Nakai Kozo, Motten Ann G, Chignell Colin F
Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, USA.
Photochem Photobiol. 2006 May-Jun;82(3):738-40. doi: 10.1562/2006-01-30-RA-787.
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.
从皮下注射α-(4-吡啶基-1-氧化物)-N-叔丁基硝酮(POBN)并暴露于局部原卟啉IX(PPIX)和可见光下的C57BL/6J小鼠皮肤中提取的脂质，与暴露于黑暗PPIX或接受载体处理的对照组相比，其POBN自旋加合物水平显著更高。对POBN加合物电子顺磁(自旋)共振(EPR)光谱的计算机分析表明，每种提取物中存在两种自由基物种，其中一种是脂质衍生的以碳为中心的加合物(1，a(N)=14.8 G，a(H)=2.6 G)，而另一种(2，a(N)=13.8 G，a(H)=1.8 G)可能是以氧为中心的。与黑暗或接受载体处理的对照组相比，加合物2在从PPIX/光照小鼠提取的脂质中所占比例更大。这些发现表明，PPIX/光照在小鼠皮肤中产生自由基，从而为PPIX诱导的光敏反应提供了一种自由基机制。我们的方法可能有助于检测其他皮肤光敏剂产生的自由基，也可能提供一种测试假定的皮肤保护剂的方法。
