detection and identification of free radicals generated by UV and visible light in ex vivo human skin / Leonhard Zastrow in IFSCC MAGAZINE, Vol. 11, N° 3 (07-08/2008)

[article]  inIFSCC MAGAZINE > Vol. 11, N° 3 (07-08/2008) . - p. 207-215 Titre : detection and identification of free radicals generated by UV and visible light in ex vivo human skin Type de document : texte imprimé Auteurs : Leonhard Zastrow, Auteur ; Norbert Groth, Auteur ; Frank Klein, Auteur ; Dieter Kockott, Auteur ; Jürgen Lademann, Auteur ; Louis Ferrero, Auteur Année de publication : 2008 Article en page(s) : p. 207-215 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Peau Peau -- Effet du rayonnement ultraviolet Peau -- Effets du rayonnement solaire Radicaux libres (chimie) Rayonnement ultraviolet -- Effets physiologiques Résonance paramagnétique électronique Simulation, Méthode de Index. décimale : 668.5 Parfums et cosmétiques Résumé : Contrary to the skin biological end points used for determination of the sun protection factor and UVA protection factor, generation of excess free radicals in skin mainly reactive oxygen species is potentially the source of much skin damage and soo represents a more general biophysical answer to the effects of sun exposure of different wavelengths. By applying electron spin resonance spectroscopy to human skin biopsies, we determined in previous work a free radical action spectrum covering the ultraviolet and visible light range. Convolution of the action spectrum with sunlight spectral irradiance (280nm-700nm) showed the importance of visible light in free radical generation. This unexpected finding led us to perform further investigations. Firstly, an existing sun simulator was modified so that its outputtruly mimics the sun's full spectrum, including visible light. Human skin biopsies were irradiated either by this device or a conventional UV source, confirming our previous calculations : half of the free radicals are generated in the 400-700nm visible wavelength range. Secondly, the visible spectrum of the modified sun simulator was divided into narrow-band lights using different pairs of short and long pass-filters. Human skin biopsies impregnated with specific spin traps were exposed to the different narrow-band lights in order to identify different types of free radicals. Generation of dangerous radical species like O2, OH and CH-R was observed in different parts of the visible range, confirming the relevance of the free racial action spectrum and its ability to predict skin protection. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3807 [article]

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In-vivo measurements of free radicals in human skin / Leonhard Zastrow in IFSCC MAGAZINE, Vol. 6, N° 4 (10-11-12/2003)

[article]  inIFSCC MAGAZINE > Vol. 6, N° 4 (10-11-12/2003) . - p. 295-301 Titre : In-vivo measurements of free radicals in human skin Type de document : texte imprimé Auteurs : Leonhard Zastrow, Auteur ; Thomas Herrling, Auteur ; Lawrence J. Berliner, Auteur ; Louis Ferrero, Auteur ; Norbert Groth, Auteur Année de publication : 2003 Article en page(s) : p. 295-301 Note générale : Bibliogr. Langues : Anglais (eng) Tags : 'Radicaux  libres'  Résonance  spin  électronique'  'Nitroxide  étiquette  par  rotation'  'Irradiation  UVA-UVB' Index. décimale : 668.5 Parfums et cosmétiques Résumé : UVA-UVB generated free radicals in human skin were measured by Electron Spin Resonance (ESR) spectroscopy and imaging. The short lifetime of the generated free radicals and reactive oxygen species like •OH−; O2-• and L• demands the application of spin traps (nitroxide spin labels) for scavenging and accumulating to get a sufficient Signal-to-Noise ratio. The ESR spectroscopy and imaging measurements showed that the free radicals in skin were mainly generated in the dermal layer by UVA. Using ESR measurements, the protective effect of different UVB-UVA filter combinations and antioxidants in the skin could be clearly assessed. The used microwave frequencies of 9.5 GHz (λ=350-600 nm) and 3 GHz (λ=9.5 nm) enabled an undisturbed investigation of the whole skin up to the lower dermis in contrast to optical detection methods that are more limited in depth (λ=350-600 nm). ESR spectroscopy is a valuable method for the evaluation of the UV-protection capacity of sunscreen products. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=10552 [article]

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