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. 2006 May-Jun;82(3):738-40.
doi: 10.1562/2006-01-30-RA-787.

An in vivo study of free radicals generated in murine skin by protoporphyrin IX and visible light

Kozo Nakai  1 , Ann G Motten, Colin F Chignell
Affiliations

An in vivo study of free radicals generated in murine skin by protoporphyrin IX and visible light

Kozo Nakai et al. Photochem Photobiol. 2006 May-Jun.

Abstract

Lipids extracted from the skin of C57BL/6J mice injected subcutaneously with alpha-(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.

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Figures

Figure 1
Figure 1
The integrated EPR intensities of skin lipids extracted from mice injected subcutaneously with POBN and treated topically with PPIX dissolved in 50% aqueous acetone or vehicle alone, followed by exposure to visible light (see Methods). Results are the mean ± standard error of data from six mice.
Figure 2
Figure 2
Typical EPR spectra of skin lipids extracted from mice injected subcutaneously with POBN and treated topically with PPIX dissolved in 50% aqueous acetone or vehicle alone, followed by exposure to visible light (see Methods).
See this image and copyright information in PMC

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