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An In Vivo Study of Free Radicals Generated in Murine Skin by Protoporphyrin IX and Visible Light
Author(s) -
Nakai Kozo,
Motten Ann G.,
Chignell Colin F.
Publication year - 2006
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1562/2006-01-30-ra-787
Subject(s) - chemistry , radical , adduct , protoporphyrin ix , electron paramagnetic resonance , photochemistry , photodynamic therapy , in vivo , protoporphyrin , human skin , spin trapping , biochemistry , nuclear magnetic resonance , organic chemistry , porphyrin , biology , physics , microbiology and biotechnology , genetics
Lipids extracted from the skin of C57BL/6J mice injected subcutaneously with α‐(4‐pyridyl‐1‐oxide)‐ N‐tert ‐butylnitrone (POBN) and exposed to topical protoporphyrin IX (PPIX) and visible light had significantly higher levels of POBN spin adducts compared with dark PPIX exposed or vehicle‐treated controls. Computer analysis of the POBN adduct electron paramagnetic (spin) resonance (EPR) spectra indicated that two radical species were present in each extract, one of which was a lipid‐derived carbon‐centered adduct (1, a N = 14.8 G and a H = 2.6 G), whereas the other (2, a N = 13.8 G and a H = 1.8 G) was probably oxygen centered. Adduct 2 was present in greater proportion in lipids extracted from PPIX/light‐exposed mice compared with dark or vehicle‐treated controls. These findings suggest that PPIX/light generates free radicals in mouse skin, thus providing a radical mechanism for PPIX‐induced photosensitivity. Our approach may be useful for the detection of free radicals generated by other skin photosensitizers and may also provide a means for testing putative skin‐protecting agents.