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https://www.readbyqxmd.com/read/29439519/biochemical-mechanism-of-rhododendrol-induced-leukoderma
#1
REVIEW
Shosuke Ito, Kazumasa Wakamatsu
-4-(4-hydroxyphenyl)-2-butanol (rhododendrol (RD))-a skin-whitening ingredient-was reported to induce leukoderma in some consumers. We have examined the biochemical basis of the RD-induced leukoderma by elucidating the metabolic fate of RD in the course of tyrosinase-catalyzed oxidation. We found that the oxidation of racemic RD by mushroom tyrosinase rapidly produces RD-quinone, which gives rise to secondary quinone products. Subsequently, we confirmed that human tyrosinase is able to oxidize both enantiomers of RD...
February 12, 2018: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/29402092/characterization-of-natural-photonic-crystals-in-iridescent-wings-of-damselfly-chalcopteryx-rutilans-by-fib-sem-tem-and-tof-sims
#2
David M Carr, Ashley A Ellsworth, Gregory L Fisher, Wescley W Valeriano, Juan P Vasco, Paulo S S Guimarães, Rodrigo R de Andrade, Elizabeth R da Silva, Wagner N Rodrigues
The iridescent wings of the Chalcopterix rutilans damselfly (Rambur) (Odonata, Polythoridae) are investigated with focused ion beam/scanning electron microscopy, transmission electron microscopy, and time-of-flight secondary ion mass spectrometry. The electron microscopy images reveal a natural photonic crystal as the source of the varying colors. The photonic crystal has a consistent number and thickness (∼195 nm) of the repeat units on the ventral side of the wing, which is consistent with the red color visible from the bottom side of the wing in all regions...
February 5, 2018: Biointerphases
https://www.readbyqxmd.com/read/29392956/origins-of-photodamage-in-pheomelanin-constituents-photochemistry-of-4-hydroxybenzothiazole
#3
Tolga N V Karsili, Barbara Marchetti, Spiridoula Matsika
4-Hydroxybenzothiazole (HBT) is a molecular constituent of pheomelanin $-$ a polymeric skin centered pigment which acts as a natural photoprotector against harmful solar-UV radiation. Its molecular structure is therefore required to sustain a degree of photostability upon electronic excitation with UV irradiation. Despite its function as a protector against UV, pheomelanin is known to be less photostable than that of its close derivative eumelanin - a dark skin centered pigment. The HBT subunit has long being attributed as a key contributor to the lack of photostability of pheomelanin - a hypothesis which we aim to test in this manuscript...
February 2, 2018: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/29389007/eumelanin-fe3o4-hybrid-nanoparticles-for-enhanced-mr-pa-imaging-assisted-local-photothermolysis
#4
Junqing Wang, Heng Liu, Yu Liu, Chengchao Chu, Youyuan Yang, Yun Zeng, Weiguo Zhang, Gang Liu
In this work, we report on biodegradable eumelanin-Fe3O4 hybrid nanoparticles (euMel-Fe3O4 NPs) for multiple imaging-assisted local photothermolysis. The euMel-Fe3O4 NPs are rationally prepared via a facile one-step co-precipitation method in the aqueous phase in the presence of eumelanin. The obtained NPs exhibited high stability and aqueous dispersity. euMel-Fe3O4 NPs could provide T2-weighted magnetic resonance (MR) and photoacoustic (PA) imaging contrast enhancement prior to the treatment, due to their high r2 relaxivity that was determined to be 245...
February 1, 2018: Biomaterials Science
https://www.readbyqxmd.com/read/29350885/unexpected-impact-of-esterification-on-the-antioxidant-activity-and-photo-stability-of-a-eumelanin-from-5-6-dihydroxyindole-2-carboxylic-acid
#5
Raffaella Micillo, Mariagrazia Iacomino, Marco Perfetti, Lucia Panzella, Kenzo Koike, Gerardino D'Errico, Marco d'Ischia, Alessandra Napolitano
To inquire into the role of the carboxyl group as determinant of the properties of 5,6-dihydroxyindole melanins, melanins from aerial oxidation of 5,6-dihydroxyindole (DHICA) and its methyl ester MeDHICA were comparatively tested for their antioxidant activity. MALDI MS spectrometry analysis of MeDHICA melanin provided evidence for a collection of intact oligomers. EPR analysis showed g-values almost identical and signal amplitudes (ΔB) comparable to those of DHICA melanin, but spin density was one order of magnitude higher, with a different response to pH changes...
January 19, 2018: Pigment Cell & Melanoma Research
https://www.readbyqxmd.com/read/29331035/noninvasive-optical-spectroscopy-for-identification-of-non-melanoma-skin-cancer-pilot-study
#6
David J Carpenter, Mirabelle B Sajisevi, Nikita Chapurin, Clifford Scott Brown, Tracy Cheng, Gregory M Palmer, Daniel S Stevenson, Caroline L Rao, Russell P Hall, Charles R Woodard
OBJECTIVE: Optical spectroscopy offers a noninvasive alternative to biopsy as a first-line screening tool for suspicious skin lesions. This study sought to define several optical parameters across malignant and benign tissue types. STUDY DESIGN: Prospective pilot trial utilizing the Zenalux IM1 optical spectroscopy device from April 2016 to February 2017. For each skin lesion, provider pre-biopsy probability of malignancy was compared to histolopathologic diagnosis...
January 13, 2018: Lasers in Surgery and Medicine
https://www.readbyqxmd.com/read/29225224/characterization-of-melanin-radicals-in-paraffin-embedded-malignant-melanoma-and-nevus-pigmentosus-using-x-band-epr-and-epr-imaging
#7
Kouichi Nakagawa, Satoko Minakawa, Daisuke Sawamura, Hideyuki Hara
Continuous wave electron paramagnetic resonance (CW EPR) and X-band (9 GHz) EPR imaging (EPRI) were used to nondestructively investigate the possible differentiation between malignant melanoma (MM) and nevus pigmentosus (NP) melanin radicals in paraffin-embedded specimens. The EPR spectra of both samples were analyzed using linewidth, spectral pattern, and X-band EPRI. The CW-EPR spectra of the MM showed an additional signal overlap. Eumelanin- and pheomelanin-related radicals were observed in the MM specimens...
2017: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
https://www.readbyqxmd.com/read/29219041/potential-causative-mutation-for-melanism-in-rats-identified-in-the-agouti-signaling-protein-gene-asip-of-the-rattus-rattus-species-complex-on-okinawa-island-japan
#8
Shoichi Sasamori, Andrew S Wiewel, Vicki A Thomson, Motoko Kobayashi, Katsushi Nakata, Hitoshi Suzuki
The occurrence of black fur, or melanism, in many mammalian species is known to be linked to DNA sequence variation in the agouti signaling protein (Asip) gene, which is a major determinant of eumelanin and pheomelanin pigments in coat color. We investigated 38 agouti (i.e., banded wildtype) and four melanistic Rattus rattus species complex (RrC) lineage II specimens from Okinawa Island, Ryukyu Islands, Japan, for genetic variation in three exons and associated flanking regions in the Asip gene. On Okinawa, a predicted loss-of-function mutation caused by a cysteine to serine amino acid change at p...
December 2017: Zoological Science
https://www.readbyqxmd.com/read/29211110/evaluation-of-melanin-production-by-sporothrix-luriei
#9
Ingrid Ludmilla Rodrigues Cruz, Maria Helena Galdino Figueiredo-Carvalho, Rosely Maria Zancopé-Oliveira, Rodrigo Almeida-Paes
There is a paucity of studies on the cell biology of Sporothrix luriei, the less common of the pathogenic Sporothrix species worldwide. The production of DHN-melanin, eumelanin, and pyomelanin were evaluated on the mycelial and yeast forms of the S. luriei ATCC 18616 strain. The mycelial form of this species produced only pyomelanin, which protected the fungus against environmental stressors such as ultraviolet light, heat, and cold. The yeast form was unable to produce any of the tested melanin types. The lack of melanin in the parasitic form of S...
January 2018: Memórias do Instituto Oswaldo Cruz
https://www.readbyqxmd.com/read/29179286/-decolorization-of-skin-and-hair-derived-melanin-by-three-ligninolytic-enzymes
#10
F Miao, T C Lei, M Y Su, W J Yi, S Jiang, S Z Xu
Objective: To compare the decolorization efficiency of lignin peroxidase (LiP), manganese peroxidase (MnP) and laccase on eumelanin and pheomelanin, and to investigate the effect of topical administration of LiP solution on hyperpigmented guinea pigs skin induced by 308 nm excimer light. Methods: Pheomelanin-enriched specimens were prepared from human hair and cutaneous melanoma tissue using alkaline lysis method.Synthetic eumelanin was purchased from a commercial supplier.The same amount (0.02%) of melanin was incubated with the equal enzyme activity (0...
November 21, 2017: Zhonghua Yi Xue za Zhi [Chinese medical journal]
https://www.readbyqxmd.com/read/29171182/acid-hydrolysis-reveals-a-low-but-constant-level-of-pheomelanin-in-human-black-to-brown-hair
#11
Shosuke Ito, Shiho Miyake, Shoji Maruyama, Itaru Suzuki, Stéphane Commo, Yukiko Nakanishi, Kazumasa Wakamatsu
We previously reported a constant ratio of the benzothiazole-pheomelanin marker thiazole-2,4,5-tricarboxylic acid (TTCA) to the eumelanin marker pyrrole-2,3,5-tricaboxylic acid (PTCA) in eumelanic, black human hair. A constant level (20-25%) of benzothiazole-type pheomelanin was recently demonstrated in human skin with varying concentrations of melanin. Therefore, in this study, we aimed to investigate the origin of pheomelanin markers in black to brown human hair by developing a method to remove protein components from hair by heating with 6 M HCl at 110°C for 16 h...
November 24, 2017: Pigment Cell & Melanoma Research
https://www.readbyqxmd.com/read/29160957/insect-cuticular-melanins-are-distinctly-different-from-those-of-mammalian-epidermal-melanins
#12
Hanine Barek, Manickam Sugumaran, Shosuke Ito, Kazumasa Wakamatsu
Melanin from several insect samples was isolated and subjected to chemical degradation and HPLC analysis for melanin markers. Quantification of different melanin markers reveals that insect melanins are significantly different from that of the mammalian epidermal melanins. The eumelanin produced in mammals is derived from the oxidative polymerization of both 5,6-dihydroxyindole and 5,6-dihydroxyindole-2-carboxylic acids. The pheomelanin is formed by the oxidative polymerization of cysteinyldopa. Thus, dopa is the major precursor for both eumelanin and pheomelanin in mammals...
November 21, 2017: Pigment Cell & Melanoma Research
https://www.readbyqxmd.com/read/29124869/polydopamine-based-colloidal-materials-synthesis-and-applications
#13
REVIEW
Ziwei Deng, Bin Shang, Bo Peng
Polydopamine is a synthetic analogue of natural melanin (eumelanin) produced from oxidative polymerization of dopamine. Owing to its strong adhesion ability, versatile chemical reactivity, biocompatibility and biodegradation, polydopamine is commonly applied as a versatile linker to synthesize colloidal materials with diverse structures, unique physicochemical properties and tunable functions, which allow for a broad scope of applications including biomedicine, sensing, catalysis, environment and energy. In this personal account, we discuss first about the different synthetic approaches of polydopamine, as well as its polymerization mechanism, and then with a comprehensive overview of recent progress in the synthesis and applications of polydopamine-based colloidal materials...
November 10, 2017: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
https://www.readbyqxmd.com/read/29124695/photodermatoses-in-the-pigmented-skin
#14
Vinod Kumar Sharma, Kanika Sahni
Skin colour (specifically in relation to its melanin content and composition) has a marked influence on its interaction with ultraviolet light. Eumelanin has mainly photoprotective properties while pheomelanin has the ability to cause formation of reactive oxygen species. This difference is responsible for the difference in incidence and presentation of various idiopathic photodermatoses in dark skinned patients compared to those with lighter skin types. Certain conditions are peculiar to darker skins including pin point popular variant of polymorphous light eruption...
2017: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/29083852/eumelanin-coated-pla-electrospun-micro-fibers-as-bio-inspired-cradle-for-sh-sy5y-neuroblastoma-cells-growth-and-maturation
#15
Ines Fasolino, Irene Bonadies, Luigi Ambrosio, Maria Grazia Raucci, Cosimo Carfagna, Federica Maria Caso, Francesca Cimino, Alessandro Pezzella
Within the framework of neurodegenerative disorder therapies, the fabrication of 3D eumelanin architectures represents a novel strategy to realize tissue-engineering scaffolds for neuronal cell growth and control by providing both mechanical support and biological signals. Here, an appropriate procedure combining electrospinning, spin coating and solid-state polymerization process is established to realize the scaffolds. For biological analysis, a human derived cell line SH-SY5Y from neuroblastoma is used. Cell maturation on eumelanin microfibers, random and aligned, is evaluated by using confocal analysis and specific markers of differentiating neurons (βIII tubulin and GAP-43 expression)...
October 30, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29051758/identification-of-yfih-and-the-catalase-cata-as-polyphenol-oxidases-of-aeromonas-media-and-cata-as-a-regulator-of-pigmentation-by-its-peroxyl-radical-scavenging-capacity
#16
Baozhong Chai, Yunqian Qiao, He Wang, Xiaoming Zhang, Jiao Wang, Choushi Wang, Ping Zhou, Xiangdong Chen
Pyomelanin is the major constituent of pigment in melanogenic Aeromonas strains of bacteria. However, eumelanin, synthesized from tyrosine via L-DOPA and polyphenol oxidases (PPOs), may also be present in this genus since L-DOPA is frequently detected in culture fluids of several species. To address this question, we used a deletion mutant of Aeromonas media strain WS, in which pyomelanin synthesis is completely blocked under normal culture conditions. When tyrosine was supplied to the medium, we observed residual melanin accumulation, which we interpret as evidence for existence of the DOPA-melanin pathway...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/29044987/sticky-fingers-at-work-palmitoylation-dependent-mc1r-activation
#17
Jose Carlos Garcia-Borron, Celia Jimenez-Cervantes
No abstract text is available yet for this article.
October 17, 2017: Pigment Cell & Melanoma Research
https://www.readbyqxmd.com/read/29039817/replacing-nitrogen-by-sulfur-from-structurally-disordered-eumelanins-to-regioregular-thiomelanin-polymers
#18
Mariagrazia Iacomino, Juan Mancebo-Aracil, Mireia Guardingo, Raquel Martín, Gerardino D'Errico, Marco Perfetti, Paola Manini, Orlando Crescenzi, Félix Busqué, Alessandra Napolitano, Marco d'Ischia, Josep Sedó, Daniel Ruiz-Molina
The oxidative polymerization of 5,6-dihydroxybenzothiophene (DHBT), the sulfur analog of the key eumelanin building block 5,6-dihydroxyindole (DHI), was investigated to probe the role of nitrogen in eumelanin build-up and properties. Unlike DHI, which gives a typical black insoluble eumelanin polymer on oxidation, DHBT is converted to a grayish amorphous solid (referred to as thiomelanin) with visible absorption and electron paramagnetic resonance properties different from those of DHI melanin. Mass spectrometry experiments revealed gradational mixtures of oligomers up to the decamer level...
October 17, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/29022703/probing-the-eumelanin-silica-interface-in-chemically-engineered-bulk-hybrid-nanoparticles-for-targeted-subcellular-antioxidant-protection
#19
Brigida Silvestri, Giuseppe Vitiello, Giuseppina Luciani, Vincenzo Calcagno, Aniello Costantini, Maria Gallo, Silvia Parisi, Simona Paladino, Mariagrazia Iacomino, Gerardino D'Errico, M Federica Caso, Alessandro Pezzella, Marco d'Ischia
We disclose herein the first example of stable monodispersed hybrid nanoparticles (termed MelaSil-NPs) made up of eumelanin biopolymer intimately integrated into a silica nanoscaffold matrix and endowed with high antioxidant and cytoprotective effects associated with a specific subcellular localization. MelaSil-NPs have been fabricated by an optimized sol-gel methodology involving ammonia-induced oxidative polymerization of a covalent conjugate of the eumelanin building block 5,6-dihydroxyindole-2-carboxylic acid (DHICA) with 3-aminopropyltriethoxysilanes (APTS)...
October 23, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28937213/structural-basis-of-polydopamine-film-formation-probing-5-6-dihydroxyindole-based-eumelanin-type-units-and-the-porphyrin-issue
#20
Maria L Alfieri, Raffaella Micillo, Lucia Panzella, Orlando Crescenzi, Stefano L Oscurato, Pasqualino Maddalena, Alessandra Napolitano, Vincent Ball, Marco d'Ischia
The role of 5,6-dihydroxyindole (DHI)-based oligomers, including porphyrin-like tetramers, in polydopamine (PDA) film formation was addressed by a comparative structural investigation against model polymers from DHI and its 2,7'-dimer. MALDI-MS data showed that (a) PDA is structurally different from DHI melanin and does not contain species compatible with DHI-based oligomers as primary building blocks; (b) PDA films and precipitate display a single main peak at m/z 402 in common; (c) no species matching the range of m/z values expected for cyclic porphyrin-type tetramers was detected in DHI melanin produced in the presence or in the absence of folic acid (FA) as templating agent, nor by oxidation of the 2,7'-dimer of DHI as putative precursor...
September 29, 2017: ACS Applied Materials & Interfaces
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