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https://www.readbyqxmd.com/read/28195487/sequential-proton-coupled-electron-transfer-mediates-excited-state-deactivation-of-a-eumelanin-building-block
#1
Juan J Nogueira, Alice Corani, Amal El Nahhas, Alessandro Pezzella, Marco d'Ischia, Leticia Gonzalez, Villy Sundstrom
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. Herein, 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 14, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28181477/eumelanin-releasing-spongy-like-hydrogels-for-skin-re-epithelialization-purposes
#2
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
#3
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
#4
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
#5
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
https://www.readbyqxmd.com/read/28024137/-secrets-of-the-red-headed
#6
REVIEW
Zygmunt Zdrojewicz, Małgorzata Kowalik, Adam Jagodziński
Only 1-2% of people is red-headed but in the Russian Udmurt Republic or United Kingdom they can be met more often. A specific variant of MC1R gene (R allele) is responsible for the red hair. The gene encodes a receptor for melanocortins. These substances stimulate melanocytes to product melanin- a dye of the skin which is transported to keratinocytes. It protects a cellular nucleus from ultraviolet radiation. Melanin has two types: eumelanin which is dark brown or even black and red/orange pheomelanin. The second one is mostly observed in red-headed which is caused by R allele...
December 22, 2016: Polski Merkuriusz Lekarski: Organ Polskiego Towarzystwa Lekarskiego
https://www.readbyqxmd.com/read/28002950/energetics-of-radical-formation-in-eumelanin-building-blocks-implications-for-understanding-photoprotection-mechanisms-in-eumelanin
#7
Filipe Agapito, Benedito J Costa Cabral
The supramolecular structure of melanin pigments is characterized by a high concentration of radical species. Therefore, the energetics of the radical formation in melanin building blocks is key for understanding the structure and the electronic properties of the pigments at the molecular level. Nevertheless, the radical energetics of even the simplest melanin building blocks are largely unknown. In order to address this fundamental issue, the bond dissociation enthalpies (BDEs) for the melanin monomers 5,6-dihydroxy-1H-indole-2-carboxylic acid (DHICA), 1H-indole-5,6-diol (DHI), and 1H-indole-5,6-dione (IQ) were determined through high-accuracy ab initio quantum chemistry methods...
December 22, 2016: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/27934397/nanoscale-disassembly-and-free-radical-reorganization-of-polydopamine-in-ionic-liquids
#8
Paola Manini, Piero Margari, Christian Pomelli, Paola Franchi, Gennaro Gentile, Alessandra Napolitano, Luca Valgimigli, Cinzia Chiappe, Vincent Ball, Marco d'Ischia
Despite the growing scientific and technological relevance of polydopamine (PDA), a eumelanin-like adhesive material widely used for surface functionalization and coating, knowledge of its structural and physicochemical properties, including in particular the origin of paramagnetic behavior, is still far from being complete. Herein, we disclose the unique ability of ionic liquids (ILs) to disassemble PDA, either as a suspension or as a thin film, up to the nanoscale, and to establish specific interactions with the free radical centers exposed by deaggregation of potential investigative value...
November 23, 2016: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/27904077/synthesis-characterization-and-evaluation-of-thiazolidine-derivatives-of-cysteine-for-suppressing-eumelanin-production
#9
Yusuke Amino, Yoshinobu Takino, Megumi Kaneko, Fumie Ookura, Mai Yamamoto, Tatsuki Kashiwagi, Keiji Iwasaki
In the pathway of melanin biosynthesis, cysteine (Cys) is utilized for the synthesis of pheomelanin. Accordingly, Cys is considered to suppress the formation of brown-black eumelanin. Although attempts have been made to utilize Cys and its derivatives as skin-whitening agents, their instability and odor hinders their application as a cosmetic agent. Herein, N-acetyl-2-methylthiazolidine-2,4-dicarboxylic acid ethyl ester (AcCP2Et) was proposed as a candidate for a stable and prolonged-release derivative of Cys to inhibit dopachrome formation after its degradation in melanocytes...
2016: Chemical & Pharmaceutical Bulletin
https://www.readbyqxmd.com/read/27671997/not-another-type-of-potato-mc1r-and-the-russet-coloration-of-burmese-cats
#10
N A Gustafson, B Gandolfi, L A Lyons
The Burmese is a breed of domestic cat that originated in Southeast Asia and was further developed in the United States. Variants in melanocortin 1 receptor (MC1R) causes common coat colour phenotypes in a variety of mammalian species but only limited colour variation in the domestic cat. Known as the extension (E) locus, melanocortin 1 receptor (MC1R) interacts with the agouti locus to produce the eumelanin and pheomelanin pigments. Recently, a novel reddish coloration, which is termed russet, was identified in the Burmese cat breed...
September 27, 2016: Animal Genetics
https://www.readbyqxmd.com/read/27586929/hydration-effects-on-the-electronic-properties-of-eumelanin-building-blocks
#11
Leonardo Bruno Assis Oliveira, Tertius L Fonseca, Benedito J Costa Cabral, Kaline Coutinho, Sylvio Canuto
Theoretical results for the electronic properties of eumelanin building blocks in the gas phase and water are presented. The building blocks presently investigated include the monomeric species DHI (5,6-dihydroxyindole) or hydroquinone (HQ), DHICA (5,6-dihydroxyindole-2-carboxylic acid), indolequinone (IQ), quinone methide (MQ), two covalently bonded dimers [HM ≡ HQ + MQ and IM ≡ IQ + MQ], and two tetramers [HMIM ≡ HQ + IM, IMIM ≡ IM + IM]. The electronic properties in water were determined by carrying out sequential Monte Carlo/time dependent density functional theory calculations...
August 28, 2016: Journal of Chemical Physics
https://www.readbyqxmd.com/read/27582758/significance-of-the-melanocortin-1-and-endothelin-b-receptors-in-melanocyte-homeostasis-and-prevention-of-sun-induced-genotoxicity
#12
REVIEW
Viki B Swope, Zalfa A Abdel-Malek
The membrane bound melanocortin 1 receptor (MC1R), and the endothelin B receptor (ENDBR) are two G-protein coupled receptors that play important roles in constitutive regulation of melanocytes and their response to ultraviolet radiation (UVR), the main etiological factor for melanoma. The human MC1R is a Gs protein-coupled receptor, which is activated by its agonists α-melanocyte stimulating hormone (α-melanocortin; α-MSH) and adrenocorticotropic hormone (ACTH). The ENDBR is a Gq coupled-receptor, which is activated by Endothelin (ET)-3 during embryonic development, and ET-1 postnatally...
2016: Frontiers in Genetics
https://www.readbyqxmd.com/read/27563719/integration-of-next-generation-sequencing-and-epr-analysis-to-uncover-molecular-mechanism-underlying-shell-color-variation-in-scallops
#13
Xiujun Sun, Zhihong Liu, Liqing Zhou, Biao Wu, Yinghui Dong, Aiguo Yang
The Yesso scallop Patinopecten yessoensis displays polymorphism in shell colors, which is of great interest for the scallop industry. To identify genes involved in the shell coloration, in the present study, we investigate the transcriptome differences by Illumina digital gene expression (DGE) analysis in two extreme color phenotypes, Red and White. Illumina sequencing yields a total of 62,715,364 clean sequence reads, and more than 85% reads are mapped into our previously sequenced transcriptome. There are 25 significantly differentially expressed genes between Red and White scallops...
2016: PloS One
https://www.readbyqxmd.com/read/27505632/aerobic-photoreactivity-of-synthetic-eumelanins-and-pheomelanins-generation-of-singlet-oxygen-and-superoxide-anion
#14
Grzegorz Szewczyk, Andrzej Zadlo, Michal Sarna, Shosuke Ito, Kazumasa Wakamatsu, Tadeusz Sarna
In this work, we examined photoreactivity of synthetic eumelanins, formed by autooxidation of DOPA, or enzymatic oxidation of 5,6-dihydroxyindole-2-carboxylic acid and synthetic pheomelanins obtained by enzymatic oxidation of 5-S-cysteinyldopa or 1:1 mixture of DOPA and cysteine. Electron paramagnetic resonance oximetry and spin trapping were used to measure oxygen consumption and formation of superoxide anion induced by irradiation of melanin with blue light, and time-resolved near-infrared luminescence was employed to determine the photoformation of singlet oxygen between 300 and 600 nm...
November 2016: Pigment Cell & Melanoma Research
https://www.readbyqxmd.com/read/27504344/changing-trends-of-skin-cancer-a-tertiary-care-hospital-study-in-malwa-region-of-punjab
#15
Sonal Tina Lal, Raja Paramjeet Singh Banipal, Deepak John Bhatti, Hanuman Prasad Yadav
INTRODUCTION: Skin cancer constitutes a small but significant proportion of patients with cancer. Although the presence of eumelanin in dark skin is protective against the development of skin cancer, it is increasingly being diagnosed in the Indian population. AIM: To study the profile of skin cancer patients presenting to a tertiary hospital in Malwa area of Punjab, India. MATERIALS AND METHODS: Retrospective study was done to analyse the profile of skin cancer patients who attended the institution over one year from 1(st) December 2013 to 30(th) November 2014...
June 2016: Journal of Clinical and Diagnostic Research: JCDR
https://www.readbyqxmd.com/read/27476599/the-genetics-of-seasonal-migration-and-plumage-color
#16
Kira E Delmore, David P L Toews, Ryan R Germain, Gregory L Owens, Darren E Irwin
Details on the genetics of behavioral and quantitative phenotypes remain limited to a few organisms. Such information is central to understanding both adaptation and speciation, as many of these phenotypes reduce gene flow between taxa [1-3]. Hybrid zones provide an ideal arena for studying this topic, as they consist of recombinant genotypes that allow genetic mapping of traits distinguishing natural populations [4]. We examined the genetic basis of migratory orientation and plumage color, both of which may contribute to speciation, in a hybrid zone between two groups of Swainson's thrushes that differ in these traits...
August 22, 2016: Current Biology: CB
https://www.readbyqxmd.com/read/27459629/clue-to-understanding-the-janus-behavior-of-eumelanin-investigating-the-relationship-between-hierarchical-assembly-structure-of-eumelanin-and-its-photophysical-properties
#17
Kuk-Youn Ju, Jeeun Kang, Jin Ho Chang, Jin-Kyu Lee
The contradictory biological function of eumelanin (photoprotection vs photosensitization) has long been a topic of debate in a wide range of disciplines such as chemistry, physics and biology. For understanding full spectrum of eumelanin's photobiological aspect, revealing how eumelanin's complex structural organization dictates its photophysical properties is critical step. Here, we report a practical approach to controlling the hierarchically assembled structure of natural eumelanin, which leads to disassembly of its structure into subunits and oxidized subunits, respectively...
September 12, 2016: Biomacromolecules
https://www.readbyqxmd.com/read/27426874/non-invasive-quantification-of-melanin-in-the-stratum-corneum-a-novel-indicator-of-skin-lesions-in-pigmentation-diseases
#18
H Matsunaka, Y Yamamoto, F Furukawa
BACKGROUND/PURPOSE: Skin melanin content is an important indicator for ascertaining the pathology of skin pigmentation diseases, but its analysis necessitates a biopsy or other means of collecting tissue, posing a considerable burden to the patient, and making it difficult to observe how a given skin site changes over time. Here, we aimed to establish a non-invasive method for quantifying the eumelanin and pheomelanin content of the stratum corneum. METHODS: Sun-exposed and non-exposed samples from 10 healthy Japanese subjects were compared...
July 18, 2016: Skin Research and Technology
https://www.readbyqxmd.com/read/27367426/identification-of-shell-colour-pigments-in-marine-snails-clanculus-pharaonius-and-c-margaritarius-trochoidea-gastropoda
#19
S T Williams, S Ito, K Wakamatsu, T Goral, N P Edwards, R A Wogelius, T Henkel, L F C de Oliveira, L F Maia, S Strekopytov, T Jeffries, D I Speiser, J T Marsden
Colour and pattern are key traits with important roles in camouflage, warning and attraction. Ideally, in order to begin to understand the evolution and ecology of colour in nature, it is important to identify and, where possible, fully characterise pigments using biochemical methods. The phylum Mollusca includes some of the most beautiful exemplars of biological pigmentation, with the vivid colours of sea shells particularly prized by collectors and scientists alike. Biochemical studies of molluscan shell colour were fairly common in the last century, but few of these studies have been confirmed using modern methods and very few shell pigments have been fully characterised...
2016: PloS One
https://www.readbyqxmd.com/read/27356601/from-tyrosine-to-melanin-signaling-pathways-and-factors-regulating-melanogenesis
#20
Zuzanna Rzepka, Ewa Buszman, Artur Beberok, Dorota Wrześniok
Melanins are natural pigments of skin, hair and eyes and can be classified into two main types: brown to black eumelanin and yellow to reddish-brown pheomelanin. Biosynthesis of melanins takes place in melanosomes, which are specialized cytoplasmic organelles of melanocytes - dendritic cells located in the basal layer of the epidermis, uveal tract of the eye, hair follicles, as well as in the inner ear, central nervous system and heart. Melanogenesis is a multistep process and begins with the conversion of amino acid L-tyrosine to DOPAquinone...
June 30, 2016: Postȩpy Higieny i Medycyny Doświadczalnej
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