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International Journal of Molecular... May 2024Nanotechnology is revolutionizing fields of high social and economic impact. such as human health preservation, energy conversion and storage, environmental... (Review)
Review
Nanotechnology is revolutionizing fields of high social and economic impact. such as human health preservation, energy conversion and storage, environmental decontamination, and art restoration. However, the possible global-scale application of nanomaterials is raising increasing concerns, mostly related to the possible toxicity of materials at the nanoscale. The possibility of using nanomaterials in cosmetics, and hence in products aimed to be applied directly to the human body, even just externally, is strongly debated. Preoccupation arises especially from the consideration that nanomaterials are mostly of synthetic origin, and hence are often seen as "artificial" and their effects as unpredictable. Melanin, in this framework, is a unique material since in nature it plays important roles that specific cosmetics are aimed to cover, such as photoprotection and hair and skin coloration. Moreover, melanin is mostly present in nature in the form of nanoparticles, as is clearly observable in the ink of some animals, like cuttlefish. Moreover, artificial melanin nanoparticles share the same high biocompatibility of the natural ones and the same unique chemical and photochemical properties. Melanin is hence a natural nanocosmetic agent, but its actual application in cosmetics is still under development, also because of regulatory issues. Here, we critically discuss the most recent examples of the application of natural and biomimetic melanin to cosmetics and highlight the requirements and future steps that would improve melanin-based cosmetics in the view of future applications in the everyday market.
Topics: Melanins; Humans; Hair Color; Animals; Cosmetics; Nanoparticles; Skin Pigmentation; Nanostructures; Nanotechnology
PubMed: 38892049
DOI: 10.3390/ijms25115862 -
Molecules (Basel, Switzerland) Jul 2022Japanese pharmaceutical cosmetics, often referred to as quasi-drugs, contain skin-lightening active ingredients formulated to prevent sun-induced pigment spots and... (Review)
Review
Japanese pharmaceutical cosmetics, often referred to as quasi-drugs, contain skin-lightening active ingredients formulated to prevent sun-induced pigment spots and freckles. Their mechanisms of action include suppressing melanin production in melanocytes and promoting epidermal growth to eliminate melanin more rapidly. For example, arbutin and rucinol are representative skin-lightening active ingredients that inhibit melanin production, and disodium adenosine monophosphate and dexpanthenol are skin-lightening active ingredients that inhibit melanin accumulation in the epidermis. In contrast, oral administration of vitamin C and tranexamic acid in pharmaceutical products can lighten freckles and melasma, and these products are more effective than quasi-drugs. On the basis of their clinical effectiveness, skin-lightening active ingredients can be divided into four categories according to their effectiveness and adverse effects. This review discusses academic research and development regarding skin-lightening ingredients in Japan.
Topics: Arbutin; Humans; Japan; Melanins; Melanosis; Skin
PubMed: 35897958
DOI: 10.3390/molecules27154774 -
Protoplasma Sep 2021
Topics: Animals; Melanins; Morphogenesis; Secondary Metabolism
PubMed: 34383139
DOI: 10.1007/s00709-021-01693-3 -
Biosensors Oct 2023Polydopamine (PDA), the synthetic counterpart of melanin, is a widely investigated bio-inspired material for its chemical and photophysical properties, and in the last... (Review)
Review
Polydopamine (PDA), the synthetic counterpart of melanin, is a widely investigated bio-inspired material for its chemical and photophysical properties, and in the last few years, bio-application of PDA and PDA-based materials have had a dramatic increase. In this review, we described PDA application in optical biosensing, exploring its multiple roles as a nanomaterial. In optical sensing, PDA can not only be used for its intrinsic fluorescent and photoacoustic properties as a probe: in some cases, a sample optical signal can be derived by melanin generation in situ or it can be enhanced in another material thanks to PDA modification. The various possibilities of PDA use coupled with its biocompatibility will indeed widen even more its application in optical bioimaging.
Topics: Melanins; Indoles; Polymers; Nanostructures
PubMed: 37998131
DOI: 10.3390/bios13110956 -
International Journal of Molecular... Jul 2023Skin pigmentation ensures efficient photoprotection and relies on the pigment melanin, which is produced by epidermal melanocytes and transferred to surrounding... (Review)
Review
Skin pigmentation ensures efficient photoprotection and relies on the pigment melanin, which is produced by epidermal melanocytes and transferred to surrounding keratinocytes. While the molecular mechanisms of melanin synthesis and transport in melanocytes are now well characterized, much less is known about melanin transfer and processing within keratinocytes. Over the past few decades, distinct models have been proposed to explain how melanin transfer occurs at the cellular and molecular levels. However, this remains a debated topic, as up to four different models have been proposed, with evidence presented supporting each. Here, we review the current knowledge on the regulation of melanin exocytosis, internalization, processing, and polarization. Regarding the different transfer models, we discuss how these might co-exist to regulate skin pigmentation under different conditions, i.e., constitutive and facultative skin pigmentation or physiological and pathological conditions. Moreover, we discuss recent evidence that sheds light on the regulation of melanin exocytosis by melanocytes and internalization by keratinocytes, as well as how melanin is stored within these cells in a compartment that we propose be named the melanokerasome. Finally, we review the state of the art on the molecular mechanisms that lead to melanokerasome positioning above the nuclei of keratinocytes, forming supranuclear caps that shield the nuclear DNA from UV radiation. Thus, we provide a comprehensive overview of the current knowledge on the molecular mechanisms regulating skin pigmentation, from melanin exocytosis by melanocytes and internalization by keratinocytes to processing and polarization within keratinocytes. A better knowledge of these molecular mechanisms will clarify long-lasting questions in the field that are crucial for the understanding of skin pigmentation and can shed light on fundamental aspects of organelle biology. Ultimately, this knowledge can lead to novel therapeutic strategies to treat hypo- or hyper-pigmentation disorders, which have a high socio-economic burden on patients and healthcare systems worldwide, as well as cosmetic applications.
Topics: Humans; Melanins; Melanocytes; Keratinocytes; Epidermis; Skin Pigmentation; Melanosomes
PubMed: 37511054
DOI: 10.3390/ijms241411289 -
Photochemistry and Photobiology Mar 2023Light is one way to excite an electron in biology. Another is chemiexcitation, birthing a reaction product in an electronically excited state rather than exciting from... (Review)
Review
Light is one way to excite an electron in biology. Another is chemiexcitation, birthing a reaction product in an electronically excited state rather than exciting from the ground state. Chemiexcited molecules, as in bioluminescence, can release more energy than ATP. Excited states also allow bond rearrangements forbidden in ground states. Molecules with low-lying unoccupied orbitals, abundant in biology, are particularly susceptible. In mammals, chemiexcitation was discovered to transfer energy from excited melanin, neurotransmitters, or hormones to DNA, creating the lethal and carcinogenic cyclobutane pyrimidine dimer. That process was initiated by nitric oxide and superoxide, radicals triggered by ultraviolet light or inflammation. Several poorly understood chronic diseases share two properties: inflammation generates those radicals across the tissue, and cells that die are those containing melanin or neuromelanin. Chemiexcitation may therefore be a pathogenic event in noise- and drug-induced deafness, Parkinson's disease, and Alzheimer's; it may prevent macular degeneration early in life but turn pathogenic later. Beneficial evolutionary selection for excitable biomolecules may thus have conferred an Achilles heel. This review of recent findings on chemiexcitation in mammalian cells also describes the underlying physics, biochemistry, and potential pathogenesis, with the goal of making this interdisciplinary phenomenon accessible to researchers within each field.
Topics: Animals; Melanins; Photochemistry; Pyrimidine Dimers; Ultraviolet Rays; Mammals
PubMed: 36681894
DOI: 10.1111/php.13781 -
Proceedings of the National Academy of... May 2023Age-related macular degeneration, Stargardt disease, and their mouse model are characterized by accelerated accumulation of the pigment lipofuscin, derived from...
Age-related macular degeneration, Stargardt disease, and their mouse model are characterized by accelerated accumulation of the pigment lipofuscin, derived from photoreceptor disc turnover in the retinal pigment epithelium (RPE); lipofuscin accumulation and retinal degeneration both occur earlier in albino mice. Intravitreal injection of superoxide (O) generators reverses lipofuscin accumulation and rescues retinal pathology, but neither the target nor mechanism is known. Here we show that RPE contains thin multi-lamellar membranes (TLMs) resembling photoreceptor discs, which associate with melanolipofuscin granules in pigmented mice but in albinos are 10-fold more abundant and reside in vacuoles. Genetically over-expressing tyrosinase in albinos generates melanosomes and decreases TLM-related lipofuscin. Intravitreal injection of generators of O or nitric oxide (NO) decreases TLM-related lipofuscin in melanolipofuscin granules of pigmented mice by ~50% in 2 d, but not in albinos. Prompted by evidence that O plus NO creates a dioxetane on melanin that excites its electrons to a high-energy state (termed "chemiexcitation"), we show that exciting electrons directly using a synthetic dioxetane reverses TLM-related lipofuscin even in albinos; quenching the excited-electron energy blocks this reversal. Melanin chemiexcitation assists in safe photoreceptor disc turnover.
Topics: Mice; Animals; Melanins; Lipofuscin; Macular Degeneration; Retina; Retinal Pigment Epithelium; ATP-Binding Cassette Transporters
PubMed: 37155898
DOI: 10.1073/pnas.2216935120 -
International Journal of Molecular... Feb 2023Melanin is a biological pigment formed by indoles and phenolic compounds. It is widely found in living organisms and has a variety of unique properties. Due to its... (Review)
Review
Melanin is a biological pigment formed by indoles and phenolic compounds. It is widely found in living organisms and has a variety of unique properties. Due to its diverse characteristics and good biocompatibility, melanin has become the focus in the fields of biomedicine, agriculture, the food industry, etc. However, due to the wide range of melanin sources, complex polymerization properties, and low solubility of specific solvents, the specific macromolecular structure and polymerization mechanism of melanin remain unclear, which significantly limits the further study and application of melanin. Its synthesis and degradation pathways are also controversial. In addition, new properties and applications of melanin are constantly being discovered. In this review, we focus on the recent advances in the research of melanin in all aspects. Firstly, the classification, source, and degradation of melanin are summarized. Secondly, a detailed description of the structure, characterization, and properties of melanin is followed. The novel biological activity of melanin and its application is described at the end.
Topics: Melanins; Indoles; Solvents; Solubility
PubMed: 36901791
DOI: 10.3390/ijms24054360 -
Chemistry (Weinheim An Der Bergstrasse,... Nov 2021Melanin-like nanomaterials have found application in a large variety of high economic and social impact fields as medicine, energy conversion and storage, photothermal... (Review)
Review
Melanin-like nanomaterials have found application in a large variety of high economic and social impact fields as medicine, energy conversion and storage, photothermal catalysis and environmental remediation. These materials have been used mostly for their optical and electronic properties, but also for their high biocompatibility and simplicity and versatility of preparation. Beside this, their chemistry is complex and it yields structures with different molecular weight and composition ranging from oligomers, to polymers as well as nanoparticles (NP). The comprehension of the correlation of the different compositions and morphologies to the optical properties of melanin is still incomplete and challenging, even if it is fundamental also from a technological point of view. In this minireview we focus on scientific papers, mostly recent ones, that indeed examine the link between composition and structural feature and photophysical and photochemical properties proposing this approach as a general one for future research.
Topics: Melanins; Nanoparticles; Nanostructures; Photochemistry; Polymers
PubMed: 34505731
DOI: 10.1002/chem.202102479 -
International Journal of Molecular... Apr 2021Skin color is determined by the processes of melanin synthesis and distribution. Problems in various molecules or signaling pathways involved in melanin synthesis... (Meta-Analysis)
Meta-Analysis Review
Skin color is determined by the processes of melanin synthesis and distribution. Problems in various molecules or signaling pathways involved in melanin synthesis contribute to skin pigmentation defects. Several trials have been conducted on the production of pigmentation-regulating agents, and drug repositioning has emerged as a modern technique to identify new uses for existing drugs. Our research team has researched substances or drugs associated with pigmentation control and, as a result, nilotinib, sorafenib, and ICG-001 have been found to promote pigmentation, while 5-iodotubercidin inhibits pigmentation. Therefore, these substances or medications were suggested as potential therapeutics for pigmentation disorders by drug repositioning.
Topics: Actins; Biomarkers; Drug Repositioning; Humans; Melanins; Melanocytes; Receptor, Melanocortin, Type 1; Signal Transduction; Skin Pigmentation; Wnt Signaling Pathway
PubMed: 33918792
DOI: 10.3390/ijms22083894