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Hałdys K, Goldeman W, Anger-Góra N, Rossowska J, Latajka R. Monosubstituted Acetophenone Thiosemicarbazones as Potent Inhibitors of Tyrosinase: Synthesis, Inhibitory Studies, and Molecular Docking. Pharmaceuticals (Basel) 2021; 14:ph14010074. [PMID: 33477655 PMCID: PMC7831505 DOI: 10.3390/ph14010074] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 01/06/2021] [Accepted: 01/11/2021] [Indexed: 12/19/2022] Open
Abstract
A set of 12 monosubstituted acetophenone thiosemicarbazone derivatives (TSCs) were synthesized and their inhibitory properties toward tyrosinase activity were tested. Moreover, their ability to inhibit melanogenesis in the B16F10 murine melanoma cell line was studied. In order to investigate the nature of interactions between the enzyme and the inhibitors, molecular docking to the active site was performed. TSCs 5, 6, 8, and 9 revealed a half maximal inhibitory concentration (IC50) below 1 µM. Compound 6 turned out to be the most potent tyrosinase inhibitor. All investigated compounds showed reversible inhibition of competitive or mixed type. The para-substituted TSCs had higher affinity for the enzyme as compared to their ortho- and meta-analogues. All investigated compounds inhibited melanin production in B16F10 cells at the micromolar level. Molecular docking showed that the sulfur atom of the thiourea moiety penetrates the active site and interacts with copper ions. The above outcomes might be helpful in the design of new tyrosinase inhibitors in the food and cosmetic industries.
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Affiliation(s)
- Katarzyna Hałdys
- Department of Bioorganic Chemistry, Wrocław University of Science and Technology, 50-370 Wrocław, Poland
- Correspondence: (K.H.); (R.L.)
| | - Waldemar Goldeman
- Department of Organic and Medicinal Chemistry, Wrocław University of Science and Technology, 50-370 Wrocław, Poland;
| | - Natalia Anger-Góra
- Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Science, 53-114 Wrocław, Poland; (N.A.-G.); (J.R.)
| | - Joanna Rossowska
- Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Science, 53-114 Wrocław, Poland; (N.A.-G.); (J.R.)
| | - Rafał Latajka
- Department of Bioorganic Chemistry, Wrocław University of Science and Technology, 50-370 Wrocław, Poland
- Correspondence: (K.H.); (R.L.)
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Cabezudo I, Ayelen Ramallo I, Alonso VL, Furlan RLE. Effect directed synthesis of a new tyrosinase inhibitor with anti-browning activity. Food Chem 2020; 341:128232. [PMID: 33039744 DOI: 10.1016/j.foodchem.2020.128232] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 09/24/2020] [Accepted: 09/24/2020] [Indexed: 11/24/2022]
Abstract
The inhibition of enzymatic browning is an attractive target to elevate the quality of foods. The objective of this work is to describe a novel platform for the discovery of tyrosinase inhibitors, based on (a) one-pot preparation of a library of thiosemicarbazide compounds, (b) biological evaluation using tyrosinase TLC bioautography, (c) inhibitor identification via mass spectrometry coupled to bioautography. During these proof-of-concept experiments, the approach led to the straightforward identification of a new thiosemicarbazone with improved tyrosinase inhibition properties and fresh-cut apple slices antibrowning effect when compared to kojic acid. In conclusion, the platform represents an interesting strategy for the discovery of this type of inhibitors.
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Affiliation(s)
- Ignacio Cabezudo
- Farmacognosia, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Suipacha 531, 2000 Rosario, Argentina.
| | - I Ayelen Ramallo
- Farmacognosia, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Suipacha 531, 2000 Rosario, Argentina.
| | - Victoria L Alonso
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Argentina.
| | - Ricardo L E Furlan
- Farmacognosia, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Suipacha 531, 2000 Rosario, Argentina.
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Song S, Mai Y, Shi H, Liao B, Wang F. Design, Synthesis, Biological Evaluation and Inhibition Mechanism of 3-/4-Alkoxy Phenylethylidenethiosemicarbazides as New, Potent and Safe Tyrosinase Inhibitors. Chem Pharm Bull (Tokyo) 2020; 68:369-379. [DOI: 10.1248/cpb.c19-00949] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Senchuan Song
- Guangdong Research Institute of Petrochemical and Fine Chemical Engineering, Guangdong Academy of Sciences
| | - Yuliang Mai
- Guangdong Research Institute of Petrochemical and Fine Chemical Engineering, Guangdong Academy of Sciences
| | - Huahong Shi
- Guangdong Research Institute of Petrochemical and Fine Chemical Engineering, Guangdong Academy of Sciences
| | - Bing Liao
- Guangdong Research Institute of Petrochemical and Fine Chemical Engineering, Guangdong Academy of Sciences
| | - Fei Wang
- Guangdong Research Institute of Petrochemical and Fine Chemical Engineering, Guangdong Academy of Sciences
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Halogenated aromatic thiosemicarbazones as potent inhibitors of tyrosinase and melanogenesis. Bioorg Chem 2020; 94:103419. [DOI: 10.1016/j.bioorg.2019.103419] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 10/10/2019] [Accepted: 10/31/2019] [Indexed: 12/15/2022]
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Zolghadri S, Bahrami A, Hassan Khan MT, Munoz-Munoz J, Garcia-Molina F, Garcia-Canovas F, Saboury AA. A comprehensive review on tyrosinase inhibitors. J Enzyme Inhib Med Chem 2019; 34:279-309. [PMID: 30734608 PMCID: PMC6327992 DOI: 10.1080/14756366.2018.1545767] [Citation(s) in RCA: 511] [Impact Index Per Article: 102.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 11/04/2018] [Accepted: 11/05/2018] [Indexed: 12/17/2022] Open
Abstract
Tyrosinase is a multi-copper enzyme which is widely distributed in different organisms and plays an important role in the melanogenesis and enzymatic browning. Therefore, its inhibitors can be attractive in cosmetics and medicinal industries as depigmentation agents and also in food and agriculture industries as antibrowning compounds. For this purpose, many natural, semi-synthetic and synthetic inhibitors have been developed by different screening methods to date. This review has focused on the tyrosinase inhibitors discovered from all sources and biochemically characterised in the last four decades.
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Affiliation(s)
- Samaneh Zolghadri
- Department of Biology, Jahrom Branch, Islamic Azad University, Jahrom, Iran
| | - Asieh Bahrami
- Department of Biology, Jahrom Branch, Islamic Azad University, Jahrom, Iran
| | | | - J. Munoz-Munoz
- Group of Microbiology, Department of Applied Sciences, Northumbria University at Newcastle, Newcastle Upon Tyne, UK
| | - F. Garcia-Molina
- GENZ-Group of Research on Enzymology, Department of Biochemistry and Molecular Biology-A, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, Espinardo, Murcia, Spain
| | - F. Garcia-Canovas
- GENZ-Group of Research on Enzymology, Department of Biochemistry and Molecular Biology-A, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, Espinardo, Murcia, Spain
| | - Ali Akbar Saboury
- Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
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Hałdys K, Latajka R. Thiosemicarbazones with tyrosinase inhibitory activity. MEDCHEMCOMM 2019; 10:378-389. [PMID: 31015905 DOI: 10.1039/c9md00005d] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 02/01/2019] [Indexed: 01/20/2023]
Abstract
Tyrosinase plays an essential role in melanogenesis. Excess production of melanin can be a reason for hyperpigmentation skin disorders in mammals and enzymatic browning in plant-derived foods. Catalyzing the rate-limiting step of melanin synthesis, tyrosinase has become the most studied target for melanogenesis inhibition. Over the past ten years, a number of synthetic thiosemicarbazone derivatives have been reported to possess strong tyrosinase inhibitory properties with IC50 values below 1 μM, placing them among the most potent tyrosinase inhibitors. This review gives an overview of tyrosinase activity and describes tyrosinase-inhibiting thiosemicarbazones in terms of their structure-activity relationships, kinetics of enzyme inhibition and mechanism of action. Results of the studies of thiosemicarbazones as tyrosinase inhibitors from over 20 research articles have been analyzed, compared and summarized in the present paper. Using thiosemicarbazones as tyrosinase inhibitors is a promising approach in developing anti-melanogenetic agents for skin-whitening cosmetics and anti-browning agents for food.
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Affiliation(s)
- Katarzyna Hałdys
- Wrocław University of Science and Technology , Department of Bioorganic Chemistry , Wybrzeże Wyspiańskiego 27 , 50-370 , Wrocław , Poland .
| | - Rafał Latajka
- Wrocław University of Science and Technology , Department of Bioorganic Chemistry , Wybrzeże Wyspiańskiego 27 , 50-370 , Wrocław , Poland .
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Inhibitory properties of aromatic thiosemicarbazones on mushroom tyrosinase: Synthesis, kinetic studies, molecular docking and effectiveness in melanogenesis inhibition. Bioorg Chem 2018; 81:577-586. [DOI: 10.1016/j.bioorg.2018.09.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 09/05/2018] [Accepted: 09/06/2018] [Indexed: 12/12/2022]
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Pillaiyar T, Namasivayam V, Manickam M, Jung SH. Inhibitors of Melanogenesis: An Updated Review. J Med Chem 2018; 61:7395-7418. [PMID: 29763564 DOI: 10.1021/acs.jmedchem.7b00967] [Citation(s) in RCA: 175] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Melanins are pigment molecules that determine the skin, eye, and hair color of the human subject to its amount, quality, and distribution. Melanocytes synthesize melanin and provide epidermal protection from various stimuli, such as harmful ultraviolet radiation, through the complex process called melanogenesis. However, serious dermatological problems occur when there is excessive production of melanin in different parts of the human body. These include freckles, melasma, senile lentigo, pigmented acne scars, and cancer. Therefore, controlling the production of melanin is an important approach for the treatment of pigmentation related disorderes. In this Perspective, we focus on the inhibitors of melanogenesis that directly/indirectly target a key enzyme tyrosinase as well as its associated signaling pathways.
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Affiliation(s)
- Thanigaimalai Pillaiyar
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I , University of Bonn , An der Immenburg 4 , D-53121 Bonn , Germany
| | - Vigneshwaran Namasivayam
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I , University of Bonn , An der Immenburg 4 , D-53121 Bonn , Germany
| | - Manoj Manickam
- College of Pharmacy and Institute of Drug Research and Development , Chungnam National University , Daejeon 34134 , Korea
| | - Sang-Hun Jung
- College of Pharmacy and Institute of Drug Research and Development , Chungnam National University , Daejeon 34134 , Korea
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Pillaiyar T, Manickam M, Namasivayam V. Skin whitening agents: medicinal chemistry perspective of tyrosinase inhibitors. J Enzyme Inhib Med Chem 2017; 32:403-425. [PMID: 28097901 PMCID: PMC6010116 DOI: 10.1080/14756366.2016.1256882] [Citation(s) in RCA: 481] [Impact Index Per Article: 68.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 09/07/2016] [Accepted: 10/11/2016] [Indexed: 12/31/2022] Open
Abstract
Melanogenesis is a process to synthesize melanin, which is a primary responsible for the pigmentation of human skin, eye and hair. Although numerous enzymatic catalyzed and chemical reactions are involved in melanogenesis process, the enzymes such as tyrosinase and tyrosinase-related protein-1 (TRP-1) and TRP-2 played a major role in melanin synthesis. Specifically, tyrosinase is a key enzyme, which catalyzes a rate-limiting step of the melanin synthesis, and the downregulation of tyrosinase is the most prominent approach for the development of melanogenesis inhibitors. Therefore, numerous inhibitors that target tyrosinase have been developed in recent years. The review focuses on the recent discovery of tyrosinase inhibitors that are directly involved in the inhibition of tyrosinase catalytic activity and functionality from all sources, including laboratory synthetic methods, natural products, virtual screening and structure-based molecular docking studies.
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Affiliation(s)
- Thanigaimalai Pillaiyar
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Manoj Manickam
- College of Pharmacy and Institute of Drug Research and Development, Chungnam National University, Daejeon, Korea
| | - Vigneshwaran Namasivayam
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
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Campos PM, Prudente AS, Horinouchi CDDS, Cechinel-Filho V, Fávero GM, Cabrini DA, Otuki MF. Inhibitory effect of GB-2a (I3-naringenin-II8-eriodictyol) on melanogenesis. JOURNAL OF ETHNOPHARMACOLOGY 2015; 174:224-229. [PMID: 26297636 DOI: 10.1016/j.jep.2015.08.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 07/26/2015] [Accepted: 08/18/2015] [Indexed: 06/04/2023]
Abstract
ETHNOPHARMACOLOGY RELEVANCE GB-2a is a I3-naringenin-II8-eriodictyol compound isolated from Garcinia gardneriana (Planchon & Triana) Zappi, a plant used in folk medicine for the treatment of skin disorders. AIM OF STUDY In the search for new depigmenting agents, this study was carried out to investigate the in vitro effects of GB-2a isolated from G. gardneriana (Planchon & Triana) Zappi in B16F10 melanoma cells. MATERIALS AND METHODS The effects of GB-2a were evaluated through determination of melanin biosynthesis in B16F10 melanoma cells in comparison with the reference drug kojic acid (500µM). In parallel, the GB-2a effect was assessed in a cell viability assay. Mushroom tyrosinase activity assays were conducted to verify the effect of this enzyme. In order to ascertain the nature of enzyme inhibition on tyrosinase, kinetics analysis of the GB-2a was performed with L-tyrosine and L-3,4-dihydroxyphenylalanine (L-DOPA) substrates. RESULTS The results showed that GB-2a biflavonoid significantly inhibited the melanin content, without reducing cell viability. GB-2a also showed a strong antityrosinase activity in the mushroom tyrosinase assay. GB-2a inhibited the tyrosinase activity, exerting a mixed inhibition. For the L-tyrosine substrate the inhibition was in non-competitive mode and for L-DOPA it was in uncompetitive mode. CONCLUSION GB-2a biflavonoid promoted inhibition on tyrosinase activity and reduced melanin biosynthesis in B16F10 cells, which suggests great potential for medical and cosmetic uses as a depigmenting agent.
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Affiliation(s)
- Patrícia Mazureki Campos
- Department of Pharmaceutical Sciences, Federal University of Parana, CEP 80210-170, Curitiba, PR, Brazil
| | | | | | - Valdir Cechinel-Filho
- Investigation Centre of Pharmaceutical Chemistry, University of Itajai Valley, CEP 88302-202, Itajai, SC, Brazil
| | - Giovani Marino Fávero
- Department of Biological Sciences, State University of Ponta Grossa, CEP 84030-900, Ponta Grossa, PR, Brazil
| | - Daniela Almeida Cabrini
- Department of Pharmacology, Federal University of Parana, CEP 81530-900, Curitiba, PR, Brazil
| | - Michel Fleith Otuki
- Department of Pharmacology, Federal University of Parana, CEP 81530-900, Curitiba, PR, Brazil.
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Tang L, Zhang W, Zhao H, Chen Z. Tyrosinase inhibitor screening in traditional Chinese medicines by electrophoretically mediated microanalysis. J Sep Sci 2015; 38:2887-92. [DOI: 10.1002/jssc.201500371] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 05/10/2015] [Accepted: 05/11/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Lilin Tang
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery; Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University; Wuhan China
- State Key Laboratory of Transducer Technology; Chinese Academy of Sciences; Beijing China
| | - Wenpeng Zhang
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery; Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University; Wuhan China
| | - Haiyan Zhao
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery; Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University; Wuhan China
| | - Zilin Chen
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery; Ministry of Education, and School of Pharmaceutical Sciences, Wuhan University; Wuhan China
- State Key Laboratory of Transducer Technology; Chinese Academy of Sciences; Beijing China
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Rational design, synthesis and structure–activity relationships of 4-alkoxy- and 4-acyloxy-phenylethylenethiosemicarbazone analogues as novel tyrosinase inhibitors. Bioorg Med Chem 2015; 23:924-31. [DOI: 10.1016/j.bmc.2015.01.024] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Revised: 01/15/2015] [Accepted: 01/17/2015] [Indexed: 01/01/2023]
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You A, Zhou J, Song S, Zhu G, Song H, Yi W. Structure-based modification of 3-/4-aminoacetophenones giving a profound change of activity on tyrosinase: From potent activators to highly efficient inhibitors. Eur J Med Chem 2015; 93:255-62. [DOI: 10.1016/j.ejmech.2015.02.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 01/16/2015] [Accepted: 02/10/2015] [Indexed: 12/30/2022]
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Novel Fe(III), Co(III), Ni(II), Cu(II) coordination compounds involving 2-[(2-hydroxyphenyl)methylene]hydrazine-N-(2-propenyl)-carbothioamide as ligand: Synthesis, crystal structures and spectral characteristics. Inorganica Chim Acta 2014. [DOI: 10.1016/j.ica.2014.08.056] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Mendes E, Perry MDJ, Francisco AP. Design and discovery of mushroom tyrosinase inhibitors and their therapeutic applications. Expert Opin Drug Discov 2014; 9:533-54. [PMID: 24708040 DOI: 10.1517/17460441.2014.907789] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
INTRODUCTION Tyrosinase inhibitors could have a huge importance in medicine, cosmetics and agriculture. Although many tyrosinase inhibitors are available, they have demonstrated only mild efficacy and safety concerns. This has led to the discovery of novel tyrosinase inhibitors that are more safe, potent and efficacious. AREAS COVERED The authors provide an overview of the recent scientific accounts describing the design of new molecules. These compounds belong to different chemical families. The review emphasizes the rationale behind the discovery, the study of structure-activity relationships, the study of the mechanism and kinetic of inhibition and the cellular effect of the inhibitors. The article is based on the literature published from 2007 onward related with the development of synthetic tyrosinase inhibitors. EXPERT OPINION Although a great number of tyrosinase inhibitors have been published in the literature, none, as of yet, have reached the potency and safety requirements needed to enter clinical trials. The emergence of new in vitro and in vivo tests will finally allow the arrival of new compounds that are more potent and safe.
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Affiliation(s)
- Eduarda Mendes
- Universidade de Lisboa, Instituto de Investigação do Medicamento (iMed.ULisboa), Faculdade de Farmácia, Department of Toxicological and Bromatological Sciences , Av. Prof. Gama Pinto, 1649-003 Lisboa , Portugal
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Inhibitory effects of novel synthetic methimazole derivatives on mushroom tyrosinase and melanogenesis. Bioorg Med Chem 2014; 22:2809-15. [PMID: 24703463 DOI: 10.1016/j.bmc.2014.03.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 03/04/2014] [Accepted: 03/06/2014] [Indexed: 11/24/2022]
Abstract
In this study, we synthesized 4 methimazole (2-mercapto-1-methylimidazole, MMI) derivatives. The kinetics of inhibition on mushroom tyrosinase by methimazole and its derivatives were investigated. The results indicated that tert-butyl 3-methyl-2-sulfanylidene-2,3-dihydro-1H-imidazole-1-carboxylate (compound 3; 3), 2-mercaptoimidazole (MI; compound 1; 1) and MMI (compound 2; 2) significantly inhibited tyrosinase activity in a dose-dependent manner, exhibiting an IC50 value of 1.50mM, 4.11 mM, and 1.43 mM. However, compound 4 (4), compound 5 (5), and compound 6 (6) exerted no inhibitory effect on mushroom tyrosinase activity. Kinetic analysis indicated that 3 was a noncompetitive tyrosinase inhibitor, whereas both 1 and 2 were exhibited as mixed-type tyrosinase inhibitors. Furthermore, 3 exerted a potent inhibitory effect on intracellular melanin formation in the B16/F10 murine melanoma cells and did not cause cytotoxicity, as 1 and 2 did.
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