Krystian Mokrzyński, Andrzej Żądło, Grzegorz Szewczyk, Michal Sarna, Theodore G. Camenisch, Shosuke Ito, Kazumasa Wakamatsu, Tadeusz Sarna
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引用次数: 0
Abstract
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.
期刊介绍:
Pigment Cell & Melanoma Researchpublishes manuscripts on all aspects of pigment cells including development, cell and molecular biology, genetics, diseases of pigment cells including melanoma. Papers that provide insights into the causes and progression of melanoma including the process of metastasis and invasion, proliferation, senescence, apoptosis or gene regulation are especially welcome, as are papers that use the melanocyte system to answer questions of general biological relevance. Papers that are purely descriptive or make only minor advances to our knowledge of pigment cells or melanoma in particular are not suitable for this journal. Keywords
Pigment Cell & Melanoma Research, cell biology, melatonin, biochemistry, chemistry, comparative biology, dermatology, developmental biology, genetics, hormones, intracellular signalling, melanoma, molecular biology, ocular and extracutaneous melanin, pharmacology, photobiology, physics, pigmentary disorders