UVA‐induced oxidative degradation of melanins: fission of indole moiety in eumelanin and conversion to benzothiazole moiety in pheomelanin

Wakamatsu, Kazumasa; Nakanishi, Yusuke; Miyazaki, Nobuyuki; Kolbe, Ludger; Ito, Shosuke

doi:10.1111/j.1755-148x.2012.01011.x

Cited by 80 publications

(132 citation statements)

References 47 publications

(49 reference statements)

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“…Eumelanin in particular is thought to be photoprotective. 34 Persons with fair skin have few melanosomes, which is associated with increased susceptibility to the damaging effects of ultraviolet radiation. 35 Persons with light-colored irises have less melanin, especially eumelanin.…”

Section: Discussionmentioning

confidence: 99%

Sunlight Exposure, Pigmentation, and Incident Age-Related Macular Degeneration

Klein

Howard

Iyengar

et al. 2014

Invest. Ophthalmol. Vis. Sci.

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Section: Discussionmentioning

confidence: 99%

Sunlight Exposure, Pigmentation, and Incident Age-Related Macular Degeneration

Klein

Howard

Iyengar

et al. 2014

Invest. Ophthalmol. Vis. Sci.

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“…These are lipophilic and are therefore potentially able to enter the nucleus. In addition, melanin polymer rapidly solubilizes when exposed to hydrogen peroxide [43] and its degradation by peroxidation or UV-photoionization had been proposed to involve dioxetane and triplet carbonyls [44, 45]. …”

Section: Melanin As a Molecular Shuttlementioning

confidence: 99%

Chemical excitation of electrons: A dark path to melanoma

Premi

Brash

2016

DNA Repair

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Sunlight’s ultraviolet wavelengths induce cyclobutane pyrimidine dimers (CPDs), which then cause mutations that lead to melanoma or to cancers of skin keratinocytes. In pigmented melanocytes, we found that CPDs arise both instantaneously and for hours after UV exposure ends. Remarkably, the CPDs arising in the dark originate by a novel pathway that resembles bioluminescence but does not end in light: First, UV activates the enzymes nitric oxide synthase (NOS) and NADPH oxidase (NOX), which generate the radicals nitric oxide (NO•) and superoxide (O2•−); these combine to form the powerful oxidant peroxynitrite (ONOO−). A fragment of the skin pigment melanin is then oxidized, exciting an electron to an energy level so high that it is rarely seen in biology. This process of chemically exciting electrons, termed “chemiexcitation”, is used by fireflies to generate light but it had never been seen in mammalian cells. In melanocytes, the energy transfers radiationlessly to DNA, inducing CPDs. Chemiexcitation is a new source of genome instability, and it calls attention to endogenous mechanisms of genome maintenance that prevent electronic excitation or dissipate the energy of excited states. Chemiexcitation may also trigger pathogenesis in internal tissues because the same chemistry should arise wherever superoxide and nitric oxide arise near cells that contain melanin.

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“…of deionized water), then analyzed for absorbance at 560 nm to determine the total melanin content. After the mixtures were incubated overnight at 70°C and centrifuged at 14,000 rpm to remove residual solids, absorbances of the supernatant at 560 nm were measured [20][21][22][23]. Standard curves of hydrolyzed Sepia melanin were constructed using 0, 0.1, 0.2, 0.5 and 1 mg ml -1 acid-hydrolyzed melanin.…”

Section: Melanin-like Pigment Characterization and Quantificationmentioning

confidence: 99%

Marine hydroid perisarc: A chitin- and melanin-reinforced composite with DOPA–iron(III) complexes

et al. 2013

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a b s t r a c tMany marine invertebrates utilize biomacromolecules as building blocks to form their load-bearing tissues. These polymeric tissues are appealing for their unusual physical and mechanical properties, including high hardness and stiffness, toughness and low density. Here, a marine hydroid perisarc of Aglaophenia latirostris was investigated to understand how nature designs a stiff, tough and lightweight sheathing structure. Chitin, protein and a melanin-like pigment, were found to represent 10, 17 and 60 wt.% of the perisarc, respectively. Interestingly, similar to the adhesive and coating of marine mussel byssus, a DOPA (3,4-dihydroxyphenylalanine) containing protein and iron were detected in the perisarc. Resonance Raman microprobe analysis of perisarc indicates the presence of catechol-iron(III) complexes in situ, but it remains to be determined whether the DOPA-iron(III) interaction plays a cohesive role in holding the protein, chitin and melanin networks together.

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UVA‐induced oxidative degradation of melanins: fission of indole moiety in eumelanin and conversion to benzothiazole moiety in pheomelanin

Cited by 80 publications

References 47 publications

Sunlight Exposure, Pigmentation, and Incident Age-Related Macular Degeneration

Sunlight Exposure, Pigmentation, and Incident Age-Related Macular Degeneration

Chemical excitation of electrons: A dark path to melanoma

Marine hydroid perisarc: A chitin- and melanin-reinforced composite with DOPA–iron(III) complexes

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