The Study On Protective Effects And Mechanisms Of Tea Water Extracts Against Skin Photoaging

Objective:To prove that tea water extracts can prevent dermis from skin photoaging, and its mechanism will be studied in this paper.Methods:To investigate whether the tea water extracts prevent dermis from skin photoaging, we analyzed the main chemical components of four types of tea water extract(Huangjin tea,Baihaoyinzhen tea,Xinyangmaojian tea,Xinyanghong tea). This research induced cellular damage of HaCaT and L929by ultraviolet B and established the photoaging model, then studied on whether the tea water extracts had the preventive and therapeutic effects on skin photoaging using the index of cell viability, SOD, GSH-Px, LDH and the content of MDA, ROS, Hyp. To investigate protective effect and mechanism of tea water extracts for skin photoaging, we took ICR mice as the experimental object and established the chronic photo-damage model. After being treated with external application to skin photoaging mice, histomorphology, activity of SOD, GSH-Px and content of MDA, Hyp were observed, then the content of MMP-1, MMP-3and TNF-α of mice skin homogenate were detected with ELISA. Also, we extracted RNA of mice skin and tested the expression of MMP-1mRNA,MMP-3mRNA and TNF-α mRNA.Results:①The constitute of maximum content in these four types of tea water extracts was tea polyphenol, and then was free amino acids and alkaloid. The variation range of the concentration of free amino acids was11.87%～14.56%; There was great differences in the content of tea polyphenol (31.956%～70.65%); The maximum content of alkaloid was caffeine with slight difference in these four types of tea (9.68%～11.07%).②The tea water extracts can obviously improve cell viability of HaCaT and L929which were damaged by UVB, and reduce the content of ROS in cell interior. Meanwhile, the tea water extracts increased the activity of SOD and GSH-Px and the content of Hyp in cell culture fluid and reduced activity of LDH and content of MDA.③After being treated with tea water extracts, mice skin photoaging improved obviously and the back skin color of mice was lighter, the desquamation was less, the epidermis thickened slightly. There were little breakage in corium layer fibrous tissue. Scattering phenomeon in the edges of collagen fiber had improved in a certain extent. Moreover, the treatment improved the activity of SOD and GSH-Px in the back tissue of mice, and reduced the content of MDA, increased the content of Hyp, and then reduced the secretion of MMP-1, MMP-3and TNF-a, and also the expression of skin photoaging-related genes in their mRNA levels were lower.Conclusion:Tea water extracts can protect HaCaT and L929cells from the UVB damage, and had preventive and therapeutic effect on chronic photoaging mice model. We speculated that the mechanism was related to the scavenging of oxygen free radical, improvement of antioxidase activity, reduction of lipid peroxidation damage degree, protecting integrality of membranal structural and functional, restraining abnormal secretion matrix metalloproteinase and tumor necrosis factor-α, reducing degradation of collagen or promoting collagen synthesis. This paper researched the protective effect of tea water extracts on the skin photoaging and its possible mechanism, and this study provided certain theory basis for the application of tea to prevent and postpone skin photoaging.