Study On The Mechanism Of Oligopeptide Compounds Against Skin Aging

Skin aging is a natural physiological process caused by the synergistic effect of endogenous aging and exogenous damage,which is the most visual manifestation of the signs of aging of the body.Endogenous aging is caused by excessive levels of reactive oxygen radicals,dysregulated cell metabolism,accelerated apoptosis,and reduced collagen content;exogenous damage is caused by UV radiation,air pollutants,fungal and bacterial colonization,etc.All of these are important factors that cause skin sagging,wrinkles,and age spots.With the rapid development of various cross-disciplines,researchers have advanced their knowledge of skin aging to the cellular and molecular levels.There is a growing demand for products with anti-skin aging effects,and how to mitigate the process of skin aging has become a hot research topic in the field of anti-aging.In recent years,peptide compounds have received a lot of attention because of their stability and low toxic side effects,and peptide-containing anti-aging agents have emerged,but there is still a lack of scientific evidence on whether they can alleviate skin aging.This thesis investigates the anti-aging effects of HZ peptide,a natural product,at the cellular and molecular levels of the skin,and also investigates its anti-skin aging efficacy and mechanism in combination with zebrafish animal models and human efficacy evaluation.This thesis firstly analyzed the anti-skin aging efficacy of HZ peptide in terms of free radical scavenging,prevention of inflammatory aging caused by bacterial proliferation,cellular biocompatibility,and inhibition of cellular reactive oxygen species accumulation through a series of in vitro models such as biochemical and cellular.Through in vitro biochemical experiments,the scavenging ability of HZ peptide on three kinds of free radicals,DPPH,hydroxyl radical,and superoxide radical,was measured,and the results showed that the peptide has obvious free radical scavenging function and antioxidant effect in vitro;the inhibition ability of HZ peptide on Staphylococcus aureus and Escherichia coli was measured by using inhibition circle method.Then,the toxicity of HZ peptide on human skin fibroblasts（HFF-1）and human immortalized keratin-forming cells（Hacat）was measured by the CCK-8method,and the peptide was determined to be non-toxic;the optimal concentration for cellular senescence modeling using hydrogen peroxide（H₂O₂）was screened and optimized.Then,after treating the cells with DCFH-DA fluorescent dye,the changes of reactive oxygen radicals（ROS）in Hacat cells were tested by flow cytometry,and it was determined that the peptide could effectively inhibit the production of intracellular ROS;finally,the protective effect of HZ peptide on zebrafish caudal fin was measured under the stimulation of UV light,and it was determined that the peptide had better efficacy in removing wrinkles on zebrafish caudal fin.Based on the above efficacy study,the mechanism of anti-skin aging effect of HZ peptide was investigated in depth in this thesis.Firstly,the effect of the HZ peptide on the expression level of type Ⅰ and type Ⅲ collagen in human fibroblasts（HFF-1）was measured,and it was determined that the peptide had a significant up-regulation effect on the expression of both type I and type III collagen genes.We also used Hacat as a model of cellular senescence and flow cytometry to determine the proportion of cells in each apoptotic period,and determined that the peptide could protect cells from damage to a certain extent;we also used western blotting to explore the apoptotic protein pathway,and found that the peptide had a relatively obvious inhibitory effect on the expression of pro-apoptotic proteins;then we used The peptide was then used to construct an inflammation model using bacterial endotoxin（LPS）induced cells to determine the effect of the peptide on the secretion of intracellular pro-inflammatory factors,and it was determined that the peptide had different degrees of regulation on pro-inflammatory cytokines at different action concentrations.Through the above experiments,it was revealed that HZ peptide has the efficacy of reducing skin aging.To verify its efficacy,we designed an HZ peptide anti-aging lotion and evaluated its safety,stability,sensory and human efficacy,etc.It was determined that the lotion meets the safety standard,has good sensory evaluation,and has the efficacy of hydration and moisturizing,improving elasticity,wrinkles,and roughness of skin.In summary,this thesis investigated the efficacy and mechanism of HZ peptide in delaying skin aging and provided a solid scientific basis for the subsequent development of skin care products with anti-aging efficacy based on this compound.