The Protective Role of Melanin Against UV Damage in Human Skin†

Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
Photochemistry and Photobiology (Impact Factor: 2.27). 05/2008; 84(3):539-49. DOI: 10.1111/j.1751-1097.2007.00226.x
Source: PubMed


Human skin is repeatedly exposed to UVR that influences the function and survival of many cell types and is regarded as the main causative factor in the induction of skin cancer. It has been traditionally believed that skin pigmentation is the most important photoprotective factor, as melanin, besides functioning as a broadband UV absorbent, has antioxidant and radical scavenging properties. Besides, many epidemiological studies have shown a lower incidence for skin cancer in individuals with darker skin compared to those with fair skin. Skin pigmentation is of great cultural and cosmetic importance, yet the role of melanin in photoprotection is still controversial. This article outlines the major acute and chronic effects of UVR on human skin, the properties of melanin, the regulation of pigmentation and its effect on skin cancer prevention.

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    • "However, the most widespread function of melanins is colour production. Because melanins strongly absorb light across all visible wavelengths, eumelanins produce many of the dark brown to black colours (Riddle, 1909) and provide UV protection for many organisms (Brenner and Hearing, 2008; Gao and Garcia-Pichel, 2011). Pheomelanins are reddish in isolation and, in combination with eumelanin, produce the vast diversity of melanin-based black to brown colouration seen in animals (Simon and Peles, 2010). "
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    ABSTRACT: Melanin pigments are broadly distributed in nature – from bacteria to fungi to plants and animals. However, many previous attempts to identify melanins in spiders were unsuccessful, suggesting that these otherwise ubiquitous pigments were lost during spider evolution. Yet, spiders exhibit many dark colours similar to those produced by melanins in other organisms, and the low solubility of melanins makes isolation and characterization difficult. Therefore, whether melanins are truly absent or have simply not yet been detected is an open question. Raman spectroscopy provides a reliable way to detect melanins in situ, without the need for isolation. In this study, we document the presence of eumelanin in diverse species of spiders using confocal Raman microspectroscopy. Comparisons of spectra with theoretically calculated data falsify the previous hypothesis that dark colours are produced solely by ommochromes in spiders. Our data indicate that melanins are present in spiders and further supporting that they are present in most living organisms.
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    • "). Overall these studies show a possible role of melanin in promoting UV-induced melanomagenesis. However, previous studies have shown that melanin plays a protective role in UVR mediated skin cancer in dark skinned individuals with eumelanin by shielding against UV radiation, while pheomelanin is harmful by inducing ROS and DNA strand breaks (Chedekel et al., 1978; Takeuchi et al., 2004; Brenner and Hearing, 2008). This raises the question: Is melanin protective or carcinogenic? "

    Full-text · Article · Oct 2015 · Frontiers in Physiology
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    • "Photoprotection of the skin is apparently one of the most important biological functions of melanin pigments. Subjects with white skin are approximately 70 times more likely to develop skin cancer than subjects with black skin, suggesting that higher levels of constitutive pigmentation decrease susceptibility to the deleterious effects of ultraviolet radiation (UVR) (Brenner and Hearing, 2008; Coelho et al., 2009). Usually, black skin and Asian skin contain higher levels of melanin than fair skin (Tadokoro et al., 2003). "
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    ABSTRACT: During the past decade, melanins and melanogenesis have attracted growing interest for a broad range of biomedical and technological applications. The burst of polydopamine-based multifunctional coatings in materials science is just one example, and the list may be expanded to include melanin thin films for organic electronics and bioelectronics, drug delivery systems, functional nanoparticles and biointerfaces, sunscreens, environmental remediation devices. Despite considerable advances, applied research on melanins and melanogenesis is still far from being mature. A closer intersectoral interaction between research centers is essential to raise the interests and increase the awareness of the biomedical, biomaterials science and hi-tech sectors of the manifold opportunities offered by pigment cells and related metabolic pathways. Starting from a survey of biological roles and functions, the present review aims at providing an interdisciplinary perspective of melanin pigments and related pathway with a view to showing how it is possible to translate current knowledge about physical and chemical properties and control mechanisms into new bioinspired solutions for biomedical, dermocosmetic, and technological applications.
    Full-text · Article · Sep 2015 · Pigment Cell & Melanoma Research
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