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Persistent racial disparities in health outcomes have catalyzed legislative reforms and heightened scientific focus recently. However, despite the well-documented properties of skin pigments in binding drug compounds, their impact on therapeutic efficacy and adverse drug responses remains insufficiently explored. This perspective examines the intricate relationships between variation in melanin-based skin pigmentation and pharmacokinetics and -dynamics, highlighting the need for considering diversity in skin pigmentation as a variable to advance the equitability of pharmacological interventions. The article provides guidelines on the selection of New Approach Methods (NAMs) to foster inclusive study designs in preclinical drug development pipelines, leading to an improved level of translatability to the clinic.

Aposematic organisms rely on their conspicuous appearance to signal that they are defended and unpalatable. Such phenotypes are strongly tied to survival and reproduction. Aposematic colors and patterns are highly variable; however, the genetic, biochemical, and physiological mechanisms producing this conspicuous coloration remain largely unidentified. Here, we identify genes potentially affecting color variation in two color morphs of Ranitomeya imitator: the orange-banded Sauce and the redheaded Varadero morphs. We examine gene expression in black and orange skin patches from the Sauce morph and black and red skin patches from the Varadero morph. We identified genes differentially expressed between skin patches, including those that are involved in melanin synthesis (e.g. mlana, pmel, tyrp1), iridophore development (e.g. paics, ppat, ak1), pteridine synthesis (e.g. gch1, pax3-a, xdh), and carotenoid metabolism (e.g. dgat2, rbp1, scarb2). In addition, using weighted correlation network analysis, we identified the top 50 genes with high connectivity from the most significant network associated with gene expression differences between color morphs. Of these 50 genes, 13 were known to be related to color production (gch1, gmps, gpr143, impdh1, mc1r, pax3-a, pax7, ppat, rab27a, rlbp1, tfec, trpm1, xdh).

Plant melanin, a natural pigment, has gained significant attention recently due to its potential therapeutic and industrial applications. In this study, melanin pigments were extracted from Nigerseed hulls (NH) via alkali and acid extraction methods, followed by acid hydrolysis, organic solvent treatment, and repeated precipitation. The solubility of NH melanin was assessed, revealing solubility in alkali and dimethyl sulfoxide (DMSO) but insolubility in other common organic solvents. High-performance liquid chromatography (HPLC) was employed to measure the purity of NH melanin in comparison to standard melanin, while elemental analysis indicated a similarity between melanin extracted from nigerseed hulls and the standard counterpart. LC-MS data revealed a molecular weight of NH melanin. Furthermore, the stability of melanin was evaluated under varying conditions including temperature, oxidants, reducing agents, light exposure, and metal ion presence. Results demonstrated significant effects of Mg2+, Cu2+, and Fe2+ metal ions on melanin stability, with a minor effect observed for Ca2+, while sodium hyposulfite was found to destabilize the pigments. Our findings suggest that nigerseed hulls hold promise as a novel source for efficient melanin production, with potential applications in the food sector, food packaging, and biomedical fields. [ABSTRACT FROM AUTHOR]

In this study, residue depletion and withdrawal time estimation of tilmicosin were examined in Taihe black-bone silky fowls (TBSFs) after oral administration for three consecutive days at a dose of 75 mg/L in water. The tilmicosin concentrations in liver, kidney, muscle, and skin/fat of TBSFs collected from different time points (0.16, 1, 3, 5, 7, 9, 12, 20, 30, 40 days after last administration) were determined by UPLC-MS/MS. The results indicated that the tilmicosin concentrations in TBSFs tissues varied significantly, and kidney had the highest average concentrations (2604.65 ± 4625.20 μg/kg), followed by liver (1125.54 ± 1479.24 μg/kg), skin/fat (372.81 ± 428.33 μg/kg), and muscle (104.52 ± 143.95 μg/kg). Meanwhile, tilmicosin was still detected in all the four studied tissues (liver, kidney, skin/fat, and muscle) of TBSFs at the last time point (40th day after administration), suggesting that tilmicosin in TBSFs depleted slowly. Based on our experiments, the recommended withdrawal time of tilmicosin for TBSFs after oral administration for three consecutive days at a dose of 75 mg/L in water should be 32 days, which is much longer than the duration specified by Chinese regulatory authorities (10 days), and the abundance of melanin in TBSFs might be responsible for this phenomenon. Hence, a special use and withdrawal procedure of veterinary drugs in TBSFs is needed, and it is essential to focus on potential involvement of melanin in tilmicosin accumulation. [ABSTRACT FROM AUTHOR]

Objective: This study investigated the effects of circRNA18_46222157_46248185 (named circRNA18) on goat melanogenesis, which differs significantly in goat skins isolated from white and brown coat-colored skins. Methods: Expression patterns of circRNA18 in goat skin and melanocytes were determined by quantitative real-time polymerase chain reaction (qRT-PCR) and in situ hybridization. The circRNA18 interference vector was designed and synthesized to transfect melanocytes and detect the effect of circRNA18 interference on melanin production. Bioinformatics software was used to predict the targeted adsorption miRNAs of circRNA18, verified by luciferase assay. A miRNA expression vector was constructed and transfected into melanocytes to detect the effect of miRNA on melanin production, and the targeted regulatory genes were detected by luciferase assay. Target gene interference vector was constructed to detect the influence of target gene interference on melanin production. Results: qRT-PCR results unveiled distinct expression patterns of circRNA18 in diverse tissues of male and female goats, while in situ hybridization assays showed that circRNA18 is expressed in the cytoplasm of melanocytes. Functional analysis demonstrated that the downregulation of circRNA18 in melanocytes leads to a significant increase (p<0.01) in melanin production. Bioinformatics analysis identified a potential miR-211 binding site on circRNA18, and luciferase assay confirmed their interaction. Overexpression of miR-211 in melanocytes significantly augmented (p<0.01) melanin production. There were two potential miR-211 binding sites on adenoviral E1A-binding protein (EP300), and the overexpression of miR-211 in melanocytes significantly decreased (p<0.001) EP300 expression, with luciferase assay confirming their interaction. Downregulation of EP300 expression in melanocytes through siRNA-EP300 transfection results in a substantial increase (p<0.05) in melanin production. qRT-PCR results indicated that overexpression of mimics-circRNA18 in melanocytes markedly suppressed (p<0.0001) miR-211 expression, significantly elevated (p<0.01) EP300 expression, and significantly inhibited (p<0.001) melanin production. Conclusion: circRNA18_46222157_46248185 acted as a negative regulator of melanogenesis in goat melanocytes by targeting the miR-211/EP300 pathway, and guiding animal hair color breeding strategies. [ABSTRACT FROM AUTHOR]

Melanin with antioxidant and antibacterial properties can be used in food, cosmetics, biotechnology, and other fields, but its insolubility become a main challenge hindering for its application. In this study, water-soluble melanin produced by the novel species Streptomyces vilmorinianum YP1 was characterized using scanning electron microscopy (SEM), UV visible spectroscopy (with an absorption peak at 220 nm), and Fourier transform infrared (FTIR) spectroscopy. The glycosyltransferase gene ORF14 was knocked out, which improved the production of water-soluble melanin by inhibiting competitive pathway. In order to further enhance production of melanin, Plackett Burman and response surface methodology statistical design was employed to screen for key factors and determine the optimal combination. The maximum melanin production (4.00 g/L) was obtained under the conditions: amylodextrine concentration of 40 g/L, soya peptone concentration of 7 g/L, tryptone concentration of 5 g/L, NaCl concentration of 5.4 g/L, pH of 6.7 and temperature of 36 °C for 180 h. The physicochemical properties and bioactivity of melanin were further investigated, revealing that melanin had a good stability across a pH range of 4–12, antioxidant (with a survival rate of over 85 %), and resistance to reducing agents (with a survival rate of over 99 %). The results underscored that S. vilmorinianum YP1 is a promising candidate for water-soluble melanin production. • The black pigment from the novel species (Streptomyces vilmorinianum YP1) was firstly identified. • The production of water-soluble melanin was increased by inhibiting competitive pathways and optimization. • The water-soluble melanin showed good pH and resistance to reducing agents. • The absence of ORF14 (Glycosyltransferase) inhibits the production of blue pigment and improves melanin pathway metabolism. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the role of transforming growth factor-beta 3 (TGF-β3) secreted by adipose-derived stem cells (ADSCs) in suppressing melanin synthesis during the wound healing process, particularly in burn injuries, and to explore the underlying mechanisms involving the cAMP/PKA signaling pathway. ADSCs were isolated from C57BL/6 mice and characterized using flow cytometry and differentiation assays. A burn injury model was established in mice, followed by UVB irradiation to induce hyperpigmentation. Mice were divided into four groups: control (PBS), ADSCs, ADSCs with TGF-β3 overexpression, and ADSCs with TGF-β3 knockdown. Melanin deposition was assessed via Fontana Masson staining, while ELISA measured the expression of MC1R and α-MSH. Western blotting was used to examine TGF-β3 and the activation of cAMP/PKA signaling pathway. Mice treated with ADSCs overexpressing TGF-β3 showed significant reductions in melanin deposition and suppressed expression of MC1R and α-MSH compared to controls. Western blot results revealed that the cAMP/PKA signaling pathway was downregulated in the TGF-β3-overexpressing ADSC group. In contrast, the knockdown of TGF-β3 led to increased melanin deposition and higher cAMP/PKA pathway activity, correlating with greater expression of MC1R and α-MSH. TGF-β3 secreted by ADSCs effectively inhibits melanin synthesis during wound healing, with potential effects on the cAMP/PKA signaling pathway. These findings suggest that TGF-β3 could serve as a potential therapeutic target for managing post-burn hyperpigmentation. [ABSTRACT FROM AUTHOR]

Optical resolution photoacoustic imaging of uneven samples without z-scanning is transformative for the fast analysis and diagnosis of diseases. However, current approaches to elongate the depth of field (DOF) typically imply cumbersome postprocessing procedures, bulky optical element ensembles, or substantial excitation beam side lobes. Metasurface technology allows for the phase modulation of light and the miniaturization of imaging systems to wavelength-size thickness. Here, we propose a metalens composed of submicrometer-thick titanium oxide nanopillars, which generates an elongated beam of diffraction-limited diameter with an aspect ratio of 286 and a uniform intensity throughout the DOF. The metalens enhances visualization of phantom samples with tilted surfaces compared to conventional lenses. Moreover, the volumetric imaging of neuromelanin is facilitated for depths of up to 500 micrometers within the human midbrain and forebrain organoids that are 3D biological models of human brain regions. This approach provides a miniaturized platform for neurodegenerative disease diagnosis and drug discovery. [ABSTRACT FROM AUTHOR]

Fifteen compounds (1–15) constructed on a hybrid structure combining a β-phenyl-α,β-unsaturated carbonyl template and a 2-aminothiazol-4(5H)-one scaffold were designed and synthesized as potential novel anti-tyrosinase substances. Two compounds (10 and 15) showed more potent inhibition against mushroom tyrosinase than kojic acid, and the inhibitory activity of 10 (IC50 value: 1.60 μM) was 11 times stronger than that of kojic acid. Lineweaver–Burk plots indicated that these two compounds were competitive inhibitors that bound to the mushroom tyrosinase active site, which was supported by in silico experiments. Compound 10 was an anti-tyrosinase and anti-melanogenic substance in B16F10 cells and was more potent than kojic acid, without cytotoxicity. Compound 15 exhibited the most potent effect on zebrafish larval depigmentation and showed a depigmentation effect comparable to kojic acid, even at a concentration 200 times lower. Compounds 8 and 10 exhibited strong antioxidant capacities, scavenging 2,2-diphenyl-1-picrylhydrazyl, (2,2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid)+ radicals, and reactive oxygen species. Hybrid compounds 10 and 15 are potential therapeutic agents for skin hyperpigmentation disorders. [ABSTRACT FROM AUTHOR]

The effect of skin pigmentation on photoplethysmography and, specifically, pulse oximetry has recently received a significant amount of attention amongst researchers, especially since the COVID-19 pandemic. With most computational studies observing overestimation of arterial oxygen saturation (SpO2) in individuals with darker skin, this study seeks to further investigate the root causes of these discrepancies. This study analysed intensity changes from Monte Carlo-simulated reflectance PPG signals across light, moderate, and dark skin types at oxygen saturations of 70% and 100% in MATLAB R2024a. With simulated intensity reflecting PPG amplitude, the results showed that systolic intensity decreased by 3–4% as pigmentation increased at 660 nm. It was also shown that the impact at 940 nm is minimal (<0.2%), indicating that the increased absorption of red light by melanin has a greater effect on the ratio of ratios calculations. These results suggest that in-built adjustments may be required for data collected from red-light sources in pulse oximeters that do not currently have the necessary post-processing algorithms to account for this difference between diverse skin populations. [ABSTRACT FROM AUTHOR]

Efficacious dosage of conventional hyperpigmentation treatments is limited by their toxicity and undesirable side effects. Bacterial cellulose (BC) patch containing plant phenolic compound is proposed as an effective yet safe alternative. In this work, curcumin-loaded BC film (Cur(BC)) was developed as a cytocompatible inhibitor of in vitro melanogenesis in hyperpigmented melanocytes. (Cur)BC was characterized to understand its morphological, physical, and chemical properties. Its anti-melanogenic effects were assessed by in vitro studies performed on putrescine induced human epidermal melanocytes. Results show that Cur(BC) is non-cytotoxic, decreases melanin production by up to 58%, and down-regulates melanogenesis-related genes TYR, TRP-1, TRP-2. This report features the first evaluation of the synergistic effects and limitations of curcumin-loaded bacterial cellulose composites on melanin production in vitro. [ABSTRACT FROM AUTHOR]

Background: This study employed melanin synthesized by Aspergillus flavus and Aspergillus carbonarius to inhibit the production of mycotoxins and bioremediation of heavy metals (HMs). Methods: First, twenty fungal isolates were obtained from soil samples, and were evaluated to produce melanin. The melanin of the most potent producers has undergone several confirmatory experiments, including, Dihydroxyphenylalanine (DOPA)-inhibitor-kojic acid pathway detection, High-performance liquid chromatography (HPLC), Fourier-transform infrared (FTIR) and Nuclear magnetic resonance (NMR). Additionally, the melanin production culture conditions were optimized. The antioxidant activity of melanin was detected with 1,1-Diphenyl-2-picrylhydrazyl (DPPH). HPLC was used to measure the mycotoxins produced in culture media supplemented with melanin. Molecular docking study investigated molecular interactions between melanin and mycotoxins through in silico approaches. FTIR and Energy-dispersive X-ray spectroscopy (EDX) were utilized to determine the percentage of melanin-chelated HMs, and an atomic absorption spectrophotometer (AAS) was used to detect HMs removal efficiency. Results: The melanin-enriched medium (0.3% and 0.4%) exhibited complete inhibition of aflatoxin B1 (AF-B1) by A. flavus and ochratoxin A (OTA) by A. carbonarius, respectively. Furthermore, melanin showed effective HM removal efficiency, increasing with melanin concentration. The removal efficiency of Cd+2 and Cr+6 by 1 mg/mL melanin was 49% and 63%, respectively. When the concentration of melanin was increased to 15 mg/mL, the removal efficiency of Cd+2 and Cr+2 increased to 60% and 77%, respectively. Conclusion: The study exhibited a natural approach for melanin production, using melanin as a heavy metal-chelating agent and capability to inhibit the production of aflatoxin B1 and ochratoxin A. Further, the study provides significant evidence regarding the bioremediation pipeline, for melanin production through biotechnological processes by filamentous fungi. [ABSTRACT FROM AUTHOR]

Melanin is a natural black-brown pigment found in animals, plants, bacteria, and human body. In its solid state, it conducts electric charge, shows photoconductivity, switches between high and low resistive states, and under certain conditions retains electric charge. The formation of melanin thin films is a prerequisite for many electronic applications, i.e., biocompatible electronics and biocompatible batteries, although it has been difficult to properly deposit high quality melanin electrodes due to its low solubility and low thermal stability. We discovered that synthetic melanin derivatives result in electrochemically active films with different electrochemical response profiles. These results aim toward the effective use of melanin thin-films for potential applications in organic biocompatible electronics. [ABSTRACT FROM AUTHOR]

Introduction: Physiologic oral pigmentation is a typical finding in paediatric dentistry. Gingival pigmentation has a wide range of occurrence rates depending on race, country and the influence of genetics. This study aims to determine the anatomic distribution of physiologic gingival melanin pigmentation and the relationship between skin colour and gingival melanin pigmentation intensity in children with primary, mixed and permanent dentition. Materials and Methods: Patient photographs of the skin of the face and intraoral soft tissues were taken in the standardised photographic conditions. Photographs were reproduced on a computer for assessment at a standardised point for skin and intraorally for interdental, marginal and attached gingivae. The intensity of melanin pigmentation of the skin of the face and marginal, interdental and attached gingiva was observed by calculating CIE*L*a*b* values on Adobe Photoshop in 2008 individuals. Results: The P value was kept significant at <0.05. The mean value of the difference in marginal and attached gingiva pigmentation was statistically significant between the primary and permanent dentition groups. The correlation was positive and low between age and pigmentation at the attached gingiva as the correlation coefficient. The correlation was positive and low between skin pigmentation and pigmentation at attached and marginal gingiva as the correlation coefficient. Conclusions: The intensity of the skin's pigmentation can be used as a predictor of the pigmentation of gingivae. Of all the other areas of the gingiva, the intensity of pigmentation in the attached gingiva is the highest. As one age, the intensity of pigmentation at the attached gingiva also increases. [ABSTRACT FROM AUTHOR]

As Streptomycetes might produce melanin to survive in stressful environmental conditions, like under metal exposure, supplementing metal ions to the growth medium could be a wise strategy for boosting the production of the pigment. The aim of this study was to test, for the first time, the possibility of boosting S. nashvillensis DSM40314 melanin biosynthesis by adding to the growth medium singularly or, at the same time, different concentrations (1.0, 1.5, and 2.0 g∙L−1) of CuSO4 or/and Fe2(SO4)3. A maximum melanin production of 4.0 ± 0.1 g·L−1 was obtained in shake flasks with a 2.0 g∙L−1 coupled addition of the two metals, while the extracellular tyrosinase activities ranged values between 5.4 and 11.6 ± 0.1 U·L−1. The pigments produced in different conditions were precipitated from the broth supernatants under acidic conditions, purified, and characterized by UV-VIS, FT-IR, and NMR analyses that determined structures like eumelanin pigments. Fermentation experiments in stirred tank reactors allowed to scale up the process in more controlled conditions, further boosting the pigment production up to 4.9 ± 0.1 g·L−1, with an increase of about 22.0% compared to the results obtained in shake flasks. [ABSTRACT FROM AUTHOR]

The melanocortin‐1 receptor (MC1R) is a G protein‐coupled receptor that plays a pivotal role in human skin pigmentation, melanin synthesis, redox homeostasis and inflammation. Loss‐of‐function MC1R variants suppress G protein‐coupled receptor coupling or cell surface expression leading to a decrease in adenyl cyclase activation and intracellular levels of cyclic adenosine monophosphate. Chronic activation of MC1R can occur in certain medical conditions such as Addison's disease and physiologic states such as pregnancy melasma. MC1R activation is more commonly caused by environmental exposure to ultraviolet (UV) radiation. Approved pharmacologic melanocortin agonists that activate MC1R signalling in a targeted manner or as a bystander effect have recently become available for erythropoietic protoporphyria, sexual desire disorders, monogenic obesity and syndromic obesity. Further, small peptide analogues of α–melanocortin‐stimulating hormone, human MC1R selective agonists, are photoprotective, decreasing the adverse impact of UV radiation (a primary risk factor for skin cancer) and are being investigated as potential chemoprevention strategies. MC1R activation through induction of UV‐protective skin pigmentation increased DNA repair, and control of aberrant cell growth may reduce the risk of melanoma but importantly does not prevent melanoma particularly in individuals with risk factors and regular skin examination remains critical in high‐risk individuals. [ABSTRACT FROM AUTHOR]

In this work a novel method for synthesis of 1,8-dihydroxynaphthalene melanin was presented, as well as the physicochemical properties, molecular structure, and characteristics of the pigment. The proposed synthesis protocol is simple and cost-effective with no enzymes or catalysts needed. The final product is not adsorbed on any surface, since the pigment is the result of autooxidation of 1,8-dihydroxynaphthalene. Performed analyses revealed that the solubility, optical and paramagnetic properties are typical for melanins, and in the EPR spectra an unusual hyperfine structure was observed. The molecular structure of the pigment consists of three different layers forming polar and non-polar surfaces. Additionally, the presence of ether bonds presence was revealed. The developed method creates new opportunities for melanin research and eliminates the need to extract melanins from biological samples, which often lead to structural changes in isolated melanins, which undermines the reliability of analyses of the properties and structure of these polymers. On the other hand, the ubiquity of melanins in living organisms and the diversity of their biological functions have let to the growing interest of researchers in this group of pigments. The analyses carried out show that the obtained synthetic DHN polymer can be considered as a model DHN-melanin in mycological studies and material research. [ABSTRACT FROM AUTHOR]

Feather colours can be produced by the organization of feather microstructure, by pigmentation (mainly due to melanins and carotenoids) or both. The expression of feather colours is usually influenced by testosterone (T) levels through several interacting mechanisms. First, high T levels can negatively affect bird condition and hence the expression of condition‐dependent feather colours (e.g. carotenoid‐based colours). Secondly, high levels of T can slow moult progression, which in turn may result in brighter colours, as moult speed has been shown to be negatively correlated with the expression of feather colours. Thirdly, T can affect the bioavailability of pigments that are involved in feather colours. The effect of experimental manipulation of T levels may therefore influence, either positively or negatively, feather colour expression according to the relative importance of these mechanisms and the type of coloration involved. We experimentally investigated whether plumage coloration is affected by T in yearling Eurasian Blue Tits Cyanistes caeruleus. We implanted 11 males and 11 females with T (T‐birds) at the onset of their post‐juvenile moult and compared the spectral reflectance of their structural ultraviolet (UV)/blue colour (crown feathers and upper lesser wing‐coverts) and carotenoid‐based yellow colour (breast feathers) with those of control birds (C‐birds) that were sham‐implanted (12 males, 16 females). At the implant date, all the right lesser wing‐coverts were plucked in both experimental groups to test the effect of T on feathers grown exclusively during our treatment. After 40 days, the implants were removed. Two weeks before removing the implants, the mean T plasma levels were assayed (average 3.21 ng/mL in T‐birds and 0.33 ng/mL in C‐birds). In T‐birds, body moult progression was suspended, and moult was resumed 33 days after implant removal. Moult duration from implant date, excluding suspension, did not differ between treatments and controls. T had a negative effect on UV coloration only in plumage that started growing exclusively during the treatment (right lesser wing‐coverts), and not in other UV/blue plumage. In contrast, the carotenoid‐based yellow coloration of the breast increased in T‐birds, suggesting an immediate effect of T on the mobilization of carotenoids available for ornamentation. Despite sexual dichromatism, T treatment had similar effects in the two sexes. Our results highlight the importance of considering the effect of T on moult speed and possibly moult suspension in the interpretation of the results of studies based on T manipulation. [ABSTRACT FROM AUTHOR]

Vernonia anthelmintica (L.) Willd. is a traditional medicinal herb in Chinese medicine, extensively used by various ethnic groups due to the numerous advantages derived from its total flavonoids. These benefits encompass anti-inflammatory and antioxidant effects, and the promotion of melanin production, showcasing its significant efficacy in addressing vitiligo. To improve transdermal absorption and enhance the antioxidant effectiveness of the treatment, ethosome containing total flavonoids were prepared utilizing the ultrasound injection technique. The resulting ethosome was then carefully mixed with 0.7% Carbomer 934 gel in equal parts, yielding a gel concentration of 0.302 mg/g. This formulation produced small, consistent ethosome that exhibited high encapsulation efficiency and notable stability. In vitro analyses demonstrated sustained release characteristics of the gel and considerable therapeutic effectiveness against vitiligo resulting from hydroquinone exposure. Histological examinations performed through hematoxylin and eosin (H&E) staining of mouse skin revealed increased melanin production and increased activities of tyrosinase (TYR), cholinesterase (CHE), and mouse monoamine oxidase (MAO), while levels of superoxide dismutase (SOD) and malondialdehyde (MDA) were reduced. These findings underscore the promising effectiveness of this treatment strategy and validate the efficacy of the dosage form. [ABSTRACT FROM AUTHOR]

Objectives: To explore the effect of mild cognitive impairment (MCI) and MCI with sleep disorders on the potency of sevoflurane anesthesia in the elderly. Design: Prospective study methods. Dixon up-and-down methods. Setting: Comprehensive public tertiary hospital, Cangzhou City, Hebei Province, China. Participants: 70 elderly patients scheduled for elective unilateral breast cancer surgery and finally analyzed 58 patients, including 30 patients with MCI (group M) and 28 patients with MCI with sleep disorders (group MS). Outcome measures: The required minimum alveolar concentration (MAC) value of sevoflurane in the two groups was determined using the Dixon up-and-down method. The MAC value of sevoflurane and its 95% confidence interval (CI) were calculated using the logistic regression method. Serum melanin-concentrating hormone concentrations were determined by Elisa kits. Results: The MAC value of sevoflurane in group M was 1.43 (95% CI 1.05–1.61%), and the MAC value of sevoflurane in group MS was 1.93 (95% CI 1.78–2.08%), There were notable differences between the two groups (P < 0.0001). The level of melanin-concentrating hormone (MCH) in the MS group was significantly lower than that in the M group (21.52 ± 3.82 vs. 37.17 ± 3.66 pg/ml, P < 0.0001). There was a significant negative correlation between MCH levels and the probability of body movement during skin incision (OR = 0.844, 95% CI: 0.715–0.996, P = 0.045). Conclusions: Patients with MCI with sleep disorders required higher doses of sevoflurane than those with MCI alone. Changes in anesthetic requirements may be related to changes in MCH levels. [ABSTRACT FROM AUTHOR]

In this study, water-soluble melanin was synthesized through the genetic recombination of Escherichia coli using gallic acid as a substrate. The recombinant host produced 2.83 g/L of gallic acid-based melanin (GA melanin) from 20 mM gallic acid. Notably, the isolated GA melanin demonstrated exceptional antioxidant and antimicrobial activities, exhibiting a 25.7 % inhibition ratio against Candida albicans. The structure and composition of GA melanin were analyzed using Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and X-ray diffraction (XRD). Remarkably, GA melanin displayed high thermal stability, maintaining integrity up to 1000 °C. Additionally, it exhibited unique electrical properties in terms of conductivity and resistivity compared to other common types of melanin. Subsequently, GA melanin was cross-linked with hydrogel to create a sensing template. The resulting GA melanin hydrogel demonstrated lower resistance (80.08 ± 3.0 kohm) compared to conventional hydrogels (108.62 ± 10.4 kohm), indicating an approximately 1.77-fold improvement in adhesion. Given its physical, biological, and electrical properties, the GA melanin hydrogel was further utilized as a flexible motion-sensing material to detect resistivity changes induced by knee, wrist, and finger bending, as well as vocal cord vibrations. In all cases, the sensing module displayed notable sensitivity to motion-induced resistivity variations. • Production of water-soluble gallic acid-based melanin pigment (GA melanin). • Formation GA melanin and hydrogel complex for flexible macromolecule. • Biological and physical properties of GA melanin pigment. • Electrical properties of conductivity and resistivity by GA melanin. • GA melanin-hydrogel complex for motion sensing flexible material. [ABSTRACT FROM AUTHOR]

Fungi can synthesize a diverse range of melanins with appropriate physicochemical and biological characteristics for numerous applications in health, environmental protection, energy, and industry. Gaining deeper insights into the chemical structures, biosynthetic pathways, and regulatory mechanisms of fungal melanin would establish a basis for metabolic engineering approaches, aimed at enhancing production efficiency and creating custom-designed melanin with desirable material properties. Due to growing interest in their beneficial effects and applications, research on the structure, biosynthesis, and regulation of fungal melanin has significantly advanced. This review highlighted recent progress in fungal melanin production and applications, concentrating on structure, biosynthesis, and regulatory networks, and suggested how an improved understanding of melanin biosynthesis could enable efficient production for future applications. [ABSTRACT FROM AUTHOR]

Copyright of Mycosystema is the property of Mycosystema Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Little is known about the anti-pigmenting effects of skin-whitening agents on solar lentigos (SLs). To characterize the anti-pigmenting effects of a newly designed derivative ascorbyl glucoside–arginine complex (AGAC) on SLs, lotions with or without 28% AGAC were applied twice daily for 24 weeks in a double-blind half-face study of 27 Japanese females with SLs. The pigmentation scores and skin colors of previously selected SLs on the right and left sides of the faces of the subjects were evaluated using a photo-scale, a color difference meter and a Mexameter. Treatment with the test lotion elicited a significant decrease in pigmentation scores at 24 weeks compared to week 0, with a significant decrease in pigmentation scores at 24 weeks compared to the placebo lotion. In the test lotion-treated SLs, the lightness (L) and melanin index (MI) values that reflect the pigmentation level significantly increased and decreased, respectively, at 12 and 24 weeks of treatment compared to week 0. Comparisons of increased L values or decreased MI values between the test and placebo lotion-treated SLs demonstrated that the test lotion-treated SLs had significantly higher increased L or decreased MI values than the placebo lotion-treated SLs both at 12 and 24 weeks of treatment. The sum of our results strongly indicates that AGAC is distinctly effective in ameliorating the hyperpigmentation levels of SLs at a level visibly recognizable by the subjects, without any hypo-pigmenting effects or skin problems. [ABSTRACT FROM AUTHOR]

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Melanin is responsible, in Nature, for photoprotection, for this reason it is expected to be poorly photoreactive. However, the photo‐reactivity of melanin and related materials is well documented. Here we discuss some relevant recent examples to demonstrate that, indeed, the actual mechanism of interaction of melanin with light is complex and still not completely understood. Photochemical and photothermal processes are involved, giving a contribution that strongly depends on light wavelength and intensity. Moreover, some interesting experiments demonstrated that photochemical reactivity of melanin related compounds is likely to be indirect, in the sense that the effect of light is to increase the number of radical species rather than creating photoreactive excited state. These suggestions open‐up new perspectives in the interpretation of the role of melanin in photoprotection and in the design of new melanin based photoactive materials for energy conversion, environmental remediation, and nanomedicine. Further complication is given by the role of atmospheric oxygen and humidity in the photoinduced processes. Beside this complexity of behavior makes it difficult a systematic understanding of the interaction of melanin with light, it surely strongly contributes to make the properties of melanin and related materials unique. [ABSTRACT FROM AUTHOR]

ABSTRACT: Tyrosinase and tyrosinase-related protein-2 (Tyrp2) play a pivotal role in melanin production within melanocytes. Both share a high degree of structural and sequence similarity, with a Root-Mean-Square Deviation (RMSD) of 0.75 Å and 62% sequence similarity, including 43% sequence identity. Despite these similarities, differences in the allosteric sites, particularly the residues that constitute these sites, contribute to distinct regulatory mechanisms. This study elucidates the contrasting allosteric modulation of tyrosinase and Tyrp2 by two flavonoids: (a) luteolin and (b) apigenin, respectively. Luteolin demonstrated its allosteric inhibitory property against tyrosinase by disturbing the spatial arrangement of histidine residues critical for copper coordination, essential for enzymatic activity. Conversely, apigenin serves as an allosteric activator for Tyrp2, enhancing structural stability and maintaining the active site conformation. Despite the structural resemblance between luteolin and apigenin, differentiated by a single hydroxyl group, their impact on melanin synthesis diverges — luteolin inhibits, whereas apigenin stimulates the process. Both showed high binding affinity at the allosteric site of tyrosinase and Tyrp2. Luteolin significantly alters the spatial arrangement of key histidine residues (HIS180, HIS202 and HIS211), forming coordination bonds in tyrosinase, affecting copper coordination and coordination with the peroxide (O22−) ion. However, apigenin did not remain bound to tyrosinase for an extended period, ruling out its role as an allosteric modulator. In contrast, apigenin stayed at the allosteric site of the Tyrp2 protein and showed a positive allosteric regulator role. The findings offer a mechanistic view of melanin synthesis regulation, demonstrating the potential of subtle structural variations in modulators to selectively influence enzyme activity in related biosynthetic pathways. This underscores the intricate control within melanogenic systems and the possibility of targeting these pathways for therapeutic and cosmetic applications. [ABSTRACT FROM AUTHOR]

Production of melanin pigments is a protective mechanism of the skin against ultraviolet (UV)-induced damage and carcinogenesis. However, the molecular basis for melanogenesis is still poorly understood. Herein, we demonstrate a critical interplay between the primary cilium and the melanocortin 1 receptor (MC1R) signaling. Our data show that UV and α-melanocyte-stimulating hormone (α-MSH) trigger cilium formation in human melanocytes and melanoma cells. Deficiency of MC1R or the presence of its red hair color (RHC) variations significantly attenuates the UV/α-MSH-induced ciliogenesis. Further investigation reveals that MC1R enters the cilium upon UV/α-MSH stimulation, which is facilitated by the interaction of MC1R with the BBSome and the palmitoylation of MC1R. MC1R interacts with the BBSome through the second and third intercellular loops, which contain the common RHC variant alleles (R151C and R160W). These RHC variants of MC1R exhibit attenuated ciliary localization, and enforced ciliary localization of these variants elevates melanogenesis. Ciliary MC1R triggers a sustained cAMP signaling and selectively stimulates Sox9, which appears to up-regulate melanogenesis-related genes as the transcriptional cofactor for MITF. These findings reveal a previously unrecognized nexus between MC1R and cilia and suggest an important mechanism for RHC variant-related pigmentary defects. Melanin production in the skin protects us against UV damage, but how? These authors show that upon UV exposure MC1R enters primary cilia and interacts with the BBSome, triggering the downstream signalling that stimulates melanogenesis. Red-haired people have a genetic variation in MC1R that affects this interaction, leading to defective melanin production. [ABSTRACT FROM AUTHOR]

Cryomyces antarcticus, a melanized cryptoendolithic fungus endemic to Antarctica, can tolerate environmental conditions as severe as those in space. Particularly, its ability to withstand ionizing radiation has been attributed to the presence of thick and highly melanized cell walls, which—according to a previous investigation—may contain both 1,8‐dihydroxynaphthalene (DHN) and L‐3,4 dihydroxyphenylalanine (L‐DOPA) melanin. The genes putatively involved in the synthesis of DHN melanin were identified in the genome of C. antarcticus. Most important is capks1 encoding a non‐reducing polyketide synthase (PKS) and being the ortholog of the functionally characterized kppks1 from the rock‐inhabiting fungus Knufia petricola. The co‐expression of CaPKS1 or KpPKS1 with a 4′‐phosphopantetheinyl transferase in Saccharomyces cerevisiae resulted in the formation of a yellowish pigment, suggesting that CaPKS1 is the enzyme providing the precursor for DHN melanin. To dissect the composition and function of the melanin layer in the outer cell wall of C. antarcticus, non‐melanized mutants were generated by CRISPR/Cas9‐mediated genome editing. Notwithstanding its slow growth (up to months), three independent non‐melanized Δcapks1 mutants were obtained. The mutants exhibited growth similar to the wild type and a light pinkish pigmentation, which is presumably due to carotenoids. Interestingly, visible light had an adverse effect on growth of both melanized wild‐type and non‐melanized Δcapks1 strains. Further evidence that light can pass the melanized cell walls derives from a mutant expressing a H2B‐GFP fusion protein, which can be detected by fluorescence microscopy. In conclusion, the study reports on the first genetic manipulation of C. antarcticus, resulting in non‐melanized mutants and demonstrating that the melanin is rather of the DHN type. These mutants will allow to elucidate the relevance of melanization for surviving extreme conditions found in the natural habitat as well as in space. [ABSTRACT FROM AUTHOR]

Significance: A data-based calibration method with enhanced depolarization contrast in polarization-sensitive optical coherence tomography (PS-OCT) was developed and demonstrated effective for detecting melanin content in the eye. Aim: We aim to mitigate the dependence between the measured depolarization metric and the intensity signal-to-noise ratio (SNR) for improved visualization of depolarizing tissues, especially in low SNR regions, and to demonstrate the enhanced depolarization contrast to evaluate melanin presence. Approach: A function for calibrating the depolarization metric was experimentally derived from the young albino guinea pig, assuming depolarization free in the retina. A longitudinal study of guinea pigs (9 weeks) was conducted to assess the accumulation of melanin during early eye growth. Furthermore, the melanin content of the sub-macular choroid was compared in eyes with light and dark irides involving 14 human subjects in early middle adulthood. Results: We observed an increase in the improved depolarization contrast, which indicates potential melanin accumulation in the early eye development with age in the pigmented guinea pig eyes. We found a significant difference in melanin content between human eyes with light and dark colors. Conclusions: Our proposed calibration method enhanced the visualization of depolarizing structures in PS-OCT, which can be generalized to all kinds of polarization-sensitive imaging and can potentially monitor melanin in healthy and pathological eyes. [ABSTRACT FROM AUTHOR]

Tyrosinase, a key protein in the biosynthesis of melanin pigments, is crucial in determining skin pigmentation. Inhibiting tyrosinase activity is a promising approach for treating conditions related to excessive pigmentation. For the synthesis of more potent tyrosinase inhibitors, we combined two approaches, para-substitution and lipophilicity, to enhance the inhibitory properties of (E)-2-(4-hydroxybenzylidene)hydrazine-1-carbotiamide, whose enzyme inhibitory properties have been previously demonstrated. The newly synthesized compounds showed potent inhibition activity against tyrosinase in the micromolar concentration range. The synthesised compounds were up to 41 times more effective than kojic acid. In addition to this biological activity, all molecules were evaluated for their sun protection factor to determine their photoprotective effects. All the compounds showed higher efficacy than reference compounds, used as sunscreens in photoprotective preparations. All compounds were noncytotoxic at the concentration required to inhibit tyrosinase activity. With the aim of defining the potential binding modes and the kind of interactions between the studied molecules and the catalytic site of mushroom tyrosinase, molecular docking simulations were also performed. [ABSTRACT FROM AUTHOR]

Melanin overexpression causes skin hyperpigmentation, which is associated with various skin disorders and cosmetic concerns. Umbelliferone, a natural coumarin found widely in plant species, has been noted for its antioxidant and anti-inflammatory effects but has received little attention for its impact on melanogenesis. Here, the effects of umbelliferone on melanogenesis were investigated in vitro and in clinical studies. The results showed that umbelliferone was non-cytotoxic to human skin and B16F10 melanoma cells. It also exhibited significant anti-melanogenic effects, reducing both melanin production and tyrosinase activity in a dose-dependent manner. This effect was achieved through a decrease in tyrosinase mRNA levels. Furthermore, umbelliferone in a formulation was stable under different temperature conditions, and after four weeks of topical application, it significantly decreased the melanin index and increased skin lightness (L*) values compared to those at the baseline. Overall, these findings demonstrate the potential of umbelliferone as a promising skin-lightening agent in the cosmetics industry. [ABSTRACT FROM AUTHOR]

The literature describes niacinamide, but also postbiotics and peptides, as ingredients that improve skin barrier function, but also affect melanin and sebum levels in individuals. However, the combined effects of these ingredients in a single cosmetic serum have not been sufficiently investigated. Therefore, the aim of this randomized controlled study, conducted at the University of Split School of Medicine (Croatia), was to evaluate the effects of cosmetic products containing these active ingredients. This study was registered with ClinicalTrials.gov (NCT06189105) and has been completed. Primary outcomes were the levels of trans epidermal water loss, skin hydration, erythema, melanin, and sebum, all measured in 25 healthy Caucasian participants. Significant differences between hydration levels were observed at week 4 (61.0 ± 11.2 vs. 68.6 ± 13.3 AU, control and intervention). Moreover, a significant decrease in erythema values from the first to last measurement in the intervention group was observed, (379.9 ± 106.8 vs. 333.6 ± 73.5 AU, baseline values and week 4, intervention group). Interestingly, both the increase in skin hydration levels and the decrease in skin erythema after niacinamide serum application were significant in study participants who did not use sun protection products. It is well known that ultraviolet radiation has detrimental effects on human skin, and our results suggest that niacinamide could help counteract these effects. [ABSTRACT FROM AUTHOR]

Ganglioneuroblastoma (GNB) is a rare neurogenic tumor with a predilection for extracranial sites. Its primary intracranial occurrence is anecdotal, with less than ten cases reported in pediatric literature. We report two cases of this unusual entity. The first was a 1-year-old boy who presented with a progressive scalp swelling that radiologically appeared to be a mesenchymal tumor. The tumor was resected completely, and its histopathological examination was suggestive of a pigmented GNB. The clinico-radiological presentation and melanin pigmentation of the tumor were unique features of the case. The second case was a 7-year-old girl who presented with left hemiparesis and raised intracranial pressure due to a large right parietal intraparenchymal tumor that histologically proved to be a GNB. The child succumbed to disease progression a month after undergoing near-total resection of the tumor. Analysis of our cases in the light of a literature review reveals that pediatric intracranial GNBs have diverse clinico-radiological features and can easily be confused for commoner pathologies in both intra- and extra-axial locations. [ABSTRACT FROM AUTHOR]

Objective: The authors sought to compare the results in Fitzpatrick Skin Type (FST) reporting among providers, trainees, and patients. They discussed the implications of discordance in FST reporting among these groups. Methods: This survey-based study was offered to all adult patients (18 years or older), dermatology residents, and dermatology faculty providers at University of Oklahoma Dermatology Clinic in Oklahoma City, Oklahoma. Deidentified information from the patient survey, provider-assigned FST, and provider credentials were consolidated, and data was analyzed by a biostatistician. Results: The provider-assigned FST was more accurate than the patient's own estimation of their own ability to tan versus burn. The patient's race played an important factor in a discrepancy between provider and patient described FST. Additionally, provider years in practice increased the odds of any discrepancy existing. Limitations: This study was conducted at one clinic location encompassing only the immediate geographic population. Conclusion: Despite being the most used skin tone classification system in dermatology, the FST system has many limitations. The classification system needs to be reevaluated or replaced with methods that more accurately, appropriately, and reliably describe skin tones and skin photo reactivity. Education is necessary for current trainees to avoid erroneous use of classifications such as the FST. [ABSTRACT FROM AUTHOR]

Dead fungal cells, known as necromass, are increasingly recognised as significant contributors to long‐term soil carbon pools, yet the genes involved in necromass decomposition are poorly understood. In particular, how microorganisms degrade necromass with differing initial cell wall chemical compositions using carbohydrate‐active enzymes (CAZymes) has not been well studied. Based on the frequent occurrence and high abundance of the fungal genus Trichoderma on decaying fungal necromass in situ, we grew Trichoderma reesei RUT‐C30 on low and high melanin necromass of Hyaloscypha bicolor (Ascomycota) in liquid cultures and assessed T. reesei gene expression relative to each other and relative to glucose. Transcriptome data revealed that T. reesei up‐regulated many genes (over 100; necromass versus glucose substrate) coding for CAZymes, including enzymes that would target individual layers of an Ascomycota fungal cell wall. We also observed differential expression of protease‐ and laccase‐encoding genes on high versus low melanin necromass, highlighting a subset of genes (fewer than 15) possibly linked to the deconstruction of melanin, a cell wall constituent that limits necromass decay rates in nature. Collectively, these results advance our understanding of the genomic traits underpinning the rates and fates of carbon turnover in an understudied pool of Earth's belowground carbon, fungal necromass. [ABSTRACT FROM AUTHOR]

Black fungi on rock surfaces endure a spectrum of abiotic stresses, including UV radiation. Their ability to tolerate extreme conditions is attributed to the convergent evolution of adaptive traits, primarily highly melanized cell walls. However, studies on fungal melanins have not provided univocal results on their photoprotective functions. Here, we investigated whether the black fungi Knufia petricola and Cryomyces antarcticus only use DHN melanin or may employ alternative mechanisms to counteract UV‐induced damage. For this, melanized wild types and non‐melanized Δpks1 mutants were exposed to different doses of UV‐B (312 nm) followed by incubation in constant darkness or in light–dark cycles to allow light‐dependent DNA repair by photolyases (photoreactivation). C. antarcticus could tolerate higher UV‐B doses but was sensitive to white light, whereas K. petricola showed the opposite trend. DHN melanin provided UV‐B protection in C. antarcticus, whereas the same pigment or even carotenoids proved ineffective in K. petricola. Both fungi demonstrated functional photoreactivation in agreement with the presence of photolyase‐encoding genes. Our findings reveal that although the adaptive trait of DHN melanization commonly occurs across black fungi, it is not equally functional and that there are species‐specific adaptations towards either UV‐induced lesion avoidance or repair strategies. [ABSTRACT FROM AUTHOR]

Tyrosinases (TYRs) are type‐3 copper proteins that are widely distributed in nature. They can hydroxylate and oxidize phenolic molecules and are mostly known for producing melanins that confer protection against photo induced damage. TYRs are also thought to play an important role in the 'latch mechanism', where high concentrations of phenolic compounds inhibit oxidative decomposition of organic biomass and subsequent CO2 release, especially relevant in wetland environments. In the present study, we describe two TYRs, HcTyr1 and HcTyr2, from halophilic bacterium Hahella sp. CCB MM4 previously isolated at Matang mangrove forest in Perak, Malaysia. The structure of HcTyr1 was determined by X‐ray crystallography at a resolution of 1.9 Å and represents an uncharacterized group of prokaryotic TYRs as demonstrated by a sequence similarity network analysis. The genes encoding the enzymes were cloned, expressed, purified and thoroughly characterized by biochemical methods. HcTyr1 was able to self‐cleave its lid‐domain (LID) in a protease independent manner, whereas the LID of HcTyr2 was essential for activity and stability. Both enzymes showed variable activity in the presence of different metals, surfactants and NaCl, and were able to oxidize lignin constituents. The high salinity tolerance of HcTyr1 indicates that the enzyme can be an efficient catalyst in the habitat of the host. [ABSTRACT FROM AUTHOR]

Eumelanin is a complex biopolymer that is ubiquitous in nature. Eumelanins are reported to exhibit extensive biochemical and functional properties. These properties attribute to the composition and structural organization of the molecules. Eumelanins are composed of Dihydroxy indole (DHI) and Dihydroxy indole 3 carboxylic acid (DHICA) units and their quinone forms. In spite of immense studies the structure of eumelanin is not completely elucidated. Molecular simulation studies had predicted oligomeric/tetrameric structure of eumelanin. Cephalopod ink eumelanins are used in treating several female reproductive disorders. Since estrogen receptors play a crucial role in female reproductive disorders, the present study aims at understanding the binding affinity of the predicted forms of eumelanin with estrogen receptors by docking and simulation analysis. It was observed that eumelanin has better binding affinity than other estrogen receptor ligands and the closed tetrameric structure of eumelanin showed better binding affinity to estrogen receptor α than β. [ABSTRACT FROM AUTHOR]

Butterfly pea (Clitoria ternatea) flowers contain high levels of anthocyanins and flavonoids, functioning as natural antioxidants to combat free radicals. The antioxidant activity can prevent cell damage and inhibit melanogenesis, contributing to skin whitening by reducing melanin production. The present study investigated the antioxidant, anti-melanogenesis, and cytotoxic effects of butterfly pea flower (BPF) extract on B16 melanoma cells, aiming to explore its potential as a safer, natural alternative for skin whitening. Antioxidant properties and antimelanogenesis potential of BPF extract were evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and tyrosinase inhibition assays, respectively. The cytotoxicity of BPF extract on B16 melanoma cells was further examined using the 3-(4, 5-dimethylthiazolyl-2)-2, 5- diphenyltetrazolium bromide (MTT) assay. The results of the DPPH assay indicated that BPF extract exhibited an IC50 value of 165.10±7.78 ppm, compared to quercetin (the reference compound) with an IC50 value of 3.53±0.08, indicating moderate antioxidant potential. Butterfly pea flower extract showed an IC50 of 130.90±3.52 ppm in tyrosinase inhibition assay, indicating a weaker anti-melanogenesis effect than hydroquinone (IC50 value of 17.04±0.14 ppm). The MTT technique revealed high biocompatibility with 85% B16 melanoma cell viability at 250 ppm for BPF, compared to only 24.45% for doxorubicin at 30 ppm. These findings underscore the potential of BPF extract as a bioactive ingredient for skin care, offering moderate antioxidant activity with safe, natural anti-melanogenesis effects. The present study supports BPF's application in cosmetic formulations aimed at skin protection and whitening, with minimized toxicity for prolonged use. [ABSTRACT FROM AUTHOR]

The rising global demand for energy requires, among others, sustainable energy storage devices. Biosourced redox‐active molecules are interesting for eco‐designed electrochemical energy storage as they increase the energy density of the electrodes adding the Faradaic (redox) storage mechanism to the electrostatic one. The engineering of the electrode surface and electrode surface/molecule interface is key to optimizing storage. Here, (i) electrodes prepared by ultrasound‐assisted modification of carbon cloth in the presence of Sepia melanin, a quinone macromolecule, and multiwalled carbon nanotubes (MWCNTs) and (ii) their use in flexible symmetric electrochemical capacitors assembled with polyvinyl alcohol (PVA)‐based hydrogel electrolyte is reported. Electrodes exhibit an areal capacitance as high as 274 mF cm−2. Corresponding semi‐solid‐state symmetric supercapacitors feature high energy density of 18 Wh kg−1, power density up to 221 W kg−1 (evaluated at 0.5 A g−1), outstanding cycling stability (100% capacitance retention, and 100% Coulombic efficiency after 10 000 cycles) along with excellent flexibility. This work contributes to the development of sustainable surface engineering approaches for environmentally benign electrochemical energy storage devices. [ABSTRACT FROM AUTHOR]

Alpinia oxyphylla Miq. is an important undergrowth species in southern China. The fruits of A. oxyphylla are recognized as one of "the four famous south medicines" and are also used in the production of preserved fruit. However, as non-medicinal parts, their stems and leaves are unutilized. In order to promote resource recycling, the chemical components of such stems and leaves were investigated, and we evaluated their melanin inhibitory potential through DPPH and ABTS radical scavenging, tyrosinase inhibition, and melanin production inhibition in B16 cells. Five new compounds, aloxy A (1), kaempferol 3-O-α-L-rhamnosyl-(1 → 2)-(3″,4″-diacetyl-β-D-glucuronate methyl ester) (2), quercetin 3-O-α-L-rhamnosyl-(1 → 2)-(3″,4″-diacetyl-β-D-glucuronate methyl ester) (3), kaempferol 3-O-α-L-rhamnosyl-(1 → 3)-(4″-acetyl-β-D-glucuronate methyl ester) (4), and kaempferol 3-O-α-L-rhamnosyl-(1 → 2)-(3″-acetyl-β-D-glucuronate methyl ester) (5), and seventeen known ones (6–22) were isolated and identified from the stems and leaves of A. oxyphylla. Among these compounds, 19 compounds presented tyrosinase inhibitory activities, among which aloxy A (1), hexahydrocurcumin (7), gingerenone A (8) and 4,4′-dimethoxy-3′-hydroxy-7,9′:7′,9-diepoxylignan-3-O-β-D-glucopyranoside (22) showed strong inhibitory activity, with IC50 values between 6.26 ± 0.42 and 22.04 ± 1.09 μM, lower than the positive control (Kojic acid, IC50 = 37.22 ± 1.64 μM). A total of 15 compounds exhibited varying degrees of DPPH and ABTS radical scavenging activities. In addition, 1, 2, and 7 showed melanin production inhibition activity in B16 cells, and the effects presented as concentration-dependent. The above results indicate that the stems and leaves of A. oxyphylla are rich with phenolic compounds, and display tyrosinase inhibition and antioxidant activities, which could lead to potential applications related to melanin production inhibition such as in the development of cosmetics. [ABSTRACT FROM AUTHOR]

Coming in a variety of forms, melanin is one of the most abundant, stable, diverse, and evolutionarily ancient pigments found in living things in nature. These pigments often serve protective functions, typically well-adapted to their specific roles. One such protective function is metal chelation and cation exchange, which help regulate and buffer metal concentrations within cells. By binding to certain metals, melanin can acquire magnetic properties. Because of this, it may play a role in magnetic effects and possibly in the response of organisms to external magnetic fields and magnetic sensing. While there is melanin in plants, microbes, fungi, and invertebrates, certain types of melanin are specifically associated with the retina in vertebrates, including migrating bird and fish species. In this review, we examine studies focusing on the properties of melanin in these parts of the body and their possible association with magnetic sensing, and generally, magnetic sensing in the retina. [ABSTRACT FROM AUTHOR]

Thermal plasticity of melanin pigmentation patterns in Drosophila species has been studied as a model to investigate developmental mechanisms of phenotypic plasticity. The developmental process of melanin pigmentation patterns on wings of Drosophila is divided into two parts, prepattern specification during the pupal period and wing vein-dependent transportation of melanin precursors after eclosion. Which part can be affected by thermal changes? To address this question, we used polka-dotted melanin spots on wings of Drosophila guttifera, whose spot areas are specified by wingless morphogen. In this research, we reared D. guttifera at different temperatures to test whether wing spots show thermal plasticity. We found that wing size becomes larger at lower temperature and that different spots have different reaction norms. Furthermore, we changed the rearing temperature in the middle of the pupal period and found that the most sensitive developmental periods for wing size and spot size are different. The results suggest that the size control mechanisms for the thermal plasticity of wing size and spot size are independent. We also found that the most sensitive stage for spot size was part of the pupal period including stages at which wingless is expressed in the polka-dotted pattern. Therefore, it is suggested that temperature change might affect the prepattern specification process and might not affect transportation through wing veins.

ABSTRACT Reptiles showcase an extensive array of skin colours and patterns, yet little is known about the genetics of reptile colouration. Here, we investigate the genetic basis of the Clown colour morph found in captive‐bred ball pythons (Python regius) to study skin pigmentation and patterning in snakes. We obtained samples by crowdsourcing shed skin from commercial breeders and hobbyists. We applied a case–control design, whole‐genome pool sequencing, variant annotation, histological analyses, and electron microscopy imaging. We identified a missense mutation in a transmembrane region of the melanocortin‐1 receptor (MC1R) associated with the Clown phenotype. In classic avian and mammalian model species, MC1R is known for controlling the type and amount of melanin produced. In contrast, our results suggest that MC1R signalling might play a key role in pattern formation in ball pythons, affecting xanthophore–melanophore distribution. This work highlights the varied functions of MC1R across different vertebrate lineages and promotes a novel model system to study reptile colouration. [ABSTRACT FROM AUTHOR]

Excessive ultraviolet (UV) radiation can cause human skin erythema, tanning, inflammation and other adverse reactions. Human skin can spontaneously synthesize endogenous melanin under UV radiation to defend against the damage of UV, but skin problems such as light damage and light aging cannot be avoided due to its low UV shielding efficiency. Therefore, we design a natural and biocompatible PGDA (poly-γ-glutamic acid/melanin-like hydrogel) sunscreen hydrogel by crosslinking melanin-like L -lysine-doped polydopamine (PDA- L) and amino acid biopolymer poly-γ-glutamic acid, which displays good biosafety, efficient UVA shielding performance and excellent anti-inflammatory performance in the applications of skin protection from the sun and repair after sunburn. The introduction of PDA- L to the hydrogel can improve the absorption intensity in the UV region and the antioxidative performance of the hydrogel. Meanwhile, the usage of biocompatible PGDA sunscreen hydrogel can avoid the skin oxidative damage and penetrative toxicity of conventional sunscreens. [ABSTRACT FROM AUTHOR]

Amino acid surfactants are widely used in areas of life and industry. Biomimetic synthesis of a new type of amino acid surfactant was based on the melanogenesis using the natural substances ethyl protocatechuate. Ethyl protocatechuate was oxidized to o‐benzoquinone using silver oxide. The amino group of amino acids, including arginine, cysteine, glutamic acid, histidine, leucine, and threonine, was conjugated with o‐benzoquinone to synthesize melanin‐like amino acid surfactants. o‐Benzoquinone moiety behaved as hydrophobic part while amino acid residue served as hydrophilic head group. The critical micelle concentration of cysteine product was 1.18 mM. The melanin‐like amino acid surfactant showed excellent foamability, wettability, emulsification, solubilization, and dispersibility properties. Arginine product showed the longest foam half lifetime of 18 min; the wetting time of threonine product was 23 s; the emulsion delamination time of cysteine product was 1034 and 1940 s for liquid paraffin and soybean oil, respectively; threonine product had the most solubilization capacity of 9430 mL mol−1 of benzene; glutamic acid product showed the highest lime soap dispersing power value of 45.58%. It was the first invention for biomimetic synthesis of amino acid surfactant from aspect of both structure and route. Melanin‐like amino acid surfactant had promising potential in both fundamental research and industrial application. [ABSTRACT FROM AUTHOR]

Neuroendocrine regulation is essential for maintaining metabolic homeostasis. However, whether neuroendocrine pathway influence bone metabolism and skeletal senescence is unelucidated. Here, a central neuroendocrine circuit is identified that directly controls osteogenesis. Using virus based tracing, this study is identified that melanin concentrating hormone (MCH) expressing neurons in the lateral hypothalamus (LH) are connected to the bone. Chemogenetic activation of MCH neurons in the LH induces osteogenesis, whereas inhibiting these neurons reduces osteogenesis. Meanwhile, MCH is released into the circulation upon chemogenetic activation of these neurons. Single cell sequencing reveals that blocking MCH neurons in the LH diminishes osteogenic differentiation of bone marrow stromal cells (BMSCs) and induces senescence. Mechanistically, MCH promotes BMSC differentiation by activating MCHR1 via PKA signaling, and activating MCHR1 by MCH agonists attenuate skeletal senescence in mice. By elucidating a brain‐bone connection that autonomously enhances osteogenesis, these findings uncover the neuroendocrinological mechanisms governing bone mass regulation and protect against skeletal senescence. [ABSTRACT FROM AUTHOR]

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 3.54 m2/g exhibiting type IV isotherms. BJH results in a total pore volume of 5.79 cc/g with a pore diameter of 6.54 ± 1 nm for pores smaller than 4544.8 Å. Exhibits Eumelanin properties were characterized by FE – SEM and FTIR functional elements. ICPMS confirmed the metal adsorption proficiency on both raw and melanized membranes before and after treatments. Over 17 heavy metals, Ni2+ were adsorbed with 100% efficiency by raw melanin alone with 42.48 µg/L of Ni2+ concentration in the water sample, whereas, Cu2+, Zn2+, Co2+, Cr2+, Pb2+, Mn2+, Al3+, Mo6+, Sb3+, Ba2+, Fe2+, and Mg2+ stands next with 99%. In this study, gentle/simple application of raw fungal melanin (without PUR tailored) can detoxify the maximum concentration of heavy metals present in the water bodies which are further used for irrigation and even drinking purposes. This mycoremediation approach can be easily adapted to industrial production than other high-performance membrane materials with minimal process modification, making it a promising strategy for improving the adsorption properties used in various applications after still furthermore investigation. [ABSTRACT FROM AUTHOR]

Several animals present ornamental colouration which acts as signals in sexual or other social contexts by indicating some trait of the bearer. This colouration is often present only in one sex and may be produced by a varied combination of structural elements and several pigments. Given that colours may be produced in different ways, the traits the colouration is indicating, and the costs or trade?offs associated, may differ according to the colour and the species studied. Here, I study a dark ventral colouration present in males of the gecko Quedenfeldtia trachyblepharus, a high‐altitude, semi‐colonial lizard endemic to the High Atlas in North Africa. I tested for the correlation between the extension of the dark colouration and several morphological traits (body size, head size and limb length) in the gecko, as well as parasitism by mites and age. No relationship was found between dark colouration and parasitism, age and limb length, but the extension of the dark colouration was positively correlated with head size controlled for body size. Given that head size is usually a good indicator of fighting capacity, and this gecko shows a strong social structure, the findings suggest that the dark colouration is used in agonistic encounters among males, allowing for evaluation of the fighting capacity of the rivals. [ABSTRACT FROM AUTHOR]