1
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Duangjai A, Rukachaisirikul V, Sukpondma Y, Srimaroeng C, Muanprasat C. Antispasmodic Effect of Asperidine B, a Pyrrolidine Derivative, through Inhibition of L-Type Ca 2+ Channel in Rat Ileal Smooth Muscle. Molecules 2021; 26:5492. [PMID: 34576962 PMCID: PMC8470553 DOI: 10.3390/molecules26185492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Revised: 08/29/2021] [Accepted: 09/07/2021] [Indexed: 11/17/2022] Open
Abstract
Antispasmodic agents are used for modulating gastrointestinal motility. Several compounds isolated from terrestrial plants have antispasmodic properties. This study aimed to explore the inhibitory effect of the pyrrolidine derivative, asperidine B, isolated from the soil-derived fungus Aspergillus sclerotiorum PSU-RSPG178, on spasmodic activity. Isolated rat ileum was set up in an organ bath. The contractile responses of asperidine B (0.3 to 30 µM) on potassium chloride and acetylcholine-induced contractions were recorded. To investigate its antispasmodic mechanism, CaCl2, acetylcholine, Nω-nitro-l-arginine methyl ester (l-NAME), nifedipine, methylene blue and tetraethylammonium chloride (TEA) were tested in the absence or in the presence of asperidine B. Cumulative concentrations of asperidine B reduced the ileal contraction by ~37%. The calcium chloride and acetylcholine-induced ileal contraction was suppressed by asperidine B. The effects of asperidine B combined with nifedipine, atropine or TEA were similar to those treated with nifedipine, atropine or TEA, respectively. In contrast, in the presence of l-NAME and methylene blue, the antispasmodic effect of asperidine B was unaltered. These results suggest that the antispasmodic property of asperidine B is probably due to the blockage of the L-type Ca2+ channel and is associated with K+ channels and muscarinic receptor, possibly by affecting non-selective cation channels and/or releasing intracellular calcium.
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Affiliation(s)
- Acharaporn Duangjai
- Unit of Excellence in Research and Product Development of Coffee, Division of Physiology, School of Medical Sciences, University of Phayao, Mueang Phayao, Phayao 56000, Thailand
- Center of Health Outcomes Research and Therapeutic Safety (Cohorts), School of Pharmaceutical Sciences, University of Phayao, Mueang Phayao, Phayao 56000, Thailand
| | - Vatcharin Rukachaisirikul
- Division of Physical Science and Center of Excellence for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand; (V.R.); (Y.S.)
| | - Yaowapa Sukpondma
- Division of Physical Science and Center of Excellence for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand; (V.R.); (Y.S.)
| | - Chutima Srimaroeng
- Department of Physiology, Faculty of Medicine, Chiang Mai University, Mueang Chiang Mai, Chiang Mai 50200, Thailand;
| | - Chatchai Muanprasat
- Chakri Naruebodindra Medical Institute, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangphli, Samutprakarn 10540, Thailand;
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BRET- and fluorescence anisotropy-based assays for real-time monitoring of ligand binding to M 2 muscarinic acetylcholine receptors. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118930. [PMID: 33347921 DOI: 10.1016/j.bbamcr.2020.118930] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 11/26/2020] [Accepted: 12/11/2020] [Indexed: 12/14/2022]
Abstract
BRET and fluorescence anisotropy (FA) are two fluorescence-based techniques used for the characterization of ligand binding to G protein-coupled receptors (GPCRs) and both allow monitoring of ligand binding in real time. In this study, we present the first direct comparison of BRET-based and FA-based binding assays using the human M2 muscarinic acetylcholine receptor (M2R) and two TAMRA (5-carboxytetramethylrhodamine)-labeled fluorescent ligands as a model system. The determined fluorescent ligand affinities from both assays were in good agreement with results obtained from radioligand competition binding experiments. The assays yielded real-time kinetic binding data revealing differences in the mechanism of binding for the investigated fluorescent probes. Furthermore, the investigation of various unlabeled M2R ligands yielded pharmacological profiles in accordance with earlier reported data. Taken together, this study showed that BRET- and FA-based binding assays represent valuable alternatives to radioactivity-based methods for screening purposes and for a precise characterization of binding kinetics supporting the exploration of binding mechanisms.
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Mazzolari A, Gervasoni S, Pedretti A, Fumagalli L, Matucci R, Vistoli G. Repositioning Dequalinium as Potent Muscarinic Allosteric Ligand by Combining Virtual Screening Campaigns and Experimental Binding Assays. Int J Mol Sci 2020; 21:ijms21175961. [PMID: 32825082 PMCID: PMC7503225 DOI: 10.3390/ijms21175961] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 08/14/2020] [Accepted: 08/16/2020] [Indexed: 12/12/2022] Open
Abstract
Structure-based virtual screening is a truly productive repurposing approach provided that reliable target structures are available. Recent progresses in the structural resolution of the G-Protein Coupled Receptors (GPCRs) render these targets amenable for structure-based repurposing studies. Hence, the present study describes structure-based virtual screening campaigns with a view to repurposing known drugs as potential allosteric (and/or orthosteric) ligands for the hM2 muscarinic subtype which was indeed resolved in complex with an allosteric modulator thus allowing a precise identification of this binding cavity. First, a docking protocol was developed and optimized based on binding space concept and enrichment factor optimization algorithm (EFO) consensus approach by using a purposely collected database including known allosteric modulators. The so-developed consensus models were then utilized to virtually screen the DrugBank database. Based on the computational results, six promising molecules were selected and experimentally tested and four of them revealed interesting affinity data; in particular, dequalinium showed a very impressive allosteric modulation for hM2. Based on these results, a second campaign was focused on bis-cationic derivatives and allowed the identification of other two relevant hM2 ligands. Overall, the study enhances the understanding of the factors governing the hM2 allosteric modulation emphasizing the key role of ligand flexibility as well as of arrangement and delocalization of the positively charged moieties.
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Affiliation(s)
- Angelica Mazzolari
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli, 25, I-20133 Milano, Italy; (A.M.); (S.G.); (A.P.); (L.F.)
| | - Silvia Gervasoni
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli, 25, I-20133 Milano, Italy; (A.M.); (S.G.); (A.P.); (L.F.)
| | - Alessandro Pedretti
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli, 25, I-20133 Milano, Italy; (A.M.); (S.G.); (A.P.); (L.F.)
| | - Laura Fumagalli
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli, 25, I-20133 Milano, Italy; (A.M.); (S.G.); (A.P.); (L.F.)
| | - Rosanna Matucci
- Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino (NEUROFARBA), Sezione di Farmacologia e Tossicologia, Università degli Studi di Firenze, Viale Pieraccini 6, 50139 Firenze, Italy;
| | - Giulio Vistoli
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli, 25, I-20133 Milano, Italy; (A.M.); (S.G.); (A.P.); (L.F.)
- Correspondence: ; Tel.: +39-02-5019349
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4
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Laurino A, Matucci R, Vistoli G, Raimondi L. 3-iodothyronamine (T1AM), a novel antagonist of muscarinic receptors. Eur J Pharmacol 2016; 793:35-42. [PMID: 27815171 DOI: 10.1016/j.ejphar.2016.10.027] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 10/17/2016] [Accepted: 10/20/2016] [Indexed: 10/20/2022]
Abstract
3-iodothyronamine (T1AM) is a trace amine suspected to derive from thyroid hormone metabolism. T1AM was described as a ligand of G-protein coupled monoaminergic receptors, including trace amine associated receptors, suggesting the amine may exert a modulatory role on the monoaminergic transmission. Nothing is known on the possibility that T1AM could also modulate the cholinergic transmission interacting with muscarinic receptors. We evaluated whether T1AM (10nM-100μM) was able to i) displace [3H]-NMS (0.20nM) binding to membrane preparations from CHO cells stably transfected with human muscarinic receptor subtypes (M1-M5); ii) modify basal or acetylcholine induced pERK1/2 levels in CHO expressing the human muscarinic type 3 receptor subtype by Western blot iii) modify basal and carbachol-induced contraction of isolated rat urinary bladder. T1AM fitting within rat muscarinic type 3 receptor was simulated by Docking studies. T1AM recognized all muscarinic receptor subtypes (pKi values in the micromolar range). Interacting at type 3, T1AM reduced acetylcholine-increased pERK1/2 levels. T1AM reduced carbachol-induced contraction of the rat urinary bladder. The fenoxyl residue and the iodide ion were found essential for establishing contacts with the active site of the rat muscarinic type 3 receptor subtype. Our results indicate that T1AM binds at muscarinic receptors behaving as a weak, not selective, antagonist. This finding adds knowledge on the pharmacodynamics features of T1AM and it may prompt investigation on novel pharmacological effects of T1AM at conditions of hyper-activation of the muscarinic tone including the overactive urinary bladder.
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Affiliation(s)
- Annunziatina Laurino
- Dept. of NEUROFARBA, Section of Pharmacology, University of Florence, 50139 Florence, Italy
| | - Rosanna Matucci
- Dept. of NEUROFARBA, Section of Pharmacology, University of Florence, 50139 Florence, Italy
| | - Giulio Vistoli
- Dept. of Pharmaceutical Science, University of Milan, 20100 Milan, Italy
| | - Laura Raimondi
- Dept. of NEUROFARBA, Section of Pharmacology, University of Florence, 50139 Florence, Italy.
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5
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Matucci R, Nesi M, Martino MV, Bellucci C, Manetti D, Ciuti E, Mazzolari A, Dei S, Guandalini L, Teodori E, Vistoli G, Romanelli MN. Carbachol dimers as homobivalent modulators of muscarinic receptors. Biochem Pharmacol 2016; 108:90-101. [DOI: 10.1016/j.bcp.2016.03.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 03/15/2016] [Indexed: 11/24/2022]
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6
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Defant A, Mancini I, Matucci R, Bellucci C, Dosi F, Malferrari D, Fabbri D. Muscarine-like compounds derived from a pyrolysis product of cellulose. Org Biomol Chem 2015; 13:6291-8. [DOI: 10.1039/c5ob00339c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Starting from a hydroxylactone anhydrosugar available from catalytic cellulose pyrolysis, five new muscarine-like compounds have been synthesized and studied for their binding affinity to human subtype muscarine receptors, obtaining results supported by docking calculation.
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Affiliation(s)
- Andrea Defant
- Università degli studi di Trento
- Dipartimento di Fisica
- Laboratorio di Chimica Bioorganica
- Trento
- Italy
| | - Ines Mancini
- Università degli studi di Trento
- Dipartimento di Fisica
- Laboratorio di Chimica Bioorganica
- Trento
- Italy
| | - Rosanna Matucci
- Dipartimento di Neuroscienze
- Psicologia
- Area del Farmaco e Salute del Bambino
- (NEUROFARBA)
- Università degli Studi di Firenze
| | - Cristina Bellucci
- Dipartimento di Neuroscienze
- Psicologia
- Area del Farmaco e Salute del Bambino
- (NEUROFARBA)
- Università degli Studi di Firenze
| | - Federico Dosi
- Università degli studi di Trento
- Dipartimento di Fisica
- Laboratorio di Chimica Bioorganica
- Trento
- Italy
| | - Danilo Malferrari
- Centro Interdipartimentale di Ricerca Industriale Energia e Ambiente (CIRI)
- 48123 Ravenna
- Italy
| | - Daniele Fabbri
- Centro Interdipartimentale di Ricerca Industriale Energia e Ambiente (CIRI)
- 48123 Ravenna
- Italy
- Dipartimento di Chimica “G. Ciamician” Alma Mater Studiorum
- Università di Bologna
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7
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Del Bello F, Bonifazi A, Quaglia W, Mazzolari A, Barocelli E, Bertoni S, Matucci R, Nesi M, Piergentili A, Vistoli G. Mode of interaction of 1,4-dioxane agonists at the M2 and M3 muscarinic receptor orthosteric sites. Bioorg Med Chem Lett 2014; 24:3255-9. [DOI: 10.1016/j.bmcl.2014.06.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 06/06/2014] [Accepted: 06/08/2014] [Indexed: 10/25/2022]
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8
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Bolchi C, Valoti E, Binda M, Fasoli F, Ferrara R, Fumagalli L, Gotti C, Matucci R, Vistoli G, Pallavicini M. Design, synthesis and binding affinity of acetylcholine carbamoyl analogues. Bioorg Med Chem Lett 2013; 23:6481-5. [DOI: 10.1016/j.bmcl.2013.09.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 09/03/2013] [Accepted: 09/06/2013] [Indexed: 02/02/2023]
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9
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Del Bello F, Barocelli E, Bertoni S, Bonifazi A, Camalli M, Campi G, Giannella M, Matucci R, Nesi M, Pigini M, Quaglia W, Piergentili A. 1,4-Dioxane, a Suitable Scaffold for the Development of Novel M3 Muscarinic Receptor Antagonists. J Med Chem 2012; 55:1783-7. [DOI: 10.1021/jm2013216] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Fabio Del Bello
- Scuola di Scienze del Farmaco
e dei Prodotti della Salute, Università di Camerino, Via S. Agostino 1, 62032 Camerino, Italy
| | - Elisabetta Barocelli
- Dipartimento di Scienze Farmacologiche,
Biologiche e Chimiche Applicate, Università degli Studi di Parma, V.le delle Scienze 27/A, 43124 Parma,
Italy
| | - Simona Bertoni
- Dipartimento di Scienze Farmacologiche,
Biologiche e Chimiche Applicate, Università degli Studi di Parma, V.le delle Scienze 27/A, 43124 Parma,
Italy
| | - Alessandro Bonifazi
- Scuola di Scienze del Farmaco
e dei Prodotti della Salute, Università di Camerino, Via S. Agostino 1, 62032 Camerino, Italy
| | - Mercedes Camalli
- Istituto di Cristallografia, CNR, Area della Ricerca Roma 1, Via Salaria Km 29.3,
00016 Monterotondo Stazione, Roma, Italy
| | - Gaetano Campi
- Istituto di Cristallografia, CNR, Area della Ricerca Roma 1, Via Salaria Km 29.3,
00016 Monterotondo Stazione, Roma, Italy
| | - Mario Giannella
- Scuola di Scienze del Farmaco
e dei Prodotti della Salute, Università di Camerino, Via S. Agostino 1, 62032 Camerino, Italy
| | - Rosanna Matucci
- Dipartimento di Farmacologia, Università di Firenze, Viale G. Pieraccini 6,
50139, Firenze, Italy
| | - Marta Nesi
- Dipartimento di Farmacologia, Università di Firenze, Viale G. Pieraccini 6,
50139, Firenze, Italy
| | - Maria Pigini
- Scuola di Scienze del Farmaco
e dei Prodotti della Salute, Università di Camerino, Via S. Agostino 1, 62032 Camerino, Italy
| | - Wilma Quaglia
- Scuola di Scienze del Farmaco
e dei Prodotti della Salute, Università di Camerino, Via S. Agostino 1, 62032 Camerino, Italy
| | - Alessandro Piergentili
- Scuola di Scienze del Farmaco
e dei Prodotti della Salute, Università di Camerino, Via S. Agostino 1, 62032 Camerino, Italy
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10
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Synthesis and properties of pyrazole carbaldehyde bis(2-hydroxyethyl)-dithioacetal hydrochlorides*. Chem Heterocycl Compd (N Y) 2012. [DOI: 10.1007/s10593-012-0927-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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11
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Scapecchi S, Nesi M, Matucci R, Bellucci C, Buccioni M, Dei S, Guandalini L, Manetti D, Martelli C, Martini E, Marucci G, Orlandi F, Romanelli MN, Teodori E, Cirilli R. Synthesis, affinity profile and functional activity of potent chiral muscarinic antagonists with a pyrrolidinylfuran structure. J Med Chem 2010; 53:201-7. [PMID: 19928767 DOI: 10.1021/jm901048j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Starting from the structure of previously studied muscarinic agonists, characterized by a pyrrolidinylfuran scaffold, a new series of muscarinic antagonists was synthesized by substituting the 5-position of the furane cycle with bulky hydrophobic groups. Both tertiary amines and the corresponding iodomethyl derivatives were obtained and studied. All the new compounds show high affinity toward cloned human muscarinic M(1)-M(5) receptors expressed in Chinese hamster ovary (CHO) cells and behave as competitive antagonists on classical models of muscarinic receptors. The diastereoisomeric mixture of the highest affinity compound of the series was resolved into the four optical isomers by chiral HPLC. The relative and absolute configuration of the obtained compounds was established by means of a combined strategy based on X-ray crystallography and chiroptical techniques. Although generally fairly potent, the compounds showed only modest subtype selectivity, with the exception of 2a and 6a, which in functional assays presented clear-cut selectivity for the muscarinic receptors present in rabbit vas deferens.
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Affiliation(s)
- Serena Scapecchi
- Dipartimento di Scienze Farmaceutiche, Universita di Firenze, Via Ugo Schiff 6, 50019 Sesto Fiorentino, Italy.
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12
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Minarini A, Marucci G, Bellucci C, Giorgi G, Tumiatti V, Bolognesi ML, Matera R, Rosini M, Melchiorre C. Design, synthesis, and biological evaluation of pirenzepine analogs bearing a 1,2-cyclohexanediamine and perhydroquinoxaline units in exchange for the piperazine ring as antimuscarinics. Bioorg Med Chem 2008; 16:7311-20. [DOI: 10.1016/j.bmc.2008.06.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2008] [Revised: 06/11/2008] [Accepted: 06/13/2008] [Indexed: 10/21/2022]
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13
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Dei S, Bellucci C, Buccioni M, Ferraroni M, Guandalini L, Manetti D, Marucci G, Matucci R, Nesi M, Romanelli MN, Scapecchi S, Teodori E. Muscarinic antagonists with multiple stereocenters: Synthesis, affinity profile and functional activity of isomeric 1-methyl-2-(2,2-alkylaryl-1,3-oxathiolan-5-yl)pyrrolidine sulfoxide derivatives. Bioorg Med Chem 2008; 16:5490-500. [PMID: 18455407 DOI: 10.1016/j.bmc.2008.04.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2007] [Revised: 04/02/2008] [Accepted: 04/08/2008] [Indexed: 11/29/2022]
Abstract
Completing a long-lasting research on 1,3-oxathiolane muscarinic ligands, we have synthesized a set of isomeric 1-methyl-2-(2,2-alkylaryl-1,3-oxathiolan-5-yl)pyrrolidine 3-sulfoxide derivatives, containing three or four stereogenic centers. In general the compounds are very potent antagonists even if, unlike the corresponding agonists, they show modest subtype selectivity.
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Affiliation(s)
- Silvia Dei
- Laboratorio di Progettazione, Sintesi e Studio di Eterocicli Biologicamente Attivi (HeteroBioLab), Dipartimento di Scienze Farmaceutiche, Università di Firenze, Via U. Schiff 6, 50019 Sesto Fiorentino (FI), Italy.
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14
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Piergentili A, Quaglia W, Giannella M, Del Bello F, Buccioni M, Nesi M, Matucci R. Rapid novel divergent synthesis and muscarinic agonist profile of all four optical isomers of N,N,N-trimethyl(6-methyl-1,4-dioxan-2-yl)methanaminium iodide. Bioorg Med Chem Lett 2008; 18:614-8. [DOI: 10.1016/j.bmcl.2007.11.073] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 11/19/2007] [Accepted: 11/19/2007] [Indexed: 01/22/2023]
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15
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Vistoli G, Pedretti A, Testa B, Matucci R. The conformational and property space of acetylcholine bound to muscarinic receptors: An entropy component accounts for the subtype selectivity of acetylcholine. Arch Biochem Biophys 2007; 464:112-21. [PMID: 17544360 DOI: 10.1016/j.abb.2007.04.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Accepted: 04/17/2007] [Indexed: 11/21/2022]
Abstract
The conformational behavior of receptor-bound acetylcholine (ACh) was investigated by molecular dynamics simulations. Based on the great similarity among muscarinic receptors, the study was focused on the human M(1), M(2), and M(5) receptors as previously modeled by us. The results showed that receptor-bound ACh was not frozen in a single preferred conformation but preserved an unexpected fraction of its conformational space. However, there were marked differences between the three receptors since the ligand was mostly trans in the M(1) receptor, equally distributed among trans and gauche conformers in M(2), and exclusively gauche in the M(5); the greater flexibility of M(2)-bound ACh was paralleled by the greater flexibility of the occupied M(2) binding site. By contrast, the property space of receptor-bound ACh, and particularly its virtual (computed, conformation-dependent) lipophilicity, was restricted to relatively narrow ranges optimal for successful interaction. Experimental binding investigations to the individual human M(1), M(2), and M(5) muscarinic receptors showed ACh to have a 10-fold higher affinity for the M(2) compared to the M(1) and M(5) receptors. This selectivity was not confirmed by the calculated binding scores, a fact postulated to be caused by the absence of an entropy component in such binding scores. Indeed, the Shannon entropy of all geometric and physicochemical properties monitored were markedly higher in M(2)-bound ACh compared to M(1)-bound and M(5)-bound ACh. This finding suggests that the selectivity profile of acetylcholine for the M(2) receptor is largely entropy-driven, a fact that might explain the intrinsic difficulty to design subtype-selective muscarinic agonists.
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Affiliation(s)
- Giulio Vistoli
- Istituto di Chimica Farmaceutica Pietro Pratesi, Facoltà di Farmacia, Università di Milano, Viale Abruzzi 42, I-20131 Milano, Italy.
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16
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Tumiatti V, Minarini A, Milelli A, Rosini M, Buccioni M, Marucci G, Ghelardini C, Bellucci C, Melchiorre C. Structure–activity relationships of methoctramine-related polyamines as muscarinic antagonist: Effect of replacing the inner polymethylene chain with cyclic moieties. Bioorg Med Chem 2007; 15:2312-21. [PMID: 17276075 DOI: 10.1016/j.bmc.2007.01.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2006] [Revised: 01/08/2007] [Accepted: 01/17/2007] [Indexed: 11/21/2022]
Abstract
The aim of the present paper was to investigate the role of the octamethylene spacer of methoctramine (1) on the biological profile. Thus, this spacer was incorporated into a dianiline or dipiperidine moiety to determine whether flexibility and the basicity of the inner nitrogen atoms are important determinants of potency with respect to muscarinic receptors. The most potent compound was 4, which displayed, in the functional assays, a comparable potency at muscarinic M(2) receptors with respect to 1, and, in the binding assays, a loss of potency and selectivity toward muscarinic M(1) and M(3) receptor subtypes. Both compounds were endowed with antinociceptive activity. Furthermore, in microdialysis tests in rat parietal cortex, they enhanced acetylcholine release, most likely by antagonizing presynaptic muscarinic receptor subtypes.
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Affiliation(s)
- Vincenzo Tumiatti
- Dipartimento di Scienze Farmaceutiche, Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy.
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17
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Kiesewetter DO, Jagoda EM, Shimoji K, Ma Y, Eckelman WC. Evaluation of [18F]fluoroxanomeline {5-{4-[(6-[18F]fluorohexyl)oxy]-1,2,5-thiadiazol-3-yl}-1-methyl-1,2,3,6-tetrahydropyridine} in muscarinic knockout mice. Nucl Med Biol 2007; 34:141-52. [PMID: 17307122 DOI: 10.1016/j.nucmedbio.2006.11.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2006] [Revised: 11/17/2006] [Accepted: 11/25/2006] [Indexed: 11/25/2022]
Abstract
INTRODUCTION We set out to develop a muscarinic M1-selective agonist (based on the structure of the functionally M1-selective xanomeline) that could be radiolabeled with fluorine-18 for use as an imaging agent for positron emission tomography. METHODS The radiochemical synthesis was achieved, employing the arts of organic and radiochemical syntheses. Binding selectivity studies employed biodistribution studies, using autoradiography and/or tissue dissection, in wild-type or muscarinic receptor knockout mice. RESULTS [(18)F]Fluoroxanomeline shows rather uniform uptake in all mouse brain regions and high specific binding, with a brain-to-blood ratio of 32 at 60 min postinjection. In addition, the specific binding is demonstrated by a 58% to 75% decrease in brain uptake upon coinjection with 5 nmol of unlabeled fluoroxanomeline or xanomeline. Brain uptake studies with [(3)H]xanomeline in muscarinic knockout mice show decreased uptake in M1 (17-34%) and M2 (2-20%) knockout mice compared with control. However, statistical significance was observed in only a few regions. Comparison of [(18)F]fluoroxanomeline in knockout mice showed no difference in M1 or M4 knockout mice but a general decrease in M2 (2-24%) knockout mice. The decrease of [(18)F]fluoroxanomeline uptake in M2 knockout mice reached statistical significance in brain stem, cerebellum, frontal cortex, hippocampus, inferior colliculus and superior colliculus. CONCLUSION Although xanomeline displays highly selective M1 agonist activity in functional assays, little selectivity for muscarinic subtype binding was observed for xanomeline or its fluorine-containing analogue, fluoroxanomeline. This emphasizes the lack of correlation between functional selectivity and binding selectivity.
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Affiliation(s)
- Dale O Kiesewetter
- Positron Emission Tomography Radiochemistry Group, NIBIB, NIH, Bethesda, MD 20892, USA.
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