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Oxidative Stress Biology: Melanin UV Shielding vs Phaeomelanin ROS
The paradox of melanin in UV biology is that while eumelanin is photoprotective, phaeomelanin acts as a UV photosensitiser — generating superoxide, hydrogen peroxide, and singlet oxygen upon UV exposure, potentially enhancing DNA oxidative damage (8-oxo-dG — 8
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- The paradox of melanin in UV biology is that while eumelanin is photoprotective, phaeomelanin acts as a UV photosensitiser — generating superoxide, hydrogen peroxide, and singlet oxygen upon UV exposure, potentially enhancing DNA oxidative damage (8-oxo-dG — 8-oxo-2′-deoxyguanosine, measured by immunostaining or HPLC-ECD) and lipid peroxidation. MT-II’s shift from phaeomelanin-dominant to eumelanin-dominant pigmentation in MC1R-variant mice may therefore provide a dual benefit: eumelanin-mediated UV attenuation plus reduction of phaeomelanin-generated ROS.
- Research dissecting these two mechanisms uses: melanin HPLC analysis (AHCA/PTCA chemical degradation markers for eumelanin/phaeomelanin quantification in skin extracts), electron spin resonance (ESR) spectroscopy for direct UV-induced free radical detection in isolated melanin fractions, and intracellular ROS measurement (CM-H₂DCFDA flow cytometry or confocal imaging in primary melanocyte cultures with defined eumelanin/phaeomelanin ratios achieved through MT-II treatment).