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Abstract
Endogenous photosensitizers play a critical role in both beneficial and harmful light-induced transformations in biological systems. Understanding their mode of action is essential for advancing fields such as photomedicine, photoredox catalysis, environmental science, and the development of sun care products. This review offers a comprehensive analysis of endogenous photosensitizers in human skin, investigating the connections between their electronic excitation and the subsequent activation or damage of organic biomolecules. We gather the physicochemical and photochemical properties of key endogenous photosensitizers and examine the relationships between their chemical reactivity, location within the skin, and the primary biochemical events following solar radiation exposure, along with their influence on skin physiology and pathology. An important take-home message of this review is that photosensitization allows visible light and UV-A radiation to have large effects on skin. The analysis presented here unveils potential causes for the continuous increase in global skin cancer cases and emphasizes the limitations of current sun protection approaches.
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Affiliation(s)
- Erick L Bastos
- Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, 05508-000 São Paulo, São Paulo, Brazil
| | - Frank H Quina
- Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, 05508-000 São Paulo, São Paulo, Brazil
- Department of Chemical Engineering, Polytechnic School, University of São Paulo, 05508-000 São Paulo, São Paulo, Brazil
| | - Maurício S Baptista
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, 05508-000 São Paulo, São Paulo, Brazil
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Galeb HA, Wilkinson EL, Stowell AF, Lin H, Murphy ST, Martin‐Hirsch PL, Mort RL, Taylor AM, Hardy JG. Melanins as Sustainable Resources for Advanced Biotechnological Applications. GLOBAL CHALLENGES (HOBOKEN, NJ) 2021; 5:2000102. [PMID: 33552556 PMCID: PMC7857133 DOI: 10.1002/gch2.202000102] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 11/04/2020] [Indexed: 05/17/2023]
Abstract
Melanins are a class of biopolymers that are widespread in nature and have diverse origins, chemical compositions, and functions. Their chemical, electrical, optical, and paramagnetic properties offer opportunities for applications in materials science, particularly for medical and technical uses. This review focuses on the application of analytical techniques to study melanins in multidisciplinary contexts with a view to their use as sustainable resources for advanced biotechnological applications, and how these may facilitate the achievement of the United Nations Sustainable Development Goals.
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Affiliation(s)
- Hanaa A. Galeb
- Department of ChemistryLancaster UniversityLancasterLA1 4YBUK
- Department of ChemistryScience and Arts CollegeRabigh CampusKing Abdulaziz UniversityJeddah21577Saudi Arabia
| | - Emma L. Wilkinson
- Department of Biomedical and Life SciencesLancaster UniversityLancasterLA1 4YGUK
| | - Alison F. Stowell
- Department of Organisation, Work and TechnologyLancaster University Management SchoolLancaster UniversityLancasterLA1 4YXUK
| | - Hungyen Lin
- Department of EngineeringLancaster UniversityLancasterLA1 4YWUK
| | - Samuel T. Murphy
- Department of EngineeringLancaster UniversityLancasterLA1 4YWUK
- Materials Science InstituteLancaster UniversityLancasterLA1 4YBUK
| | - Pierre L. Martin‐Hirsch
- Lancashire Teaching Hospitals NHS TrustRoyal Preston HospitalSharoe Green LanePrestonPR2 9HTUK
| | - Richard L. Mort
- Department of Biomedical and Life SciencesLancaster UniversityLancasterLA1 4YGUK
| | - Adam M. Taylor
- Lancaster Medical SchoolLancaster UniversityLancasterLA1 4YWUK
| | - John G. Hardy
- Department of ChemistryLancaster UniversityLancasterLA1 4YBUK
- Materials Science InstituteLancaster UniversityLancasterLA1 4YBUK
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Napolitano A, Panzella L, Monfrecola G, d'Ischia M. Pheomelanin-induced oxidative stress: bright and dark chemistry bridging red hair phenotype and melanoma. Pigment Cell Melanoma Res 2014; 27:721-33. [PMID: 24814217 DOI: 10.1111/pcmr.12262] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 05/08/2014] [Indexed: 01/20/2023]
Abstract
The complex interplay of genetic and epigenetic factors linking sun exposure to melanoma in the red hair phenotype hinges on the peculiar physical and chemical properties of pheomelanins and the underlying biosynthetic pathway, which is switched on by the effects of inactivating polymorphisms in the melanocortin 1 receptor gene. In addition to the long recognized UV-dependent pathways of toxicity and cell damage, a UV-independent pro-oxidant state induced by pheomelanin within the genetically determined background of the red hair phenotype has recently been disclosed. This review provides a detailed discussion of the possible UV-dependent and UV-independent chemical mechanisms underlying pheomelanin-mediated oxidative stress, with special reference to the oxygen-dependent depletion of glutathione and other cell antioxidants. The new concept of pheomelanin as a 'living' polymer and biocatalyst that may grow by exposure to monomer building blocks and may trigger autooxidative processes is also discussed. As a corollary, treatment of inflammatory skin diseases in RHP patients is briefly commented. Finally, possible concerted strategies for melanoma prevention in the red hair phenotype are proposed.
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Costa TG, Szpoganicz B, Caramori GF, de Almeida VR, Mangrich AS, Mangoni AP. Spectroscopy and theoretical studies of natural melanin (eumelanin) and its complexation by iron(III). J COORD CHEM 2014. [DOI: 10.1080/00958972.2014.905686] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Thiago G. Costa
- Laboratório de Equilíbrio Químico, Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, Brazil
| | - Bruno Szpoganicz
- Laboratório de Equilíbrio Químico, Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, Brazil
| | - Giovanni F. Caramori
- Grupo de Estrutura Eletrônica Molecular, Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, Brazil
| | - Vicente R. de Almeida
- Laboratório de Equilíbrio Químico, Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, Brazil
| | - Antônio S. Mangrich
- Laboratório de Química Inorgânica, Universidade Federal do Paraná, Curitiba, Brazil
| | - Ana P. Mangoni
- Laboratório de Química Inorgânica, Universidade Federal do Paraná, Curitiba, Brazil
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Napolitano A, Panzella L, Leone L, d’Ischia M. Red hair benzothiazines and benzothiazoles: mutation-inspired chemistry in the quest for functionality. Acc Chem Res 2013; 46:519-28. [PMID: 23270471 DOI: 10.1021/ar300219u] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Nature provides a primary source of leads for the design of π-conjugated organic chromophores and other functional molecular systems useful for molecular recognition, light harvesting, photoconversion, and other technological applications. In this Account, we draw attention to a unique group of naturally occurring heterocyclic compounds, the 2H-1,4-benzothiazines and related benzothiazole derivatives. Derived from tyrosine and cysteine, these molecules arise from a mutation-induced deviation of the melanin pathway to provide the core structure of the red human hair pigments pheomelanins. Since the elucidation of the biosynthetic pathway of pheomelanins in the 1960s, researchers have focused on 1,4-benzothiazines and red hair pigments. Not only do these molecules have interesting photochemical and molecular recognition properties, they also have compelling biomedical significance. Numerous studies have linked higher levels of pheomelanins and mutations in the pathways that produce these pigments in individuals with red hair and fair skin with an increased sensitivity to UV light and a higher susceptibility to melanoma and other skin cancers. Prompted by new data about the structure and photochemistry of the bibenzothiazine system, this Account highlights the chemistry of benzothiazines in red-haired individuals as a novel source of inspiration in the quest for innovative scaffolds and biomimetic functional systems. Model studies have gradually shed light on a number of remarkable physical and chemical properties of benzothiazine-based systems. Bibenzothiazine is a robust visible chromophore that combines photochromism and acidichromism. Benzothiazine-based polymers (synthetic pheomelanins) show remarkable photochemical, paramagnetic, and redox cycling properties. Biomimetic or synthetic manipulations of the benzothiazine systems, through decarboxylation pathways controlled by metal ions or unusually facile ring-contraction processes, can produce a diverse set of molecular scaffolds.
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Affiliation(s)
- Alessandra Napolitano
- Department of Chemical Sciences, University of Naples Federico II, Via Cinthia 4, I-80126 Naples, Italy
| | - Lucia Panzella
- Department of Chemical Sciences, University of Naples Federico II, Via Cinthia 4, I-80126 Naples, Italy
| | - Loredana Leone
- Department of Chemical Sciences, University of Naples Federico II, Via Cinthia 4, I-80126 Naples, Italy
| | - Marco d’Ischia
- Department of Chemical Sciences, University of Naples Federico II, Via Cinthia 4, I-80126 Naples, Italy
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Leone L, Crescenzi O, Napolitano A, Barone V, d'Ischia M. The Δ2,2′-Bi(2H-1,4-benzothiazine) Structural Motif of Red Hair Pigments Revisited: Photochromism and Acidichromism in a Unique Four-State System. European J Org Chem 2012. [DOI: 10.1002/ejoc.201200673] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Greco G, Panzella L, Verotta L, d'Ischia M, Napolitano A. Uncovering the structure of human red hair pheomelanin: benzothiazolylthiazinodihydroisoquinolines as key building blocks. JOURNAL OF NATURAL PRODUCTS 2011; 74:675-682. [PMID: 21341762 DOI: 10.1021/np100740n] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Biomimetic oxidation of the pheomelanin precursor 5-S-cysteinyldopa in the presence of Zn(2+) ions led to the isolation of two isomeric products, one of which could be identified as the benzothiazolylthiazinodihydroisoquinoline 5, while the other proved too unstable for a complete characterization. Both these products were converted into more stable oxidized forms, which after ethylchloroformate derivatization were characterized as the ethyl ester/ethoxycarbonyl isoquinolines 8 and 9. Compound 5 exhibited absorption characteristics similar to those of red hair pheomelanin, including a main band around 400 nm in acids. Similarly to red hair pheomelanin and synthetic pigments, 5 afforded on chemical degradation a thiazolylpyridinecarboxylic acid fragment. Model chemical studies allowed the proposal of a formation mechanism for the benzothiazole and dihydroisoquinoline systems in compound 5.
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Affiliation(s)
- Giorgia Greco
- Department of Organic Chemistry and Biochemistry, University of Naples Federico II, Via Cintia 4, I-80126 Naples, Italy
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8
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Huijser A, Pezzella A, Sundström V. Functionality of epidermal melanin pigments: current knowledge on UV-dissipative mechanisms and research perspectives. Phys Chem Chem Phys 2011; 13:9119-27. [DOI: 10.1039/c1cp20131j] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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9
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Panzella L, Szewczyk G, D’Ischia M, Napolitano A, Sarna T. Zinc-induced Structural Effects Enhance Oxygen Consumption and Superoxide Generation in Synthetic Pheomelanins on UVA/Visible Light Irradiation†. Photochem Photobiol 2010; 86:757-64. [DOI: 10.1111/j.1751-1097.2010.00726.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Ma C, Kwok W, An HY, Guan X, Fu M, Toy P, Phillips D. A Time-Resolved Spectroscopic Study of the Bichromophoric Phototrigger 3′,5′-Dimethoxybenzoin Diethyl Phosphate: Interaction Between the Two Chromophores Determines the Reaction Pathway. Chemistry 2010; 16:5102-18. [DOI: 10.1002/chem.200902891] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Simon JD, Peles D, Wakamatsu K, Ito S. Current challenges in understanding melanogenesis: bridging chemistry, biological control, morphology, and function. Pigment Cell Melanoma Res 2009; 22:563-79. [PMID: 19627559 DOI: 10.1111/j.1755-148x.2009.00610.x] [Citation(s) in RCA: 263] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Melanin is a natural pigment produced within organelles, melanosomes, located in melanocytes. Biological functions of melanosomes are often attributed to the unique chemical properties of the melanins they contain; however, the molecular structure of melanins, the mechanism by which the pigment is produced, and how the pigment is organized within the melanosome remains to be fully understood. In this review, we examine the current understanding of the initial chemical steps in the melanogenesis. Most natural melanins are mixtures of eumelanin and pheomelanin, and so after presenting the current understanding of the individual pigments, we focus on the mixed melanin systems, with a critical eye towards understanding how studies on individual melanin do and do not provide insight in the molecular aspects of their structures. We conclude the review with a discussion of important issues that must be addressed in future research efforts to more fully understand the relationship between molecular and functional properties of this important class of natural pigments.
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Affiliation(s)
- John D Simon
- Department of Chemistry, Duke University, Durham, NC, USA.
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Greco G, Wakamatsu K, Panzella L, Ito S, Napolitano A, d’Ischia M. Isomeric cysteinyldopas provide a (photo)degradable bulk component and a robust structural element in red human hair pheomelanin. Pigment Cell Melanoma Res 2009; 22:319-27. [DOI: 10.1111/j.1755-148x.2009.00561.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Napolitano A, De Lucia M, Panzella L, d’Ischia M. The "Benzothiazine" Chromophore of Pheomelanins: A Reassessment. Photochem Photobiol 2008; 84:593-9. [DOI: 10.1111/j.1751-1097.2007.00232.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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14
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Ye T, Pawlak A, Sarna T, Simon JD. Different Molecular Constituents in Pheomelanin are Responsible for Emission, Transient Absorption and Oxygen Photoconsumption. Photochem Photobiol 2008; 84:437-43. [DOI: 10.1111/j.1751-1097.2007.00281.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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15
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Nighswander-Rempel SP. Quantitative fluorescence spectra and quantum yield map of synthetic pheomelanin. Biopolymers 2006; 82:631-7. [PMID: 16575861 DOI: 10.1002/bip.20518] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Spectroscopic studies of pheomelanin and its constituents have been sparse. These data present what is by far the most complete description of the fluorescence characteristics of synthetic pheomelanin. Emission spectra between 260 and 600 nm were acquired for excitation wavelengths between 250 and 500 nm at 1-nm intervals. A quantum yield map is also presented, correcting the fluorescence intensities for differences in species concentration and molar absorptivity. These fluorescence features exhibit interesting similarities and differences to eumelanin, and these data are interpreted with respect to possible chemical structures. Overall, these data suggest that pheomelanin oligomers may be more tightly coupled than those of eumelanin. Finally, the quantum yield is shown to be on the order of 10(-4) and exhibit a complex dependence on excitation energy, varying by a factor of 4 across the energies employed here.
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Affiliation(s)
- S P Nighswander-Rempel
- Centre for Biophotonics and Laser Science, Department of Physics, University of Queensland, Brisbane, QLD Australia 4072
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