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Journal of Materials Chemistry. B Feb 2021Here we present the important findings related to biologically derived pigments for potential use as antibacterial agents. Melanin biopigments extracted from Equus ferus...
Here we present the important findings related to biologically derived pigments for potential use as antibacterial agents. Melanin biopigments extracted from Equus ferus hair exhibit a homogeneous elliptical microstructure with highly ordered semicrystalline features. Spectroscopic analysis indicates that melanin contains a high degree of redox active catechol groups, which can produce reactive oxygen species. The antibacterial activity of melanins was tested by incubating Escherichia coli and Staphylococcus aureus with melanins. The results showed 100% bacterial growth inhibition within 4 h. This finding suggests that melanin pigments may serve as naturally occurring antibacterial agents with unique redox chemistry and reactive oxygen species generation capability.
Topics: Animals; Anti-Bacterial Agents; Escherichia coli; Hair; Horses; Melanins; Microbial Sensitivity Tests; Particle Size; Pigments, Biological; Staphylococcus aureus; Surface Properties
PubMed: 33320923
DOI: 10.1039/d0tb02475a -
Applied Microbiology and Biotechnology Feb 2012Melanin is a unique pigment with myriad functions that is found in all biological kingdoms. It is multifunctional, providing defense against environmental stresses such... (Review)
Review
Melanin is a unique pigment with myriad functions that is found in all biological kingdoms. It is multifunctional, providing defense against environmental stresses such as ultraviolet (UV) light, oxidizing agents and ionizing radiation. Melanin contributes to the ability of fungi to survive in harsh environments. In addition, it plays a role in fungal pathogenesis. Melanin is an amorphous polymer that is produced by one of two synthetic pathways. Fungi may synthesize melanin from endogenous substrate via a 1,8-dihydroxynaphthalene (DHN) intermediate. Alternatively, some fungi produce melanin from L-3,4-dihydroxyphenylalanine (L-dopa). The detailed chemical structure of melanin is not known. However, microscopic studies show that it has an overall granular structure. In fungi, melanin granules are localized to the cell wall where they are likely cross-linked to polysaccharides. Recent studies suggest the fungal melanin may be synthesized in internal vesicles akin to mammalian melanosomes and transported to the cell wall. Potential applications of melanin take advantage of melanin's radioprotective properties and propensity to bind to a variety of substances.
Topics: Cell Wall; Cryptococcus neoformans; Fungi; Melanins; Melanosomes; Microscopy, Electron, Transmission
PubMed: 22173481
DOI: 10.1007/s00253-011-3777-2 -
Prikladnaia Biokhimiia I Mikrobiologiia 2014This review is dedicated to the research on the functions of melanin pigments in fungi. The participation of melanin pigments in protection from environmental factors is... (Review)
Review
This review is dedicated to the research on the functions of melanin pigments in fungi. The participation of melanin pigments in protection from environmental factors is considered. Data on the biosynthetic pathways and types of melanin pigments in fungi are presented.
Topics: Adaptation, Biological; Cell Wall; Fungi; Melanins; Pigments, Biological; Temperature; Ultraviolet Rays
PubMed: 25272728
DOI: 10.7868/s0555109914020093 -
Traffic (Copenhagen, Denmark) Jul 2006Skin pigmentation is accomplished by production of melanin in specialized membrane-bound organelles termed melanosomes and by transfer of these organelles from... (Review)
Review
Skin pigmentation is accomplished by production of melanin in specialized membrane-bound organelles termed melanosomes and by transfer of these organelles from melanocytes to surrounding keratinocytes. The mechanism by which these cells transfer melanin is yet unknown. A central role has been established for the protease-activated receptor-2 of the keratinocyte which effectuates melanin transfer via phagocytosis. What exactly is being phagocytosed - naked melanin, melanosomes or melanocytic cell parts - remains to be defined. Analogy of melanocytes to neuronal cells and cells of the haemopoietic lineage suggests exocytosis of melanosomes and subsequent phagocytosis of naked melanin. Otherwise, microscopy studies demonstrate cytophagocytosis of melanocytic dendrites. Other plausible mechanisms are transfer via melanosome-containing vesicles shed by the melanocyte or transfer via fusion of keratinocyte and melanocyte plasma membranes with formation of tunnelling nanotubes. Molecules involved in transfer are being identified. Transfer is influenced by the interactions of lectins and glycoproteins and, probably, by the action of E-cadherin, SNAREs, Rab and Rho GTPases. Further clues as to what mechanism and molecular machinery will arise with the identification of the function of specific genes which are mutated in diseases that affect transfer.
Topics: Animals; Biological Transport; Cell Membrane; Disease; Exocytosis; Humans; Melanins; Pigmentation
PubMed: 16787393
DOI: 10.1111/j.1600-0854.2006.00425.x -
Macromolecular Bioscience Dec 2021Melanin and polydopamine are potent biopolymers for the development of biomedical nanosystems. However, applications of melanin or polydopamine-based nanoparticles are...
Melanin and polydopamine are potent biopolymers for the development of biomedical nanosystems. However, applications of melanin or polydopamine-based nanoparticles are limited by drawbacks related to a compromised colloidal stability over long time periods and associated cytotoxicity. To overcome these hurdles, a novel strategy is proposed that mimics the confinement of natural melanin in melanosomes. Melanosome mimics are developed by co-encapsulating the melanin/polydopamine precursors L-DOPA/dopamine with melanogenic enzyme Tyrosinase within polymersomes. The conditions of polymersome formation are optimized to obtain melanin/polydopamine polymerization within the cavity of the polymersomes. Similar to native melanosomes, polymersomes containing melanin/polydopamine show long-term colloidal stability, cell-compatibility, and potential for cell photoprotection. This novel kind of artificial melanogenesis is expected to inspire new applications of the confined melanin/polydopamine biopolymers.
Topics: Cell Line; Humans; Indoles; Melanins; Melanosomes; Monophenol Monooxygenase; Polymers
PubMed: 34510748
DOI: 10.1002/mabi.202100249 -
Applied and Environmental Microbiology Jan 2021is a phytopathogenic fungus responsible for corn smut disease. Although it is a very well-established model organism for the study of plant-microbe interactions, its...
is a phytopathogenic fungus responsible for corn smut disease. Although it is a very well-established model organism for the study of plant-microbe interactions, its potential to produce specialized metabolites, which might contribute to this interaction, has not been studied in detail. By analyzing the genome, we identified a biosynthetic gene cluster whose activation led to the production of a black melanin pigment. Single deletion mutants of the cluster genes revealed that five encoded enzymes are required for the accumulation of the black pigment, including three polyketide synthases (, , and ), a cytochrome P450 monooxygenase (), and a protein with similarity to versicolorin B synthase (). Metabolic profiles of deletion mutants in this gene cluster suggested that Pks3 and Pks4 act in concert as heterodimers to generate orsellinic acid (OA), which is reduced to the corresponding aldehyde by Pks5. The OA-aldehyde can then react with triacetic acid lactone (TAL), also derived from Pks3/Pks4 heterodimers to form larger molecules, including novel coumarin derivatives. Our findings suggest that synthesizes a novel type of melanin based on coumarin and pyran-2-one intermediates, while most fungal melanins are derived from 1,8-dihydroxynaphthalene (DHN) or l-3,4-dihydroxyphenylalanine (l-DOPA). Along with these observations, this work also provides insight into the mechanisms of polyketide synthases in this filamentous fungus. The fungus represents one of the major threats to maize plants since it is responsible for corn smut disease, which generates considerable economical losses around the world. Therefore, contributing to a better understanding of the biochemistry of defense mechanisms used by to protect itself against harsh environments, such as the synthesis of melanin, could provide improved biological tools for tackling the problem and protect the crops. In addition, the fact that this fungus synthesizes melanin in an unconventional way, requiring more than one polyketide synthase for producing melanin precursors, gives a different perspective on the complexity of these multidomain enzymes and their evolution in the fungal kingdom.
Topics: Basidiomycota; Melanins; Multigene Family
PubMed: 33218994
DOI: 10.1128/AEM.01510-20 -
Fortschritte Der Chemie Organischer... 2007
Review
Topics: Animals; Humans; Light; Melanins; Melanocytes; Oxidation-Reduction; Tryptophan; Vitiligo
PubMed: 17302180
DOI: 10.1007/978-3-211-49389-2_3 -
Journal of Enzyme Inhibition and... Dec 2017Melanogenesis is a process to synthesize melanin, which is a primary responsible for the pigmentation of human skin, eye and hair. Although numerous enzymatic catalyzed... (Review)
Review
Melanogenesis is a process to synthesize melanin, which is a primary responsible for the pigmentation of human skin, eye and hair. Although numerous enzymatic catalyzed and chemical reactions are involved in melanogenesis process, the enzymes such as tyrosinase and tyrosinase-related protein-1 (TRP-1) and TRP-2 played a major role in melanin synthesis. Specifically, tyrosinase is a key enzyme, which catalyzes a rate-limiting step of the melanin synthesis, and the downregulation of tyrosinase is the most prominent approach for the development of melanogenesis inhibitors. Therefore, numerous inhibitors that target tyrosinase have been developed in recent years. The review focuses on the recent discovery of tyrosinase inhibitors that are directly involved in the inhibition of tyrosinase catalytic activity and functionality from all sources, including laboratory synthetic methods, natural products, virtual screening and structure-based molecular docking studies.
Topics: Animals; Catalysis; Enzyme Inhibitors; Humans; Melanins; Monophenol Monooxygenase; Skin Lightening Preparations
PubMed: 28097901
DOI: 10.1080/14756366.2016.1256882 -
Journal of Photochemistry and... Feb 1992This paper reviews the biosynthesis and physicochemical properties of the ocular melanin. Age-related changes of melanin granules and the corresponding formation of... (Review)
Review
This paper reviews the biosynthesis and physicochemical properties of the ocular melanin. Age-related changes of melanin granules and the corresponding formation of lipofuscin pigments in the retinal pigment epithelium (RPE) are also described. Adverse photoreactions of the eye and, in particular, light-induced damage to the RPE-retina are reviewed in relation to the ocular pigmentation. A hypothesis on the photoprotective role of the RPE melanin is presented that is based on the ability of the cellular melanin to bind redoxactive metal ions. Since bound-to-melanin metal ions are expected to be less damaging to the pigment cells, it is proposed that sequestration of heavy metal ions by the RPE melanin is an efficient detoxifying mechanism. It is postulated that oxidative degradation of RPE melanin may lower its metal-binding capability and decrease its anti-oxidant efficiency. Cellular and environmental factors that may contribute to possible oxidative damage of the RPE melanin are discussed in connection with the etiology of age-related macular degeneration.
Topics: Aging; Animals; Humans; Light; Melanins; Pigment Epithelium of Eye; Retina
PubMed: 1635010
DOI: 10.1016/1011-1344(92)85027-r -
Photochemistry and Photobiology 2008Melanin has a photo-screening, a biophysical/biochemical and a cosmetic effect. Melanin content of cultured pigmented cells can be measured by spectrophotometry and... (Review)
Review
Melanin has a photo-screening, a biophysical/biochemical and a cosmetic effect. Melanin content of cultured pigmented cells can be measured by spectrophotometry and expressed either as melanin content per cell or melanin content per culture (area). Melanin production can be calculated from melanin content and cell number at the beginning and at the end of a culture using various formulas and expressed as melanin production per cell per day or melanin production per culture per day. Melanin content or production per cell have been used widely to compare melanin content in various cell lines or to compare the melanin content during different stages in the culture (e.g. growing stage and senescent stage). For the evaluation of changes in melanin content and production in a given pigment cell line after treatment with a special chemical, physical or biological stimulator or inhibitor, different parameters used for the evaluation of experimental data can lead to conflicting results. Melanin content per area is determined by melanin content per cell and the number of cells in this area. The biological and cosmetic effects of melanin in vivo are determined mainly by melanin content per area, not melanin content per cell. For example, if melanin content per cell is the same, but the number of cells in a given area is increased after the treatment, then the melanin content per area is also increased. Under this circumstance, the color of skin turns darker and the total antioxidant activity provided by melanin in this area is increased even though the melanin content per cell measured remains the same; therefore, melanin content or production per culture is more important than melanin content or production per cell under this circumstance.
Topics: Cell Count; Cells, Cultured; Melanins; Melanocytes; Pigment Epithelium of Eye; Spectrophotometry; Uvea
PubMed: 18435617
DOI: 10.1111/j.1751-1097.2007.00228.x