| Photoprotection by porcine eumelanin against singlet oxygen production. | |
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MedLine Citation:
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PMID: 18422874 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Melanin, a major pigment found in retinal pigment epithelium (RPE) cells, is considered to function in dual roles, one protective and one destructive. By quenching free radical species and reactive oxygen species (ROS) melanin counteracts harmful redox stress. However, melanin is also thought to be capable of creating ROS. In this destructive role, melanin increases redox strain in the cell. This study uses readily available eumelanin extracted from porcine RPE cells as a more authentic model than synthetic melanin to determine specific mechanisms of melanin activity with regard to singlet oxygen in the presence and absence of rose bengal, a singlet-oxygen photosensitizer. Optical detection of singlet-oxygen was determined by monitoring the bleaching of p-nitrosodimethylaniline in the presence of histidine. Production of singlet oxygen in aqueous oxygen-saturated solutions of rose bengal without eumelanin was readily accomplished. In contrast, detection of singlet oxygen in oxygen-saturated solutions of eumelanin without rose bengal failed, consistent with results of others. However, a significant decrease in singlet oxygen production by rose bengal was observed in the presence of eumelanin. After correction for light absorption and chemical bleaching of eumelanin, the results show that eumelanin also provides a photoprotective mode arising from chemistry, that is, not just the physical process of light absorption followed by energy dissipation as heat. |
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Authors:
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Alice Wang; Anthony R Marino; Zbigniew Gasyna; Elzbieta Gasyna; James Norris |
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Publication Detail:
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Type: Journal Article Date: 2008-04-12 |
Journal Detail:
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Title: Photochemistry and photobiology Volume: 84 ISSN: 0031-8655 ISO Abbreviation: Photochem. Photobiol. Publication Date: 2008 May-Jun |
Date Detail:
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Created Date: 2008-04-25 Completed Date: 2008-09-11 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0376425 Medline TA: Photochem Photobiol Country: United States |
Other Details:
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Languages: eng Pagination: 679-82 Citation Subset: IM |
Affiliation:
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Department of Chemistry, University of Chicago, Chicago, IL, USA. alicew@uchicago.edu |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Cells, Cultured Dose-Response Relationship, Drug Light Melanins / pharmacology* Nitroso Compounds / metabolism Oxidants / metabolism Photosensitizing Agents / metabolism Pigment Epithelium of Eye / cytology, drug effects*, metabolism* Rose Bengal / metabolism Singlet Oxygen* / antagonists & inhibitors, metabolism Swine |
| Chemical | |
Reg. No./Substance:
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0/Melanins; 0/Nitroso Compounds; 0/Oxidants; 0/Photosensitizing Agents; 11121-48-5/Rose Bengal; 12627-86-0/eumelanin; 138-89-6/4-nitrosodimethylaniline; 17778-80-2/Singlet Oxygen |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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