Electron paramagnetic resonance and mass spectrometry: Useful tools to detect ultraviolet light induced skin lesions on a molecular basis – A short review

Abstract

Abstract. Ultraviolet radiation is considered responsible for sunburning, premature skin aging, and cancerogenesis through the production of free radical species. Therefore, the favoured possibility for direct detection of unpaired electrons -electron paramagnetic resonance spectroscopy -is predestinated for detection and structural and dynamic analysis of this kind of molecules. However, many of UV induced radicals in skin have a short lifetime at ambient conditions and possibilities for stabilisation or transformation into definite para-or diamagnetic products have to be found. On the other hand, diamagnetic products, potentially also originated by reporter molecules, which are not detectable by EPR, are target molecules for mass spectrometric analysis. In this review, potentials and limitations of both spectroscopic methods are reviewed, and the effect of ultraviolet radiation on human skin is discussed in particular. Suitable combinations of both techniques result in detailed information about photoproducts and processes taking place within skin during and after irradiation. The literature is viewed from a recent perspective; historical aspects were not in the scope of this paper.

The role of EPR spectroscopy in studies of the oxidative status of biological systems and the antioxidative properties of various compounds

“…Hence, it can be used to stud y the antioxidative activity of some compounds or extracts in the extracellular medium. Hochkirch et al 154 used EPR with Cat 1 to measure the antioxidative capacity of extracellular solu tions in human skin biopsies exposed to UV irradiation. By evaluating the decrease in the EPR signal, they showed that UV light diminishes the activity of antioxidants in the extracellular milieu.…”

ESR imaging investigations of two‐phase systems

“…The spatial resolution of about 10 µm is sufficient to describe the presented model systems and should be applicable to structured biological objects such as human skin. 8,15 The present paper was aimed at investigating the possibilities of ESRI with respect to the lateral diffusion of spin probes in two-phase systems, including the changes in micropolarity and microviscosity in model systems. For the interpretation of the changes in micropolarity, a simple model was developed based on the Nernst distribution law, which can also be applied to other heterogeneous or structured systems such as nanoemulsions, solid lipid nanoparticles, and last but not least to human skin.…”

“…Figure 13 reveals another effect, which is easily recognizable in the tomogram but much weaker in the cw spectra. With increasing concentration of the spin probe 15 N-TEMPO aggregation in the matrix Precirol occurs, causing the broad central line in the tomogram after image reconstruction.…”

“…19 Because of the peculiarities of spectralspatial ESR imaging, weighted averages of the isotropic hyperfine coupling constants in specific layers (slices) are obtained, allowing the establishment of polarity profiles. 15 The rotational correlation times R have been calculated using the algorithm by Budil et al…”