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Tsotinis A, Afroudakis PA, Papanastasiou IP, Sakellaropoulou A, Boniakou M, Komiotis D, Garratt PJ, Delagrange P, Bocianowska-Zbrog A, Sugden D. Mapping the Melatonin Receptor. 8. Selective MT2 Agonists derived from 5,6-dihydroindolo[2,1-a]isoquinolines and related systems. ChemMedChem 2022; 17:e202200129. [PMID: 35478275 DOI: 10.1002/cmdc.202200129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 04/15/2022] [Indexed: 11/10/2022]
Abstract
A series of substituted indolo[2,1- a ]isoquinolines and indolo[1,2- a ]benzoxazines have been prepared, as melatonin analogues, to investigate the nature of the binding site of the melatonin receptor. Agonist and antagonist potency of all the analogues was measured using the [35S]GTPγS binding assay protocol. The binding affinity of the analogues were measured by competition binding studies against the human MT1 (hMT1) and MT2 (hMT2) receptors stably transfected in Chinese Hamster Ovarian (CHO) cells, using 2-[ 125 I]-iodomelatonin, as a ligand. N -Acetyl 2-(10-methoxy-5,6-dihydroindolo[2,1- a ]isoquinolin-12-yl)propyl-1-amine (12a) binds strongly to both the hMT1 and hMT2 receptors, and shows a preference for the hMT2, as does Its propanamido counterpart 12b . The introduction of two methyl groups into their side chain, analogues 15a and 1 5b, leads to antagonism, in the case of the former, and drastically diminishes its hMT1 binding; an analogous profile is seen for 15b , which, however, is a partial agonist.. Introduction of chlorine or methoxyl groups into ring 4 gives compounds, that are weakly binding, with a preference for MT2. Substitution of oxygen for carbon at position 5 gives the indolo[1,2- c ]benzoxazines 33 , 36a and b , that bind strongly to the human receptors, 33 , 36b are potent agonists at the melatonin receptors, but do not discriminate between hMT1 and hMT2.
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Affiliation(s)
- Andrew Tsotinis
- University of Athens: Ethniko kai Kapodistriako Panepistemio Athenon, Faculty of Pharmacy, Department of Pharmaceutical Chemistry, Panepistimioupoli-Zografou, 15771, Athens, GREECE
| | - Pandelis A Afroudakis
- National and Kapodistrian University of Athens School of Health Sciences: Ethniko kai Kapodistriako Panepistemio Athenon, Pharmacy, GREECE
| | - Ioannis P Papanastasiou
- National and Kapodistrian University of Athens School of Health Sciences: Ethniko kai Kapodistriako Panepistemio Athenon, Pharmacy, GREECE
| | - Aikaterini Sakellaropoulou
- National and Kapodistrian University of Athens School of Health Sciences: Ethniko kai Kapodistriako Panepistemio Athenon, Pharmacy, GREECE
| | - Marina Boniakou
- National and Kapodistrian University of Athens: Ethniko kai Kapodistriako Panepistemio Athenon, Pharmacy, GREECE
| | - Dimitri Komiotis
- University of Thessaly: Panepistemio Thessalias, Department of Biochemistry & Biotechnology, GREECE
| | | | | | | | - David Sugden
- King's College London, Pharmacology, UNITED KINGDOM
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2
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Alkozi HA, Sánchez Montero JM, Doadrio AL, Pintor J. Docking studies for melatonin receptors. Expert Opin Drug Discov 2017; 13:241-248. [PMID: 29271261 DOI: 10.1080/17460441.2018.1419184] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
INTRODUCTION Melatonin is a neurohormone that controls many relevant physiological processes beyond the control of circadian rhythms. Melatonin's actions are carried out by two main types of melatonin receptors; MT1 and MT2. These receptors are important, and not just because of the biological actions of its natural agonist; but also, because melatonin analogues can improve or antagonize their biological effect. Area covered: The following article describes the importance of melatonin as a biologically relevant molecule. It also defines the receptors for this substance, as well as the second messengers coupled to these receptors. Lastly, the article describes the amino acid residues involved in the docking process in both MT1 and MT2 melatonin receptors. Expert opinion: The biological actions of melatonin and their interpretations are becoming more relevant and therefore require the development of new pharmacological tools. Understanding the second messenger mechanisms involved in melatonin actions, as well as the characteristics of the docking of this molecule to MT1 and MT2 melatonin receptors, will permit the development of more selective agonists and antagonists which will help us to better understand this molecule as well to develop new therapeutic compounds.
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Affiliation(s)
- Hanan Awad Alkozi
- a Department of Biochemistry and Molecular Biology IV, Faculty of Optometry , Universidad Complutense de Madrid , Madrid , Spain
| | - José Maria Sánchez Montero
- b Department of Organic Chemistry and Pharmaceutical, Faculty of Pharmacy , Ciudad Universitaria , Madrid , Spain
| | - Antonio Luis Doadrio
- c Department of Inorganic Chemistry and Bioorganic, Faculty of Pharmacy , University Complutense of Madrid , Ciudad Universitaria, Madrid , Spain
| | - Jesus Pintor
- a Department of Biochemistry and Molecular Biology IV, Faculty of Optometry , Universidad Complutense de Madrid , Madrid , Spain
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3
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Tsotinis A, Afroudakis PA, Garratt PJ, Bocianowska-Zbrog A, Sugden D. Benzocyclobutane, Benzocycloheptane and Heptene Derivatives as Melatonin Agonists and Antagonists. ChemMedChem 2014; 9:2238-43. [DOI: 10.1002/cmdc.201402122] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Indexed: 12/15/2022]
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Zlotos DP, Jockers R, Cecon E, Rivara S, Witt-Enderby PA. MT1 and MT2 Melatonin Receptors: Ligands, Models, Oligomers, and Therapeutic Potential. J Med Chem 2013; 57:3161-85. [DOI: 10.1021/jm401343c] [Citation(s) in RCA: 114] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Darius. P. Zlotos
- Department
of Pharmaceutical Chemistry, The German University in Cairo, New Cairo City, 11835 Cairo, Egypt
| | - Ralf Jockers
- Inserm, U1016,
Institut Cochin, Paris, France
- CNRS UMR
8104, Paris, France
- Univ. Paris Descartes, Sorbonne Paris Cite, Paris, France
| | - Erika Cecon
- Department
of Physiology, Institute of Bioscience, University of Sao Paulo, Sao Paulo 05508-090, Brazil
| | - Silvia Rivara
- Dipartimento
di Farmacia, Università degli Studi di Parma, Parco Area
delle Scienze 27/A, 43124 Parma, Italy
| | - Paula A. Witt-Enderby
- Division
of Pharmaceutical Sciences, School of Pharmacy, Duquesne University, 421 Mellon Hall, Pittsburgh, Pennsylvania 15282, United States
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5
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Homology models of melatonin receptors: challenges and recent advances. Int J Mol Sci 2013; 14:8093-121. [PMID: 23584026 PMCID: PMC3645733 DOI: 10.3390/ijms14048093] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 03/28/2013] [Accepted: 03/28/2013] [Indexed: 12/15/2022] Open
Abstract
Melatonin exerts many of its actions through the activation of two G protein-coupled receptors (GPCRs), named MT1 and MT2. So far, a number of different MT1 and MT2 receptor homology models, built either from the prototypic structure of rhodopsin or from recently solved X-ray structures of druggable GPCRs, have been proposed. These receptor models differ in the binding modes hypothesized for melatonin and melatonergic ligands, with distinct patterns of ligand-receptor interactions and putative bioactive conformations of ligands. The receptor models will be described, and they will be discussed in light of the available information from mutagenesis experiments and ligand-based pharmacophore models. The ability of these ligand-receptor complexes to rationalize structure-activity relationships of known series of melatonergic compounds will be commented upon.
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6
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Pala D, Beuming T, Sherman W, Lodola A, Rivara S, Mor M. Structure-based virtual screening of MT2 melatonin receptor: influence of template choice and structural refinement. J Chem Inf Model 2013; 53:821-35. [PMID: 23541165 DOI: 10.1021/ci4000147] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Developing GPCR homology models for structure-based virtual screening requires the choice of a suitable template and refinement of binding site residues. We explored this systematically for the MT2 melatonin receptor, with the aim to build a receptor homology model that is optimized for the enrichment of active melatoninergic ligands. A set of 12 MT2 melatonin receptor models was built using different GPCR X-ray structural templates and submitted to a virtual screening campaign on a set of compounds composed of 29 known melatonin receptor ligands and 2560 drug-like decoys. To evaluate the effect of including a priori information in receptor models, 12 representative melatonin receptor ligands were placed into the MT2 receptor models in poses consistent with known mutagenesis data and with assessed pharmacophore models. The receptor structures were then adapted to the ligands by induced-fit docking. Most of the 144 ligand-adapted MT2 receptor models showed significant improvements in screening enrichments compared to the unrefined homology models, with some template/refinement combinations giving excellent enrichment factors. The discriminating ability of the models was further tested on the 29 active ligands plus a set of 21 inactive or low-affinity compounds from the same chemical classes. Rotameric states of side chains for some residues, presumed to be involved in the binding process, were correlated with screening effectiveness, suggesting the existence of specific receptor conformations able to recognize active compounds. The top MT2 receptor model was able to identify 24 of 29 active ligands among the first 2% of the screened database. This work provides insights into the use of refined GPCR homology models for virtual screening.
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Affiliation(s)
- Daniele Pala
- Dipartimento di Farmacia, Università degli Studi di Parma, Parco Area delle Scienze 27/A, I-43124 Parma, Italy
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New quinoxaline derivatives as potential MT₁ and MT₂ receptor ligands. Molecules 2012; 17:7737-57. [PMID: 22732886 PMCID: PMC6269071 DOI: 10.3390/molecules17077737] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 06/14/2012] [Accepted: 06/18/2012] [Indexed: 11/17/2022] Open
Abstract
Ever since the idea arose that melatonin might promote sleep and resynchronize circadian rhythms, many research groups have centered their efforts on obtaining new melatonin receptor ligands whose pharmacophores include an aliphatic chain of variable length united to an N-alkylamide and a methoxy group (or a bioisostere), linked to a central ring. Substitution of the indole ring found in melatonin with a naphthalene or quinoline ring leads to compounds of similar affinity. The next step in this structural approximation is to introduce a quinoxaline ring (a bioisostere of the quinoline and naphthalene rings) as the central nucleus of future melatoninergic ligands.
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8
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Design and synthesis of 2-phenylimidazo[1,2-a]pyridines as a novel class of melatonin receptor ligands. Eur J Med Chem 2011; 46:4252-7. [DOI: 10.1016/j.ejmech.2011.06.030] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Revised: 06/22/2011] [Accepted: 06/23/2011] [Indexed: 12/15/2022]
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9
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Harris PW, Hügel HM, Nurlawis F. A review of the molecular conformations of melatonin ligands at the melatonin receptor. MOLECULAR SIMULATION 2010. [DOI: 10.1080/089270204000002557] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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10
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Dubocovich ML, Delagrange P, Krause DN, Sugden D, Cardinali DP, Olcese J. International Union of Basic and Clinical Pharmacology. LXXV. Nomenclature, classification, and pharmacology of G protein-coupled melatonin receptors. Pharmacol Rev 2010; 62:343-80. [PMID: 20605968 PMCID: PMC2964901 DOI: 10.1124/pr.110.002832] [Citation(s) in RCA: 392] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The hormone melatonin (5-methoxy-N-acetyltryptamine) is synthesized primarily in the pineal gland and retina, and in several peripheral tissues and organs. In the circulation, the concentration of melatonin follows a circadian rhythm, with high levels at night providing timing cues to target tissues endowed with melatonin receptors. Melatonin receptors receive and translate melatonin's message to influence daily and seasonal rhythms of physiology and behavior. The melatonin message is translated through activation of two G protein-coupled receptors, MT(1) and MT(2), that are potential therapeutic targets in disorders ranging from insomnia and circadian sleep disorders to depression, cardiovascular diseases, and cancer. This review summarizes the steps taken since melatonin's discovery by Aaron Lerner in 1958 to functionally characterize, clone, and localize receptors in mammalian tissues. The pharmacological and molecular properties of the receptors are described as well as current efforts to discover and develop ligands for treatment of a number of illnesses, including sleep disorders, depression, and cancer.
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Affiliation(s)
- Margarita L Dubocovich
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo State University of New York, 3435 Main Street, Buffalo, NY 14214, USA.
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11
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Cogé F, Guenin SP, Fery I, Migaud M, Devavry S, Slugocki C, Legros C, Ouvry C, Cohen W, Renault N, Nosjean O, Malpaux B, Delagrange P, Boutin JA. The end of a myth: cloning and characterization of the ovine melatonin MT(2) receptor. Br J Pharmacol 2009; 158:1248-62. [PMID: 19814723 DOI: 10.1111/j.1476-5381.2009.00453.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND AND PURPOSE For many years, it was suspected that sheep expressed only one melatonin receptor (closely resembling MT(1) from other mammal species). Here we report the cloning of another melatonin receptor, MT(2), from sheep. EXPERIMENTAL APPROACH Using a thermo-resistant reverse transcriptase and polymerase chain reaction primer set homologous to the bovine MT(2) mRNA sequence, we have cloned and characterized MT(2) receptors from sheep retina. KEY RESULTS The ovine MT(2) receptor presents 96%, 72% and 67% identity with cattle, human and rat respectively. This MT(2) receptor stably expressed in CHO-K1 cells showed high-affinity 2[(125)I]-iodomelatonin binding (K(D)= 0.04 nM). The rank order of inhibition of 2[(125)I]-iodomelatonin binding by melatonin, 4-phenyl-2-propionamidotetralin and luzindole was similar to that exhibited by MT(2) receptors of other species (melatonin > 4-phenyl-2-propionamidotetralin > luzindole). However, its pharmacological profile was closer to that of rat, rather than human MT(2) receptors. Functionally, the ovine MT(2) receptors were coupled to G(i) proteins leading to inhibition of adenylyl cyclase, as the other melatonin receptors. In sheep brain, MT(2) mRNA was expressed in pars tuberalis, choroid plexus and retina, and moderately in mammillary bodies. Real-time polymerase chain reaction showed that in sheep pars tuberalis, premammillary hypothalamus and mammillary bodies, the temporal pattern of expression of MT(1) and MT(2) mRNA was not parallel in the three tissues. CONCLUSION AND IMPLICATIONS Co-expression of MT(1) and MT(2) receptors in all analysed sheep brain tissues suggests that MT(2) receptors may participate in melatonin regulation of seasonal anovulatory activity in ewes by modulating MT(1) receptor action.
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Affiliation(s)
- F Cogé
- Pharmacologie Moléculaire et Cellulaire, Institut de Recherches SERVIER, Suresnes, France
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12
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Chugunov AO, Farce A, Chavatte P, Efremov RG. Differences in Binding Sites of Two Melatonin Receptors Help to Explain Their Selectivity to Some Melatonin Analogs: A Molecular Modeling Study. J Biomol Struct Dyn 2006; 24:91-107. [PMID: 16928133 DOI: 10.1080/07391102.2006.10507103] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Numerous diseases have been linked to the malfunction of G-protein coupled receptors (GPCRs). Their adequate treatment requires rational design of new high-affinity and high-selectivity drugs targeting these receptors. In this work, we report three-dimensional models of the human MT(1) and MT(2) melatonin receptors, members of the GPCR family. The models are based on the X-ray structure of bovine rhodopsin. The computational approach employs an original procedure for optimization of receptor-ligand structures. It includes rotation of one of the transmembrane alpha-helices around its axis with simultaneous assessment of quality of the resulting complexes according to a number of criteria we have developed for this purpose. The optimal geometry of the receptor-ligand binding is selected based on the analysis of complementarity of hydrophobic/hydrophilic properties between the ligand and its protein environment in the binding site. The elaborated "optimized" models are employed to explore the details of protein-ligand interactions for melatonin and a number of its analogs with known affinity to MT(1) and MT(2) receptors. The models permit rationalization of experimental data, including those that were not used in model building. The perspectives opened by the constructed models and by the optimization procedure in the design of new drugs are discussed.
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Affiliation(s)
- Anton O Chugunov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, GSP Moscow, 117997, Russia.
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13
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Rivara S, Diamantini G, Di Giacomo B, Lamba D, Gatti G, Lucini V, Pannacci M, Mor M, Spadoni G, Tarzia G. Reassessing the melatonin pharmacophore—Enantiomeric resolution, pharmacological activity, structure analysis, and molecular modeling of a constrained chiral melatonin analogue. Bioorg Med Chem 2006; 14:3383-91. [PMID: 16431121 DOI: 10.1016/j.bmc.2005.12.053] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2005] [Revised: 12/22/2005] [Accepted: 12/23/2005] [Indexed: 01/01/2023]
Abstract
3-(Acetylaminomethyl)-2-(ethoxycarbonyl)-6-methoxy-1,3,4,5-tetrahydrobenzo[cd]indole (2) is a rigid melatonin analogue that as a racemate displays about the same affinity and intrinsic activity of melatonin (1) in in vitro experiments. We report here the resolution of the racemate by preparative medium pressure liquid chromatography (MPLC) and the X-ray determination of the R absolute configuration of the (-)-enantiomer. The two enantiomers were separately tested as MT1 and MT2 ligands, and the (+)-(S)-2 showed a potency comparable to that of melatonin and about three orders of magnitude greater than that of its enantiomer. The information obtained by crystallographic analysis and NMR studies about the conformational preference for 2 and by the pharmacological characterization of (R)-2 and (S)-2 was employed in a molecular modeling study, aimed at reassessing the melatonin receptor pharmacophore model for agonist compounds. Chiral enantioselective agonists reported in the literature were also included in the study.
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Affiliation(s)
- Silvia Rivara
- Dipartimento Farmaceutico, Università degli Studi di Parma, 43100 Parma, Italy
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Mazna P, Berka K, Jelinkova I, Balik A, Svoboda P, Obsilova V, Obsil T, Teisinger J. Ligand binding to the human MT2 melatonin receptor: the role of residues in transmembrane domains 3, 6, and 7. Biochem Biophys Res Commun 2005; 332:726-34. [PMID: 15913560 DOI: 10.1016/j.bbrc.2005.05.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2005] [Accepted: 05/03/2005] [Indexed: 12/15/2022]
Abstract
To better understand the mechanism of interactions between G-protein-coupled melatonin receptors and their ligands, our previously reported homology model of human MT2 receptor with docked 2-iodomelatonin was further refined and used to select residues within TM3, TM6, and TM7 potentially important for receptor-ligand interactions. Selected residues were mutated and radioligand-binding assay was used to test the binding affinities of hMT2 receptors transiently expressed in HEK293 cells. Our data demonstrate that residues N268 and A275 in TM6 as well as residues V291 and L295 in TM7 are essential for 2-iodomelatonin binding to the hMT2 receptor, while TM3 residues M120, G121, V124, and I125 may participate in binding of other receptor agonists and/or antagonists. Presented data also hint at possible specific interaction between the side-chain of Y188 in second extracellular loop and N-acetyl group of 2-iodomelatonin.
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Affiliation(s)
- Petr Mazna
- Institute of Physiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague, Czech Republic
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15
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Voronkov AE, Ivanov AA, Baskin II, Palyulin VA, Zefirov NS. Molecular Modeling Study of the Mechanism of Ligand Binding to Human Melatonin Receptors. DOKL BIOCHEM BIOPHYS 2005; 403:284-8. [PMID: 16229143 DOI: 10.1007/s10628-005-0093-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- A E Voronkov
- Department of Chemistry, Moscow State University, Vorob'evy gory, Moscow, 119992 Russia
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16
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Abstract
Melatonin is a hormone exerting its multiple actions mainly through two G-protein-coupled receptors MT(1) and MT(2). Exploring the physiological role of each of these subtypes requires subtype selective MT(1) and MT(2) ligands. While several MT(2)-selective ligands were developed in the 1990s, no selective agonists and antagonists for the MT(1) subtype were described. The present article reviews mela toninergic ligands developed in the current millennium focusing on subtype selective agents and on drug candidates. Notable compounds are the MT(1)-selective agonists 35 and 134, MT(1)-selective antagonists 117 and 131, MT(2)-selective agonists 58, 70, 79, 97 and 125, MT(2)-selective antagonists 27, 73 and 119, and the highly potent non-selective agonist 120. The non-selective agonists agomelatine 2, and ramelteon 87 are drug candidates as antidepressive agent and for the treatment of insomnia and circadian rhythm disfunction, respectively.
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MESH Headings
- Animals
- Chemistry, Pharmaceutical/methods
- Chemistry, Pharmaceutical/trends
- Humans
- Ligands
- Molecular Structure
- Receptor, Melatonin, MT1/agonists
- Receptor, Melatonin, MT1/chemistry
- Receptor, Melatonin, MT1/physiology
- Receptor, Melatonin, MT2/agonists
- Receptor, Melatonin, MT2/chemistry
- Receptor, Melatonin, MT2/physiology
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Davies DJ, Faust R, Garratt PJ, Marivingt-Mounir C, Teh MT, Sugden D. Binding affinity and biological activity of oxygen and sulfur isosteres at melatonin receptors as a function of their hydrogen bonding capability. Bioorg Chem 2004; 32:1-12. [PMID: 14700558 DOI: 10.1016/j.bioorg.2003.09.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Analogues of melatonin (1) and of N-acetyl 5-ethoxytryptamine (3) in which the oxygen atoms are replaced by sulfur have been prepared and tested against human and amphibian melatonin receptors. All sulfur analogues show a decreased binding affinity at human MT1 and MT2 receptors and a reduced potency as melatonin agonists on the Xenopus melanophore assay. The 5-methoxy oxygen of melatonin is significantly more important for receptor binding than the amide oxygen. N-Acetyl 5-ethoxytryptamine shows a decrease in both binding affinity and potency in comparison with melatonin. In this series, replacing either the ethoxy or amide oxygen by sulfur has a similar but smaller effect on both binding affinity and potency. Using K(B)(H) values from Abraham's equations we have assessed the possibility of estimating EC50 values for sulfur isosteres from the EC50 values of their oxygen analogues.
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Affiliation(s)
- David J Davies
- Department of Chemistry, University College London, WC1H 0AJ, UK
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18
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Csontos J, Kálmán M, Tasi G. Conformational analysis of melatonin at Hartree–Fock ab initio level. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/j.theochem.2003.08.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Abstract
Melatonin mediates its physiological effects through activation of high affinity G protein-coupled receptors. The vertebrate MT(1), MT(2) and Mel(1c) melatonin receptors are molecularly and pharmacologically distinct. Three molecular models of melatonin recognition for the MT(1) and/or Mel(1c) melatonin receptors have been proposed. To determine if these models applied to the MT(2) melatonin receptor, we mutated seven conserved residues to alanine in the hMT(2) melatonin receptor and expressed the receptors in HEK-293 cells. Competition of melatonin for 2-[125I]-iodomelatonin binding revealed that mutation of Asn 16 in TM4 or His 7 in TM5 of the hMT(2) melatonin receptor significantly decreased the binding affinity for melatonin when compared with wild-type. In addition, competition of 4P-ADOT, N-acetyltryptamine, luzindole, and 5-methoxytryptophol for 2-[125I]-iodomelatonin binding suggested Asn 16 in TM4 may facilitate binding of the 5-methoxy group of the melatonin molecule to the hMT(2) melatonin receptor. Trp 13 or Phe 6 in TM6 while not critical for melatonin binding, may interact with aromatic regions of luzindole and 4P-ADOT. Mutation of Ser 8 or Ser 12 in TM3, or Ser 6 in TM7 did not affect the affinity of melatonin for competition with 2-[125I]-iodomelatonin to the hMT(2) melatonin receptor, although equivalent serines (Ser 8 and Ser 12 in TM3) were reported to be critical for melatonin binding to the hMT(1) melatonin receptor. Thus these results are the first to identify residues within the transmembrane regions of the hMT(2) melatonin receptor critical for melatonin binding, highlighting potential structural differences between the MT(1) and MT(2) melatonin receptor binding pockets.
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MESH Headings
- Amino Acid Sequence
- Cells, Cultured
- Humans
- Melatonin/metabolism
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Receptors, Cell Surface/chemistry
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Receptors, Cytoplasmic and Nuclear/chemistry
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/metabolism
- Receptors, Melatonin
- Sequence Homology, Amino Acid
- Transfection
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Affiliation(s)
- Matthew J Gerdin
- Department of Molecular Pharmacology and Biological Chemistry (S215), The Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611-3008, USA
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Tsotinis A, Panoussopoulou M, Hough K, Sugden D. Synthesis and biological evaluation of new beta,beta'-disubstituted 6,7,8,9-tetrahydropyrido[1,2-a]indol-10-yl ethylamido melatoninergic ligands. Eur J Pharm Sci 2003; 18:297-304. [PMID: 12694881 DOI: 10.1016/s0928-0987(03)00020-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Tricyclic analogs of melatonin with alkyl and cycloalkyl moieties in the beta position of the ethylamido chain have been prepared and tested for their ability to activate pigment granule aggregation in Xenopus laevis melanophores. The introduction of two methyl groups in the beta position of the side-chain of the methoxyl-substituted ligands induces a synergistic effect in agonist potency, which, importantly, is maintained after the methoxyl substituent is removed. The presence of more bulky beta-substituents, regardless of the size of the R group, seems to lead to antagonism.
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Affiliation(s)
- A Tsotinis
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of Athens, Panepistimiopolis-Zografou, 157 71 Athens, Greece.
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21
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Florio GM, Christie RA, Jordan KD, Zwier TS. Conformational preferences of jet-cooled melatonin: probing trans- and cis-amide regions of the potential energy surface. J Am Chem Soc 2002; 124:10236-47. [PMID: 12188688 DOI: 10.1021/ja0265916] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The hormone melatonin (N-acetyl-5-methoxytryptamine) is an indole derivative with a flexible peptide-like side chain attached at the C3 position. Using a combination of two-color resonant two-photon ionization (2C-R2PI), laser-induced fluorescence excitation (LIF), resonant ion-dip infrared spectroscopy (RIDIRS), fluorescence-dip infrared spectroscopy (FDIRS), and UV-UV hole-burning spectroscopy, the conformational preferences of melatonin in a molecular beam have been determined. Three major trans-amide conformers and two minor cis-amide conformers have been identified in the R2PI spectrum and characterized with RIDIRS and FDIRS. Structural assignments are made using the infrared spectra in concert with density functional theory and localized MP2 calculations. Observation of cis-amide melatonin conformers in the molecular beam, despite the large energy gap (approximately 3 kcal/mol) between trans- and cis-amides, is striking because there are at least nine lower-energy trans-amide minima that are not detected. The implications of this observation for cooling and trapping conformational population in a supersonic expansion are discussed.
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Affiliation(s)
- Gina M Florio
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-1393, USA
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22
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Iakovou K, Varvaresou A, Kourounakis AP, Stead K, Sugden D, Tsotinis A. Design, synthesis and biological evaluation of novel beta-substituted indol-3-yl ethylamido melatoninergic analogues. J Pharm Pharmacol 2002; 54:147-56. [PMID: 11829126 DOI: 10.1211/0022357021771869] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A series of new melatonin analogues have been synthesized. Interestingly, two of the new compounds, 11c and 11e, which did not show any appreciable affinity for the melatonin receptor, were found to be potent inhibitors of lipid peroxidation in rat liver microsomes. Analogue 11c, in particular, is a better antioxidant than melatonin.
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Affiliation(s)
- K Iakovou
- School of Pharmacy, Department of Pharmaceutical Chemistry, University of Athens, Panepistimiopolis-Zografou, Greece
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23
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Tarzia G, Diamantini G, Mor M, Spadoni G. Design and synthesis of melatonin receptors agonists and antagonists. FARMACO (SOCIETA CHIMICA ITALIANA : 1989) 2000; 55:184-7. [PMID: 10919077 DOI: 10.1016/s0014-827x(00)00017-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We review our work towards the design and synthesis of high-affinity melatonin (N-acetyl-5-methoxytryptamine) agonist and antagonist compounds. High affinity melatonergic agonists were obtained by shifting the melatonin side chain from C3 to N1 of the indole ring system. Conversely, by moving the side chain from C3 to C2 it was possible to obtain melatonin antagonist compounds, albeit of moderate affinity.
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Affiliation(s)
- G Tarzia
- Istituto di Chimica Farmaceutica e Tossicologica, Università degli Studi di Urbino, Italy.
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24
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Homan EJ, Wikström HV, Grol CJ. Molecular modeling of the dopamine D2 and serotonin 5-HT1A receptor binding modes of the enantiomers of 5-OMe-BPAT. Bioorg Med Chem 1999; 7:1805-20. [PMID: 10530928 DOI: 10.1016/s0968-0896(99)00134-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Molecular modeling studies were undertaken in order to elucidate the possible dopamine D2 and serotonin 5-HT1A receptor binding modes of the enantiomers of 5-methoxy-2-[N-(2-benzamidoethyl)-N-n-propylamino]tetralin (5-OMe-BPAT, 1). For this purpose, a combination of indirect molecular modeling and direct construction of the seven transmembrane (7TM) domains of the receptors was employed in a stepwise, objective manner. Pharmacophore models and corresponding receptor maps were identified by superimposing selected sets of receptor agonists in their presumed pharmacologically active conformations, while taking the conformational freedom of the ligands into account. The 7TM models were then constructed around the agonist pharmacophore models, by adding the TM domains one-by-one. Initially, the relative positions of TM3, TM4, and TM5 were determined using the three-dimensional structure of bacteriorhodopsin, but subsequently the orientations of all TM domains were adjusted in order to mimic the topology of the TM domains of rhodopsin. The presumed dopamine D2 receptor binding conformations of (S)- and (R)-1 were determined by using the semirigid dopamine D2 receptor antagonist N-benzylpiquindone as a template for superposition. Similarly, the selective serotonin 5-HT1A receptor agonist flesinoxan was employed for identifying the serotonin 5-HT1A receptor binding conformations of the enantiomers of 1. After docking of the presumed pharmacologically active conformations in the 7TM models and subsequent optimization of the binding sites, specific interactions between the ligands and the surrounding amino acid residues, consistent with the structure-activity relationships, were observed. Thus, both enantiomers of 1 bound to the dopamine D2 receptor model in a similar fashion: a reinforced electrostatic interaction was present between the protonated nitrogen atoms and Asp114 in TM3; their carbonyl groups accepted a H-bond from Ser121 in TM3; their amide NH groups acted as H-bond donor to Tyr416 in TM7; and their benzamide phenyl rings were involved in a hydrophobic edge-to-face interaction with Trp386 in TM6. Differences were observed in the orientations of the 2-aminotetralin moieties, which occupied the agonist binding site. Whereas the (S)-enantiomer could form a H-bond between its 5-methoxy substituent and Ser193 in TM5, the (R)-enantiomer could not, which may account for the differences in their intrinsic efficacies at the dopamine D2 receptor. In the serotonin 5-HT1A receptor model, the benzamide phenyl rings of both enantiomers were involved in hydrophobic face-to-face interactions with Phe112 in TM3, while their protonated nitrogen atoms formed a reinforced electrostatic interaction with Asp116 in TM3. Consistent with the structure-affinity relationships of 1, the amide moieties were not involved in specific interactions. Both enantiomers of 1 could form a hydrogen bond between their 5-methoxy substituent and Thr200 in TM5, which may account for their full serotonin 5-HT1A receptor agonist properties.
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MESH Headings
- Amino Acid Sequence
- Benzamides/metabolism
- Binding Sites
- Humans
- Models, Molecular
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Protein Binding
- Receptors, Dopamine D2/chemistry
- Receptors, Dopamine D2/genetics
- Receptors, Dopamine D2/metabolism
- Receptors, Serotonin/chemistry
- Receptors, Serotonin/genetics
- Receptors, Serotonin/metabolism
- Receptors, Serotonin, 5-HT1
- Sequence Homology, Amino Acid
- Stereoisomerism
- Tetrahydronaphthalenes/metabolism
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Affiliation(s)
- E J Homan
- Department of Medicinal Chemistry, University Centre for Pharmacy, University of Groningen, The Netherlands.
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Kokkola T, Watson MA, White J, Dowell S, Foord SM, Laitinen JT. Mutagenesis of human Mel1a melatonin receptor expressed in yeast reveals domains important for receptor function. Biochem Biophys Res Commun 1998; 249:531-6. [PMID: 9712731 DOI: 10.1006/bbrc.1998.9182] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A yeast functional colorimetric assay was employed to test the effects of site-directed point mutations on the function of the human Mel1a melatonin receptor. Seven mutants were created in transmembrane domains III, V, and VII of the receptor to test the rhodopsin-based model of melatonin recognition. Two mutants in transmembrane domains III and VI were created to investigate the mechanisms of G protein activation in the melatonin receptor. Mutations in transmembrane domain V either potentiated agonist efficiencies (H195A) or totally abolished all responses to tested compounds (V192T+H195A). Mutation N124A in the conserved NRY motif in the end of transmembrane domain III seriously impaired receptor activation. Several mutants were found to have decreased ability to activate functional responses, reflecting the importance of these residues for receptor function. These data also suggest that activation of the receptor involves interaction of the 5-methoxy group of melatonin with the conserved histidine H195 in transmembrane domain V.
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Affiliation(s)
- T Kokkola
- Department of Physiology, University of Kuopio, Kuopio, Finland
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Abstract
Melatonin is produced rhythmically by the pineal gland and the retina with increased synthesis during darkness. Pineal melatonin serves as the 'chemical expression of darkness' conveying information on the ambient light-dark cycle into rhythmic bodily functions. On-going debate on modes and sites of action ranges from views of melatonin affecting each and every cell ('cure-all') to those of melatonin having restricted actions through specific high-affinity receptors. The present review deals with the latter view. The use of 2-[125I]-iodomelatonin has allowed the exact localization and characterization of high-affinity melatonin receptors that signal through the G(i/o) class of G proteins. Molecular cloning of melatonin receptor genes has confirmed that most, if not all, high-affinity melatonin-binding sites represent the G-protein-coupled melatonin receptors. Based on sequence dissimilarities, melatonin receptors are classified into three subtypes, Mel1a, Mel1b and Mel1c. A distribution wider than originally thought of melatonin receptors in the human brain and peripheral sites has brought these receptors into focus of several drug companies, promising exciting times for research on melatonin and new therapeutic possibilities.
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Affiliation(s)
- T Kokkola
- Department of Physiology, University of Kuopio, Finland
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27
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Mahle CD, Takaki KS, Watson AJ. Chapter 4. Melatonin Receptor Ligands and Their Potential Clinical Applications. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 1997. [DOI: 10.1016/s0065-7743(08)61462-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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