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PHOTOSENSITIZATION OF MELANIN: AN ELECTRON SPIN RESONANCE STUDY OF SENSITIZED RADICAL PRODUCTION AND OXYGEN CONSUMPTION

Authors

  • R. C. Sealy,

    Corresponding author
    1. National Biomedical ESR Center, Department of Radiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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  • T. Sarna,

    1. National Biomedical ESR Center, Department of Radiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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    • On leave from Institute of Molecular Biology, Jagiellonian University, Department of Biophysics, Krakow, Poland.

  • E. J. Wanner,

    1. National Biomedical ESR Center, Department of Radiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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  • K. Reszka

    1. National Biomedical ESR Center, Department of Radiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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    • On leave from Institute of Molecular Biology, Jagiellonian University, Department of Biophysics, Krakow, Poland.


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Abstract

Abstract Rose Bengal is shown to photosensitize free-radical production and oxygen consumption in solutions of melanin from autooxidation of 3,4-dihydroxyphenylalanine (DOPA). In anaerobic solutions the sensitizer enhances rates of free-radical production by up to a factor of 20. In aerobic solutions, rates of oxygen consumption can be increased by a factor of several hundred. The reactions appear to involve the triplet state of the sensitizer. The effect of the sensitizer in increasing oxygen consumption is quenched by low concentrations of azide and enhanced by D2O, suggesting that a singlet oxygen mechanism is involved.

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