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Structure of melanin precursors for the different types of melanin (in brackets). Only the most representative for every type is shown. (a) L-tyr and L-Dopa (eumelanin); (b) 5-cys-dopa (pheomelanin); (c) dopamine and 5-S-cys-dopamine (neuromelanin); (d) N-acetyl-dopamine (insect-melanin); (e) catechol (catechol-melanin, plants); (f) DHN, 1,8-dihydroxynaphthalene (DHN-melanin, fungi); (g) GHB, 4-glutaminyhydroxylbenzene (GHB-melanin, mushroom); (h) HGA, homogentisic acid (pyomelanin).

Structure of melanin precursors for the different types of melanin (in brackets). Only the most representative for every type is shown. (a) L-tyr and L-Dopa (eumelanin); (b) 5-cys-dopa (pheomelanin); (c) dopamine and 5-S-cys-dopamine (neuromelanin); (d) N-acetyl-dopamine (insect-melanin); (e) catechol (catechol-melanin, plants); (f) DHN, 1,8-dihydroxynaphthalene (DHN-melanin, fungi); (g) GHB, 4-glutaminyhydroxylbenzene (GHB-melanin, mushroom); (h) HGA, homogentisic acid (pyomelanin).

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Article
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This review presents a general view of all types of melanin in all types of organisms. Melanin is frequently considered just an animal cutaneous pigment and is treated separately from similar fungal or bacterial pigments. Similarities concerning the phenol precursors and common patterns in the formation routes are discussed. All melanins are formed...

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... In general, there is a consensus that MNs are formed through the oxidation of phenolic precursors and a wide variety of such precursors can be used to generate MN-like materials. [1][2][3][4] In human (and other animal species) physiology two distinct classes of MNs are responsible for the coloration of the skin and hair: eumelanin (EuMN) and pheomelanin (PhMN). [5][6] EuMN is typically described as brown to black colored material built from L-DOPA as the precursor. ...
... Other types of precursors, para-dihydroxybenzene compounds like homogentisic acid (HGA) or dihydroxynaphthalene compounds like 1,8-dihydroxynaphthalene (DHN), can serve as precursors for MN-like materials. 1 It remains to be seen whether any of our observations are applicable to these other types of precursors. In addition, it remains to be seen whether our results have any relevance to the biochemistry of MN in vivo. ...
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This report is a combination of new and former experimental results collected over the past three years. It details our observations and spectroscopic studies of the air-mediated oxidation of a wide variety of catecholic precursors into melanin-like materials. Depending on the precursor involved and the reaction conditions employed, dark-brown to black or yellow to rusty-orange colored reaction mixtures, akin to eumelanin- or pheomelanin-like materials, can be obtained. This report expands and confirms an earlier report that behind the dark colors of eumelanin-like materials, distinct, light-colored, pheomelanin-like materials are hidden. In addition, this report expands and confirms earlier observations regarding the effect of the presence of amino acids on the color of the reaction mixture; particularly the effect of the presence of cysteine. The presence of cysteine delays the onset of color formation and leads to dark-colored reaction mixtures; turning pheomelanin-like reaction mixtures into eumelanin-like mixtures. Visible and infrared spectroscopic analyses were made to evaluate the nature, eumelanin- vs. pheomelanin-like, of the materials generated under the varying reaction conditions. Reactions involving epinephrine as the precursor presented unique results which are detailed in this report.
... Melanocytes produce melanin within membrane-bound organelles termed melanosomes; then, melanosomes are transferred to the surrounding keratinocytes and positioned over the sun-exposed side of nuclei to protect the epidermis from ultraviolet radiation (UVR)-induced DNA damage [3,4]. Melanin is the main determinant of human skin color, although other biomolecules such as carotenoids and hemoglobin can also contribute to skin tone [5]. Skin pigmentation is a sophisticated biological process in which many genes are involved and can be modulated by several intrinsic (e.g., hormonal fluctuations and inflammation) and extrinsic factors (e.g., solar ultraviolet irradiation and environmental pollution) [4,6]. ...
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Fraser’s dolphins (Lagenodelphis hosei) exhibit the capability to restore nearly normal pigmentation after full-thickness wounding. However, the association among melanocytes, melanin and skin pigmentation during wound healing in cetaceans has yet to be addressed. Here, the number of melanocytes and the distribution of melanocytes and melanin in different-colored skin and different wound-healing stages in Fraser’s dolphins were analyzed by using Fontana–Masson staining, immunofluorescence staining and immunohistochemical staining. It was noticed that there was the highest number of melanocytes in dark skin and the lowest number of melanocytes in white skin. The appearance of functional melanocytes and full-melanized neoepidermis was observed in the early stage of wound healing in Fraser’s dolphins. Furthermore, the melanocyte number and skin pigmentation and pattern in healed wounds recovered to a similar condition of unwounded skin. This study provides fundamental knowledge of skin repigmentation in cetaceans for further research, and it will be warranted to elucidate the mechanisms of the replenishment of melanocytes and the regulation of melanocyte activity that contribute to the successful repigmentation in cetacean skin wounds.
... Skin pigmentation is a complex, polygenic trait (Cichorek et al., 2013;Ainger et al., 2017). This trait is the result of differences in biochemical processes and the activity of melanocytes (Solano, 2014), which produce two types of melanin, eumelanin (black/brown) and pheomelanin (red/yellow) (Le Pape et al., 2008). The lack of eyelid pigmentation in Hereford cattle is the result of a genetic background that impact melanocyte development, including cell migration. ...
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Several ocular pathologies in cattle, such as ocular squamous cell carcinoma and infectious keratoconjunctivitis, have been associated with low pigmentation of the eyelids. The main objective of this study was to analyze the transcriptome of eyelid skin in Hereford cattle using strand-specific RNA sequencing technology to characterize and identify long noncoding RNAs (lncRNAs). We compared the expression of lncRNAs between pigmented and unpigmented eyelids and analyzed the interaction of lncRNAs and putative target genes to reveal the genetic basis underlying eyelid pigmentation in cattle. We predicted 4,937 putative lncRNAs mapped to the bovine reference genome, enriching the catalog of lncRNAs in Bos taurus. We found 27 differentially expressed lncRNAs between pigmented and unpigmented eyelids, suggesting their involvement in eyelid pigmentation. In addition, we revealed potential links between some significant differentially expressed lncRNAs and target mRNAs involved in the immune response and pigmentation. Overall, this study expands the catalog of lncRNAs in cattle and contributes to a better understanding of the biology of eyelid pigmentation.
... In general, melanin performs important physiological functions [60,61]. In the biosystem, melanins have a significant range of roles [62,63] in the field of biomedicine and biological functions [64,65] and also it is a very hopeful drug due to its good biocompatibility and biodegradability [27]. ...
Article
Melanin is a complex group of natural pigment substance, and it shows excellent biological and biomedical applications which is commonly present in algae, fungi, bacteria, cephalopoda, and sea cucumber. From the past few decades, great attention has been given to melanin and its derivative for the product development in the area of medical, industrial, food and cosmetic industries. In addition, melanin plays an important in pharmaceutical product development in antioxidant, anti‐inflammatory, immunomodulatory, radioprotective, and gastrointestinal benefits. In this review, we focus on melanin production from various marine species, summarized Purification and extraction strategies of various marine melanin with their analyzes and also their application in medical and industries.
... Nowadays, the term melanins generally refers to a wide group of dark pigments originating from the enzymatic oxidative polymerization of phenolic derivatives and differing from composition, occurrence, and function. 1 The diversity exhibited by these pigments reflects the need of each species to adapt to a specific environment with the more robust nitrogen-free allomelanins found mainly in plants, fungi, and bacteria ( Figure 1). ...
... The modern classification of melanins sets these pigments into five groups on the basis of the structural features of the key monomeric units: (a) eumelanins, pheomelanins, and neuromelanin, found mainly in mammals and characterized by the presence of 5,6-dihydroxyindole and/or benzothiazine units; (b) allomelanins found in plants and fungi, characterized by the presence of phenolic, catecholic, and 1,8-dihydroxynaphthalene (1, units; (c) pyomelanins found mainly in bacteria, characterized by the presence of homogentisic acid units ( Figure 1). 1 Despite the structural diversity exhibited by these pigments, which reflects the different chemistry of the starting monomers in the oxidative polymerization process, all melanins exhibit almost complete insolubility in any solvent, except in the case of pheomelanins and of some bacterial melanins that are slightly alkali soluble, a consequence of the high degree of chemical, structural, redox, and supramolecular disorder. For these reasons, unlike most of the natural pigments, the structure of melanins is not well defined and only a description of the main units, connections, and functional groups is available. ...
... The modern classification of melanins sets these pigments into five groups on the basis of the structural features of the key monomeric units: (a) eumelanins, pheomelanins, and neuromelanin, found mainly in mammals and characterized by the presence of 5,6-dihydroxyindole and/or benzothiazine units; (b) allomelanins found in plants and fungi, characterized by the presence of phenolic, catecholic, and 1,8-dihydroxynaphthalene (1, units; (c) pyomelanins found mainly in bacteria, characterized by the presence of homogentisic acid units ( Figure 1). 1 Despite the structural diversity exhibited by these pigments, which reflects the different chemistry of the starting monomers in the oxidative polymerization process, all melanins exhibit almost complete insolubility in any solvent, except in the case of pheomelanins and of some bacterial melanins that are slightly alkali soluble, a consequence of the high degree of chemical, structural, redox, and supramolecular disorder. For these reasons, unlike most of the natural pigments, the structure of melanins is not well defined and only a description of the main units, connections, and functional groups is available. ...
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Melanins are a wide class of natural pigments biosynthesized by different kinds of living organisms throughout all of the life domains, from bacteria to fungi, plants, and mammals. The biological functions played by these natural pigments are different (i.e., camouflage, radioprotection, thermoregulation) and ascribable to a peculiar set of physical-chemical properties making melanins a unique class of biopolymers. Among these, allomelanins from 1,8-dihydroxynaphthalene (1,8-DHNmel) produced by some Ascomycetes have recently attracted particular interest for their robustness and ability to protect fungi against both hostile (i.e., attack from fungicidal agents) and extreme (i.e., high energy radiations) environments. Starting from this background, in this mini-review we offer a panorama of the recent advances on the oxidative chemistry of 1,8-DHN leading to the formation of allomelanin mimics with tailored structural and functional properties for technological applications.
... Differences in skin pigmentation are due to differences in melanocyte activity in combination with other nongenetic factors, such as environmental and physiological conditions, e.g., exposure to ultraviolet radiation and reaction to thermal stress (Jablonski and Chaplin, 2000). Both animals and humans with higher degree of pigmentation have a greater proportion of melanin in the skin, and hence, better protection against ultraviolet radiation (Haider et al., 2014;Solano, 2014). Our previous work has shown that eyelid pigmentation in cattle is related to the expression of genes involved in melanocyte biology, inflammatory response, infectious processes, and tumoral pathways (Jara et al., 2020). ...
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Ocular squamous cell carcinoma and infectious keratoconjunctivitis are common ocular pathologies in Hereford cattle with considerable economic impact. Both pathologies have been associated with low eyelid pigmentation, and thus, genetic selection for higher eyelid pigmentation could reduce their incidence. The objective of the present study was to reveal the genetic basis of eyelid pigmentation in Hereford cattle. The analysis included a single-step genome-wide association study (ssGWAS) and a subsequent gene-set analysis in order to identify individual genes, genetic mechanisms and biological pathways implicated in this trait. Data consisted of eyelid pigmentation records in 1,165 Hereford bulls and steers, visually assessed in five categories between 0% and 100%. Genotypic data for 774,660 single nucleotide polymorphism markers were available for 886 animals with pigmentation records. Pedigree information of three generations of ancestors of animals with phenotype was considered in this study, with a total of 4,929 animals. Our analyses revealed that eyelid pigmentation is a moderately heritable trait, with heritability estimates around 0.41. The ssGWAS identified at least eight regions, located on BTA1, BTA3, BTA5, BTA14, BTA16, BTA18, BTA19 and BTA24, associated with eyelid pigmentation. These regions harbor genes that are directly implicated in melanocyte biology and skin pigmentation, such as ADCY8, PLD1, KITLG, and PRKCA. The gene-set analysis revealed several functional terms closely related to melanogenesis, such as positive regulation of melanocyte differentiation and regulation of ERK1 and ERK2 cascade. Overall, our findings provide evidence that eyelid pigmentation is a heritable trait influenced by many loci. Indeed, the ssGWAS detected several candidate genes that are directly implicated in melanocyte biology, including melanogenesis. This study contributes to a better understanding of the genetic and biological basis of eyelid pigmentation and presents novel information that could aid to design breeding strategies for reducing the incidence of ocular pathologies in cattle. Additional research on the genetic link between eyelid pigmentation and ocular pathologies is needed.
... Tyrosinase triggers the browning of fruits and vegetables resulting in a decrease of their nutritional value. The development of new tyrosinase inhibitors is of great interest due to their application potential in food, cosmetic, and pharmaceutical industries [3]. ...
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In this study, we tested tyrosinase and α-glucosidase effects of different extracts of Ziziphus jujuba fruits. The n-BuOH subextract inhibited both tyrosinase and α-glucosidase (IC50 = 18.82 ± 1.13 and 25.03 ± 0.77 µg/mL, respectively) better than the positive controls kojic acid and acarbose (IC50 = 58.26 ± 0.25 and 46.10 ± 2.3 µg/mL, respectively). Thus, the n-BuOH extract was selected for further phytochemical studies. Indole-3-lactic acid methylester, catechin, magnoflorine, kaempferol 3-O-α-rhamnopyranosyl-(1 → 6)-β-galactopyranoside, quercetin 3-O-α-rhamnopyranosyl-(1 → 6)-β-galactopyranoside, and procyanidin B4 were isolated from the extract. We tested α-glucosidase and tyrosinase inhibitory effects, as well as DNA nuclease effects of the isolated compounds. Procyanidin B4 exhibited the best activity against both tyrosinase and α-glucosidase (IC50 = 60.25 ± 0.88 and 170.18 ± 5.60 µg/mL, respectively). The isolates did not show any nuclease effect at increasing concentrations. Molecular docking studies provided insights into inhibition mechanisms of the isolates against tyrosinase and α-glucosidase at the molecular level. Supplementary information: The online version contains supplementary material available at 10.1007/s00217-021-03946-0.
... Focus newly on pigment synthesized from biophysical and chemists who were concerned with the bacteriological method. Historically, recorded secondary metabolites' as a wide set of molecules affected at delayed phases of microbial growth in cultures of a laboratory (Soliev et al., 2011) (Solano, 2014) (Stankovic et al., 2014) (Wadday et al., 2019) (Numan et al., 2018). Phenazines are derivatives including heterogeneous nitrogen-containing antibiotic action (Karuppiah et al., 2016) (Pierson and Pierson, 2010), and antimicrobial activity. ...
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This study has focused on just synthesized materials that were produced from bacteriological practice. So, the density functional theory calculations with hybrid B3LYP at 6-31G sets of basis retain lived utilized to examine the properties of structural and electronic properties of biomaterial original. The determinations include been displayed thereof that is a lowering in the energy of total beyond merging the OH and CH3 with Phenazine. HOMO and LUMO levels of energy investigations exhibit that the estimation HOMO energy was boosted slightly at 1-Hydroxyphenazine and 2-Hydroxyphenazine but increasing more in 5-Methylphenazin-1(5H)-one, while the value for the LUMO level energy lowered greatly in these strategies of adding the OH at Phenazine. In addition, the lowering of the gap of energy between HOMO and LUMO ensures a bond of strongly between the hydroxyl group and Phenazine. Ultimately, the Biomaterial stability was investigated by estimating the reaction of chemical factors such as the potential of Ionization (I), Affinity (A), global hardness, and Electronegativity χ. As a result, the hydroxyl group and a methyl group can be considered as factors of important changes within biological systems in many chemical and physical properties.
... Regarding the possibility that it may have been pyomelanin, another substitution pattern would have been observed in the deformation signals in the in plane and outside this for the aromatic nucleus different from the 1:2:3 substitution. The characteristic signals of phenols and their derivatives also would not appear; therefore, the pyomelanin pathway was doubtful as the pyomelanin pathway is reported only in a few mushrooms and basidiomycetes [52]. Here, we were capable of assigning a molecular and bound functional group description to each peak (Table 1) and when comparing our data with the signals reported for A. fumigatus [29], we found similar peaks describing DHN-melanin. ...
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Sclerotium cepivorum Berk is the etiological agent of white rot disease that affects plants of the genus Allium. This fungus produces resistance structures called sclerotia that are formed by a rolled mycelium with a thick layer of melanin and it can remain dormant for many years in the soil. Current interest in S. cepivorum has arisen from economic losses in Allium crops in the agricultural sector. Melanin is a component that protects the sclerotia from adverse environmental conditions In many organisms, it plays an important role in the infectious process; in S. cepivorum, the pathway by which this component is synthetized is not fully described. By using infrared spectrophotometric assays applied direct to the sclerotia and a melanin extract followed by an NMR analysis and a tricyclazole melanin inhibition experiment, it allowed us to determine the dihydroxynaphthalene (DHN)-melanin pathway by which S. cepivorum performs its melanin synthesis. Moreover, we focused on studying scytalone dehydratase (SDH) as a key enzyme of the DHN-melanin synthesis. We obtained the recombinant SDH enzyme and tested its activity by a zymogram assay. Thereby, the S. cepivorum melanogenic route was established as a DHN pathway.
... Since the melanocytes used in this study were derived from Caucasians having a low level of melanin production, L-DOPA, a precursor in melanin synthesis, 38 was applied to stimulate melanogenesis in vitro. 8 L-DOPA is converted to L-dopaquinone, which is further transformed to produce eumelanin or pheomelanin. ...
Article
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Skin hyperpigmentation is commonly treated by topical drug application. Several naturally occurring compounds exhibit attractive biological effects including anti‐melanogenic activity. Chemically modified derivatives of those compounds are expected to be more efficient. However, efficacy and safety testing processes are of significant consideration to identify the most effective compound among them. Herein, we demonstrated a tiered approach to investigate the antipigmentation activity of 17 trans‐N‐coumaroyltyramine derivatives. First, we evaluated the in chemico antityrosinase activity, then the cytotoxicity of the most potent derivatives using a mitochondrial activity‐based assay, followed with the in vitro anti‐melanogenic activity in two dimensional (2D) monolayer human melanocytes. The selected derivatives were topically applied on a three dimensional (3D) pigmented‐reconstructed human epidermis (pRhE) containing melanocytes and keratinocytes to evaluate their depigmenting activity. Two of the 17 derivatives displayed a significant reduction in pigmentation in the 3D pRhE, comparable to kojic acid, a known tyrosinase inhibitor. In addition, a molecular docking experiment indicated an interaction of the three derivatives and tyrosinase, suggesting that these derivatives have potent anti‐melanogenic activity through tyrosinase inhibition. Our findings provide an alternative approach for investigating skin‐whitening agents, thereby facilitating the research and development of skin‐whitening products that need not be tested on animals.