Effect of microwave power on EPR spectra of DOPA-melanin-netilmicin complexes with different drug concentrations – a study at temperatures in the range of 125-275 K

Free radicals in the human organism play an important role during living processes [1]. Free radicals are formed in tissues in natural biological conditions, at pathological stages and also as a result of pharmaceutical interactions or physical factors [1, 7, 9, 26]. The extraordinary high contents of free radicals (~ 1017–1021 spin/g) characterize melanin biopolymers [5, 8, 10, 13, 16–18, 22, 24, 25]. Melanin exists in skin, inner ear, hair, eyes and Substantia nigra [15, 23, 28]. Melanin reveals the susceptibility for interactions with ligands, especially drugs and metal ions. o-Semiquinone free radicals of melanin take part in binding of ligands and as the effect free radicals concentrations change in this polymer [2, 5, 6, 14, 19, 30]. The complexation of drug molecules by melanin changes spin-lattice interactions in the polymer [20, 21, 31, 32]. EPR lines of melanin complexes with drugs and both drugs and metal ions saturate at different microwave powers [14, 32]. These microwave changes of spectroscopic lines reflect the structural modification in melanin complexes with drugs. The aim of this work was to study the effect of microwave power on EPR spectra of DOPA-melanin complexes with netilmicin. We focused on microwave power and temperature effects on the EPR lines of free radicals. The influence of concentration of netilmicin and the measuring temperature on the correlations between the parameters of EPR lines was tested. The model DOPA-melanin was chosen to studies, because Effect of microwave power on EPR spectra of DOPA-melanin-netilmicin complexes with different drug concentrations – a study at temperatures in the range of 125-275 K Magdalena Zdybel, Barbara Pilawa, Ewa Buszman, Dorota Wrześniok, Ryszard Krzyminiewski, Zdzisław Kruczyński