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Article Dans Une Revue Journal of the American Chemical Society Année : 2014

Superior Photoprotective Motifs and Mechanisms in Eumelanins Uncovered

Résumé

Human pigmentation is a complex phenomenon commonly believed to serve a photoprotective function through the generation and strategic localization of black insoluble eumelanin biopolymers in sun exposed areas of the body. Despite compelling biomedical relevance to skin cancer and melanoma, eumelanin photoprotection is still an enigma: What makes this pigment so efficient in dissipating the excess energy brought by harmful UV-light as heat? Why has Nature selected 5,6-dihydroxyindole-2-carboxylic acid (DHICA) as the major building block of the pigment instead of the decarboxylated derivative (DHI)? By using pico- and femtosecond fluorescence spectroscopy we demonstrate herein that the excited state deactivation in DHICA oligomers is 3 orders of magnitude faster compared to DHI oligomers. This drastic effect is attributed to their specific structural patterns enabling multiple pathways of intra- and interunit proton transfer. The discovery that DHICA-based scaffolds specifically confer uniquely robust photoprotective properties to natural eumelanins settles a fundamental gap in the biology of human pigmentation and opens the doorway to attractive advances and applications.

Dates et versions

hal-01074533 , version 1 (14-10-2014)

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Citer

Alice Corani, Annemarie Huijser, Thomas Gustavsson, Dimitra Markovitsi, Per-Åke Malmqvist, et al.. Superior Photoprotective Motifs and Mechanisms in Eumelanins Uncovered. Journal of the American Chemical Society, 2014, 136 (33), pp.11626-11635. ⟨10.1021/ja501499q⟩. ⟨hal-01074533⟩
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