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Mailavaram RP, Al-Attraqchi OH, Kar S, Ghosh S. Current Status in the Design and Development of Agonists and Antagonists of Adenosine A3 Receptor as Potential Therapeutic Agents. Curr Pharm Des 2019; 25:2772-2787. [DOI: 10.2174/1381612825666190716114056] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 07/03/2019] [Indexed: 12/31/2022]
Abstract
Adenosine receptors (ARs) belongs to the family of G-protein coupled receptors (GPCR) that are responsible
for the modulation of a wide variety of physiological functions. The ARs are also implicated in many
diseases such as cancer, arthritis, cardiovascular and renal diseases. The adenosine A3 receptor (A3AR) has
emerged as a potential drug target for the progress of new and effective therapeutic agents for the treatment of
various pathological conditions. This receptor’s involvement in many diseases and its validity as a target has been
established by many studies. Both agonists and antagonists of A3AR have been extensively investigated in the last
decade with the goal of developing novel drugs for treating diseases related to immune disorders, inflammation,
cancer, and others. In this review, we shall focus on the medicinal chemistry of A3AR ligands, exploring the
diverse chemical classes that have been projected as future leading drug candidates. Also, the recent advances in
the therapeuetic applications of A3AR ligands are highlighted.
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Affiliation(s)
- Raghu P. Mailavaram
- Department of Pharmaceutical Chemistry, Shri Vishnu College of Pharmacy, Vishnupur (Affiliated to Andhra University), Bhimavaram, W.G. Dist., AP, India
| | - Omar H.A. Al-Attraqchi
- Faculty of Pharmacy, Philadelphia University-Jordan, P.O BOX (1), Philadelphia University- 19392, Amman, Jordan
| | - Supratik Kar
- Interdisciplinary Center for Nanotoxicity, Department of Chemistry, Physics and Atmospheric Sciences, Jackson State University, Jackson, MS 39217, United States
| | - Shinjita Ghosh
- School of Public Health, Jackson State University, Jackson, MS 39217, United States
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2
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Varano F, Catarzi D, Falsini M, Dal Ben D, Buccioni M, Marucci G, Volpini R, Colotta V. Novel human adenosine receptor antagonists based on the 7-amino-thiazolo[5,4-d]pyrimidine scaffold. Structural investigations at the 2-, 5- and 7-positions to enhance affinity and tune selectivity. Bioorg Med Chem Lett 2018; 29:563-569. [PMID: 30638876 DOI: 10.1016/j.bmcl.2018.12.062] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 12/28/2018] [Accepted: 12/29/2018] [Indexed: 12/11/2022]
Abstract
This paper describes the synthesis of novel 7-amino-thiazolo[5,4-d]pyrimidines bearing different substituents at positions 2, 5 and 7 of the thiazolopyrimidine scaffold. The synthesized compounds 2-27 were evaluated in radioligand binding (A1, A2A and A3) and adenylyl cyclase activity (A2B and A2A) assays, in order to evaluate their affinity and potency at human adenosine receptor subtypes. The current study allowed us to support that affinity and selectivity of 7-amino-thiazolo[5,4-d]pyrimidine derivatives towards the adenosine receptor subtypes can be modulated by the nature of the groups attached at positions 2, 5 and 7 of the bicyclic scaffold. To rationalize the hypothetical binding mode of the newly synthesized compounds, we also performed docking calculations in human A2A, A1 and A3 structures.
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Affiliation(s)
- Flavia Varano
- Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino, Sezione di Farmaceutica e Nutraceutica, Università degli Studi di Firenze, via Ugo Schiff, 6, 50019 Sesto Fiorentino, Italy.
| | - Daniela Catarzi
- Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino, Sezione di Farmaceutica e Nutraceutica, Università degli Studi di Firenze, via Ugo Schiff, 6, 50019 Sesto Fiorentino, Italy
| | - Matteo Falsini
- Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino, Sezione di Farmaceutica e Nutraceutica, Università degli Studi di Firenze, via Ugo Schiff, 6, 50019 Sesto Fiorentino, Italy
| | - Diego Dal Ben
- Scuola di Scienze del Farmaco e dei Prodotti della Salute, Università degli Studi di Camerino, Via S. Agostino 1, 62032 Camerino, MC, Italy
| | - Michela Buccioni
- Scuola di Scienze del Farmaco e dei Prodotti della Salute, Università degli Studi di Camerino, Via S. Agostino 1, 62032 Camerino, MC, Italy
| | - Gabriella Marucci
- Scuola di Scienze del Farmaco e dei Prodotti della Salute, Università degli Studi di Camerino, Via S. Agostino 1, 62032 Camerino, MC, Italy
| | - Rosaria Volpini
- Scuola di Scienze del Farmaco e dei Prodotti della Salute, Università degli Studi di Camerino, Via S. Agostino 1, 62032 Camerino, MC, Italy
| | - Vittoria Colotta
- Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino, Sezione di Farmaceutica e Nutraceutica, Università degli Studi di Firenze, via Ugo Schiff, 6, 50019 Sesto Fiorentino, Italy
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3
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Savateev KV, Ulomsky EN, Butorin II, Charushin VN, Rusinov VL, Chupakhin ON. Azoloazines as A2a receptor antagonists. Structure–activity relationship. RUSSIAN CHEMICAL REVIEWS 2018. [DOI: 10.1070/rcr4792] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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4
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Jacobson KA, Merighi S, Varani K, Borea PA, Baraldi S, Tabrizi MA, Romagnoli R, Baraldi PG, Ciancetta A, Tosh DK, Gao ZG, Gessi S. A 3 Adenosine Receptors as Modulators of Inflammation: From Medicinal Chemistry to Therapy. Med Res Rev 2018; 38:1031-1072. [PMID: 28682469 PMCID: PMC5756520 DOI: 10.1002/med.21456] [Citation(s) in RCA: 111] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 05/02/2017] [Accepted: 06/13/2017] [Indexed: 01/09/2023]
Abstract
The A3 adenosine receptor (A3 AR) subtype is a novel, promising therapeutic target for inflammatory diseases, such as rheumatoid arthritis (RA) and psoriasis, as well as liver cancer. A3 AR is coupled to inhibition of adenylyl cyclase and regulation of mitogen-activated protein kinase (MAPK) pathways, leading to modulation of transcription. Furthermore, A3 AR affects functions of almost all immune cells and the proliferation of cancer cells. Numerous A3 AR agonists, partial agonists, antagonists, and allosteric modulators have been reported, and their structure-activity relationships (SARs) have been studied culminating in the development of potent and selective molecules with drug-like characteristics. The efficacy of nucleoside agonists may be suppressed to produce antagonists, by structural modification of the ribose moiety. Diverse classes of heterocycles have been discovered as selective A3 AR blockers, although with large species differences. Thus, as a result of intense basic research efforts, the outlook for development of A3 AR modulators for human therapeutics is encouraging. Two prototypical selective agonists, N6-(3-Iodobenzyl)adenosine-5'-N-methyluronamide (IB-MECA; CF101) and 2-chloro-N6-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (Cl-IB-MECA; CF102), have progressed to advanced clinical trials. They were found safe and well tolerated in all preclinical and human clinical studies and showed promising results, particularly in psoriasis and RA, where the A3 AR is both a promising therapeutic target and a biologically predictive marker, suggesting a personalized medicine approach. Targeting the A3 AR may pave the way for safe and efficacious treatments for patient populations affected by inflammatory diseases, cancer, and other conditions.
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Affiliation(s)
- Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD20892
| | - Stefania Merighi
- Department of Medical Sciences, Pharmacology Section, University of Ferrara, Via Fossato di Mortara 17/19, 44121 Ferrara, Italy
| | - Katia Varani
- Department of Medical Sciences, Pharmacology Section, University of Ferrara, Via Fossato di Mortara 17/19, 44121 Ferrara, Italy
| | - Pier Andrea Borea
- Department of Medical Sciences, Pharmacology Section, University of Ferrara, Via Fossato di Mortara 17/19, 44121 Ferrara, Italy
| | - Stefania Baraldi
- Department of Pharmaceutical Sciences, University of Ferrara, Via Fossato di Mortara 17, 44121 Ferrara, Italy
| | - Mojgan Aghazadeh Tabrizi
- Department of Pharmaceutical Sciences, University of Ferrara, Via Fossato di Mortara 17, 44121 Ferrara, Italy
| | - Romeo Romagnoli
- Department of Pharmaceutical Sciences, University of Ferrara, Via Fossato di Mortara 17, 44121 Ferrara, Italy
| | - Pier Giovanni Baraldi
- Department of Pharmaceutical Sciences, University of Ferrara, Via Fossato di Mortara 17, 44121 Ferrara, Italy
| | - Antonella Ciancetta
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD20892
| | - Dilip K. Tosh
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD20892
| | - Zhan-Guo Gao
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD20892
| | - Stefania Gessi
- Department of Medical Sciences, Pharmacology Section, University of Ferrara, Via Fossato di Mortara 17/19, 44121 Ferrara, Italy
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5
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In search of novel ligands using a structure-based approach: a case study on the adenosine A 2A receptor. J Comput Aided Mol Des 2016; 30:863-874. [PMID: 27629350 PMCID: PMC5083784 DOI: 10.1007/s10822-016-9963-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 09/02/2016] [Indexed: 12/03/2022]
Abstract
In this work, we present a case study to explore the challenges associated with finding novel molecules for a receptor that has been studied in depth and has a wealth of chemical information available. Specifically, we apply a previously described protocol that incorporates explicit water molecules in the ligand binding site to prospectively screen over 2.5 million drug-like and lead-like compounds from the commercially available eMolecules database in search of novel binders to the adenosine A2A receptor (A2AAR). A total of seventy-one compounds were selected for purchase and biochemical assaying based on high ligand efficiency and high novelty (Tanimoto coefficient ≤0.25 to any A2AAR tested compound). These molecules were then tested for their affinity to the adenosine A2A receptor in a radioligand binding assay. We identified two hits that fulfilled the criterion of ~50 % radioligand displacement at a concentration of 10 μM. Next we selected an additional eight novel molecules that were predicted to make a bidentate interaction with Asn2536.55, a key interacting residue in the binding pocket of the A2AAR. None of these eight molecules were found to be active. Based on these results we discuss the advantages of structure-based methods and the challenges associated with finding chemically novel molecules for well-explored targets.
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6
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Varano F, Catarzi D, Squarcialupi L, Betti M, Vincenzi F, Ravani A, Varani K, Dal Ben D, Thomas A, Volpini R, Colotta V. Exploring the 7-oxo-thiazolo[5,4-d]pyrimidine core for the design of new human adenosine A3 receptor antagonists. Synthesis, molecular modeling studies and pharmacological evaluation. Eur J Med Chem 2015; 96:105-21. [PMID: 25874336 DOI: 10.1016/j.ejmech.2015.04.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 03/31/2015] [Accepted: 04/03/2015] [Indexed: 11/28/2022]
Abstract
A new series of 5-methyl-thiazolo[5,4-d]pyrimidine-7-ones bearing different substituents at position 2 (aryl, heteroaryl and arylamino groups) was synthesized and evaluated in radioligand binding assays to determine their affinities at the human (h) A1, A2A, and A3 adenosine receptors (ARs). Efficacy at the hA(2B) and antagonism of selected ligands at the hA3 were also assessed through cAMP experiments. Some of the new derivatives exhibited good to high hA3AR affinity and selectivity versus all the other AR subtypes. Compound 2-(4-chlorophenyl)-5-methyl-thiazolo[5,4-d]pyrimidine-7-one 4 was found to be the most potent and selective ligand of the series (K(I) hA3 = 18 nM). Molecular docking studies of the reported derivatives were carried out to depict their hypothetical binding mode in our hA3 receptor model.
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Affiliation(s)
- Flavia Varano
- Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino, Sezione di Farmaceutica e Nutraceutica, Universita' di Firenze, Polo Scientifico, Via Ugo Schiff 6, 50019 Sesto Fiorentino, FI, Italy.
| | - Daniela Catarzi
- Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino, Sezione di Farmaceutica e Nutraceutica, Universita' di Firenze, Polo Scientifico, Via Ugo Schiff 6, 50019 Sesto Fiorentino, FI, Italy
| | - Lucia Squarcialupi
- Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino, Sezione di Farmaceutica e Nutraceutica, Universita' di Firenze, Polo Scientifico, Via Ugo Schiff 6, 50019 Sesto Fiorentino, FI, Italy
| | - Marco Betti
- Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino, Sezione di Farmaceutica e Nutraceutica, Universita' di Firenze, Polo Scientifico, Via Ugo Schiff 6, 50019 Sesto Fiorentino, FI, Italy
| | - Fabrizio Vincenzi
- Dipartimento di Medicina Clinica e Sperimentale, Sezione di Farmacologia, Universita' di Ferrara, Via Fossato di Mortara 17-19, 44121 Ferrara, Italy
| | - Annalisa Ravani
- Dipartimento di Medicina Clinica e Sperimentale, Sezione di Farmacologia, Universita' di Ferrara, Via Fossato di Mortara 17-19, 44121 Ferrara, Italy
| | - Katia Varani
- Dipartimento di Medicina Clinica e Sperimentale, Sezione di Farmacologia, Universita' di Ferrara, Via Fossato di Mortara 17-19, 44121 Ferrara, Italy
| | - Diego Dal Ben
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, Via S. Agostino 1, 62032 Camerino, MC, Italy
| | - Ajiroghene Thomas
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, Via S. Agostino 1, 62032 Camerino, MC, Italy
| | - Rosaria Volpini
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, Via S. Agostino 1, 62032 Camerino, MC, Italy
| | - Vittoria Colotta
- Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino, Sezione di Farmaceutica e Nutraceutica, Universita' di Firenze, Polo Scientifico, Via Ugo Schiff 6, 50019 Sesto Fiorentino, FI, Italy
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7
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Squarcialupi L, Colotta V, Catarzi D, Varano F, Betti M, Varani K, Vincenzi F, Borea PA, Porta N, Ciancetta A, Moro S. 7-Amino-2-phenylpyrazolo[4,3-d]pyrimidine derivatives: Structural investigations at the 5-position to target human A1 and A2A adenosine receptors. Molecular modeling and pharmacological studies. Eur J Med Chem 2014; 84:614-27. [DOI: 10.1016/j.ejmech.2014.07.060] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 07/11/2014] [Accepted: 07/16/2014] [Indexed: 01/27/2023]
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8
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Squarcialupi L, Colotta V, Catarzi D, Varano F, Filacchioni G, Varani K, Corciulo C, Vincenzi F, Borea PA, Ghelardini C, Di Cesare Mannelli L, Ciancetta A, Moro S. 2-Arylpyrazolo[4,3-d]pyrimidin-7-amino derivatives as new potent and selective human A3 adenosine receptor antagonists. Molecular modeling studies and pharmacological evaluation. J Med Chem 2013; 56:2256-69. [PMID: 23427825 DOI: 10.1021/jm400068e] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
On the basis of our previously reported 2-arylpyrazolo[4,3-d]pyrimidin-7-ones, a set of 2-arylpyrazolo[4,3-d]pyrimidin-7-amines were designed as new human (h) A3 adenosine receptor (AR) antagonists. Lipophilic groups with different steric bulk were introduced at the 5-position of the bicyclic scaffold (R5 = Me, Ph, CH2Ph), and different acyl and carbamoyl moieties (R7) were appended on the 7-amino group, as well as a para-methoxy group inserted on the 2-phenyl ring. The presence of acyl groups turned out to be of paramount importance for an efficient and selective binding at the hA3 AR. In fact, most of the 7-acylamino derivatives showed low nanomolar affinity (Ki = 2.5-45 nM) and high selectivity toward this receptor. A few selected pyrazolo[4,3-d]pyrimidin-7-amides were effective in counteracting oxaliplatin-induced apoptosis in rat astrocyte cell cultures, an in vitro model of neurotoxicity. Through an in silico receptor-driven approach the obtained binding data were rationalized and the molecular bases of the observed hA3 AR affinity and hA3 versus hA2A AR selectivity were explained.
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Affiliation(s)
- Lucia Squarcialupi
- Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino, Sezione di Farmaceutica e Nutraceutica, Università di Firenze, Via Ugo Schiff, 6, 50019 Sesto Fiorentino, Italy
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9
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Kozma E, Jayasekara PS, Squarcialupi L, Paoletta S, Moro S, Federico S, Spalluto G, Jacobson KA. Fluorescent ligands for adenosine receptors. Bioorg Med Chem Lett 2013; 23:26-36. [PMID: 23200243 PMCID: PMC3557833 DOI: 10.1016/j.bmcl.2012.10.112] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Revised: 10/05/2012] [Accepted: 10/28/2012] [Indexed: 10/27/2022]
Abstract
Interest is increasing in developing fluorescent ligands for characterization of adenosine receptors (ARs), which hold a promise of usefulness in the drug discovery process. The size of a strategically labeled AR ligand can be greatly increased after the attachment of a fluorophore. The choice of dye moiety (e.g. Alexa Fluor 488), attachment point and linker length can alter the selectivity and potency of the parent molecule. Fluorescent derivatives of adenosine agonists and antagonists (e.g. XAC and other heterocyclic antagonist scaffolds) have been synthesized and characterized pharmacologically. Some are useful AR probes for flow cytometry, fluorescence correlation spectroscopy, fluorescence microscopy, fluorescence polarization, fluorescence resonance energy transfer, and scanning confocal microscopy. Thus, the approach of fluorescent labeled GPCR ligands, including those for ARs, is a growing dynamic research field.
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Affiliation(s)
- Eszter Kozma
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810 USA
| | - P Suresh Jayasekara
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810 USA
| | - Lucia Squarcialupi
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810 USA
| | - Silvia Paoletta
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810 USA
| | - Stefano Moro
- Molecular Modeling Section (MMS), Dipartimento di Scienze del Farmaco, Università di Padova, via Marzolo 5, I-35131 Padova, Italy
| | - Stephanie Federico
- Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Trieste, Piazzale Europa 1, I-34127 Trieste, Italy
| | - Giampiero Spalluto
- Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Trieste, Piazzale Europa 1, I-34127 Trieste, Italy
| | - Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810 USA
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10
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Chang EC, Wen YL, Chang CH, Shen YH, Wen SB, Yeh MY, Wong FF. A novel one-pot synthesis of 2-arylpyrazoloquinolinone derivatives. Tetrahedron 2012. [DOI: 10.1016/j.tet.2012.04.093] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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11
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Vernall AJ, Stoddart LA, Briddon SJ, Hill SJ, Kellam B. Highly potent and selective fluorescent antagonists of the human adenosine A₃ receptor based on the 1,2,4-triazolo[4,3-a]quinoxalin-1-one scaffold. J Med Chem 2012; 55:1771-82. [PMID: 22277057 DOI: 10.1021/jm201722y] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The adenosine-A(3) receptor (A(3)AR) is a G protein-coupled receptor that shows promise as a therapeutic target for cancer, glaucoma, and various autoimmune inflammatory disorders, and as such, there is a need for molecular probes to study this receptor. Here, we report a series of fluorescent ligands containing different linkers and fluorophores based around a 1,2,4-triazolo[4,3-a]quinoxalin-1-one antagonist. One of these conjugates (19) displayed high affinity for the A(3)AR (pK(D) = 9.36 ± 0.12) and is >650-fold selective over other adenosine receptor subtypes. Confocal microscopy revealed clear, displaceable membrane labeling of CHO-A(3) cells with 19, with no detectable labeling of CHO-A(1) cells under identical conditions. This fluorescent ligand was also able to specifically label the A(3)AR in HEK293T cells containing a mixed adenosine receptor population. The subtype specificity, along with its excellent imaging properties, make 19 an ideal tool for studying A(3)AR distribution and organization, particularly in the presence of other adenosine receptor subtypes.
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Affiliation(s)
- Andrea J Vernall
- School of Pharmacy, Centre for Biomolecular Sciences, University of Nottingham, United Kingdom
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12
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Cheong SL, Federico S, Venkatesan G, Mandel AL, Shao YM, Moro S, Spalluto G, Pastorin G. The A3 adenosine receptor as multifaceted therapeutic target: pharmacology, medicinal chemistry, and in silico approaches. Med Res Rev 2011; 33:235-335. [PMID: 22095687 DOI: 10.1002/med.20254] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Adenosine is an ubiquitous local modulator that regulates various physiological and pathological functions by stimulating four membrane receptors, namely A(1), A(2A), A(2B), and A(3). Among these G protein-coupled receptors, the A(3) subtype is found mainly in the lung, liver, heart, eyes, and brain in our body. It has been associated with cerebroprotection and cardioprotection, as well as modulation of cellular growth upon its selective activation. On the other hand, its inhibition by selective antagonists has been reported to be potentially useful in the treatment of pathological conditions including glaucoma, inflammatory diseases, and cancer. In this review, we focused on the pharmacology and the therapeutic implications of the human (h)A(3) adenosine receptor (AR), together with an overview on the progress of hA(3) AR agonists, antagonists, allosteric modulators, and radioligands, as well as on the recent advances pertaining to the computational approaches (e.g., quantitative structure-activity relationships, homology modeling, molecular docking, and molecular dynamics simulations) applied to the modeling of hA(3) AR and drug design.
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Affiliation(s)
- Siew Lee Cheong
- Department of Pharmacy, National University of Singapore, 3 Science Drive 2, Singapore 117543, Singapore
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13
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Synthesis, structure–affinity relationships, and molecular modeling studies of novel pyrazolo[3,4-c]quinoline derivatives as adenosine receptor antagonists. Bioorg Med Chem 2011; 19:3757-68. [DOI: 10.1016/j.bmc.2011.05.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 04/28/2011] [Accepted: 05/01/2011] [Indexed: 11/18/2022]
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14
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Pharmacophore elucidation for a new series of 2-aryl-pyrazolo-triazolo-pyrimidines as potent human A3 adenosine receptor antagonists. Bioorg Med Chem Lett 2011; 21:2898-905. [DOI: 10.1016/j.bmcl.2011.03.073] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2011] [Revised: 03/17/2011] [Accepted: 03/18/2011] [Indexed: 11/18/2022]
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15
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Poli D, Catarzi D, Colotta V, Varano F, Filacchioni G, Daniele S, Trincavelli L, Martini C, Paoletta S, Moro S. The identification of the 2-phenylphthalazin-1(2H)-one scaffold as a new decorable core skeleton for the design of potent and selective human A3 adenosine receptor antagonists. J Med Chem 2011; 54:2102-13. [PMID: 21401121 DOI: 10.1021/jm101328n] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Following a molecular simplification approach, we have identified the 2-phenylphthalazin-1(2H)-one (PHTZ) ring system as a new decorable core skeleton for the design of novel hA(3) adenosine receptor (AR) antagonists. Interest for this new series was driven by the structural similarity between the PHTZ skeleton and both the 2-aryl-1,2,4-triazolo[4,3-a]quinoxalin-1-one (TQX) and the 4-carboxamido-quinazoline (QZ) scaffolds extensively investigated in our previously reported studies. Our attention was focused at position 4 of the phthalazine nucleus where different amido and ureido moieties were introduced (compounds 2-20). Some of the new PHTZ compounds showed high hA(3) AR affinity and selectivity, the 2,5-dimethoxyphenylphthalazin-1(2H)-one 18 being the most potent and selective hA(3) AR antagonist among this series (K(i) = 0.776 nM; hA(1)/hA(3) and hA(2A)/hA(3) > 12000). Molecular docking studies on the PHTZ derivatives revealed for these compounds a binding mode similar to that of the previously reported TQX and QZ series, as was expected from the simplification approach.
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Affiliation(s)
- Daniela Poli
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Firenze, Polo Scientifico, Via U. Schiff, 6-50019 Sesto Fiorentino (Firenze), Italy
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Kleine T, Bergander K, Fröhlich R, Wibbeling B, Würthwein EU. Ring-Closure Reactions of 1,2-Diaza-4,5-benzoheptatrienyl Metal Compounds: Experiment and Theory. J Org Chem 2011; 76:1979-91. [DOI: 10.1021/jo2001534] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Tillmann Kleine
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstrasse 40, D-48149 Münster, Germany
| | - Klaus Bergander
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstrasse 40, D-48149 Münster, Germany
| | - Roland Fröhlich
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstrasse 40, D-48149 Münster, Germany
| | - Birgit Wibbeling
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstrasse 40, D-48149 Münster, Germany
| | - Ernst-Ulrich Würthwein
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstrasse 40, D-48149 Münster, Germany
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Pyrazolo derivatives as potent adenosine receptor antagonists: an overview on the structure-activity relationships. INTERNATIONAL JOURNAL OF MEDICINAL CHEMISTRY 2011; 2011:480652. [PMID: 25954519 PMCID: PMC4411897 DOI: 10.1155/2011/480652] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Accepted: 02/10/2011] [Indexed: 11/17/2022]
Abstract
In the past few decades, medicinal chemistry research towards potent and selective antagonists of human adenosine receptors (namely, A1, A2A, A2B, and A3) has been evolving rapidly. These antagonists are deemed therapeutically beneficial in several pathological conditions including neurological and renal disorders, cancer, inflammation, and glaucoma. Up to this point, many classes of compounds have been successfully synthesized and identified as potent human adenosine receptor antagonists. In this paper, an overview of the structure-activity relationship (SAR) profiles of promising nonxanthine pyrazolo derivatives is reported and discussed. We have emphasized the SAR for some representative structures such as pyrazolo-[4,3-e]-1,2,4-triazolo-[1,5-c]pyrimidines; pyrazolo-[3,4-c] or -[4,3-c]quinolines; pyrazolo-[4,3-d]pyrimidinones; pyrazolo-[3,4-d]pyrimidines and pyrazolo-[1,5-a]pyridines. This overview not only clarifies the structural requirements deemed essential for affinity towards individual adenosine receptor subtypes, but it also sheds light on the rational design and optimization of existing structural templates to allow us to conceive new, more potent adenosine receptor antagonists.
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Pran Kishore D, Balakumar C, Raghuram Rao A, Roy PP, Roy K. QSAR of adenosine receptor antagonists: Exploring physicochemical requirements for binding of pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine derivatives with human adenosine A3 receptor subtype. Bioorg Med Chem Lett 2011; 21:818-23. [DOI: 10.1016/j.bmcl.2010.11.094] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Revised: 11/13/2010] [Accepted: 11/19/2010] [Indexed: 10/18/2022]
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Katritch V, Kufareva I, Abagyan R. Structure based prediction of subtype-selectivity for adenosine receptor antagonists. Neuropharmacology 2010; 60:108-15. [PMID: 20637786 DOI: 10.1016/j.neuropharm.2010.07.009] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 07/01/2010] [Accepted: 07/07/2010] [Indexed: 01/15/2023]
Abstract
One of the major hurdles in the development of safe and effective drugs targeting G-protein coupled receptors (GPCRs) is finding ligands that are highly selective for a specific receptor subtype. Structural understanding of subtype-specific binding pocket variations and ligand-receptor interactions may greatly facilitate design of selective ligands. To gain insights into the structural basis of ligand subtype selectivity within the family of adenosine receptors (AR: A(1), A(2A), A(2B), and A(3)) we generated 3D models of all four subtypes using the recently determined crystal structure of the A(A2)AR as a template, and employing the methodology of ligand-guided receptor optimization for refinement. This approach produced 3D conformational models of AR subtypes that effectively explain binding modes and subtype selectivity for a diverse set of known AR antagonists. Analysis of the subtype-specific ligand-receptor interactions allowed identification of the major determinants of ligand selectivity, which may facilitate discovery of more efficient drug candidates.
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Affiliation(s)
- Vsevolod Katritch
- University of California, San Diego Skaggs School of Pharmacy and Pharmaceutical Sciences, 9500 Gilman Drive, MC-0747, La Jolla, CA 92093, USA
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Cheong SL, Dolzhenko A, Kachler S, Paoletta S, Federico S, Cacciari B, Dolzhenko A, Klotz KN, Moro S, Spalluto G, Pastorin G. The significance of 2-furyl ring substitution with a 2-(para-substituted) aryl group in a new series of pyrazolo-triazolo-pyrimidines as potent and highly selective hA(3) adenosine receptors antagonists: new insights into structure-affinity relationship and receptor-antagonist recognition. J Med Chem 2010; 53:3361-75. [PMID: 20307065 DOI: 10.1021/jm100049f] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Among the heterocyclic structures identified as potent human A(3) (hA(3)) adenosine receptor's antagonists, we have demonstrated that the new pyrazolo-triazolo-pyrimidines, bearing an aryl group in replacement of the C(2)-furyl ring, not only confer a good pharmacological profile (with significantly enhanced selectivity against other adenosine receptor subytpes) but also overcome the metabolic transformation of the furan ring into toxic intermediates. All the synthesized [2-(para-substituted) phenyl]-pyrazolo-triazolo-pyrimidines showed affinity at the hA(3) receptor in the low nanomolar range. The most potent derivative of the series presented better affinity and excellent selectivity (compound 31, K(i) hA(3) = 0.108 nM; hA(1)/hA(3) = 5200; hA(2A)/hA(3) = 7200), in comparison to the C(2)-furyl counterpart. A receptor-driven molecular modeling investigation, based on a recently proposed model of A(3) receptor derived from the crystallographic structure of human A(2A) receptor, has been carried out in order to support the experimental binding data and to justify the enhanced selectivity against the other receptor subtypes.
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Affiliation(s)
- Siew Lee Cheong
- Department of Pharmacy, National University of Singapore, 3 Science Drive 2, Block S15, no. 05-PI-03, Singapore 117543
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21
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Lenzi O, Colotta V, Catarzi D, Varano F, Poli D, Filacchioni G, Varani K, Vincenzi F, Borea PA, Paoletta S, Morizzo E, Moro S. 2-Phenylpyrazolo[4,3-d]pyrimidin-7-one as a new scaffold to obtain potent and selective human A3 adenosine receptor antagonists: new insights into the receptor-antagonist recognition. J Med Chem 2009; 52:7640-52. [PMID: 19743865 DOI: 10.1021/jm900718w] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A molecular simplification approach of previously reported 2-arylpyrazolo[3,4-c]quinolin-4-ones was applied to design 2-arylpyrazolo[4,3-d]pyrimidin-7-one derivatives as new human A(3) adenosine receptor antagonists. Substituents with different lipophilicity and steric hindrance were introduced at the 5-position of the bicyclic scaffold (R(5) = H, Me, Et, Ph, CH(2)Ph) and on the 2-phenyl ring (OMe, Me). Most of the synthesized derivatives were highly potent hA(3) adenosine receptor antagonists, the best being the 2-(4-methoxyphenyl)pyrazolo[4,3-d]pyrimidin-7-one (K(i) = 1.2 nM). The new compounds were also highly selective, being completely devoid of affinity toward hA(1), hA(2A), and hA(2B) adenosine receptors. On the basis of the recently published human A(2A) receptor crystallographic information, we propose a novel receptor-driven hypothesis to explain both A(3) AR affinity and A(3) versus A(2A) selectivity profiles of these new antagonists.
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Affiliation(s)
- Ombretta Lenzi
- Dipartimento di Scienze Farmaceutiche, Laboratorio di Progettazione, Sintesi e Studio di Eterocicli Biologicamente Attivi, Università di Firenze, Polo Scientifico, Via Ugo Schiff, 6, 50019 Sesto Fiorentino, Italy
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22
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Volpini R, Dal Ben D, Lambertucci C, Marucci G, Mishra RC, Ramadori AT, Klotz KN, Trincavelli ML, Martini C, Cristalli G. Adenosine A2A receptor antagonists: new 8-substituted 9-ethyladenines as tools for in vivo rat models of Parkinson's disease. ChemMedChem 2009; 4:1010-9. [PMID: 19343763 DOI: 10.1002/cmdc.200800434] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A new series of 8-substituted 9-ethyladenine derivatives has been synthesized and tested at rat and human adenosine receptors. Binding data demonstrates that some compounds could represent new tools suitable for in vivo studies in rat models of Parkinson's disease and for the design of new molecules with improved affinity and selectivity at human AA(2A)R.Clinical evidence has demonstrated that AA(2A)R antagonists could be an alternative approach to the treatment of Parkinson's disease. Recently, three 9-ethyladenine derivatives bearing a bromine atom, an ethoxy group, and a furyl ring, respectively, in the 8-position have been reported to ameliorate motor deficits in rat Parkinson's disease models, suggesting a potential therapeutic role for these compounds. Starting from these observations, a new series of 9-ethyladenine derivatives, bearing different substituents such as halogens, alkoxy groups, aromatic and heteroaromatic rings in the 8-position, were synthesized. Radioligand binding assays demonstrated that some of the new compounds bind rat AA(2A)R with higher affinity than the previously reported congeners and that there is a good correlation between binding to rat and human receptors. Hence, the new molecules could represent new tools suitable for the in vivo studies in rat models of Parkinson's disease. Finally, a molecular docking analysis of the compounds was performed using a homology model of rat AA(2A)R, built using the human crystal structure as the template, and results are in agreement with the binding data.
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Affiliation(s)
- Rosaria Volpini
- Dipartimento di Scienze Chimiche, Università di Camerino via S. Agostino 1, 62032 Camerino, MC, Italy.
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23
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Colotta V, Lenzi O, Catarzi D, Varano F, Filacchioni G, Martini C, Trincavelli L, Ciampi O, Pugliese AM, Traini C, Pedata F, Morizzo E, Moro S. Pyrido[2,3-e]-1,2,4-triazolo[4,3-a]pyrazin-1-one as a new scaffold to develop potent and selective human A3 adenosine receptor antagonists. Synthesis, pharmacological evaluation, and ligand-receptor modeling studies. J Med Chem 2009; 52:2407-19. [PMID: 19301821 DOI: 10.1021/jm8014876] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The paper describes a new class of human (h) A(3) adenosine receptor antagonists, the 2-arylpyrido[2,3-e]-1,2,4-triazolo[4,3-a]pyrazin-1-one derivatives (PTP), either 4-oxo (1-6, series A) or 4-amino-substituted (7-20, series B). In both series A and B, substituents able to act as hydrogen bond acceptors (OMe, OH, F, COOEt) were inserted on the 2-phenyl ring. In series B, cycloalkyl and acyl residues were introduced on the 4-amino group. Some of the new derivatives showed high hA(3) AR affinities (K(i) < 50 nM) and selectivities vs both hA(1) and hA(2A) receptors. The selected 4-benzoylamino-2-(4-methoxyphenyl)pyrido[2,3-e]-1,2,4-triazolo[4,3-a]pyrazin-1-one (18), tested in an in vitro rat model of cerebral ischemia, proved to be effective in preventing the failure of synaptic activity induced by oxygen and glucose deprivation in the hippocampus. Molecular docking of this new class of hA(3) AR antagonists was carried out to depict their hypothetical binding mode to our refined model of hA(3) receptor.
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Affiliation(s)
- Vittoria Colotta
- Laboratorio di Progettazione, Sintesi e Studio di Eterocicli Biologicamente Attivi, Dipartimento di Scienze Farmaceutiche, Universita di Firenze, Polo Scientifico, Via Ugo Schiff, 6, 50019 Sesto Fiorentino, Italy.
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24
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Colotta V, Capelli F, Lenzi O, Catarzi D, Varano F, Poli D, Vincenzi F, Varani K, Borea PA, Dal Ben D, Volpini R, Cristalli G, Filacchioni G. Novel potent and highly selective human A3 adenosine receptor antagonists belonging to the 4-amido-2-arylpyrazolo[3,4-c]quinoline series: Molecular docking analysis and pharmacological studies. Bioorg Med Chem 2009; 17:401-10. [DOI: 10.1016/j.bmc.2008.10.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Revised: 10/07/2008] [Accepted: 10/08/2008] [Indexed: 10/21/2022]
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Abstract
The development of potent and selective agonists and antagonists of adenosine receptors (ARs) has been a target of medicinal chemistry research for several decades, and recently the US Food and Drug Administration has approved Lexiscan, an adenosine derivative substituted at the 2 position, for use as a pharmacologic stress agent in radionuclide myocardial perfusion imaging. Currently, some other adenosine A(2A) receptor (A(2A)AR) agonists and antagonists are undergoing preclinical testing and clinical trials. While agonists are potent antiinflammatory agents also showing hypotensive effects, antagonists are being developed for the treatment of Parkinson's disease.However, since there are still major problems in this field, including side effects, low brain penetration (for the targeting of CNS diseases), short half-life, or lack of in vivo effects, the design and development of new AR ligands is a hot research topic.This review presents an update on the medicinal chemistry of A(2A)AR agonists and antagonists, and stresses the strong need for more selective ligands at the human A(2A)AR subtype, in particular in the case of agonists.
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Affiliation(s)
- Gloria Cristalli
- Dipartimento di Scienze Chimiche, Università di Camerino, 62032 Camerino (MC), Italy.
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26
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Cristalli G, Cacciari B, Dal Ben D, Lambertucci C, Moro S, Spalluto G, Volpini R. Highlights on the development of A(2A) adenosine receptor agonists and antagonists. ChemMedChem 2008; 2:260-81. [PMID: 17177231 DOI: 10.1002/cmdc.200600193] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Although significant progress has been made in the past few decades demonstrating that adenosine modulates a variety of physiological and pathophysiological processes through the interaction with four subtypes of a family of cell-surface G-protein-coupled receptors, clinical evaluation of some adenosine receptor ligands has been discontinued. Major problems include side effects due to the wide distribution of adenosine receptors, low brain penetration (which is important for the targeting of CNS diseases), short half-life of compounds, or a lack of effects, in some cases perhaps due to receptor desensitization or to low receptor density in the targeted tissue. Currently, three A(2A) adenosine receptor agonists have begun phase III studies. Two of them are therapeutically evaluated as pharmacologic stress agents and the third proved to be effective in the treatment of acute spinal cord injury (SCI), while avoiding the adverse effects of steroid agents. On the other hand, the great interest in the field of A(2A) adenosine receptor antagonists is related to their application in neurodegenerative disorders, in particular, Parkinson's disease, and some of them are currently in various stages of evaluation. This review presents an update of medicinal chemistry and molecular recognition of A(2A) adenosine receptor agonists and antagonists, and stresses the strong need for more selective ligands at the A(2A) human subtype.
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Affiliation(s)
- Gloria Cristalli
- Dipartimento di Scienze Chimiche, Università di Camerino, Via S. Agostino 1, 62032 Camerino, Italy.
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27
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Colotta V, Catarzi D, Varano F, Lenzi O, Filacchioni G, Martini C, Trincavelli L, Ciampi O, Traini C, Pugliese AM, Pedata F, Morizzo E, Moro S. Synthesis, ligand–receptor modeling studies and pharmacological evaluation of novel 4-modified-2-aryl-1,2,4-triazolo[4,3-a]quinoxalin-1-one derivatives as potent and selective human A3 adenosine receptor antagonists. Bioorg Med Chem 2008; 16:6086-102. [PMID: 18468446 DOI: 10.1016/j.bmc.2008.04.039] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Revised: 04/09/2008] [Accepted: 04/18/2008] [Indexed: 01/15/2023]
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28
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Cosimelli B, Greco G, Ehlardo M, Novellino E, Da Settimo F, Taliani S, La Motta C, Bellandi M, Tuccinardi T, Martinelli A, Ciampi O, Trincavelli ML, Martini C. Derivatives of 4-amino-6-hydroxy-2-mercaptopyrimidine as novel, potent, and selective A3 adenosine receptor antagonists. J Med Chem 2008; 51:1764-70. [PMID: 18269230 DOI: 10.1021/jm701159t] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A number of derivatives of 4-amino-6-hydroxy-2-mercaptopyrimidine ( 5) were synthesized and biologically evaluated as A 3 adenosine receptor (A 3 AR) antagonists. The new compounds were designed as open chain analogues of a triazolopyrimidinone derivative displaying submicromolar affinity for the A 3 AR, which had been previously identified using a 3D database search. Substituents R, R', and R'' attached to the parent compound 5 were chosen according to factorial design and stepwise lead optimization approaches, taking into account the essentially hydrophobic nature of the A 3 AR binding site. As a result, 5m (R = n-C 3H 7, R' = 4-ClC 6H 4CH 2, R'' = CH 3) was identified among the pyrimidine derivatives as the ligand featuring the best combination of potency and selectivity for the target receptor. This compound binds to the A 3 AR with a K i of 3.5 nM and is devoid of appreciable affinity for the A 1, A 2A, and A 2B ARs.
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Affiliation(s)
- Barbara Cosimelli
- Departimento di Chimica Farmaceutica e Tossicologica, Università di Napoli Federico II, Via D. Montesano 49, Naples, Italy.
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29
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González MP, Terán C, Teijeira M. Search for new antagonist ligands for adenosine receptors from QSAR point of view. How close are we? Med Res Rev 2008; 28:329-71. [PMID: 17668454 DOI: 10.1002/med.20108] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
In view of the large libraries of nucleoside analogues that are now being handled in organic synthesis, the identification of drug biological activity is advisable prior to synthesis and this can be achieved by employing predictive biological property methods. In this sense, Quantitative Structure-Activity Relationships (QSAR) or docking approaches have emerged as promising tools. Although a large number of in silico approaches have been described in the literature for the prediction of different biological activities, the use of QSAR applications to develop adenosine receptor (AR) antagonists is not common as for the case of the antibiotics and anticancer compounds for instance. The intention of this review is to summarize the present knowledge concerning computational predictions of new molecules as adenosine receptor antagonists.
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30
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Sharma BK, Sarbhai K, Singh P, Sharma S. Quantitative structure-activity relationship study on affinity profile of a series of 1,8-naphthyridine antagonists toward bovine adenosine receptors. J Enzyme Inhib Med Chem 2008; 23:437-43. [DOI: 10.1080/14756360701655073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Affiliation(s)
- B. K. Sharma
- Department of Chemistry, S. K. Government College, Sikar, 332 001
| | - Kirti Sarbhai
- Department of Chemistry, S. K. Government College, Sikar, 332 001
| | - P. Singh
- Department of Chemistry, S. K. Government College, Sikar, 332 001
| | - Susheela Sharma
- Department of Engineering Chemistry, Sobhasaria Engineering College, Sikar, 332 021, INDIA
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31
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Morizzo E, Capelli F, Lenzi O, Catarzi D, Varano F, Filacchioni G, Vincenzi F, Varani K, Borea PA, Colotta V, Moro S. Scouting human A3 adenosine receptor antagonist binding mode using a molecular simplification approach: from triazoloquinoxaline to a pyrimidine skeleton as a key study. J Med Chem 2007; 50:6596-606. [PMID: 18047262 DOI: 10.1021/jm070852a] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The concept of molecular simplification as a drug design strategy to shorten synthetic routes, while keeping or enhancing the biological activity of the lead drug, has been applied to design new classes of human A3 adenosine receptor (AR) antagonists. Over the past decade, we have focused a part of our research on the study of AR antagonists belonging to strictly correlated classes of tricyclic compounds. One of these classes is represented by the 2-aryl-1,2,4-triazolo[4,3-a]quinoxalin-1-one derivatives, either 4-amino or 4-oxo-substituted, which were intensively investigated by evaluating the effect of different substituents on the 2-phenyl ring and on the 4-amino group. Using an in silico molecular simplification approach, a new series of easily synthesizable 2-amino/2-oxoquinazoline-4-carboxamido derivatives have been discovered, presenting high affinity and selectivity against human A3 AR.
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Affiliation(s)
- Erika Morizzo
- Molecular Modeling Section, Dipartimento di Scienze Farmaceutiche, Università di Padova, via Marzolo 5, Padova, Italy
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32
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Richardson CM, Gillespie RJ, Williamson DS, Jordan AM, Fink A, Knight AR, Sellwood DM, Misra A. Identification of non-furan containing A2A antagonists using database mining and molecular similarity approaches. Bioorg Med Chem Lett 2006; 16:5993-7. [DOI: 10.1016/j.bmcl.2006.08.116] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2006] [Revised: 08/29/2006] [Accepted: 08/30/2006] [Indexed: 11/17/2022]
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33
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Wang L, Liu J, Tian H, Qian C. Ytterbium Triflate Catalyzed Heterocyclization of 1,2‐Phenylenediamines and Alkyl Oxalates Under Solvent‐Free Conditions via Phillips Reaction: A Facile Synthesis of Quinoxaline‐2,3‐diones Derivatives. SYNTHETIC COMMUN 2006. [DOI: 10.1081/scc-120030683] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Limin Wang
- a Institute of Fine Chemicals , East China University of Science and Technology , 130 Meilong Lu, Shanghai, 200237, P.R. China
| | - Jijun Liu
- a Institute of Fine Chemicals , East China University of Science and Technology , 130 Meilong Lu, Shanghai, 200237, P.R. China
| | - He Tian
- a Institute of Fine Chemicals , East China University of Science and Technology , 130 Meilong Lu, Shanghai, 200237, P.R. China
| | - Changtao Qian
- b Laboratory of Organometallic Chemistry , Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , Shanghai, P.R. China
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Moro S, Gao ZG, Jacobson KA, Spalluto G. Progress in the pursuit of therapeutic adenosine receptor antagonists. Med Res Rev 2006; 26:131-59. [PMID: 16380972 PMCID: PMC9194718 DOI: 10.1002/med.20048] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Ever since the discovery of the hypotensive and bradycardiac effects of adenosine, adenosine receptors continue to represent promising drug targets. First, this is due to the fact that the receptors are expressed in a large variety of tissues. In particular, the actions of adenosine (or methylxanthine antagonists) in the central nervous system, in the circulation, on immune cells, and on other tissues can be beneficial in certain disorders. Second, there exists a large number of ligands, which have been generated by introducing several modifications in the structure of the lead compounds (adenosine and methylxanthine), some of them highly specific. Four adenosine receptor subtypes (A1, A2A, A2B, and A3) have been cloned and pharmacologically characterized, all of which are G protein-coupled receptors. Adenosine receptors can be distinguished according to their preferred mechanism of signal transduction: A1 and A3 receptors interact with pertussis toxin-sensitive G proteins of the Gi and Go family; the canonical signaling mechanism of the A2A and of the A2B receptors is stimulation of adenylyl cyclase via Gs proteins. In addition to the coupling to adenylyl cyclase, all four subtypes may positively couple to phospholipase C via different G protein subunits. The development of new ligands, in particular, potent and selective antagonists, for all subtypes of adenosine receptors has so far been directed by traditional medicinal chemistry. The availability of genetic information promises to facilitate understanding of the drug-receptor interaction leading to the rational design of a potentially therapeutically important class of drugs. Moreover, molecular modeling may further rationalize observed interactions between the receptors and their ligands. In this review, we will summarize the most relevant progress in developing new therapeutic adenosine receptor antagonists.
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Affiliation(s)
- Stefano Moro
- Molecular Modeling Section, Dipartimento di Scienze Farmaceutiche, Università di Padova, Via Marzolo 5, I-35131 Padova, Italy.
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35
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Baraldi PG, Fruttarolo F, Tabrizi MA, Romagnoli R, Preti D, Carriòn MD, Iaconinoto A, Borea PA. Recent improvements in the field of A3adenosine receptor ligands. Expert Opin Ther Pat 2005. [DOI: 10.1517/13543776.15.11.1507] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Biagi G, Bianucci AM, Coi A, Costa B, Fabbrini L, Giorgi I, Livi O, Micco I, Pacchini F, Santini E, Leonardi M, Nofal FA, Salerni OL, Scartoni V. 2,9-disubstituted-N6-(arylcarbamoyl)-8-azaadenines as new selective A3 adenosine receptor antagonists: synthesis, biochemical and molecular modelling studies. Bioorg Med Chem 2005; 13:4679-93. [PMID: 15908217 DOI: 10.1016/j.bmc.2005.04.063] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2004] [Revised: 04/22/2005] [Accepted: 04/22/2005] [Indexed: 11/19/2022]
Abstract
A number of N6-(N-arylcarbamoyl)-2-substituted-9-benzyl-8-azaadenines, obtained by a modification of the synthetic scheme used to prepare selective A1 ligands, by only three or two steps, are described. At first we prepared a series of 2-phenyl-9-benzyl-8-azaadenines having as N6 substituent a variously substituted N-phenylcarbamoyl group. Some of these derivatives demonstrated good affinity towards the A3 subtype but low selectivity. Compounds having p-CF3, p-F and p-OCH3, as substituents on the phenylcarbamoyl group were selected as lead compounds for the second part of this study. Without modifying the N6 substituent, which would assure A3 affinity, we varied the 9 and 2 positions on these molecules to enhance selectivity. Some compounds having a p-methyl group on the 2-phenyl substituent showed a very good affinity and selectivity for the A3 subtype, revealing the first class of A3 adenosine receptor selective antagonists with a bicyclic structure strictly correlated to the adenine nucleus. The molecular modelling work, carried out using the DOCK program, supplied two models which may be useful for a better understanding of the binding modes. Both models highlighted the preferred interacting tautomeric forms of the antagonists for human A1 and A3 receptors.
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Affiliation(s)
- Giuliana Biagi
- Dipartimento di Scienze Farmaceutiche, Università di Pisa, via Bonanno 6, 56126 Pisa, Italy
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Catarzi D, Colotta V, Varano F, Calabri FR, Lenzi O, Filacchioni G, Trincavelli L, Martini C, Tralli A, Montopoli C, Moro S. 2-aryl-8-chloro-1,2,4-triazolo[1,5-a]quinoxalin-4-amines as highly potent A1 and A3 adenosine receptor antagonists. Bioorg Med Chem 2005; 13:705-15. [PMID: 15653338 DOI: 10.1016/j.bmc.2004.10.050] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2004] [Revised: 10/20/2004] [Accepted: 10/25/2004] [Indexed: 11/27/2022]
Abstract
Some 2-aryl-8-chloro-1,2,4-triazolo[1,5-a]quinoxaline derivatives 2-18, obtained by introducing different substituents on either the 4-amino moiety (acyl or carbamoyl groups) or the 2-phenyl ring (4-OCH3) of previously reported 8-chloro-2-phenyl-1,2,4-triazolo[1,5-a]quinoxalin-4-amine (1), have been synthesized and tested in radioligand binding assays at bovine A1 and A(2A) and at cloned human A1 and A3 adenosine receptors. The rationally designed 8-chloro-2-(4-methoxy-phenyl)-1,2,4-triazolo[1,5-a]quinoxalin-4-acetylamine (14) can be considered one of the most potent and hA3 versus hA1 selective AR antagonists reported till now. The structure-activity relationships of compounds 2-18 are in agreement with those of previously reported 2-aryl-1,2,4-triazolo[4,3-a]quinoxalines (series A) and 2-arylpyrazolo[3,4-c]quinolines (series B), thus suggesting a similar AR binding mode. In fact, the importance for the A3 receptor-ligand interaction of both a strong acidic NH proton donor and a C=O proton acceptor at position-4, able to engage hydrogen-bonding interactions with specific sites on the A3 AR, has been confirmed. Using our recently published hA3 receptor model, to better elucidate our experimental results, we decided to theoretically depict the putative TM binding motif of the herein reported 1,2,4-triazolo[1,5-a]quinoxaline derivatives on human A3 receptor. Structure-activity relationships have been explained analyzing the three-dimensional structure of the antagonist-receptor models obtained by molecular docking simulation.
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Affiliation(s)
- Daniela Catarzi
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Firenze, Polo Scientifico, Via U. Schiff, 6, 50019 Sesto Fiorentino (Firenze), Italy.
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Fossa P, Pestarino M, Menozzi G, Mosti L, Schenone S, Ranise A, Bondavalli F, Trincavelli ML, Lucacchini A, Martini C. New pyrazolo[3,4-b]pyridones as selective A(1) adenosine receptor antagonists: synthesis, biological evaluation and molecular modelling studies. Org Biomol Chem 2005; 3:2262-70. [PMID: 16010360 DOI: 10.1039/b502831k] [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: 11/21/2022]
Abstract
A series of ethyl 4-amino-1-(2-chloro-2-phenylethyl)-6-oxo-6,7-dihydro-1H-pyrazolo[3,4-b]pyridine-5-carboxylates () has been synthesized as potential A(1) adenosine receptor (A(1) AR) ligands. Binding affinities of the new compounds were determined for adenosine A(1), A(2A) and A(3) receptors. Compounds and showed good affinity (K(i)= 299 nM and 517 nM, respectively) and selectivity towards A(1) AR, whereas showed good affinity for A(2A) AR (K(i)= 290 nM), higher than towards A(1) AR (K(i)= 1000 nM). The only arylamino derivative of the series displayed high affinity (K(i)= 4.6 nM) and selectivity for A(3) AR. Molecular modelling and 3D-QSAR (CoMFA) studies carried out on the most active compounds gave further support to the pharmacological results.
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Affiliation(s)
- Paola Fossa
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Genova, Viale Benedetto XV 3, 16132 Genova, Italy
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Volpini R, Costanzi S, Lambertucci C, Vittori S, Martini C, Trincavelli ML, Klotz KN, Cristalli G. 2- and 8-alkynyl-9-ethyladenines: Synthesis and biological activity at human and rat adenosine receptors. Purinergic Signal 2005; 1:173-81. [PMID: 18404502 PMCID: PMC2096531 DOI: 10.1007/s11302-005-6216-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2004] [Revised: 10/21/2004] [Indexed: 12/05/2022] Open
Abstract
The synthesis of a series of 9-ethyladenine derivatives bearing alkynyl chains in 2- or 8-position was undertaken, based on the observation that replacement of the sugar moiety in adenosine derivatives with alkyl groups led to adenosine receptor antagonists. All the synthesized compounds were tested for their affinity at human and rat A1, A2A, and A3 adenosine receptors in binding assays; the activity at the human A2B receptor was determined in adenylyl cyclase experiments. Biological data showed that the 2-alkynyl derivatives possess good affinity and are slightly selective for the human A2A receptor. The same compounds tested on the rat A1 and A2A subtypes showed in general lower affinity for both receptors. On the other hand, the affinity of the 8-alkynyl derivatives at the human A1, A2A, and A2B receptors proved to be lower than that of the corresponding 2-alkynyl derivatives. On the contrary, the affinity of the same compounds for the human A3 receptor was improved, resulting in A3 selectivity. As in the case of the 2-alkynyl-substituted compounds, the 8-alkynyl derivatives showed decreased affinity for rat receptors. However, it is worthwhile to note that the 8-phenylethynyl-9-ethyladenine was the most active compound of the two series (Ki in the nanomolar range) at both the human and rat A3 subtype. Docking experiments of the 2- and 8-phenylethynyl-9-ethyladenines, at a rhodopsin-based homology model, gave a rational explanation of the preference of the human A3 receptor for the 8-substituted compound.
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Affiliation(s)
- Rosaria Volpini
- Dipartimento di Scienze Chimiche, Università di Camerino, Camerino, Italy
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Chang LCW, Brussee J, Ijzerman AP. Non-Xanthine Antagonists for the Adenosine A1 Receptor. Chem Biodivers 2004; 1:1591-626. [PMID: 17191804 DOI: 10.1002/cbdv.200490122] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Lisa C W Chang
- Leiden/Amsterdam Center for Drug Research, Division of Medicinal Chemistry, P.O. Box 9502, NL-2300 RA Leiden
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Schenone S, Bruno O, Bondavalli F, Ranise A, Mosti L, Menozzi G, Fossa P, Manetti F, Morbidelli L, Trincavelli L, Martini C, Lucacchini A. Synthesis of 1-(2-chloro-2-phenylethyl)-6-methylthio-1H-pyrazolo[3,4-d]pyrimidines 4-amino substituted and their biological evaluation. Eur J Med Chem 2004; 39:153-60. [PMID: 14987824 DOI: 10.1016/j.ejmech.2003.11.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2003] [Revised: 11/19/2003] [Accepted: 11/19/2003] [Indexed: 11/23/2022]
Abstract
A new series of 4-amino-6-methylthio-1H-pyrazolo[3,4-d]pyrimidines (2a-m) bearing the 2-chloro-2-phenylethyl chain at the N1 position, has been synthesized. The affinity of these compounds for A1 adenosine receptor (A1AR) was measured. The compounds showed poor affinity. A more interesting result was obtained by 2a, 2d, 2g, which demonstrated inhibitory activity on cell proliferation of the A-431 cell line stimulated by epithelial growth factor (EGF) and on EGF receptor tyrosine kinase (EGFR-TK) phosphorylation.
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Affiliation(s)
- Silvia Schenone
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Genova, viale Benedetto XV, 16132 Genoa, Italy.
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Catarzi D, Colotta V, Varano F, Filacchioni G, Martini C, Trincavelli L, Lucacchini A. 1,2,4-Triazolo[1,5-a]quinoxaline derivatives: synthesis and biological evaluation as adenosine receptor antagonists. ACTA ACUST UNITED AC 2004; 59:71-81. [PMID: 14871498 DOI: 10.1016/j.farmac.2003.09.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2003] [Accepted: 09/05/2003] [Indexed: 11/24/2022]
Abstract
Since most of the reported adenosine receptor antagonists are 2-(hetero)aryl-substituted tricyclic heteroaromatic derivatives, in the present study we report the synthesis and the biological evaluation of a new set of 4-amino-1,2,4-triazolo[1,5-a]quinoxalines containing at position-2 an ethyl carboxylate group or a hydrogen atom. The structure-activity relationships on these compounds were in accordance with those of a previously reported series of analogous size and shape, thus suggesting a similar A(1)-binding mode. In particular, the binding data indicate that alkylation of the 4-amino group of these derivatives lead to potent A(1)-receptor antagonists. Moreover, as new results, this study has pointed out that the ethyl 2-carboxylate group can advantageously replace the 2-(hetero)aryl ring of previously reported triazoloquinoxaline derivatives, affording an ameliorated interaction with the A(1)-receptor subtype.
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Affiliation(s)
- Daniela Catarzi
- Dipartimento di Scienze Farmaceutiche, Polo Scientifico, Università degli Studi di Firenze, Via U. Schiff, 6, Sesto Fiorentino (FZ), 50019, Italy.
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Colotta V, Catarzi D, Varano F, Filacchioni G, Martini C, Trincavelli L, Lucacchini A. Synthesis of 4-amino-6-(hetero)arylalkylamino-1,2,4-triazolo[4,3-a]quinoxalin-1-one derivatives as potent A2A adenosine receptor antagonists. Bioorg Med Chem 2003; 11:5509-18. [PMID: 14642595 DOI: 10.1016/j.bmc.2003.09.019] [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: 10/26/2022]
Abstract
In previous papers (Colotta, V. et al. Arch. Pharm. Pharm. Med. Chem. 1999, 332, 39. Colotta, V. et al. J. Med. Chem. 2000, 43, 1158) we reported the synthesis and binding affinity at bovine (b) A(1) and A(2A) and human (h) A(3) adenosine receptors (ARs) of the 4-amino-6-benzylamino-2-phenyl-1,2,4-triazolo[4,3-a]quinoxalin-1-one (compound A) which resulted in a potent and selective A(2A) AR antagonist. Compound A provided the lead compound of a series of 6- or 8-(hetero)arylalkylamino-4-amino-2-phenyl-1,2,4-triazolo[4,3-a]quinoxalin-1-one derivatives (compounds 1-20) which are the object of this paper. Most of the newly synthesized compounds are inactive at hA(3) ARs while they possess both nanomolar bA(2A) affinities and different degrees of bA(2A) versus bA(1) selectivity. The binding data show that hydrophilic substituents on the benzyl moiety are the most profitable for bA(2A) receptor affinity. Furthermore, their steric hindrance seems to play an important role for the bA(2A) AR interaction, thus suggesting that the 6-aralkylamino moiety of these ligands interacts with a size-limited binding pocket of this AR subtype. Thus, the SAR studies provided us some new insights about the structural requirements of the bA(2A) AR recognition site.
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Affiliation(s)
- Vittoria Colotta
- Dipartimento di Scienze Farmaceutiche, Polo Scientifico, Universitá di Firenze, Via Ugo Schiff, 6, 50019 Sesto (FJ), Fiorentino, Italy.
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Baraldi PG, Tabrizi MA, Fruttarolo F, Bovero A, Avitabile B, Preti D, Romagnoli R, Merighi S, Gessi S, Varani K, Borea PA. Recent developments in the field of A3 adenosine receptor antagonists. Drug Dev Res 2003. [DOI: 10.1002/ddr.10167] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Abstract
In the early 1990s it became clear that the A2A adenosine receptor had characteristics that made it distinct from the other A1, A2B and A3 adenosine receptors. Great progress has been made with the discovery of selective A2A receptor antagonists. A variety of synthetic substitutions on the xanthine moiety led the chemists of Kyowa-Hakko to discover that introduction of the styryl group in the 8 position of xanthines was critical in achieving compounds endowed with selective A2A receptor antagonistic properties. One compound, KW 6002, (E)1,3-diethyl-8-(3,4-dimethoxystyryl)-7-methylxanthine, is currently being developed for treatment of Parkinson's disease. A number of non-xanthine heterocycles have also been synthesized starting from the non-selective adenosine antagonist CGS 15943, a triazoloquinazoline. Thus, replacement of the phenyl ring of CGS 15943 with a heterocyclic ring such as pyrazole or imidazole, led to a series of interesting compounds whose prototype, SCH 58261, 7-(2-phenylethyl)-5-amino-2-(2-furyl)-pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine, has become a reference A2A receptor antagonist. Modification of N7 substituents has progressed to optimize A2A receptor selectivity and pharmacokinetic characteristics. A related class of compounds having a bicyclic instead of the tricyclic ring structure is also of interest. The prototype of these triazintriazolo derivatives, ZM 241385, is a potent A2A receptor antagonist; however, it also shows interactions with A2B receptors. The relevance of the A2A receptors in specific disease states, especially in the central nervous system, makes this class of adenosine receptor blockers of interest for treatment of neurodegenerative disorders such as Parkinson's disease.
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Affiliation(s)
- E Ongini
- Schering Plough Research Institute, San Raffaele Science Park, Milan, Italy
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Affiliation(s)
- P G Baraldi
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Ferrara, Via Fossato di Mortara 17-19, I-44100, Ferrara, Italy.
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