2009 Volume 65 Issue 12 Pages 344-350
For preventing damages on the skin by UV-rays, various UV-cut materials have been developed. In the present study, the authors made a collagen sheet (hereafter "collagen artificial skin") to imitate the human skin on an experimental basis and, after having covered this sheet with a film added with various UV-protecting agents, subjected it artificially to UV-irradiation. Under such condition, the skin protective effect of each kind of UV-cut materials against UV rays was examined, and the various methods to evaluate damages on the sheet caused by UV rays were also reviewed. First, the UV-rays were applied to the collagen artificial skin that was not covered with the film, and the extracts were obtained from the sheet after irradiation. The analysis of the extracts by electrophoresis revealed that the bands of three molecular chains such as alpha-, beta-, and gamma-chains of polypeptides were disappeared under UV-irradiation even only for 15 minutes (UV-Energy : 7.58X104 J/m2, at 310nm). When the irradiation time reached 25 hours (UVEnergy : 7.58X106 J/m2, at 310nm), hydrolysates from the collagen in the sheet started to appear, and when the irradiation time exceeded further 200 hours (UV-Energy : 6.06X107 J/m2, at 310nm), a considerable amount of hydrolysates was recognized. Also it was found that the longer the irradiation time of UV-rays, the higher the concentration of the terminal amino group in the extracts from the collagen was observed. Then, the UV-rays were irradiated to the collagen artificial skin added with various UV-scattering agents. As a result, addition of UV-scattering agents to the film of any of the materials reduced scission of the collagen molecular chains caused by UV-rays, resulting in reduction of the increase of the terminal amino group concentration. From the above results, it was suggested that the use of a collagen artificial skin was one of the effective measures as a method for examining the protective effect against UV-rays.
