Location of anthralin radical generation in mouse skin by UV-A irradiation: an estimation using microscopic EPR spectral-spatial imaging.

In vivo location of the anthralin radical generated in mouse skin by ultraviolet A (UV-A) irradiation was estimated by microscopic electron paramagnetic resonance (EPR) spectral-spatial imaging. An X-band EPR spectrometer equipped with specially designed high-power imaging coils and a TE-mode cavity was employed. The maximum field gradient used in this study was 6.77 mT/mm. Anthralin was applied to the dorsal skin of live mice, which were then exposed to UV-A irradiation. A broad singlet EPR spectrum (peak-to-peak line width = 0.6 mT and g = 2.004) was obtained. Microscopic EPR spectral-spatial imaging of the skin tissue showed that the anthralin radical was located mainly in the epidermis (27 microm from the skin surface). This result was consistent with the finding that the proportions of the radical in the dermis and epidermis were about 15% and 85%, respectively. Published 2006 Wiley-Liss, Inc.