Preparation And Biological Activity Of Chicken Skin Collagen Peptide-Zinc Chelate

Zinc is an important nutrient element of human body,which plays a very important role in many physiological and biochemical processes.Zinc cannot be synthesized by human body,and zinc is mainly obtained from diet.The imbalance of zinc homeostasis will lead to abnormal growth and metabolism,including growth retardation,decreased immune function,and difficult wound healing.In addition,recent studies have found that zinc is closely related to the occurrence and development of malignant tumors.Clinical studies have shown that tumor patients are deficient in zinc,and dietary zinc supplementation can help delay the occurrence and development of tumor.Therefore,zinc supplement in diet by taking zinc supplement is widely favored by consumers.However,there are some problems in the organic weak acid zinc supplement on the market,such as low zinc supplement efficiency and adverse reactions after taking it.With the emergence of polypeptide-zinc chelate with polypeptide as ligand,this zinc supplement with the advantages of high zinc supplement efficiency and no adverse reactions has attracted wide attention.Moreover,anti-tumor drugs developed with polypeptides as ligands have attracted wide attention because of their high affinity and high tissue permeability.As the second largest meat consumer goods in China,chicken will produce many by-products,such as chicken skin,chicken bones,chicken lungs and so on.Chicken skin is generally processed into feed or low-end minced meat,The utilization rate is not high,so this topic uses chicken skin by-products produced during broiler processing as raw materials,uses step-by-step double-enzyme hydrolysis of chicken skin to prepare chicken skin collagen peptide(CCP),and then chelates the polypeptide with zinc ions to obtain chicken skin collagen peptide-zinc(CCP-Zn),and further studies its biological activity in vivo.The main research results of this topic are as follows:(1)Through the screening of enzyme species,bromelain and flavor enzyme were selected,and the chicken skin fragments of fat and impurity removal protein were removed by step-by-step double enzyme method.On the basis of single factor experiment,orthogonal test was carried out to optimize the best enzymatic hydrolysis parameters.Under the condition of solid-liquid ratio of 1:10(g/m L),the best conditions of flavor enzyme hydrolysis were as follows: temperature 60 ?,adding enzyme with3 % weight of chicken skin,enzymatic hydrolysis time 4 h;The optimum conditions of bromelain enzymatic hydrolysis were as follows: temperature 55 ?,adding 3 %enzyme from chicken skin and enzymatic hydrolysis time 4 h.The hydrolysis degree of collagen peptide was 25.37 %,and the conversion rate of polypeptide was 55.74 %.By detecting the relative molecular weight and free radical scavenging ability of CCP,it was known that the relative molecular weight of the polypeptide prepared in this study was mainly distributed around 4 KDa,and the IC50 of CCP for scavenging DPPH was37.09 mg/m L,and the IC50 for scavenging OH-was 3.06 mg/m L.(2)Through the response surface optimization experimental design,the optimal conditions for the chelation of chicken skin collagen peptide with zinc were determined as follows: the mass ratio of peptide to zinc was 0.88: 1,the temperature was 43.6 ° C,the time was 42.5 min,and the p H was 6.57.Under these conditions,the chelation rate is 87.8 %.Through infrared spectrum scanning analysis,it is known that zinc ions mainly chelate with carboxyl groups on the polypeptide.(3)By adding 50 M of zinc ion chelator TPEN(N,N,N ',N'-tetrakis(2-pyridyl methyl)ethylenediamine)to the food to construct a zinc-deficient Drosophila model to evaluate the bioavailability of CCP-Zn.The experimental results showed that compared with the Zn SO4 supplementation group,the zinc ion level in the fat body cytoplasm of the zinc-deficient Drosophila larvae in the CCP-Zn supplementation group increased by about 22.9%,and the whole body Mtnb expression level increased significantly.(4)Choosing the malignant tumor model Raf GOFscrib-/-to detect the anti-tumor activity of CCP-Zn in vivo.The effect of CCP-Zn on the phenotype of tumor diseases was observed by adding CCP-Zn to diet.The experimental results show that compared with Zn SO4 and CCP,CCP-Zn can better inhibit tumor growth,indicating that it has higher anti-tumor activity.Further observation of autophagy Atg8 signal of tumor cells and microenvironment shows that under normal dietary conditions,tumor can activate cell autophagy and microenvironment autophagy,and autophagy is accompanied by tumor cell invasion;Dietary addition of CCP-Zn can obviously inhibit the autophagy level of tumor cells and their microenvironment.Moreover,it was found that adding CCP-Zn to diet could reduce the oxidative stress level of tumor Drosophila melanogaster.Therefore,CCP-Zn may inhibit tumor growth and invasion by reducing oxidative stress and autophagy levels in tumor Drosophila melanogaster.To sum up,CCP was prepared and CCP-Zn was prepared on this basis.The bioavailability of Mtnb was analyzed by detecting the expression level of Mtnb in Drosophila melanogaster and the zinc ion level in fat body cytoplasm,and the anti-tumor activity of CCP-Zn was analyzed by detecting the tumor growth,tumor cell invasion and autophagy level of the brain complex of the malignant tumor model Raf GOFscrib-/-.The purpose is to increase the value of chicken skin and provide some reference for the development of polypeptide-zinc supplement and anti-tumor drugs.