side effects.The development of bioactive peptides can provide broad prospects for the development of the traditional food industry.In this paper,the extraction of collagen from Nile tilapia skin were optimized orthogonally on the basis of single factor experiments,the best experiment conditions showed that the temperature was 40?,the ratio of solid to liquid was 1:15,the extraction time was14 h,under this condition,the yield was 71.13%.The physicochemical properties of the collagen were studied,it was found that the content of hydroxyproline in collagen is high and the collagen has a good ability to form gels,it is in line with the characteristics of collagen.In addition,the isoelectric point of collagen is in the acidic range,it showed good hydrophilicity,oil absorption,emulsification and emulsification stability,and can be preferably used in dairy products,meat products and other foods that need to retain grease.The optimum conditions for the preparation of collagen peptides of tilapia skin collagen were determined by enzyme screening,single factor experiments and response surface analysis.The amount of complex protease was 3.2%and the enzyme hydrolysis was carried out at pH 8.0 and 48?for 6 h.After being separated by ultrafiltration membrane,DEAE-52Cellulose ion exchange column chromatography,Sephadex G-25 gel filtration and Re-HPLC preparative column,a single peak TP was finally obtained.The IC₅₀0 value of inhibitory activity for xanthine oxidase?XOD?was 3.51 mg/mL.After amino acid sequence analysis,the amino acid sequence of TP was Thr-Ser-Pro-Trp.In vitro cell experiments,it showed that TP had no obvious toxicity to cells at 1.0-10.0mg/mL.When TP reached a certain concentration,it could effectively reduce the uric acid production of the cells.TP was administered to different doses of hyperuricemia model mice.Mouse serum-related indicators,liver function indicators,and kidney function indicators were measured.The results showed that compared with hyperuricemia mice,serum uric acid,creatinine,uric acid nitrogen levels,GOT,and GPT enzyme activity were significantly decreased in TP-treated mice,and the activities of SOD and CAT in liver and kidney tissues were increased,and MDA content was decreased.This showed that TP has the effect of lowering uric acid and has a certain degree of protective effect on the liver and kidney of mice with hyperuricemia.The mechanism of lowering uric acid was studied by measuring serum sex hormone levels,testosterone content in testis and oxidative damage markers,uric acid metabolic enzyme activity in liver tissue,and changes in renal-associated urate transporter protein expression.The experimental results showed that TP can significantly reduce the serum levels of estradiol,luteinizing hormone,testosterone,and follicle-stimulating hormone in mice with hyperuricemia and increase the activity of antioxidant enzyme CAT and SOD in testicular tissues,and reduce the MDA content and liver XOD,ADA activity,thereby reducing the production of uric acid in vivo.Western blot was used to analyze the expression of uric acid transporter protein in the kidney.The results showed that TP can down-regulate the expression of URAT1 protein,reduce uric acid reabsorption,and also promote the excretion of uric acid.