eumelanin

Research on new ingredients that can prevent excessive melanin production in the skin while considering efficacy, safety but also environmental impact is of great importance to significantly improve the profile of existing actives on the market and avoid undesirable side effects. Here, the discovery of an innovative technology for the management of hyperpigmentation is described. High-throughput screening tests on a wide chemical diversity of molecules and in silico predictive methodologies were essential to design an original thiopyridinone backbone and select 2-mercaptonicotinoyl glycine (2-MNG) as exhibiting the most favorable balance between the impact on water footprint, skin penetration potential and performance...

Eumelanins play a crucial role as photoprotective agents for living organisms, yet the nature of the stationary and transient species involved in the light absorption and deactivation processes remains controversial. Moreover, the critical sub-100 fs time scale, which is key to the characterization of the primary excited species, has remained unexplored. Here, we study the eumelanin analogue polydopamine (PDA) and employ a combination of steady-state and transient optical spectroscopies to reveal the presence of spectrally broad coupled electronic transitions with, at least partial, charge-transfer (CT) character...

We report the room temperature phosphorescence upon iodination on a crystalline eumelanin monomer with shielded hydroxyl moieties, ethyl 5,6-dimethoxyindole-2-carboxylate (DMICE). Ultrafast intersystem crossing (ISC) is observed in the iodinated (IDMICE) as well as brominated (BDMICE) analogues of the eumelanin monomer derivative in solution. The triplet quantum yields (ϕT) and intersystem crossing rates (kISC) of the halogenated eumelanin derivatives are 𝜙𝐵𝐷𝑀𝐼𝐶𝐸𝑇 =25...

Although the evolutionary ecology of melanin pigments and melanin-based coloration has been studied in great details, particularly in birds, little is known about the function of melanin stored inside the body. In the barn owl Tyto alba , in which individuals vary in the degree of reddish pheomelanin-based coloration and in the size of black eumelanic feather spots, we measured the concentration in melanin pigments in seven organs. The eyes had by far the most melanin then the skin, pectoral muscle, heart, liver, trachea, and uropygial gland...

In the current years, polydopamine nanoparticles (PDA NPs) have been extensively investigated as an eumelanin mimic. However, unlike natural eumelanin, PDA NPs contain no 5,6-dihydroxyindole-2-carboxylic acid (DHICA)-derived units and may be limited in certain intrinsic properties; superior eumelanin-like nanomaterials are still actively being sought. Levodopa ( l -DOPA) is a natural eumelanin precursor and expected to convert into DHICA and further remain within the final product through covalent or physical interactions...

Defect centers in a nanodiamond (ND) allow the detection of tiny magnetic fields in their direct surroundings, rendering them as an emerging tool for nanoscale sensing applications. Eumelanin, an abundant pigment, plays an important role in biology and material science. Here, for the first time, we evaluate the comproportionation reaction in eumelanin by detecting and quantifying semiquinone radicals through the nitrogen-vacancy color center. A thin layer of eumelanin is polymerized on the surface of nanodiamonds (NDs), and depending on the environmental conditions, such as the local pH value, near-infrared, and ultraviolet light irradiation, the radicals form and react in situ...

Eumelanin is a natural pigment that can be particularly valuable for sustainable bioelectronic devices due to its inherent biocompatibility and hydration-dependent conductivity. However, the low conductivity of eumelanin limits its technological development. In this research, electrochemical doping was proposed as an alternative route to increase the electronic conductivity of synthetic eumelanin derivatives. Thin films of sulfonated eumelanin were deposited on platinum interdigitated electrodes and electrochemically treated by using cyclic voltammetry and chronoamperometry treatments...

Tietz albinism-deafness syndrome (TADS) is a rare and severe manifestation of Waardenburg syndrome that is primarily linked to mutations in MITF. In this report, we present a case of TADS resulting from a novel c.637G>C mutation in MITF (p.Glu213Gln; GenBank Accession number: NM_000248). A 3-year-old girl presented with congenital generalized hypopigmentation of the hair, skin, and irides along with complete sensorineural hearing loss. Histopathological and electron microscopy investigations indicated that this variant did not alter the number of melanocytes in the skin but significantly impaired melanosome maturation within melanocytes...

Melanins are pigments employed in food, cosmetic, and textile industries, manufactured by extraction from cuttlefishes. Their biotechnological production by Streptomycetes, instead, has been poorly investigated so far. In this paper, for the first time, the strain Streptomyces nashvillensis DSM 40314 was tested as an extracellular melanin producer by investigating the influence of diverse temperatures (26, 28, and 30 °C) and pH values (6.0 and 7.0) on bacterial growth, melanin production, and on the activity of the secreted tyrosinase, the first enzyme of the pigment biosynthetic pathway...

Pigmentary coloration is widespread in animals. Its evolutionary and ecological features are often attributed to the property of predominant pigments; therefore, most research has focused on predominant pigments such as carotenoids in carotenoid-based coloration. However, coloration results from predominant pigments and many other minority pigments, and the importance of the latter is overlooked. Here, we focused on porphyrin, an "uncommon" pigment found in bird feathers, and investigated its importance in the context of feather color changes in the barn swallow Hirundo rustica...

Eradication of heavy metal pollution has become the prime priority over the conservation of water resources in the upcoming era. Herein, the study involved the halophilic fungal melanin from Curvularia lunata showed a promising biosorbent for the removal of toxic heavy metals which shows eco-friendly, cost-effective, high stability, and adsorbent efficiency. Polyurethane blended with fungal melanin polymers, makes polymeric nanofibrous membranes through electrospinning techniques. BET isotherms revealed the raw fungal melanin holds a surface area of 3...

The coat color phenotype 'sable' occurs in the English Cocker Spaniel dog breed. It closely resembles other canine color patterns known as domino/grizzle/pied (eA allele) and grizzle/domino (eG allele) determined by variants in the melanocortin 1 receptor gene (MC1R; 'extension' or E locus), a key multi-allele regulator of coat color. We examined genetic variation in MC1R, and found one new non-synonymous variant, c.250G>A (p.(Asp84Asn)), consistently associated with the English Cocker Spaniel 'sable' phenotype...

BACKGROUND: Melasma is a skin hyperpigmentary disorder that develops over time. Genetic factors, oxidative stress, female sex hormones, and UV light may all play a role in the disorder's progression. AIMS: To compare the levels of oxidative stress and tyrosinase activity in melasma patients with healthy volunteers. METHODS: After written consent, 130 patients were enrolled in a case-control study. 65 cases were of melasma disorder, and 65 were served as control...

Local adaptation is critical in speciation and evolution, yet comprehensive studies on proximate and ultimate causes of local adaptation are generally scarce. Here, we integrated field ecological experiments, genome sequencing, and genetic verification to demonstrate both driving forces and molecular mechanisms governing local adaptation of body coloration in a lizard from the Qinghai-Tibet Plateau. We found dark lizards from the cold meadow population had lower spectrum reflectance but higher melanin contents than light counterparts from the warm dune population...

The genetic foundation of chicken body plumage color has been extensively studied. However, little attention has been paid to the inheritance patterns and molecular mechanisms underlying the formation of distal feather colors (tail and wingtip). Differences in these colors are common; for example, the Chinese Huiyang Beard chicken has black tail feathers, but yellow body plumage. Here, the hybrid offspring of Huiyang Beard and White Leghorn chickens were used to study the inheritance patterns of tail-feather color...

Effective diagnosis and therapy for bacterial infections, especially those caused by multidrug-resistant (MDR) species, greatly challenge current antimicrobial stewardship. Monocytes, which can chemotactically migrate from the blood to infection site and elicit a robust infection infiltration, provide a golden opportunity for bacterial theranostics. Here, a nano-Trojan Horse was facilely engineered using mannose-functionalized manganese-eumelanin coordination nanoparticles (denoted as MP-MENP) for precise two-step localization and potent photothermal-immunotherapy of MDR bacterial infection...

Using first-principles calculations, we investigate the absorption spectra (in the near-infrared, visible, and first UV range) of the two most probable eumelanin tetrameric molecules exhibiting either a linear open-chain or a cyclic porphyrine-like configuration. In order to simulate a realistic molecular system, an implicit solvent model is used in our calculations to mimic the effect of the solvated environment around the eumelanin molecule. Although the presence of solvent is found not to significantly affect the absorption pattern of both molecules, the onset of the spectra are shifted toward higher energies, especially for the linear tetramer...

Superficial discolored spots on Atlantic salmon ( Salmo salar ) fillets are a serious quality problem for commercial seafood farming. Previous reports have proposed that the black spots (called melanized focal changes (MFCs)) may be melanin, but no convincing evidence has been reported. In this study, we performed chemical characterization of MFCs and of red pigment (called red focal changes (RFCs)) from salmon fillets using alkaline hydrogen peroxide oxidation and hydroiodic acid hydrolysis. This revealed that the MFCs contain 3,4-dihydroxyphenylalanine (DOPA)-derived eumelanin, whereas the RFCs contain only trace amounts of eumelanin...

A common feature of Parkinson's disease (PD) and melanoma is their starting points being based on cells capable of converting tyrosine into melanin. Melanocytes produce two types of melanin: eumelanin and pheomelanin. These dyes are designed to protect epidermal cells from the harmful effects of UV radiation. Neurones of the substantia nigra, which degenerate during PD, produce neuromelanin, the physiological role of which is not fully explained. This article discusses the potential role of melanins in the pathogenesis of both diseases...

This review summarizes the effectiveness of photodynamic therapy (PDT) in the treatment of the pigmented subtype of basal cell carcinoma (BCC) based on the current literature. PDT is a light-activated treatment, non-invasive, that selectively destroys tumor cells and tissues via the interaction of a photosensitizer, light, and molecular oxygen. It can induce cancer cell death through direct tumor vascular damage or via the induction of immune response. However, human skin is also an absorption and scattering medium since it contains hemoglobin and melanin that act as chromophores...