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https://www.readbyqxmd.com/read/28614705/a-uv-independent-topical-small-molecule-approach-for-melanin-production-in-human-skin
#1
Nisma Mujahid, Yanke Liang, Ryo Murakami, Hwan Geun Choi, Allison S Dobry, Jinhua Wang, Yusuke Suita, Qing Yu Weng, Jennifer Allouche, Lajos V Kemeny, Andrea L Hermann, Elisabeth M Roider, Nathanael S Gray, David E Fisher
The presence of dark melanin (eumelanin) within human epidermis represents one of the strongest predictors of low skin cancer risk. Topical rescue of eumelanin synthesis, previously achieved in "redhaired" Mc1r-deficient mice, demonstrated significant protection against UV damage. However, application of a topical strategy for human skin pigmentation has not been achieved, largely due to the greater barrier function of human epidermis. Salt-inducible kinase (SIK) has been demonstrated to regulate MITF, the master regulator of pigment gene expression, through its effects on CRTC and CREB activity...
June 13, 2017: Cell Reports
https://www.readbyqxmd.com/read/28570058/elucidating-the-photoprotection-mechanism-of-eumelanin-monomers
#2
Paulami Ghosh, Debashree Ghosh
Eumelanin, the functional polymer in human skin, forms a heterogeneous layered structure intrinsic to its broadband monotonic spectra. The inherent structural heterogeneity of eumelanin makes the photoprocesses very complex and diverse in nature. Due to this diversity, a complete mechanistic picture of these photoprocesses, essential to understanding the photoprotective properties, has been missing to date. In this study, we recreate the potential energy surfaces of the low-lying excited states of the multiple monomeric forms of eumelanin constituents that play a prominent role in either photoprotection or photodamage pathways...
June 9, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28566355/spiders-have-rich-pigmentary-and-structural-colour-palettes
#3
Bor-Kai Hsiung, Nicholas M Justyn, Todd A Blackledge, Matthew D Shawkey
Elucidating the mechanisms of colour production in organisms is important for understanding how selection acts upon a variety of behaviours. Spiders provide many spectacular examples of colours used in courtship, predation, defence and thermoregulation, but are thought to lack many types of pigments common in other animals. Ommochromes, bilins and eumelanin have been identified in spiders, but not carotenoids or melanosomes. Here, we combined optical microscopy, refractive index matching, confocal Raman microspectroscopy and electron microscopy to investigate the basis of several types of colourful patches in spiders...
June 1, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28560094/eumelanin-and-pheomelanin-are-predominant-pigments-in-bumblebee-apidae-bombus-pubescence
#4
Carlo Polidori, Alberto Jorge, Concepción Ornosa
BACKGROUND: Bumblebees (Hymenoptera: Apidae: Bombus) are well known for their important inter- and intra-specific variation in hair (or pubescence) color patterns, but the chemical nature of the pigments associated with these patterns is not fully understood. For example, though melanization is believed to provide darker colors, it still unknown which types of melanin are responsible for each color, and no conclusive data are available for the lighter colors, including white. METHODS: By using dispersive Raman spectroscopy analysis on 12 species/subspecies of bumblebees from seven subgenera, we tested the hypothesis that eumelanin and pheomelanin, the two main melanin types occurring in animals, are largely responsible for bumblebee pubescence coloration...
2017: PeerJ
https://www.readbyqxmd.com/read/28533464/the-colours-of-humanity-the-evolution-of-pigmentation-in-the-human-lineage
#5
REVIEW
Nina G Jablonski, George Chaplin
Humans are a colourful species of primate, with human skin, hair and eye coloration having been influenced by a great variety of evolutionary forces throughout prehistory. Functionally naked skin has been the physical interface between the physical environment and the human body for most of the history of the genus Homo, and hence skin coloration has been under intense natural selection. From an original condition of protective, dark, eumelanin-enriched coloration in early tropical-dwelling Homo and Homo sapiens, loss of melanin pigmentation occurred under natural selection as Homo sapiens dispersed into non-tropical latitudes of Africa and Eurasia...
July 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28510134/paramagnetics-melanin-and-mn-2-in-black-soldier-fly-hermetia-illucens
#6
N A Ushakova, A E Dontsov, A I Bastrakov, N Y Garmash, D S Pavlov
Larva, prepupa (last instar larva), pupa, and an empty shell of pupa after hatching of the black soldier fly Hermetia illucens contain eumelanin, an active synthesis of which is observed at the prepupal stage, which is probably due to the release of prepupa from the feed substrate thickness to the open space for pupation. It was shown for the first time that prepupa contains high quantities of the magnetically active form of manganese Mn(2+). This fact indicates that Mn(2+) stimulates the copper-containing tyrosinase-the key enzyme in the synthesis of melanin in the period of migration and adaptation of the insect to the solar radiation...
March 2017: Doklady. Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28457648/circulating-testosterone-and-feather-gene-expression-of-receptors-and-metabolic-enzymes-in-relation-to-melanin-based-colouration-in-the-barn-owl
#7
Paul Béziers, Anne-Lyse Ducrest, Céline Simon, Alexandre Roulin
Knowledge of how and why secondary sexual characters are associated with sex hormones is important to understand their signalling function. Such a link can occur if i) testosterone participates in the elaboration of sex-traits, ii) the display of an ornament triggers behavioural response in conspecifics that induce a rise in testosterone, or iii) genes implicated in the elaboration of a sex-trait pleiotropically regulate testosterone physiology. To evaluate the origin of the co-variation between melanism and testosterone, we measured this hormone and the expression of enzymes involved in its metabolism in feathers of barn owl (Tyto alba) nestlings at the time of melanogenesis and in adults outside the period of melanogenesis...
April 27, 2017: General and Comparative Endocrinology
https://www.readbyqxmd.com/read/28451292/polydopamine-and-eumelanin-molecular-structures-investigated-with-ab-initio-calculations
#8
Chun-Teh Chen, Francisco J Martin-Martinez, Gang Seob Jung, Markus J Buehler
A set of computational methods that contains a brute-force algorithmic generation of chemical isomers, molecular dynamics (MD) simulations, and density functional theory (DFT) calculations is reported and applied to investigate nearly 3000 probable molecular structures of polydopamine (PDA) and eumelanin. All probable early-polymerized 5,6-dihydroxyindole (DHI) oligomers, ranging from dimers to tetramers, have been systematically analyzed to find the most stable geometry connections as well as to propose a set of molecular models that represents the chemically diverse nature of PDA and eumelanin...
February 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28415485/antimicrobial-activity-of-eumelanin-based-hybrids-the-role-of-tio2-in-modulating-the-structure-and-biological-performance
#9
Giuseppe Vitiello, Alessandro Pezzella, Anna Zanfardino, Brigida Silvestri, Paola Giudicianni, Aniello Costantini, Mario Varcamonti, Francesco Branda, Giuseppina Luciani
Eco-friendly hybrid Eumelanin-TiO2 nanostructures, recently obtained through in situ methodology based on hydrothermal route, have shown a striking antimicrobial activity, after exposure to oxidative environment, even under visible light induction condition. Nevertheless, the role of each component in defining the efficacy of these biological properties is far from being clearly defined. Furthermore, the effect of oxidative step on hybrids structure has not yet addressed. This study aims at elucidating the role of the ratio between eumelanin precursor, 5,6-dihydroxyindole-2-carboxylic acid (DHICA), and TiO2, for its polymerization in defining morphology and structural organization of TiO2-melanin nanostructures...
June 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28378380/re-evaluation-of-insect-melanogenesis-research-views-from-the-dark-side
#10
REVIEW
Miranda M A Whitten, Christopher J Coates
Melanins (eumelanin and pheomelanin) are synthesized in insects for several purposes including cuticle sclerotization and color patterning, clot formation, organogenesis, and innate immunity. Traditional views of insect immunity detail the storage of pro-phenoloxidases inside specialized blood cells (hemocytes) and their release upon recognition of foreign bodies. Activated phenoloxidases convert monophenols into reactive quinones in a two-step enzymatic reaction, and until recently, the mechanism of tyrosine hydroxylation remained a mystery...
July 2017: Pigment Cell & Melanoma Research
https://www.readbyqxmd.com/read/28364123/anomalous-evolution-of-broadband-optical-absorption-reveals-dynamic-solid-state-reorganization-during-eumelanin%C3%A2-build-up-in-thin-films
#11
Carmela Bonavolontà, Corrado de Lisio, Marco d'Ischia, Pasqualino Maddalena, Paola Manini, Alessandro Pezzella, Massimo Valentino
The origin of eumelanin optical properties remains a formidable conundrum preventing a detailed understanding of the complex photo-protective role of these widespread natural pigments and the rational design of innovative bioinspired materials for optoelectronic applications. Here we report the unusual kinetic and thickness-dependent evolution of the optical properties of black eumelanin polymers generated by spontaneous aerial polymerization of 5,6-dihydroxyindole (DHI) thin films (0.1-1 μm), consistent with peculiar solid state reorganization mechanisms governing broadband absorption...
March 31, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28332659/hydration-controlled-anisotropic-and-giant-permittivity-in-teg-functionalized-eumelanin
#12
Marianna Ambrico, Paolo F Ambrico, Teresa Ligonzo, Antonio Cardone, Maria Grazia Bridelli, Giuseppe Casamassima, Paola Manini, Marco d'Ischia
Although it has long been known that the peculiar electronic-ionic conductor behavior of eumelanin is critically dependent on hydration, the detailed mechanisms by which water-polymer interactions control and affect the conduction properties have remained largely obscure. In this paper, we report a remarkable anisotropy and giant polarization effect in a synthetic eumelanin (TEGMe) chemically functionalized with hydrophilic TEG residues. FT-IR analyses of water sorption isotherms and AC measurements were consistent with a microporous structure binding or hosting mainly isolated water molecules...
March 23, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28314098/pathways-for-excited-state-nonradiative-decay-of-5-6-dihydroxyindole-a-building-block-of-eumelanin
#13
Avdhoot Datar, Anirban Hazra
The photophysics of 5,6-dihydroxyindole (DHI) following excitation to its lowest two optically bright states was investigated using the complete active space self-consistent field method with second-order perturbative energy corrections. There is a barrierless pathway for the molecule to relax from the second-lowest bright state (2(1)ππ*) to the lowest bright state (1(1)ππ*). The 1(1)ππ* state has a conical intersection with the optically dark 1(1)πσ* state, which further intersects with the ground state along the NH and OH stretching coordinates...
April 3, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28271633/pheomelanogenesis-is-promoted-at-a-weakly-acidic-ph
#14
Kazumasa Wakamatsu, Ayano Nagao, Miu Watanabe, Kenta Nakao, Shosuke Ito
The diversity of pigmentation in the skin, hair, and eyes of humans has been largely attributed to the diversity of pH in melanosomes with an acidic pH being proposed to suppress melanin production, especially eumelanogenesis. We previously showed that an acidic pH greatly suppresses the late stage of eumelanogenesis after the dopachrome stage. The oxidation of tyrosine by tyrosinase in the presence of cysteine forms cysteinyldopa isomers, which are further oxidized to give rise to pheomelanin via benzothiazine intermediates...
May 2017: Pigment Cell & Melanoma Research
https://www.readbyqxmd.com/read/28240252/novel-quantitative-pigmentation-phenotyping-enhances-genetic-association-epistasis-and-prediction-of-human-eye-colour
#15
Andreas Wollstein, Susan Walsh, Fan Liu, Usha Chakravarthy, Mati Rahu, Johan H Seland, Gisèle Soubrane, Laura Tomazzoli, Fotis Topouzis, Johannes R Vingerling, Jesus Vioque, Stefan Böhringer, Astrid E Fletcher, Manfred Kayser
Success of genetic association and the prediction of phenotypic traits from DNA are known to depend on the accuracy of phenotype characterization, amongst other parameters. To overcome limitations in the characterization of human iris pigmentation, we introduce a fully automated approach that specifies the areal proportions proposed to represent differing pigmentation types, such as pheomelanin, eumelanin, and non-pigmented areas within the iris. We demonstrate the utility of this approach using high-resolution digital eye imagery and genotype data from 12 selected SNPs from over 3000 European samples of seven populations that are part of the EUREYE study...
February 27, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28195487/sequential-proton-coupled-electron-transfer-mediates-excited-state-deactivation-of-a-eumelanin-building-block
#16
Juan J Nogueira, Alice Corani, Amal El Nahhas, Alessandro Pezzella, Marco d'Ischia, Leticia González, Villy Sundström
Skin photoprotection is commonly believed to rely on the photochemistry of 5,6-dihydroxyindole (DHI)- and 5,6-dihydroxyindole-2-carboxylic acid (DHICA)-based eumelanin building blocks. Attempts to elucidate the underlying excited-state relaxation mechanisms have been partly unsuccessful due to the marked instability to oxidation. We report a study of the excited-state deactivation of DHI using steady-state and time-resolved fluorescence accompanied by high-level quantum-chemistry calculations including solvent effects...
February 16, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28181477/eumelanin-releasing-spongy-like-hydrogels-for-skin-re-epithelialization-purposes
#17
Lucília Pereira da Silva, Sílvia Oliveira, Rogério Pirraco, Tírcia Santos, Rui Reis, Alexandra Marques, Vitor Correlo
Melanin function in the skin has been associated to pigmentation but other properties such as electrical conductance, photoprotection, antioxidant and antimicrobial activity, have also been recognized. Nonetheless, the use of melanin in a skin wound healing context was never considered. In this sense, eumelanin particles with a typical round and nano-sized morphology and electrical conductivity of 2.09x10-8S·cm-1 were extracted from the ink of Sepia officinalis. The ability of primary human keratinocytes to phagocyte eumelanin, which was then accumulated in cytosolic vesicles and nuclei surroundings, was demonstrated...
February 9, 2017: Biomedical Materials
https://www.readbyqxmd.com/read/28150707/eumelanin-broadband-absorption-develops-from-aggregation-modulated-chromophore-interactions-under-structural-and-redox-control
#18
Raffaella Micillo, Lucia Panzella, Mariagrazia Iacomino, Giacomo Prampolini, Ivo Cacelli, Alessandro Ferretti, Orlando Crescenzi, Kenzo Koike, Alessandra Napolitano, Marco d'Ischia
Eumelanins, the chief photoprotective pigments in man and mammals, owe their black color to an unusual broadband absorption spectrum whose origin is still a conundrum. Excitonic effects from the interplay of geometric order and disorder in 5,6-dihydroxyindole (DHI)-based oligomeric/polymeric structures play a central role, however the contributions of structural (scaffold-controlled) and redox (π-electron-controlled) disorder have remained uncharted. Herein, we report an integrated experimental-theoretical entry to eumelanin chromophore dynamics based on poly(vinyl alcohol)-controlled polymerization of a large set of 5,6-dihydroxyindoles and related dimers...
February 2, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28132436/the-potent-pro-oxidant-activity-of-rhododendrol-eumelanin-induces-cysteine-depletion-in-b16-melanoma-cells
#19
Shosuke Ito, Masae Okura, Kazumasa Wakamatsu, Toshiharu Yamashita
RS-4-(4-Hydroxyphenyl)-2-butanol (rhododendrol, RD), a skin-whitening agent, is known to induce leukoderma in some people. To explore the mechanism underlying this effect, we previously showed that the oxidation of RD with mushroom or human tyrosinase produces cytotoxic quinone oxidation products. We then examined the metabolism of RD in B16F1 melanoma cells in vitro and detected RD-pheomelanin and RD-quinone bound to non-protein and protein thiols. In this study, we examined the changes in glutathione (GSH) and cysteine in B16 cells exposed to RD for up to 24 h...
January 2017: Pigment Cell & Melanoma Research
https://www.readbyqxmd.com/read/28094871/divergence-of-camp-signaling-pathways-mediating-augmented-nucleotide-excision-repair-and-pigment-induction-in-melanocytes
#20
Erin M Wolf Horrell, Stuart G Jarrett, Katharine M Carter, John A D'Orazio
Loss-of-function melanocortin 1 receptor (MC1R) polymorphisms are common in UV-sensitive fair-skinned individuals and are associated with blunted cAMP second messenger signaling and higher lifetime risk of melanoma because of diminished ability of melanocytes to cope with UV damage. cAMP signaling positions melanocytes to resist UV injury by up-regulating synthesis of UV-blocking eumelanin pigment and by enhancing the repair of UV-induced DNA damage. cAMP enhances melanocyte nucleotide excision repair (NER), the genome maintenance pathway responsible for the removal of mutagenic UV photolesions, through cAMP-activated protein kinase (protein kinase A)-mediated phosphorylation of the ataxia telangiectasia mutated and Rad3 related (ATR) protein on the S435 residue...
January 17, 2017: Experimental Dermatology
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