title: EPR persistence measurements of UV-induced melanin free radicals in whole skin.
abstract: Electron paramagnetic resonance is used to detect the formation of free radicals caused by exposure to ultraviolet radiation in chemically untreated rabbit skin. A fast jump in EPR signal level, occurring over a few seconds, is observed immediately after a skin sample is exposed to UV. This is followed by a slower increase toward an elevated steady-state signal over a period of hours as the skin is continuously exposed to a UV light source. Upon cessation of UV light exposure, EPR signal levels undergo an abrupt drop followed by a slower decay toward natural levels. Elevated free radical concentrations following UV exposure are found to persist for several hours in whole skin. These results are consistent with time-resolved EPR measurements of photoinduced radicals in various natural melanins.
authors.affiliation: Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21218, USA.
authors.forename: B
authors.initials: B
authors.lastname: Collins
authors.forename: T O
authors.initials: TO
authors.lastname: Poehler
authors.forename: W A
authors.initials: WA
authors.lastname: Bryden
mesh_terms: D000818:Animals; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000378:metabolism; D008543:Melanins / Q000737:chemistry / Q000378:metabolism* / Q000528:radiation effects*; D011817:Rabbits; D012867:Skin / Q000737:chemistry / Q000378:metabolism* / Q000528:radiation effects*; D014466:Ultraviolet Rays / Q000009:adverse effects*
chemical_list: D005609:Free Radicals; D008543:Melanins