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Xie W, Dhinojwala A, Gianneschi NC, Shawkey MD. Interactions of Melanin with Electromagnetic Radiation: From Fundamentals to Applications. Chem Rev 2024; 124:7165-7213. [PMID: 38758918 DOI: 10.1021/acs.chemrev.3c00858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2024]
Abstract
Melanin, especially integumentary melanin, interacts in numerous ways with electromagnetic radiation, leading to a set of critical functions, including radiation protection, UV-protection, pigmentary and structural color productions, and thermoregulation. By harnessing these functions, melanin and melanin-like materials can be widely applied to diverse applications with extraordinary performance. Here we provide a unified overview of the melanin family (all melanin and melanin-like materials) and their interactions with the complete electromagnetic radiation spectrum (X-ray, Gamma-ray, UV, visible, near-infrared), which until now has been absent from the literature and is needed to establish a solid fundamental base to facilitate their future investigation and development. We begin by discussing the chemistries and morphologies of both natural and artificial melanin, then the fundamentals of melanin-radiation interactions, and finally the exciting new developments in high-performance melanin-based functional materials that exploit these interactions. This Review provides both a comprehensive overview and a discussion of future perspectives for each subfield of melanin that will help direct the future development of melanin from both fundamental and applied perspectives.
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Affiliation(s)
- Wanjie Xie
- Department of Biology, Evolution and Optics of Nanostructure Group, University of Ghent, Gent 9000, Belgium
| | - Ali Dhinojwala
- School of Polymer Science and Polymer Engineering, The University of Akron, Akron, Ohio 44325, United States
| | - Nathan C Gianneschi
- Department of Chemistry, Department of Materials Science and Engineering, Department of Biomedical Engineering, Simpson-Querrey Institute, Chemistry of Life Processes Institute, Lurie Cancer Center, and International Institute of Nanotechnology, Northwestern University, Evanston, Illinois 60208, United States
| | - Matthew D Shawkey
- Department of Biology, Evolution and Optics of Nanostructure Group, University of Ghent, Gent 9000, Belgium
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Vinod K, Jadhav SD, Hariharan M. Room Temperature Phosphorescence in Crystalline Iodinated Eumelanin Monomer. Chemistry 2024; 30:e202400499. [PMID: 38502668 DOI: 10.1002/chem.202400499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Revised: 03/01/2024] [Accepted: 03/19/2024] [Indexed: 03/21/2024]
Abstract
We report the room temperature phosphorescence upon iodination on a crystalline eumelanin monomer with shielded hydroxyl moieties, ethyl 5,6-dimethoxyindole-2-carboxylate (DMICE). Ultrafast intersystem crossing (ISC) is observed in the iodinated (IDMICE) as well as brominated (BDMICE) analogues of the eumelanin monomer derivative in solution. The triplet quantum yields (φT) and intersystem crossing rates (kISC) of the halogenated eumelanin derivatives areφ T B D M I C E ${{\phi{} }_{T}^{BDMICE}}$ =25.4±1.1 %;k I S C B D M I C E ${{k}_{ISC}^{BDMICE}}$ =1.95×109 s-1 andφ T I D M I C E ${{\phi{} }_{T}^{IDMICE}}$ =59.1±1.6 %;k I S C I D M I C E = ${{k}_{ISC}^{IDMICE}=}$ 1.36×1010 s-1, as monitored using transient absorption spectroscopy. Theoretical calculations based on nuclear ensemble method reveal that computed kISC and spin-orbit coupling matrix elements for eumelanin derivatives are larger for IDMICE relative to BDMICE. The halogen and π-π interactions, with distinct excitonic coupling and higher ISC rate promote phosphorescence in IDMICE molecular crystals. Accessing triplet excited states and resultant photoluminescence through structural modification of eumelanin scaffolds paves way for exploring the versatility of eumelanin-inspired molecules as bio-functional materials.
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Affiliation(s)
- Kavya Vinod
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram (IISER TVM), Maruthamala P.O., Vithura, Thiruvananthapuram, 695551, Kerala, India
| | - Sohan D Jadhav
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram (IISER TVM), Maruthamala P.O., Vithura, Thiruvananthapuram, 695551, Kerala, India
| | - Mahesh Hariharan
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram (IISER TVM), Maruthamala P.O., Vithura, Thiruvananthapuram, 695551, Kerala, India
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Sasikumar D, Vinod K, Sunny J, Hariharan M. Exciton interactions in helical crystals of a hydrogen-bonded eumelanin monomer. Chem Sci 2022; 13:2331-2338. [PMID: 35310511 PMCID: PMC8864807 DOI: 10.1039/d1sc06755a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 01/19/2022] [Indexed: 12/04/2022] Open
Abstract
Eumelanin, a naturally occurring group of heterogeneous polymers/aggregates providing photoprotection to living organisms, consist of 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) building blocks. Despite their prevalence in the animal world, the structure and therefore the mechanism behind the photoprotective broadband absorption and non-radiative decay of eumelanin remain largely unknown. As a small step towards solving the incessant mystery, DHI is crystallized in a non-protic solvent environment to obtain DHI crystals having a helical packing motif. The present approach reflects the solitary directional effect of hydrogen bonds between the DHI chromophores for generating the crystalline assembly and filters out any involvement of the surrounding solvent environment. The DHI single crystals having an atypical chiral packing motif (P212121 Sohncke space group) incorporate enantiomeric zig-zag helical stacks arranged in a herringbone fashion with respect to each other. Each of the zig-zag helical stacks originates from a bifurcated hydrogen bonding interaction between the hydroxyl substituents in adjacent DHI chromophores which act as the backbone structure for the helical assembly. Fragment-based excited state analysis performed on the DHI crystalline assembly demonstrates exciton delocalization along the DHI units that connect each enantiomeric helical stack while, within each stack, the excitons remain localized. Fascinatingly, over the time evolution for generation of single-crystals of the DHI-monomer, mesoscopic double-helical crystals are formed, possibly attributed to the presence of covalently connected DHI trimers in chloroform solution. The oligomeric DHI (in line with the chemical disorder model) along with the characteristic crystalline packing observed for DHI provides insights into the broadband absorption feature exhibited by the chromophore. Single crystals of DHI monomer, a eumelanin precursor, adopt an atypical chiral packing arrangement incorporating enantiomeric zig-zag helical stacks while its covalently connected DHI trimer forms double-helical crystals in the mesoscopic scale.![]()
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Affiliation(s)
- Devika Sasikumar
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram Maruthamala P.O., Vithura Thiruvananthapuram Kerala 695551 India
| | - Kavya Vinod
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram Maruthamala P.O., Vithura Thiruvananthapuram Kerala 695551 India
| | - Jeswin Sunny
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram Maruthamala P.O., Vithura Thiruvananthapuram Kerala 695551 India
| | - Mahesh Hariharan
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram Maruthamala P.O., Vithura Thiruvananthapuram Kerala 695551 India
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4
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Nonenzymatic Spontaneous Oxidative Transformation of 5,6-Dihydroxyindole. Int J Mol Sci 2020; 21:ijms21197321. [PMID: 33023030 PMCID: PMC7583787 DOI: 10.3390/ijms21197321] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 09/26/2020] [Accepted: 10/01/2020] [Indexed: 01/11/2023] Open
Abstract
Melanin is an important phenolic skin pigment found throughout the animal kingdom. Tyrosine and its hydroxylated product dopa provide the starting material for melanin biosynthesis in all animals. Through a set of well-established reactions, they are converted to 5,6-dihydroxyindole (DHI) and DHI-2-carboxylic acid (DHICA). Oxidative polymerization of these two indoles produces the brown to black eumelanin pigment. The steps associated with these transformations are complicated by the extreme instability of the starting materials and the transient and highly reactive nature of the intermediates. We have used mass spectral studies to explore the nonenzymatic mechanism of oxidative transformation of DHI in water. Our results indicate the facile production of not only dimeric and trimeric products but also higher oligomeric forms of DHI upon exposure to air in solution, even under nonenzymatic conditions. Such instantaneous polymerization of DHI avoids toxicity to self-matter and ensures the much-needed deposition of melanin at (a) the wound site and (b) the infection site in arthropods. The rapid deposition of DHI melanin is advantageous for arthropods given their open circulatory system; the process limits blood loss during wounding and prevents the spread of parasites by encapsulating them in melanin, limiting the damage.
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Ito S, Sugumaran M, Wakamatsu K. Chemical Reactivities of ortho-Quinones Produced in Living Organisms: Fate of Quinonoid Products Formed by Tyrosinase and Phenoloxidase Action on Phenols and Catechols. Int J Mol Sci 2020; 21:ijms21176080. [PMID: 32846902 PMCID: PMC7504153 DOI: 10.3390/ijms21176080] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/19/2020] [Accepted: 08/20/2020] [Indexed: 12/27/2022] Open
Abstract
Tyrosinase catalyzes the oxidation of phenols and catechols (o-diphenols) to o-quinones. The reactivities of o-quinones thus generated are responsible for oxidative browning of plant products, sclerotization of insect cuticle, defense reaction in arthropods, tunichrome biochemistry in tunicates, production of mussel glue, and most importantly melanin biosynthesis in all organisms. These reactions also form a set of major reactions that are of nonenzymatic origin in nature. In this review, we summarized the chemical fates of o-quinones. Many of the reactions of o-quinones proceed extremely fast with a half-life of less than a second. As a result, the corresponding quinone production can only be detected through rapid scanning spectrophotometry. Michael-1,6-addition with thiols, intramolecular cyclization reaction with side chain amino groups, and the redox regeneration to original catechol represent some of the fast reactions exhibited by o-quinones, while, nucleophilic addition of carboxyl group, alcoholic group, and water are mostly slow reactions. A variety of catecholamines also exhibit side chain desaturation through tautomeric quinone methide formation. Therefore, quinone methide tautomers also play a pivotal role in the fate of numerous o-quinones. Armed with such wide and dangerous reactivity, o-quinones are capable of modifying the structure of important cellular components especially proteins and DNA and causing severe cytotoxicity and carcinogenic effects. The reactivities of different o-quinones involved in these processes along with special emphasis on mechanism of melanogenesis are discussed.
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Affiliation(s)
- Shosuke Ito
- Department of Chemistry, Fujita Health University School of Medical Sciences, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan
- Correspondence: (S.I.); (K.W.); Tel.: +81-562-93-9849 (S.I. & K.W.); Fax: +81-562-93-4595 (S.I. & K.W.)
| | - Manickam Sugumaran
- Department of Biology, University of Massachusetts, Boston, MA 02125, USA;
| | - Kazumasa Wakamatsu
- Department of Chemistry, Fujita Health University School of Medical Sciences, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan
- Correspondence: (S.I.); (K.W.); Tel.: +81-562-93-9849 (S.I. & K.W.); Fax: +81-562-93-4595 (S.I. & K.W.)
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6
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Jaramillo A, Barrera-Gutiérrez R, Cortés MT. Synthesis, Follow-Up, and Characterization of Polydopamine-like Coatings Departing from Micromolar Dopamine- o-Quinone Precursor Concentrations. ACS OMEGA 2020; 5:15016-15027. [PMID: 32637775 PMCID: PMC7330902 DOI: 10.1021/acsomega.0c00676] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 04/01/2020] [Indexed: 06/11/2023]
Abstract
The understanding of oxidized species derived from the neurotransmitter dopamine (DA) is a relevant topic for both the medical field (Parkinson's disease) as well as for the field of materials science where the formation process of polydopamine (PDA) films is an active area of research. Polymers that interact strongly with almost all surfaces but have a low electrical conductivity have been obtained by the chemical oxidation of DA. Since electrical conductivity is a desired property for several applications, deposition alternatives such as electrochemical PDA synthesis have been proposed, but the results are still insufficient. In this context, we propose a new PDA chemical-electrochemical deposition process on glassy carbon electrodes. The chemical oxidation step that converts dopamine into dopamine-o-quinone previous to the electrochemical deposition was crucial to decrease the precursor concentration to the micromolar range. The PDA-like films synthesized by this method had high adhesion and low charge-transfer resistance, which was evidenced by impedance measurements and the successful electrodeposition of a polypyrrole coating on top of a PDA-like film. In addition, we observed that anodization of GC surfaces increases sensitivity toward six electroactive couples derived from DA oxidation in the pH regimes studied. These results show the complexity of the intermediates formed during the electrochemical polymerization of PDA.
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Affiliation(s)
- Andrés
M. Jaramillo
- Department of Chemistry, Universidad de Los Andes, Cra 1 N° 18A-12, Bogotá 111711, Colombia
| | | | - María T. Cortés
- Department of Chemistry, Universidad de Los Andes, Cra 1 N° 18A-12, Bogotá 111711, Colombia
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Lyu Q, Hsueh N, Chai CLL. Direct Evidence for the Critical Role of 5,6-Dihydroxyindole in Polydopamine Deposition and Aggregation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:5191-5201. [PMID: 30916980 DOI: 10.1021/acs.langmuir.9b00392] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The definitive role of the intermediate 5,6-dihydroxyindole (DHI) in the formation of polydopamine (PDA) coatings from aqueous dopamine (DA) has not been clearly elucidated and remains highly controversial. Our foray into this debate as reported in this study agrees with some reported assertions that DHI-based coatings are not synonymous with PDA coatings. Our conclusion arises from a systematic comparison of the components and properties of DHI-based coatings and PDA coatings. In addition, through careful copolymerization studies of DA and DHI, our studies reported herein unequivocally suggest that both DA and DHI are partial building blocks for PDA formation. Our results also provide additional evidence of the critical role of DHI in controlling the thickness of PDA coatings, through competitive events between PDA aggregation in solutions and deposition onto substrates. These findings highlight the complex interplay between both DHI and uncyclized DA moieties in the formation of adhesive catechol/amine materials.
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Affiliation(s)
- Qinghua Lyu
- Department of Pharmacy , National University of Singapore , 18 Science Drive 4 , Singapore 117543
| | - Nathanael Hsueh
- Department of Pharmacy , National University of Singapore , 18 Science Drive 4 , Singapore 117543
| | - Christina L L Chai
- Department of Pharmacy , National University of Singapore , 18 Science Drive 4 , Singapore 117543
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8
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Huang Z, Kwon O, Huang H, Fadli A, Marat X, Moreau M, Lumb JP. A Bioinspired Synthesis of Polyfunctional Indoles. Angew Chem Int Ed Engl 2018; 57:11963-11967. [PMID: 29978600 DOI: 10.1002/anie.201806490] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 06/29/2018] [Indexed: 01/25/2023]
Affiliation(s)
- Zheng Huang
- Department of Chemistry; McGill University; 801 Sherbrooke Street West Montreal QC H3A 0B8 Canada
| | - Ohhyeon Kwon
- Department of Chemistry; McGill University; 801 Sherbrooke Street West Montreal QC H3A 0B8 Canada
| | - Haiyan Huang
- Department of Chemistry; McGill University; 801 Sherbrooke Street West Montreal QC H3A 0B8 Canada
| | - Aziz Fadli
- L'Oréal Research and Innovation; Aulnay-sous-Bois France
| | - Xavier Marat
- L'Oréal Research and Innovation; Aulnay-sous-Bois France
| | | | - Jean-Philip Lumb
- Department of Chemistry; McGill University; 801 Sherbrooke Street West Montreal QC H3A 0B8 Canada
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9
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Huang Z, Kwon O, Huang H, Fadli A, Marat X, Moreau M, Lumb JP. A Bioinspired Synthesis of Polyfunctional Indoles. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201806490] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Zheng Huang
- Department of Chemistry; McGill University; 801 Sherbrooke Street West Montreal QC H3A 0B8 Canada
| | - Ohhyeon Kwon
- Department of Chemistry; McGill University; 801 Sherbrooke Street West Montreal QC H3A 0B8 Canada
| | - Haiyan Huang
- Department of Chemistry; McGill University; 801 Sherbrooke Street West Montreal QC H3A 0B8 Canada
| | - Aziz Fadli
- L'Oréal Research and Innovation; Aulnay-sous-Bois France
| | - Xavier Marat
- L'Oréal Research and Innovation; Aulnay-sous-Bois France
| | | | - Jean-Philip Lumb
- Department of Chemistry; McGill University; 801 Sherbrooke Street West Montreal QC H3A 0B8 Canada
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Galván I, Araujo-Andrade C, Marro M, Loza-Alvarez P, Wakamatsu K. Raman spectroscopy quantification of eumelanin subunits in natural unaltered pigments. Pigment Cell Melanoma Res 2018; 31:673-682. [DOI: 10.1111/pcmr.12707] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 04/19/2018] [Accepted: 04/20/2018] [Indexed: 11/25/2022]
Affiliation(s)
- Ismael Galván
- Departamento de Ecología Evolutiva; Estación Biológica de Doñana; CSIC; Sevilla Spain
| | - Cuauhtemoc Araujo-Andrade
- ICFO - Institut de Ciencies Fotoniques; The Barcelona Institute of Science and Technology; Castelldefels Spain
- Unidad Académica de Física; Universidad Autónoma de Zacatecas; Zacatecas Mexico
| | - Mónica Marro
- ICFO - Institut de Ciencies Fotoniques; The Barcelona Institute of Science and Technology; Castelldefels Spain
| | - Pablo Loza-Alvarez
- ICFO - Institut de Ciencies Fotoniques; The Barcelona Institute of Science and Technology; Castelldefels Spain
| | - Kazumasa Wakamatsu
- Department of Chemistry; Fujita Health University School of Health Sciences; Toyoake Japan
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11
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ArgTX-636, a polyamine isolated from spider venom: A novel class of melanogenesis inhibitors. Bioorg Med Chem 2016; 24:5685-5692. [DOI: 10.1016/j.bmc.2016.08.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 08/14/2016] [Accepted: 08/18/2016] [Indexed: 11/19/2022]
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12
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Critical Analysis of the Melanogenic Pathway in Insects and Higher Animals. Int J Mol Sci 2016; 17:ijms17101753. [PMID: 27775611 PMCID: PMC5085778 DOI: 10.3390/ijms17101753] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 10/11/2016] [Accepted: 10/12/2016] [Indexed: 12/24/2022] Open
Abstract
Animals synthesize melanin pigments for the coloration of their skin and use it for their protection from harmful solar radiation. Insects use melanins even more ingeniously than mammals and employ them for exoskeletal pigmentation, cuticular hardening, wound healing and innate immune responses. In this review, we discuss the biochemistry of melanogenesis process occurring in higher animals and insects. A special attention is given to number of aspects that are not previously brought to light: (1) the molecular mechanism of dopachrome conversion that leads to the production of two different dihydroxyindoles; (2) the role of catecholamine derivatives other than dopa in melanin production in animals; (3) the critical parts played by various biosynthetic enzymes associated with insect melanogenesis; and (4) the presence of a number of important gaps in both melanogenic and sclerotinogenic pathways. Additionally, importance of the melanogenic process in insect physiology especially in the sclerotization of their exoskeleton, wound healing reactions and innate immune responses is highlighted. The comparative biochemistry of melanization with sclerotization is also discussed.
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Sugumaran M. Reactivities of Quinone Methides versus o-Quinones in Catecholamine Metabolism and Eumelanin Biosynthesis. Int J Mol Sci 2016; 17:ijms17091576. [PMID: 27657049 PMCID: PMC5037842 DOI: 10.3390/ijms17091576] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 09/08/2016] [Accepted: 09/12/2016] [Indexed: 12/18/2022] Open
Abstract
Melanin is an important biopolymeric pigment produced in a vast majority of organisms. Tyrosine and its hydroxylated product, dopa, form the starting material for melanin biosynthesis. Earlier studies by Raper and Mason resulted in the identification of dopachrome and dihydroxyindoles as important intermediates and paved way for the establishment of well-known Raper-Mason pathway for the biogenesis of brown to black eumelanins. Tyrosinase catalyzes the oxidation of tyrosine as well as dopa to dopaquinone. Dopaquinone thus formed, undergoes intramolecular cyclization to form leucochrome, which is further oxidized to dopachrome. Dopachrome is either converted into 5,6-dihydroxyindole by decarboxylative aromatization or isomerized into 5,6-dihydroxyindole-2-carboxylic acid. Oxidative polymerization of these two dihydroxyindoles eventually produces eumelanin pigments via melanochrome. While the role of quinones in the biosynthetic pathway is very well acknowledged, that of isomeric quinone methides, however, remained marginalized. This review article summarizes the key role of quinone methides during the oxidative transformation of a vast array of catecholamine derivatives and brings out the importance of these transient reactive species during the melanogenic process. In addition, possible reactions of quinone methides at various stages of melanogenesis are discussed.
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Affiliation(s)
- Manickam Sugumaran
- Department of Biology, University of Massachusetts Boston, Boston, MA 02125, USA.
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14
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Heiduschka P, Blitgen-Heinecke P, Tura A, Kokkinou D, Julien S, Hofmeister S, Bartz-Schmidt KU, Schraermeyer U. Melanin Precursor 5,6-Dihydroxyindol: Protective Effects and Cytotoxicity on Retinal Cells in vitro and in vivo. Toxicol Pathol 2016; 35:1030-8. [DOI: 10.1080/01926230701831358] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
5,6-Dihydroxyindole (DHI) is a melanin pigment precursor with antioxidant properties. In the light of a report about cytotoxicity of DHI, the aim of this study was to assess possible toxic effects of DHI on cells related to the eye, such as human ARPE-19 cells and mouse retinal explants. Moreover, DHI was tested on its effects on retinal function in vivo using electroretinography. We found cytotoxicity of DHI against ARPE-19 cells at 100 μM, but not at 10 μM. 10 μM DHI exhibited a slight, though not significant protective activity against UV-A damage in ARPE-19 cells. We found cytoprotection in cultured mouse retinas by 50 μM DHI or its diacetylated derivative 5,6-diacetoxyindole (DAI), respectively. In ERG measurements in vivo, amplitudes were decreased only slightly by 100 μM DHI compared to saline, whereas a better preservation of amplitudes was visible at 10 μM DHI, in particular with respect to cones. In histological sections, more cones were found at 10 μM DHI than at 100 μM DHI. As a conclusion, DHI shows a slight protective effect at 10 μM both in vitro and in vivo. At 100 μM, it shows a strong cytotoxicity in vitro, which is strongly reduced in vivo.
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Affiliation(s)
- Peter Heiduschka
- Section for Experimental Vitreoretinal Surgery, University Eye Hospital Tübingen, Schleichstr. 12/1, D-72076 Tübingen, Germany
- Steinbeis Transfer Centre for Pathology and Toxicology of the Eye, Schleichstr. 12/1, D-72076 Tübingen, Germany
| | - Petra Blitgen-Heinecke
- Section for Experimental Vitreoretinal Surgery, University Eye Hospital Tübingen, Schleichstr. 12/1, D-72076 Tübingen, Germany
- Steinbeis Transfer Centre for Pathology and Toxicology of the Eye, Schleichstr. 12/1, D-72076 Tübingen, Germany
| | - Aysegül Tura
- University Eye Hospital Dept. I, Schleichstr. 12, D-72076 Tübingen, Germany
| | - Despina Kokkinou
- Section for Experimental Vitreoretinal Surgery, University Eye Hospital Tübingen, Schleichstr. 12/1, D-72076 Tübingen, Germany
| | - Sylvie Julien
- Section for Experimental Vitreoretinal Surgery, University Eye Hospital Tübingen, Schleichstr. 12/1, D-72076 Tübingen, Germany
| | - Sabine Hofmeister
- Section for Experimental Vitreoretinal Surgery, University Eye Hospital Tübingen, Schleichstr. 12/1, D-72076 Tübingen, Germany
| | | | - Ulrich Schraermeyer
- Section for Experimental Vitreoretinal Surgery, University Eye Hospital Tübingen, Schleichstr. 12/1, D-72076 Tübingen, Germany
- Steinbeis Transfer Centre for Pathology and Toxicology of the Eye, Schleichstr. 12/1, D-72076 Tübingen, Germany
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15
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Mechanism of dopachrome tautomerization into 5,6-dihydroxyindole-2-carboxylic acid catalyzed by Cu(II) based on quantum chemical calculations. Biochim Biophys Acta Gen Subj 2014; 1850:281-6. [PMID: 25450182 DOI: 10.1016/j.bbagen.2014.10.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Revised: 10/18/2014] [Accepted: 10/21/2014] [Indexed: 12/18/2022]
Abstract
BACKGROUND Tautomerization of dopachrome to 5,6-dihydroxyindole-2-carboxylic acid (DHICA) is a biologically crucial reaction relevant to melanin synthesis, cellular antioxidation, and cross-talk among epidermal cells. Since dopachrome spontaneously converts into 5,6-dihydroxyindole (DHI) via decarboxylation without any enzymes at physiologically usual pH, the mechanism of how tautomerization to DHICA occurs in physiological system is a subject of intense debate. A previous work has found that Cu(II) is an important factor to catalyze the tautomerization of dopachrome to DHICA. However, the effect of Cu(II) on the tautomerization has not been clarified at the atomic level. METHODS We propose the reaction mechanism of the tautomerization to DHICA by Cu(II) from density functional theory-based calculation. RESULTS We clarified that the activation barriers of α-deprotonation, β-deprotonation, and decarboxylation from dopachrome are significantly reduced by coordination of Cu(II) to quinonoid oxygens (5,6-oxygens) of dopachrome, with the lowest activation barrier of β-deprotonation among them. In contrast to our previous work, in which β-deprotonation and quinonoid protonation (O5/O6-protonation) were shown to be important to form DHI, our results show that the Cu(II) coordination to quinonoid oxygens inhibits the quinonoid protonation, leading to the preference of proton rearrangement from β-carbon to carboxylate group but not to the quinonoid oxygens. CONCLUSION Integrating these results, we conclude that dopachrome tautomerization first proceeds via proton rearrangement from β-carbon to carboxylate group and subsequently undergoes α-deprotonation to form DHICA. GENERAL SIGNIFICANCE This study would provide the biochemical basis of DHICA metabolism and the generalized view of dopachrome conversion which is important to understand melanogenesis.
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Kishida R, Ushijima Y, Saputro AG, Kasai H. Effect of pH on elementary steps of dopachrome conversion from first-principles calculation. Pigment Cell Melanoma Res 2014; 27:734-43. [PMID: 24807014 DOI: 10.1111/pcmr.12256] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 05/01/2014] [Indexed: 11/29/2022]
Abstract
Dopachrome conversion, in which dopachrome is converted into 5,6-dihydroxyindole (DHI) or 5,6-dihydroxyindole-2-carboxylic acid (DHICA) upstream of eumelanogenesis, is a key step in determining the DHI/DHICA monomer ratio in eumelanin, which affects the antioxidant activity. Although the ratio of DHI/DHICA formed and the conversion rate can be regulated depending on pH, the mechanism is still unclear. To clarify the mechanism, we carried out first-principles calculations. The results showed the kinetic preference of proton rearrangement to form quinone methide intermediate via β-deprotonation. We also identified possible pathways to DHI/DHICA from the quinone methide. The DHI formation can be achieved by spontaneous decarboxylation after proton rearrangement from carboxyl group to 6-oxygen. α-Deprotonation, which leads to DHICA formation, can also proceed with a significantly reduced activation barrier compared with that of the initial dopachrome. Considering the rate of the proton rearrangements in a given pH, we conclude that the conversion is suppressed at acidic pH.
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Affiliation(s)
- Ryo Kishida
- Department of Applied Physics, Osaka University, Suita, Osaka, Japan
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Ito S, Suzuki N, Takebayashi S, Commo S, Wakamatsu K. Neutral pH and copper ions promote eumelanogenesis after the dopachrome stage. Pigment Cell Melanoma Res 2013; 26:817-25. [PMID: 23844795 DOI: 10.1111/pcmr.12137] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Accepted: 07/08/2013] [Indexed: 11/28/2022]
Abstract
The diversity of pigmentation in the skin, hair, and eyes of humans has been largely attributed to the diversity of pH in melanosomes with acidic pH being proposed to suppress melanin production. Tyrosinase has an optimum pH of 7.4 and its activity is suppressed greatly at lower pH values. The first step of eumelanogenesis is the oxidation of tyrosine to dopachrome (DC) via dopaquinone. However, how eumelanogenesis is controlled by pH beyond this stage is not known. In this study, we examined the effects of pH (5.3-7.3) on the conversion of DC to 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) and the subsequent oxidation of DHI and DHICA to form eumelanin. The effects of Cu(2+) ions on those reactions were also compared. The results indicate that an acidic pH greatly suppresses the late stages of eumelanogenesis and that Cu(2+) ions accelerate the conversion of DC to DHICA and its subsequent oxidation.
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Affiliation(s)
- Shosuke Ito
- Department of Chemistry, Fujita Health University School of Health Sciences, Toyoake, Aichi, Japan
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Pezzella A, Crescenzi O, Panzella L, Napolitano A, Land EJ, Barone V, d’Ischia M. Free Radical Coupling of o-Semiquinones Uncovered. J Am Chem Soc 2013; 135:12142-9. [DOI: 10.1021/ja4067332] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Alessandro Pezzella
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, I-80126
Naples, Italy
| | - Orlando Crescenzi
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, I-80126
Naples, Italy
| | - Lucia Panzella
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, I-80126
Naples, Italy
| | - Alessandra Napolitano
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, I-80126
Naples, Italy
| | - Edward J. Land
- STFC Daresbury Laboratory, Daresbury, WA4 4AD, United
Kingdom
- Chemistry Section,
School of Physical and Geographical Sciences, Keele University, Staffs ST5 5BG, United Kingdom
| | - Vincenzo Barone
- Scuola Normale Superiore, Piazza dei Cavalieri
7, I-56126 Pisa, Italy
| | - Marco d’Ischia
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, I-80126
Naples, Italy
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d'Ischia M, Wakamatsu K, Napolitano A, Briganti S, Garcia-Borron JC, Kovacs D, Meredith P, Pezzella A, Picardo M, Sarna T, Simon JD, Ito S. Melanins and melanogenesis: methods, standards, protocols. Pigment Cell Melanoma Res 2013; 26:616-33. [PMID: 23710556 DOI: 10.1111/pcmr.12121] [Citation(s) in RCA: 281] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2013] [Accepted: 05/17/2013] [Indexed: 01/03/2023]
Abstract
Despite considerable advances in the past decade, melanin research still suffers from the lack of universally accepted and shared nomenclature, methodologies, and structural models. This paper stems from the joint efforts of chemists, biochemists, physicists, biologists, and physicians with recognized and consolidated expertise in the field of melanins and melanogenesis, who critically reviewed and experimentally revisited methods, standards, and protocols to provide for the first time a consensus set of recommended procedures to be adopted and shared by researchers involved in pigment cell research. The aim of the paper was to define an unprecedented frame of reference built on cutting-edge knowledge and state-of-the-art methodology, to enable reliable comparison of results among laboratories and new progress in the field based on standardized methods and shared information.
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Affiliation(s)
- Marco d'Ischia
- Department of Chemical Sciences, University of Naples Federico II, Naples, Italy.
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Direct chemical evidence for eumelanin pigment from the Jurassic period. Proc Natl Acad Sci U S A 2012; 109:10218-23. [PMID: 22615359 DOI: 10.1073/pnas.1118448109] [Citation(s) in RCA: 136] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Melanin is a ubiquitous biological pigment found in bacteria, fungi, plants, and animals. It has a diverse range of ecological and biochemical functions, including display, evasion, photoprotection, detoxification, and metal scavenging. To date, evidence of melanin in fossil organisms has relied entirely on indirect morphological and chemical analyses. Here, we apply direct chemical techniques to categorically demonstrate the preservation of eumelanin in two > 160 Ma Jurassic cephalopod ink sacs and to confirm its chemical similarity to the ink of the modern cephalopod, Sepia officinalis. Identification and characterization of degradation-resistant melanin may provide insights into its diverse roles in ancient organisms.
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The eumelanin intermediate 5,6-dihydroxyindole-2-carboxylic acid is a messenger in the cross-talk among epidermal cells. J Invest Dermatol 2012; 132:1196-205. [PMID: 22297637 DOI: 10.1038/jid.2011.457] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Interest in colorless intermediates of melanocyte metabolism has traditionally been related to their role as melanin precursors, though several lines of evidence scattered in the literature suggested that these compounds may exert an antioxidant and protective function per se unrelated to pigment synthesis. Herein, we disclose the remarkable protective and differentiating effects of 5,6-dihydroxyindole-2-carboxylic acid (DHICA), a diffusible dopachrome tautomerase (DCT)-dependent eumelanin intermediate, on primary cultures of human keratinocytes. At micromolar concentrations, DHICA induced: (a) time- and dose-dependent reduction of cell proliferation without concomitant toxicity; (b) enhanced expression of early (spinous keratins K1 and K10 and envelope protein involucrin) and late (loricrin and filaggrin) differentiation markers; (c) increased activities and expression of antioxidant enzymes; and (d) decreased cell damage and apoptosis following UVA exposure. The hitherto unrecognized role of DHICA as an antiproliferative, protective, and antiapoptotic endogenous cell messenger points to a reappraisal of the biological functions of melanocytes and DCT in skin homeostasis and photoprotection beyond the mere provision of melanin pigments, and provides, to our knowledge, a previously unreported possible explanation to the higher resistance of the dark-skinned eumelanic phenotypes to sunburn and skin cancer.
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22
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Hyogo R, Nakamura A, Okuda H, Wakamatsu K, Ito S, Sota T. Mid-infrared vibrational spectroscopic characterization of 5,6-dihydroxyindole and eumelanin derived from it. Chem Phys Lett 2011. [DOI: 10.1016/j.cplett.2011.10.043] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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23
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d'Ischia M, Napolitano A, Pezzella A. 5,6‐Dihydroxyindole Chemistry: Unexplored Opportunities Beyond Eumelanin. European J Org Chem 2011. [DOI: 10.1002/ejoc.201100796] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Marco d'Ischia
- Department of Organic Chemistry and Biochemistry, University of Naples “Federico II”, Via Cintia 4, 80126 Naples, Italy
| | - Alessandra Napolitano
- Department of Organic Chemistry and Biochemistry, University of Naples “Federico II”, Via Cintia 4, 80126 Naples, Italy
| | - Alessandro Pezzella
- Department of Organic Chemistry and Biochemistry, University of Naples “Federico II”, Via Cintia 4, 80126 Naples, Italy
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Porter J, Arreguin S, Pierpont CG. Ferric iron complexes of dopamine and 5,6-dihydroxyindole with nta, edda, and edta as ancillary ligands. Inorganica Chim Acta 2010. [DOI: 10.1016/j.ica.2010.05.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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25
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Zhang X, Erb C, Flammer J, Nau WM. Absolute Rate Constants for the Quenching of Reactive Excited States by Melanin and Related 5,6-Dihydroxyindole Metabolites: Implications for Their Antioxidant Activity. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2000)0710524arcftq2.0.co2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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26
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Okuda H, Nakamura A, Wakamatsu K, Ito S, Sota T. Mid-infrared absorption spectrum of 5,6-dihydroxyindole-2-carboxylic acid. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2006.11.058] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Charkoudian LK, Franz KJ. Fe(III)-Coordination Properties of Neuromelanin Components: 5,6-Dihydroxyindole and 5,6-Dihydroxyindole-2-carboxylic Acid. Inorg Chem 2006; 45:3657-64. [PMID: 16634598 DOI: 10.1021/ic060014r] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The Fe(III)-coordination chemistry of neuromelanin building-block compounds, 5,6-dihydroxyindole (DHI), 5,6-dihydroxyindole-2-carboxylic acid (DHICA), and 5,6-dihydroxy-N-methyl-indole (Me-DHI), and the neurotransmitter dopamine were explored in aqueous solution by anaerobic pH-dependent spectrophotometric titrations. The Fe(III)-binding constants and pH-dependent speciation parallel those of catechol in that mono, bis, and tris FeLx species are present at concentrations dependent on the pH. The bis FeL2 dihydroxyindole species are favorable for L = DHI and DHICA under neutral to mildly acidic conditions. DHI and DHICA are stronger Fe(III) chelates than catechol, dopamine, and Me-DHI at pH values from 3 to 10. Oxidation studies reveal that iron accelerates the air oxidation of DHI and DHICA.
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Affiliation(s)
- Louise K Charkoudian
- Department of Chemistry, Duke University, P.O. Box 90346, Durham, North Carolina 27708, USA
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Adachi K, Wakamatsu K, Ito S, Miyamoto N, Kokubo T, Nishioka T, Hirata T. An oxygen transporter hemocyanin can act on the late pathway of melanin synthesis. ACTA ACUST UNITED AC 2005; 18:214-9. [PMID: 15892718 DOI: 10.1111/j.1600-0749.2005.00232.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
5,6-Dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) are precursors of eumelanin. The effects of crustacean hemolymph proteins on these eumelanin-related metabolites were investigated. Zymogram analysis indicated that polymers of hemocyanin (Hc) subunits converted DHI into black pigment while no effects were observed using DHICA as a substrate. Spectrum changes for mixtures of purified Hc and DHI showed a profile similar to oxidized DHI by mushroom tyrosinase while Hc had only slight effects on DHICA. Typical inhibitors of tyrosinase and phenoloxidase severely hampered the production of oxidized DHI. Taken together with previous results, these data indicate that Hc plays a crucial role in the conversion of DHI in the hemolymph of crustaceans, which promotes late reactions in the melanin synthetic pathway as well as early reactions (oxidation of tyrosine and DOPA to dopaquinone).
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Affiliation(s)
- Kohsuke Adachi
- Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Japan
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29
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d’Ischia M, Napolitano A, Pezzella A, Land EJ, Ramsden CA, Riley PA. 5,6-Dihydroxyindoles and Indole-5,6-diones. ADVANCES IN HETEROCYCLIC CHEMISTRY 2005. [DOI: 10.1016/s0065-2725(05)89001-4] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Maeda K, Hatao M. Involvement of photooxidation of melanogenic precursors in prolonged pigmentation induced by ultraviolet A. J Invest Dermatol 2004; 122:503-9. [PMID: 15009737 DOI: 10.1046/j.0022-202x.2004.22223.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Melanin is usually produced in melanocytes; however, our histologic research indicates that brownish black persistent pigmentation occurs at the basal layer and, partially, at the suprabasal layer of the epidermis, outside of melanocytes, in skin exposed to high doses of ultraviolet (UV) A radiation. This pigmentation remains for several weeks. We examined whether colorless melanogenic precursors participate in this UVA-induced persistent pigmentation. Among them, 5,6-dihydroxyindole-2-carboxylic acid (DHICA) and its O-methyl metabolite, 6-hydroxy-5-methoxyindole-2-carboxylic acid (6H5MICA), can change into dark-colored pigment upon exposure to UVA, but not UVB, radiation, producing irreversible brownish black pigmentation. These hydroxyindole derivatives readily changed into dark-colored pigment upon UVA irradiation in the presence of hydrogen peroxide in vitro. Histochemical and biochemical studies demonstrated that 6H5MICA accumulates in excised skin specimens and supernatant of cultured human melanocytes. These results suggest that dark-colored pigment is generated directly, outside of melanocytes, in response to UVA exposure, by photooxidation of O-methyl metabolites of DHICA, such as 6H5MICA, at least. We propose that the pigmentation derived from this compound at the basal and suprabasal layers of the epidermis is involved in the mechanism of skin persistent pigmentation without reddening, observed after exposure to sunlight.
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Affiliation(s)
- Kazuhisa Maeda
- Life Science Research Center, Basic Research Division, Shiseido Co. Ltd., Tsuzuki, Yokahama, Japan.
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31
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Abstract
The significance of our understanding of the chemistry of melanin and melanogenesis is reviewed. Melanogenesis begins with the production of dopaquinone, a highly reactive o-quinone. Pulse radiolysis is a powerful tool to study the fates of such highly reactive melanin precursors. Based on pulse radiolysis data reported by Land et al. (J Photochem Photobiol B: Biol 2001;64:123) and our biochemical studies, a pathway for mixed melanogenesis is proposed. Melanogenesis proceeds in three distinctive steps. The initial step is the production of cysteinyldopas by the rapid addition of cysteine to dopaquinone, which continues as long as cysteine is present (1 microM). The second step is the oxidation of cysteinyldopas to give pheomelanin, which continues as long as cysteinyldopas are present (10 microM). The last step is the production of eumelanin, which begins only after most cysteinyldopas are depleted. It thus appears that eumelanin is deposited on the preformed pheomelanin and that the ratio of eu- to pheomelanin is determined by the tyrosinase activity and cysteine concentration. In eumelanogenesis, dopachrome is a rather stable molecule and spontaneously decomposes to give mostly 5,6-dihydroxyindole. Dopachrome tautomerase (Dct) catalyses the tautomerization of dopachrome to give mostly 5,6-dihydroxyindole-2-carboxylic acid (DHICA). Our study confirmed that the role of Dct is to increase the ratio of DHICA in eumelanin and to increase the production of eumelanin. In addition, the cytotoxicity of o-quinone melanin precursors was found to correlate with binding to proteins through the cysteine residues. Finally, it is still unknown how the availability of cysteine is controlled within the melanosome.
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Affiliation(s)
- Shosuke Ito
- Department of Chemistry, Fujita Health University School of Health Sciences, Toyoake, Aichi 470-1192, Japan.
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Han Q, Fang J, Ding H, Johnson JK, Christensen BM, Li J. Identification of Drosophila melanogaster yellow-f and yellow-f2 proteins as dopachrome-conversion enzymes. Biochem J 2002; 368:333-40. [PMID: 12164780 PMCID: PMC1222967 DOI: 10.1042/bj20020272] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2002] [Revised: 07/31/2002] [Accepted: 08/07/2002] [Indexed: 11/17/2022]
Abstract
This study describes the identification of Drosophila yellow-f and yellow-f2 as dopachrome-conversion enzymes responsible for catalysing the conversion of dopachrome into 5,6-dihydroxyindole in the melanization pathway. Drosophila yellow -y gene and yellow -b, -c, -f and -f2 genes were expressed in an insect cell/baculovirus expression system and their corresponding recombinant proteins were screened for dopachrome-conversion enzyme activity. Among the yellow and yellow -related genes, the yellow -f and yellow -f2 genes were identified as the genes coding for Drosophila dopachrome-conversion enzyme based on the high activity of their recombinant proteins in catalysing the production of 5,6-dihydroxyindole from dopachrome. Both yellow-f and yellow-f2 are capable of mediating a decarboxylative structural rearrangement of dopachrome, as well as an isomerization/tautomerization of dopamine chrome and dopa methyl ester chrome. Northern hybridization revealed the transcription of yellow -f in larvae and pupae, but a high abundance of mRNA was observed in later larval and early pupal stages. In contrast, yellow-f2 transcripts were present at all stages, but high abundance of its mRNA was observed in later-stage pupae and adults. These data indicate that yellow-f and yellow-f2 complement each other during Drosophila development and that the yellow-f is involved in larval and pupal melanization, and yellow-f2 plays a major role in melanization reactions in Drosophila during later pupal and adult development. Results from this study provide the groundwork towards a better understanding of the physiological roles of the Drosophila yellow gene family.
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Affiliation(s)
- Qian Han
- Department of Veterinary Pathobiology, University of Illinois at Urbana-Champaign, 2001 South Lincoln Avenue, Urbana, IL 61802, U.S.A
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Hartleb J, Arndt R. Cysteine and indole derivatives as markers for malignant melanoma. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 2001; 764:409-43. [PMID: 11817040 DOI: 10.1016/s0378-4347(01)00278-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Malignant melanoma is a skin tumour, which carries a very unfavourable prognosis. The early detection of a melanoma and even more its metastasis is of decisive importance for the survival prognosis of the patients. So there is always a desire for simple, economical and meaningful serological markers. From the cysteine- and indole-related derivatives, 5-S-cysteinyldopa (5-SCD) and 6-hydroxy-5-methoxy-indole-2-carboxylic acid (6H5MI2C) are the most important substances for this purpose. For 5-SCD, the sample pretreatment was carried out either by a manual extraction onto alumina, by an automated method onto boronic acid affinity gels or by an automated solid-phase extraction. For 6H5MI2C, liquid-liquid extractions or direct injection techniques were applied. The chromatographic analyses in the early years were mostly performed with GC-MS. Today HPLC is the nearly exclusively used separation technique. For HPLC, standard RP18 separating columns and usual compositions of eluents were applied. As detectors both the ECD and the FD showed a sufficient sensitivity and selectivity. 5-SCD and 6H5MI2C are very sensitive to light and oxidation. These properties must be taken into account in the complete analysis procedure, including the sample collection, otherwise false low values will result especially for plasma samples. For a critical discussion of the analytical methods and still more for the interpretation of the obtained results, the detailed analytical procedures must be considered. 5-SCD in plasma is one of the best markers of malignant melanoma. It shows an excellent specificity and also an adequate sensitivity in the metastatic melanoma stages. For the detection of primary melanomas and for urine instead of plasma samples, the sensitivity of 5-SCD is generally lower. Altogether, the sensitivity of this parameter is not yet sufficient. 6H5MI2C and other indole derivatives have been investigated far less than 5-SCD. 6H5MI2C correlates less clearly with the different stages of the melanoma and is therefore a less suitable marker. To improve the sensitivity of the findings, in future the investigations should be performed as multi-marker analysis with the simultaneous measurements of more than one marker substance in a given patient sample. Not only one measurement should be carried out per patient, it would be more meaningful to observe the patients with laboratory diagnostics in the follow-up.
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Borges CR, Roberts JC, Wilkins DG, Rollins DE. Relationship of melanin degradation products to actual melanin content: application to human hair. Anal Biochem 2001; 290:116-25. [PMID: 11180945 DOI: 10.1006/abio.2000.4976] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Methods not only for characterizing but also for quantitating melanin subtypes from the two types of melanin found in hair--eumelanin and pheomelanin--have been established. In relation to testing for drugs of abuse in hair, these methods will allow for correction of drug binding to specific melanin subtypes and will serve to improve drug measurement in hair. 5,6-Dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) make up the majority of the eumelanin polymer while benzothiazene units derived from 2-cysteinyl-S-Dopa (2-CysDopa) and 5-cysteinyl-S-Dopa (5-CysDopa) compose the majority of the pheomelanin polymer. Our results show that: (1) pyrrole-2,3-dicarboxylic acid (PDCA) and pyrrole-2,3,5-tricarboxylic acid (PTCA), markers for DHI and DHICA units, respectively, are produced in 0.37 and 4.8% yields, respectively, when melanins are subjected to alkaline hydrogen peroxide degradation, (2) 3-aminotyrosine (3AT) and 4-amino-3-hydroxyphenylalanine (AHP), markers for 2-CysDopa and 5-CysDopa, respectively, are produced in 16 and 23% yield, respectively, when subjected to hydriodic acid hydrolysis, and (3) that black human hair contains approximately 99% eumelanin and 1% pheomelanin, brown and blond hair contain 95% eumelanin and 5% pheomelanin; and red hair contains 67% eumelanin and 33% pheomelanin. These data will allow deeper investigation into the relationship between melanin composition and drug incorporation into hair.
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Affiliation(s)
- C R Borges
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah 84112, USA.
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35
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Zhang X, Erb C, Flammer J, Nau WM. Absolute rate constants for the quenching of reactive excited states by melanin and related 5,6-dihydroxyindole metabolites: implications for their antioxidant activity. Photochem Photobiol 2000; 71:524-33. [PMID: 10818782 DOI: 10.1562/0031-8655(2000)071<0524:arcftq>2.0.co;2] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The triplet-excited state of benzophenone and the singlet-excited state of 2,3-diazabicyclo[2.2.2]oct-2-ene (Fluorazophore-P) have been employed as kinetic probes to obtain information on the antioxidant activity of the skin and eye pigment melanin and its biogenetic precursors 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA). The excited states were generated by the laser-flash photolysis technique and their reaction kinetics was examined by time-resolved transient absorption or fluorescence spectroscopy, respectively. The reaction between triplet benzophenone and DHI produced with unit efficiency the corresponding 6O-centered semiquinone radical, which was characterized by its characteristic transient absorption. The quenching rate constants for DHI (3.1-8.4 x 10(9) M-1 s-1) and DHICA (3.3-5.5 x 10(9) M-1 s-1) were near the diffusion-controlled limit, indicating excellent antioxidant properties. Kinetic solvent effects were observed. The reactivity of synthetic melanin, assessed through the quenching rate constant of Fluorazophore-P and normalized to the number of monomer units, was more than one order of magnitude lower (2.7 x 10(8) M-1 s-1) than that of its precursors. The trend of the quenching rate constants, i.e. DHI > DHICA approximately alpha-tocopherol > melanin, along with the preferential solubility of DHICA in aqueous environments, serves to account for several experimental results from biochemical studies on the inhibition of lipid peroxidation by these natural antioxidants.
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Affiliation(s)
- X Zhang
- Departement Chemie, Universität Basel, Switzerland
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36
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Sugumaran M, Duggaraju R, Generozova F, Ito S. Insect melanogenesis. II. Inability of Manduca phenoloxidase to act on 5,6-dihydroxyindole-2-carboxylic acid. PIGMENT CELL RESEARCH 1999; 12:118-25. [PMID: 10231199 DOI: 10.1111/j.1600-0749.1999.tb00751.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Eumelanins in animals are biosynthesized by the combined action of tyrosinase, 3,4-dihydroxyphenylalanine (DOPA)chrome isomerase, and other factors. Two kinds of eumelanins were characterized from mammalian systems; these are 5,6-dihydroxyindole (DHI)-melanin and 5,6-dihydroxyindole-2-carboxylic acid (DHICA)-melanin. In insects, melanin biosynthesis is initiated by phenoloxidase and supported by DOPAchrome isomerase (decarboxylating). Based on the facts that DOPA is a poor substrate for insect phenoloxidases and DHI is the sole product of insect DOPAchrome isomerase reaction, it is proposed that insects lack DHICA-melanin. Accordingly, the phenoloxidase isolated from the hemolymph of Manduca sexta failed to oxidize DHICA. Control experiments reveal that mushroom tyrosinase, as well as laccase, which is a contaminant in the commercial preparations of mushroom tyrosinase, are capable of oxidizing DHICA. Neither the whole hemolymph nor the cuticular extracts of M. sexta possessed any detectable oxidase activity towards this substrate. Thus, insects do not seem to produce DHICA-eumelanin. A useful staining procedure to localize DHICA oxidase activity on gels is also presented.
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Affiliation(s)
- M Sugumaran
- Department of Biology, University of Massachusetts at Boston, 02125, USA.
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37
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Blarzino C, Mosca L, Foppoli C, Coccia R, De Marco C, Rosei MA. Lipoxygenase/H2O2-catalyzed oxidation of dihdroxyindoles: synthesis of melanin pigments and study of their antioxidant properties. Free Radic Biol Med 1999; 26:446-53. [PMID: 9895237 DOI: 10.1016/s0891-5849(98)00225-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
5,6-Dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA), which are important intermediates in melanogenesis, can be converted into the corresponding melanin pigments by the action of the lipoxygenase/H2O2 system. Kinetic and HPLC analyses indicate that both DHI and DHICA are good substrates for this enzymatic system. Enzyme activity on both substrates was measured in comparison with peroxidase and tyrosinase; the oxidizing behaviour of lipoxygenase is more similar to that of peroxidase rather than that of tyrosinase. The antioxidant properties of DHI- and DHICA-melanins have been investigated in comparison with other kinds of melanins. DHICA-melanin shows a more pronounced antioxidant effect than that of DHI-melanin and this behaviour can be ascribed to the different structure and solubility of the two pigments. The mixed polymer synthesized from DHI and DHICA is the most effective one. Some implications about the possible explanation of the above mentioned behaviour are discussed.
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Affiliation(s)
- C Blarzino
- Department of Biochemical Sciences, University of Rome La Sapieza, Italy
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38
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Cherqui A, Duvic B, Reibel C, Brehélin M. Cooperation of dopachrome conversion factor with phenoloxidase in the eumelanin pathway in haemolymph of Locusta migratoria (Insecta). INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 1998; 28:839-848. [PMID: 9818385 DOI: 10.1016/s0965-1748(98)00076-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Dopachrome Conversion Factor (DCF) was found in the plasma of the locust Locusta migratoria. It has an apparent molecular mass of 85,000. Its K(m) was 0.2 mM at 22 degrees C and pH 7 with L-dopachrome as substrate. It had a high substrate specificity for L-dopachrome, methyl-L-dopachrome and L-dopachrome methyl ester but no activity on the corresponding D-isomers or on dopaminechrome. DCF was devoid of any phenoloxidase activity. Under action of DCF, L-dopachrome was converted into dihydroxyindole, which showed that a decarboxylation occured in the course of reaction. Locust DCF was inhibited by indole-3-propionic acid but not by indole-3- or indole-2-carboxylic acid. It was also inhibited by L-tryptophan in a competitive manner. Inhibition and substrate specificity suggest that a carboxyl group, either free or as a methyl ester, is necessary but not sufficient for enzyme recognition. When purified prophenoloxidase was activated and then added to dihydroxyindole either prepared by chemical synthesis or obtained by action of purified DCF on dopachrome, black pigments with a maximum absorption at 540 nm were generated. Therefore in the eumelanin pathway of locust plasma, phenoloxidase can catalyze the reaction that converts the product generated by DCF.
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Affiliation(s)
- A Cherqui
- Laboratoire de Pathologie Comparée, INRA-CNRS (URA 2209), Montpellier, France
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39
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Rosei MA, Foppoli C, Wang XT, Coccia R, Mateescu MA. Production of melanins by ceruloplasmin. PIGMENT CELL RESEARCH 1998; 11:98-102. [PMID: 9585247 DOI: 10.1111/j.1600-0749.1998.tb00717.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
It was shown that ceruloplasmin, apart from the known oxidative conversion of dopamine into melanin, can also produce (DHI)-melanin from 5,6-dihydroxyindole and THP-melanin from tetrahydropapaveroline. Ceruloplasmin acts as an oxidase and the kinetic parameters for these oxidative reactions are reported. Since these ceruloplasmin-catalyzed reactions occur also at pH 7.4, they could have a significant physiological impact. This ceruloplasmin-oxidasic activity is enhanced by copper ions and inhibited by chelators, such as ethylenediaminetetraacetic acid (EDTA) and desferoxamine (DEF). Some possible implication of melanin production in blood are discussed.
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Affiliation(s)
- M A Rosei
- Department of Biochemical Sciences, University La Sapienza of Rome, Italy.
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40
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Ozeki H, Wakamatsu K, Ito S, Ishiguro I. Chemical characterization of eumelanins with special emphasis on 5,6-dihydroxyindole-2-carboxylic acid content and molecular size. Anal Biochem 1997; 248:149-57. [PMID: 9177734 DOI: 10.1006/abio.1997.2079] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Mammalian melanins exist in two chemically distinct forms; the brown to black eumelanins and the yellow to reddish pheomelanins. Eumelanins are derived from copolymerization of 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA). Eumelanins can be quantified by HPLC analysis of the oxidation product pyrrole-2,3,5-tricarboxylic acid (PTCA) and by our spectrophotometric method (Sp.EM). We also developed a spectrophotometric method for assaying the total amount of eu- and pheomelanins by dissolving them in Soluene-350 (TM). In addition, we previously showed that Sp.EM/TM and PTCA/TM ratios are significant parameters in characterizing eumelanins produced in follicular melanocytes. The objectives of this study were (1) to clarify the significance of Sp.EM/TM and PTCA/TM ratios in synthetic eumelanins and (2) to apply these methods to characterizing natural eumelanins with various DHI/ DHICA ratios and molecular sizes. The results obtained show that (1) the Sp.EM/TM ratio of synthetic eumelanins increases as polymerization proceeds, (2) the Sp.EM/TM and PTCA/TM ratios in copolymers of DHI and DHICA correlate to the percentage content of DHICA-derived units, and (3) combination of the Sp.EM/TM and PTCA/TM ratios serves to estimate the DHICA content and the degree of polymerization in natural eumelanins.
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Affiliation(s)
- H Ozeki
- School of Medicine, Fujita Health University, Aichi, Japan
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Maeda K, Yokokawa Y, Hatao M, Naganuma M, Tomita Y. Comparison of the melanogenesis in human black and light brown melanocytes. J Dermatol Sci 1997; 14:199-206. [PMID: 9138477 DOI: 10.1016/s0923-1811(96)00575-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We examined how and to what extent the constitution of melanin and the expression, as well as the activity, of melanosomal proteins influence the production of melanin pigment by human black and light brown melanocytes, Mel (b) cells and Mel (l) cells, respectively. Melanin pigment in Mel (b) and Mel (l) cells consisted of a mixture of eumelanin and pheomelanin, and Mel (b) cells contained a larger amount. The signal intensity ratio of eumelanin to pheomelanin was similar in both cell types, though the two cell types differed in appearance. Tyrosinase activity and the amount of tyrosinase-related protein (TRP-1) of Mel (b) cells were higher than those of Mel (l) cells. Dopachrome tautomerase (DCT) activity and the amount of 6H5MICA were reduced in Mel (b) cells in comparison with Mel (l) cells. No significant difference in DHICA-converting activity or catechol-O-methyltransferase activity was found between Mel (b) and Mel (l) cells. There was no correlation between DHICA-converting activity and amount of TRP-1. These results suggest that the difference in the pigmentation of the two human melanocyte cell lines, Mel (b) and Mel (l), is derived from differences in the activity and expression of tyrosinase, TRP-1 and DCT, which affect the content and constitution of melanin polymers.
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Affiliation(s)
- K Maeda
- Shiseido Research Center, Yokohama, Japan
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Martínez-Esparza M, Jiménez-Cervantes C, Beermann F, Aparicio P, Lozano JA, García-Borrón JC. Transforming growth factor-beta1 inhibits basal melanogenesis in B16/F10 mouse melanoma cells by increasing the rate of degradation of tyrosinase and tyrosinase-related protein-1. J Biol Chem 1997; 272:3967-72. [PMID: 9020101 DOI: 10.1074/jbc.272.7.3967] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Current evidence suggests that melanogenesis is controlled by epidermal paracrine modulators. We have analyzed the effects of transforming growth factor-beta1 (TGF-beta1) on the basal melanogenic activities of B16/F10 mouse melanoma cells. TGF-beta1 treatment (48 h) elicited a concentration-dependent decrease in basal tyrosine hydroxylase and 3,4-dihydroxyphenylalanine (Dopa) oxidase activities, to less than 30% of the control values but had no effect on dopachrome tautomerase activity (TRP-2). The inhibition affected to similar extents the Dopa oxidase activity associated to tyrosinase-related protein-1 (TRP-1) and tyrosinase. This inhibition was noticeable between 1 and 3 h after the addition of the cytokine, and maximal after 6 h of treatment. The decrease in the enzymatic activity was paralleled by a decrease in the abundance of the TRP-1 and tyrosinase proteins. TGF-beta1 mediated this effect by increasing the rate of degradation of tyrosinase and TRP-1. Conversely, after 48 h of treatment, the expression of the tyrosinase gene decreased only slightly, while TRP-1 and TRP-2 gene expression was not affected. An increased rate of proteolytic degradation of TRP-1 and tyrosinase seems the main mechanism accounting for the inhibitory effect of TGF-beta1 on the melanogenic activity of B16/F10 cells.
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Affiliation(s)
- M Martínez-Esparza
- Department of Biochemistry and Molecular Biology, School of Medicine, University of Murcia, 30100 Espinardo, Murcia, Spain
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Wong KT, Tan BKH, Sim KY, Goh SH. A Cytotoxic Melanin Precursor, 5,6-Dihydroxyindole, from the Folkloric Anti-Cancer PlantRhaphidophora Korthalsii. ACTA ACUST UNITED AC 1996. [DOI: 10.1080/10575639608044937] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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44
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45
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Benedito E, Jiménez-Cervantes C, Cubillana JD, Solano F, Lozano JA, García-Borrón JC. Biochemical characterization of the melanogenic system in the eye of adult rodents. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1252:217-24. [PMID: 7578226 DOI: 10.1016/0167-4838(95)00130-m] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The melanogenic activities in the eye of the adult gerbil (Meriones unguiculatus) have been investigated and compared to those found in the B16 mouse melanoma model. Eye extracts contain tyrosine hydroxylase, DOPA oxidase, DOPAchrome tautomerase and DHICA oxidase activities. The subcellular distribution of these activities was investigated by differential centrifugation and detergent solubilization of the particulate fractions. The distribution pattern closely resembled the one found for mouse melanoma, with a higher percentage of activity associated to the particulate fractions but a substantial proportion in the cytosolic fraction. The tyrosine hydroxylase activity was characterized by a KM of 62 microM for L-tyrosine and a stringent requirement for the co-factor L-DOPA (Ka 10.3 microM). The KM for L-DOPA was 0.41 mM. The sensitivity of the eye and mouse melanoma tyrosinase activity to a variety of substrate analogs and metal chelators was found to be identical. In keeping with these kinetic similarities, eye tyrosinase displayed some structural properties resembling those of the melanoma enzyme. The molecular weight of the enzyme, determined by SDS-PAGE and DOPA oxidase activity stain, was 75 kDa for the eye enzyme and 66.2 kDa for melanoma tyrosinase, and both enzymes were apparently dimeric in non ionic detergent solution. Immunoprecipitation with specific antibodies proved that at least 80% of the total tyrosinase activity could be immunoprecipitated with the specific anti-tyrosinase antibody alpha PEP7, while the anti-TRP-1 monoclonal antibody TMH-1 precipitated little, if any, tyrosinase activity. Taken together, these observations provide the first vis-à-vis comparison of an extracutaneous melanogenic system and the melanogenic system of melanoma. Our results prove that, at least in rodents, the melanogenic system in the eye is similar, but not identical, to the melanin biosynthesis machinery of epidermal melanocytes.
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Affiliation(s)
- E Benedito
- Departamento de Bioquímica y Biología Molecular e Inmunología, Facultad de Medicina, Universidad de Murcia, Spain
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46
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Routaboul C, Serpentini CL, Msika P, Cesarini JP, Paillous N. PHOTOSENSITIZATION OF SUPERCOILED DNA DAMAGE BY 5,6-DIHYDROXYINDOLE-2-CARBOXYLIC ACID, A PRECURSOR OF EUMELANIN. Photochem Photobiol 1995. [DOI: 10.1111/j.1751-1097.1995.tb02370.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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47
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Schmitz S, Thomas PD, Allen TM, Poznansky MJ, Jimbow K. Dual role of melanins and melanin precursors as photoprotective and phototoxic agents: inhibition of ultraviolet radiation-induced lipid peroxidation. Photochem Photobiol 1995; 61:650-5. [PMID: 7568412 DOI: 10.1111/j.1751-1097.1995.tb09883.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Ultraviolet radiation (UVR) is one of the risk factors for skin cancer and the main inducer of melanin pigmentation, the major protective mechanism of mammalian skin against radiation damage. The melanin pigments, eumelanin and pheomelanin, are likely to be important in protection against UVR, but their precursors are generally considered as phototoxic. The available data suggest DNA damage as the mechanism of phototoxicity. However, the effect of melanin precursors on membrane damage through lipid peroxidation, another important and probably more relevant (from the point-of-view of the melanosomal confinement of these molecules) mechanism of phototoxicity, not known. As a model system for UVR-melanin-membrane interactions, we irradiated liposomes in the presence of eumelanin, pheomelanin and two of their major precursors, 5,6-dihydroxyindole (DHI) and 5-S-cysteinyldopa (SCD). The presence of the two melanin precursors substantially reduced the formation of lipid peroxidation products resulting from UVR exposure. The antioxidant activity of the melanin precursors was diminished under strong prooxidant conditions (presence of Fe3+). These results suggest that melanin precursors may have an important role in the protection of skin against the harmful effects of UVR including photocarcinogenesis.
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Affiliation(s)
- S Schmitz
- Department of Physiology, University of Alberta, Edmonton, Canada
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48
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Smit NP, Westerhof W, Smit W, Nanninga B, Pavel S. Some aspects of melanin formation of melanocytes cultured on collagen-coated microcarrier beads. PIGMENT CELL RESEARCH 1995; 8:89-96. [PMID: 7659682 DOI: 10.1111/j.1600-0749.1995.tb00647.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Melanocytes cultured on collagen-coated Cytodex 3 microcarrier Sephadex beads caused remarkable pigmentation of the beads during the period of culture when optimal density was reached. Electron microscopy of melanocytes on the microcarriers revealed that the cells and their dendrites invaginate into the microcarrier surface layer. Removal of the cells by trypsinization showed that some pigment granules were left on the carrier surface and within the cavities present on the microcarrier surface. In order to investigate whether the pigmentation of the microcarriers could be a result of indole intermediates of melanogenesis present in the culture medium, extracts were studied by gas chromatography/mass spectrometry for the presence of these compounds. Two compounds (5,6-dihydroxyindole-2-carboxylic acid and 6-hydroxy-5-methoxyindole-2-carboxylic acid) so far have been identified in the medium extracts. Results indicate that microcarrier culture of melanocytes can serve as an interesting model for electron microscopy studies of melanocytes with regard to pigmentation and cell attachment.
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Affiliation(s)
- N P Smit
- Department of Dermatology, Academic Medical Centre, Amsterdam, the Netherlands
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49
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Kameyama K, Sakai C, Kuge S, Nishiyama S, Tomita Y, Ito S, Wakamatsu K, Hearing VJ. The expression of tyrosinase, tyrosinase-related proteins 1 and 2 (TRP1 and TRP2), the silver protein, and a melanogenic inhibitor in human melanoma cells of differing melanogenic activities. PIGMENT CELL RESEARCH 1995; 8:97-104. [PMID: 7659683 DOI: 10.1111/j.1600-0749.1995.tb00648.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The expression of various melanogenic proteins, including tyrosinase, the tyrosinase-related proteins 1 (TRP1) and 2 (TRP2/DOPAchrome tautomerase), and the silver protein in human melanocytes was studied in six different human melanoma cell lines and compared to a mouse derived melanoma cell line. Analysis of the expression of tyrosinase, TRP1, TRP2, and the silver protein using flow cytometry revealed that in general there was a positive correlation between melanin formation and the expression of those melanogenic enzymes. Although several of the melanoma cell lines possessed significant activities of TRP2, the levels of DOPAchrome tautomerase in extracts of human cells were relatively low compared to those in murine melanocytes. Melanins derived from melanotic murine JB/MS cells, from melanotic human Ihara cells and HM-IY cells, from sepia melanin, and from C57BL/6 mouse hair were chemically analyzed. JB/MS cells, as well as Ihara cells and HM-TY cells, possessed significant amounts of 5,6-dihydroxyindole-2-carboxylic acid (DHICA) derived melanins, this being dependent on the activity of TRP2. Kinetic HPLC assays showed that 5,6-dihydroxyindole (DHI) produced during melanogenesis was metabolized quickly to melanin in pigmented KHm-1/4 cells, whereas DHI was stable in amelanotic human SK-MEL-24 cells. A melanogenic inhibitor that has been purified from SK-MEL-24 cells that suppressed oxidation of DHI in the presence or absence of tyrosinase, but had no effect on DHICA oxidation. The sum of these results suggests that the expression of melanogenic enzymes as well as the activity of a melanogenic inhibitor are critical to the production of melanin synthesis in humans.
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Affiliation(s)
- K Kameyama
- Department of Dermatology, Kitasato Institute Medical Center Hospital, Saitama, Japan
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50
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Li J, Christensen BM. Effect of pH on the oxidation pathway of dopamine and dopa. J Electroanal Chem (Lausanne) 1994. [DOI: 10.1016/0022-0728(94)03389-7] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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