The effect of oxidative degradation of Dopa-melanin on its basic physicochemical properties and photoreactivity.

Autor: Mokrzyński K; Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland., Żądło A; Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland.; Department of Biophysics, Chair of Physiology, Jagiellonian University Medical College, Krakow, Poland., Szewczyk G; Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland., Sarna M; Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland., Camenisch TG; Department of Biophysics, Medial College of Wisconsin, Milwaukee, Wisconsin, USA., Ito S; Institute for Melanin Chemistry, Fujita Health University, Toyoake, Aichi, Japan., Wakamatsu K; Institute for Melanin Chemistry, Fujita Health University, Toyoake, Aichi, Japan., Sarna T; Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland.
Jazyk: angličtina
Zdroj: Pigment cell & melanoma research [Pigment Cell Melanoma Res] 2024 Nov; Vol. 37 (6), pp. 769-782. Date of Electronic Publication: 2024 May 27.
DOI: 10.1111/pcmr.13176
Abstrakt: Melanin, particularly eumelanin, is commonly viewed as an efficient antioxidant and photoprotective pigment. Nonetheless, the ability of melanin to photogenerate reactive oxygen species and sensitize the formation of cyclobutane pyrimidine dimers may contribute to melanin-dependent phototoxicity. The phototoxic potential of melanin depends on a variety of factors, including molecular composition, redox state, and degree of aggregation. Using complementary spectroscopic and analytical methods we analyzed the physicochemical properties of Dopa-melanin, a synthetic model of eumelanin, subjected to oxidative degradation induced by aerobic photolysis or exposure to 0.1 M hydrogen peroxide. Both modes of oxidative degradation were accompanied by dose-dependent bleaching of melanin and irreversible modifications of its paramagnetic, ion- and electron-exchange and antioxidant properties. Bleached melanin exhibited enhanced efficiency to photogenerate singlet oxygen in both UVA and short-wavelength visible light. Although chemical changes of melanin subunits, including a relative increase of DHICA content and disruption of melanin polymer induced by oxidative degradation were considered, these two mechanisms may not be sufficient for a satisfactory explanation of the elevated photosensitizing ability of the bleached eumelanin. This study points out possible adverse changes in the photoprotective and antioxidant properties of eumelanin that could occur in pigmented tissues after exposure to high doses of intense solar radiation.
(© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)
Databáze: MEDLINE
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