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Evaluation of 1,2,5-thiadiazoles as modulators of M1/M5 muscarinic receptor subtypes. Bioorg Med Chem 2014; 22:1838-44. [DOI: 10.1016/j.bmc.2014.01.049] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 01/20/2014] [Accepted: 01/30/2014] [Indexed: 11/21/2022]
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2
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DFT calculation of four new potential agents muscarinic of bispyridinium type: structure, synthesis, biological activity, hydration, and relations with the potents W84 and DUO-3O. J Comput Aided Mol Des 2010; 25:145-61. [DOI: 10.1007/s10822-010-9406-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 12/05/2010] [Indexed: 10/18/2022]
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3
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Molecular mechanisms of action and in vivo validation of an M4 muscarinic acetylcholine receptor allosteric modulator with potential antipsychotic properties. Neuropsychopharmacology 2010; 35:855-69. [PMID: 19940843 PMCID: PMC3055367 DOI: 10.1038/npp.2009.194] [Citation(s) in RCA: 132] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We recently identified LY2033298 as a novel allosteric potentiator of acetylcholine (ACh) at the M(4) muscarinic acetylcholine receptor (mAChR). This study characterized the molecular mode of action of this modulator in both recombinant and native systems. Radioligand-binding studies revealed that LY2033298 displayed a preference for the active state of the M(4) mAChR, manifested as a potentiation in the binding affinity of ACh (but not antagonists) and an increase in the proportion of high-affinity agonist-receptor complexes. This property accounted for the robust allosteric agonism displayed by the modulator in recombinant cells in assays of [(35)S]GTPgammaS binding, extracellular regulated kinase 1/2 phosphorylation, glycogen synthase kinase 3beta phosphorylation, and receptor internalization. We also found that the extent of modulation by LY2033298 differed depending on the signaling pathway, indicating that LY2033298 engenders functional selectivity in the actions of ACh. This property was retained in NG108-15 cells, which natively express rodent M(4) mAChRs. Functional interaction studies between LY2033298 and various orthosteric and allosteric ligands revealed that its site of action overlaps with the allosteric site used by prototypical mAChR modulators. Importantly, LY2033298 reduced [(3)H]ACh release from rat striatal slices, indicating retention of its ability to allosterically potentiate endogenous ACh in situ. Moreover, its ability to potentiate oxotremorine-mediated inhibition of condition avoidance responding in rodents was significantly attenuated in M(4) mAChR knockout mice, validating the M(4) mAChR as a key target of action of this novel allosteric ligand.
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4
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Sürig U, Gaal K, Kostenis E, Tränkle C, Mohr K, Holzgrabe U. Muscarinic allosteric modulators: atypical structure-activity-relationships in bispyridinium-type compounds. Arch Pharm (Weinheim) 2006; 339:207-12. [PMID: 16572483 DOI: 10.1002/ardp.200600005] [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: 11/05/2022]
Abstract
Allosteric modulators of receptor binding are known for a variety of membrane receptors. In case of muscarinic receptors, a considerable number of structurally divergent modulators have been described. For the M2 receptor subtype which has a high sensitivity to allosteric modulation most of the allosteric agents bind to the common allosteric binding site of the receptor protein. In this study, a series of DUO compounds characterized by a bispyridinium middle chain and lateral benzyloximeether moieties of a systematically varied substitution pattern has been evaluated with regard to their allosteric potency to affect M2 receptors, whose orthosteric site was blocked by [3H]N-methylscopolamine. The variations in potency were found to be surprisingly small and the structure-activity relationships of the DUO compounds diverged from those of correspondingly substituted hexamethonio-type allosteric modulators. One has to conclude that DUO compounds bind in an "atypical" manner which is in agreement with recently reported side-directed mutagenesis and molecular modeling studies.
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Affiliation(s)
- Ulf Sürig
- Institute of Pharmacy and Food Chemistry, University of Würzburg, Würzburg, Germany
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5
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Disingrini T, Muth M, Dallanoce C, Barocelli E, Bertoni S, Kellershohn K, Mohr K, De Amici M, Holzgrabe U. Design, synthesis, and action of oxotremorine-related hybrid-type allosteric modulators of muscarinic acetylcholine receptors. J Med Chem 2006; 49:366-72. [PMID: 16392821 DOI: 10.1021/jm050769s] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A novel series of muscarinic receptor ligands of the hexamethonio-type was prepared which contained, on one side, the phthalimidopropane or 1,8-naphthalimido-2,2-dimethylpropane moiety typical for subtype selective allosteric antagonists and, on the other, the acetylenic fragment typical for the nonselective orthosteric muscarinic agonists oxotremorine, oxotremorine-M, and related muscarinic agonists. Binding experiments in M(2) receptors using [(3)H]N-methylscopolamine as an orthosteric probe proved an allosteric action of both groups of hybrids, 7a-10a and 8b-10b. The difference in activity between a-group and b-group hybrids corresponded with the activity difference between the allosteric parent compounds. In M(1)-M(3) muscarinic isolated organ preparations, most of the hybrids behaved as subtype selective antagonists. [(35)S]GTPgammaS binding assays using human M(2) receptors overexpressed in CHO cells revealed that a weak intrinsic efficacy was preserved in 8b-10b. Thus, attaching muscarinic allosteric antagonist moieties to orthosteric muscarinic agonists may lead to hybrid compounds in which functions of both components are mixed.
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Affiliation(s)
- Teresa Disingrini
- Istituto di Chimica Farmaceutica e Tossicologica, Università degli Studi di Milano, Viale Abruzzi 42, 20131 Milano, Italy
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6
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Tränkle C, Dittmann A, Schulz U, Weyand O, Buller S, Jöhren K, Heller E, Birdsall NJM, Holzgrabe U, Ellis J, Höltje HD, Mohr K. Atypical Muscarinic Allosteric Modulation: Cooperativity between Modulators and Their Atypical Binding Topology in Muscarinic M2and M2/M5Chimeric Receptors. Mol Pharmacol 2005; 68:1597-610. [PMID: 16157694 DOI: 10.1124/mol.105.017707] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The binding and function of muscarinic acetylcholine receptors can be modulated allosterically. Some allosteric muscarinic ligands are "atypical", having steep concentration-effect curves and not interacting competitively with "typical" allosteric modulators. For atypical agents, a second allosteric site has been proposed. Different approaches have been used to gain further insight into the interaction with M2 receptors of two atypical agents, tacrine and the bispyridinium compound 4,4'-bis-[(2,6-dichloro-benzyloxy-imino)-methyl]-1,1'-propane-1,3-diyl-bispyridinium dibromide (Duo3). Interaction studies, using radioligand binding assays and the allosteric ligands obidoxime, Mg2+, and the new tool hexamethonium to antagonize the allosteric actions of the atypical ligands, showed different modes of interaction for tacrine and Duo3 at M2 receptors. A negatively cooperative interaction was observed between hexamethonium and tacrine (but not Duo3). A tacrine dimer that exhibited increased allosteric potency relative to tacrine but behaved like a typical allosteric modulator was competitively inhibited by hexamethonium. M2/M5-receptor mutants revealed a dependence of tacrine and Duo3 affinity on different receptor epitopes. This was confirmed by docking simulations using a three-dimensional model of the M2 receptor. These showed that the allosteric site could accommodate two molecules of tacrine simultaneously but only one molecule of Duo3, which binds in different mode from typical allosteric agents. Therefore, the atypical actions of tacrine and Duo3 involve different modes of receptor interaction, but their sites of attachment seem to be the "common" allosteric binding domain at the entrance to the orthosteric ligand binding pocket of the M2-receptor. Additional complex behavior may be rationalized by allosteric interactions transmitted within a receptor dimer.
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Affiliation(s)
- Christian Tränkle
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Bonn, Gerhard-Domagk-Str. 3, D-53121 Bonn, Germany.
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7
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8
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Muth M, Sennwitz M, Mohr K, Holzgrabe U. Muscarinic Allosteric Enhancers of Ligand Binding: Pivotal Pharmacophoric Elements in Hexamethonio-Type Agents. J Med Chem 2005; 48:2212-7. [PMID: 15771463 DOI: 10.1021/jm049616f] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Bisphthalimidopropyl-substituted hexamethonio compounds have been established as allosteric modulators of ligand binding to muscarinic acetylcholine receptors. Enhancers of ligand binding are of special interest. This study aimed to unravel the structural elements inducing positive cooperativity with the binding of an antagonist. [(3)H]-N-methylscopolamine binding to muscarinic M(2) receptors was measured in porcine heart homogenates. Dimethylation, but not monomethylation, of the lateral propyl chain in combination with an affinity increasing aromatic imide moiety, such as a 5-methylphthalimide and naphthalimide, on the same side of the molecule shifts the cooperativity toward positive values, resulting in enhancers of antagonist binding. Thus, lateral side chain dimethylation is a pivotal pharmacophoric element for positive cooperativity in hexamethonio-type muscarinic allosteric agents.
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Affiliation(s)
- Mathias Muth
- Institute of Pharmacy and Food Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
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9
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Mohr M, Heller E, Ataie A, Mohr K, Holzgrabe U. Development of a new type of allosteric modulator of muscarinic receptors: hybrids of the antagonist AF-DX 384 and the hexamethonio derivative W84. J Med Chem 2004; 47:3324-7. [PMID: 15163212 DOI: 10.1021/jm031095t] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Various fragments of the hexamethonio-type allosteric agent W84 were linked to the secondary amino group of the muscarinic M(2) acetylcholine receptor-preferring antagonist AF-DX 384 to increase the area of attachment with the allosteric site. Addition of only the phthalimido moiety of W84 gave an allosteric enhancer of NMS binding. Thus, a new lead structure for the development of allosteric enhancers of NMS binding has been discovered.
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Affiliation(s)
- Marion Mohr
- Institute of Pharmacy and Food Chemistry, Pharmaceutical Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
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10
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Zlotos DP, Buller S, Stiefl N, Baumann K, Mohr K. Probing the Pharmacophore for Allosteric Ligands of Muscarinic M2 Receptors: SAR and QSAR Studies in a Series of Bisquaternary Salts of Caracurine V and Related Ring Systems. J Med Chem 2004; 47:3561-71. [PMID: 15214783 DOI: 10.1021/jm0311341] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Allosteric effects on muscarinic acetylcholine M(2) receptors were examined in a series of bisquaternary salts of the Strychnos alkaloid caracurine V (6) and related iso-caracurine V, tetrahydrocaracurine V, and bisnortoxiferine ring systems. The compounds inhibited dissociation of the orthosteric antagonist [(3)H]N-methylscopolamine (NMS) from porcine cardiac M(2) receptors with EC(0.5,diss) values from 4 to 3270 nM. The majority of compounds hardly changed [(3)H]NMS equilibrium binding, indicating similar binding affinities in free and NMS-occupied M(2) receptors. The most potent agents were found in the caracurine V, iso-caracurine V, and tetrahydrocaracurine V series and carried nonpolar alkyl groups with a maximal chain length of three carbon atoms. 3D QSAR (CoMSIA) analysis explained the wide range of binding affinities by steric and electrostatic properties of the side chains. Furthermore, the findings suggest that the spatial orientation of the "caracurine" aromatic rings compared with the bisnortoxiferine ring skeleton is favorable to optimal allostere-receptor interactions.
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Affiliation(s)
- Darius P Zlotos
- Pharmaceutical Institute, University of Würzburg, Am Hubland, 97074 Würzburg, Germany.
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11
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Synthesis and pharmacological characterization of new silicon-based W84-type allosteric modulators for ligand binding to muscarinic M2 receptors. J Organomet Chem 2003. [DOI: 10.1016/s0022-328x(03)00553-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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12
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Zlotos DP, Buller S, Holzgrabe U, Mohr K. Bisquaternary dimers of strychnine and brucine. A new class of potent enhancers of antagonist binding to muscarinic M2 receptors. Bioorg Med Chem 2003; 11:2627-34. [PMID: 12757728 DOI: 10.1016/s0968-0896(03)00146-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Bisquaternary dimers of strychnine and brucine were synthesized and their allosteric effect on muscarinic acetylcholine M(2) receptors was examined. The compounds retarded the dissociation of the antagonist [(3)H]N-methylscopolamine ([(3)H]NMS) from porcine cardiac cholinoceptors. This action indicated ternary complex formation. All compounds exhibited higher affinity to the allosteric site of [(3)H]NMS-occupied M(2) receptors than the monomeric strychnine and brucine, while the positive cooperativity with NMS was fully maintained. SAR studies revealed the unchanged strychnine ring as an important structural feature for high allosteric potency.
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Affiliation(s)
- D P Zlotos
- Pharmaceutical Institute, University of Würzburg, Am Hubland, 97074 Würzburg, Germany.
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13
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Stiefl N, Baumann K. Mapping property distributions of molecular surfaces: algorithm and evaluation of a novel 3D quantitative structure-activity relationship technique. J Med Chem 2003; 46:1390-407. [PMID: 12672239 DOI: 10.1021/jm021077w] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A novel molecular descriptor called MaP (mapping property distributions of molecular surfaces) is presented. It combines facile computation, translational and rotational invariance, and straightforward interpretability of the computed models. A three-step procedure is used to compute the MaP descriptor. First, an approximation to the molecular surface with equally distributed surface points is computed. Next, molecular properties are projected onto this surface. Finally, the distribution of surface properties is encoded into a translationally and rotationally invariant molecular descriptor that is based on radial distribution functions (distance-dependent count statistics). The calculated descriptor is correlated with biological data through chemometric regression techniques in combination with a variable selection. The latter is used to identify variables that are highly relevant for the model and hence for its interpretation. Three applications of the new descriptor are presented, each representing a different area of 3D-QSAR. For reasons of comparability, the new descriptor was tested on the steroid "benchmark" data set. Furthermore, a highly diverse data set with potentially eye-irritating compounds was studied, and third, a set of flexible structures with a modulating effect on the muscarinic M(2) receptor were studied. Not only were all models highly predictive but interpretation of the back-projected variables into the original molecular space led to biologically and chemically relevant conclusions.
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Affiliation(s)
- Nikolaus Stiefl
- Department of Pharmacy and Food Chemistry, University of Wuerzburg, Am Hubland, Germany
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14
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Muth M, Bender W, Scharfenstein O, Holzgrabe U, Balatkova E, Tränkle C, Mohr K. Systematic development of high affinity bis(ammonio)alkane-type allosteric enhancers of muscarinic ligand binding. J Med Chem 2003; 46:1031-40. [PMID: 12620079 DOI: 10.1021/jm021017q] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bis(ammonio)alkane compounds carrying lateral phthalimidopropyl substituents on the nitrogen atoms belong to the archetypal muscarinic allosteric agents. Herein, a series of symmetrical and nonsymmetrical compounds was synthesized in which the phthalimide residues were replaced by differently substituted imide moieties. The allosteric action was measured in porcine heart muscarinic M(2) receptors using [(3)H]N-methylscopolamine (NMS) as a ligand for the orthosteric receptor site in equilibrium binding and dissociation experiments. 1,8-Naphthalimido residues conferred an up to 100-fold gain in affinity leading into the low nanomolar range, while the inhibition of NMS binding was maintained. Additional propyl chain methylation was accompanied by an allosteric elevation of orthosteric ligand binding. In general, the gain in allosteric activity achieved by ring variation plus propyl chain methylation on one side of the molecule could not be augmented by symmetrical variations. The elevation of the ligand binding can be explained by different quantitative structure-activity relationships for the affinities to the free and the orthoster-liganded receptor.
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Affiliation(s)
- Mathias Muth
- Institute of Pharmacy and Food Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Federal Republic of Germany
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15
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Raasch A, Scharfenstein O, Tränkle C, Holzgrabe U, Mohr K. Elevation of ligand binding to muscarinic M(2) acetylcholine receptors by bis(ammonio)alkane-type allosteric modulators. J Med Chem 2002; 45:3809-12. [PMID: 12166953 DOI: 10.1021/jm020871e] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bis(ammonio)alkane-type compounds are archetypal muscarinic allosteric modulators. Phthalimido-substituted hexane-bis-ammonium agents were methylated in the phthalimide moieties and the lateral propyl side chains. All compounds retarded allosterically the dissociation of the orthosteric ligand [(3)H]N-methylscopolamine ([(3)H]NMS) from porcine heart M(2) receptors. [(3)H]NMS equilibrium binding was reduced, left unaltered, or elevated, depending on the degree and position of methylation. This is the first time that an allosteric elevation of ligand binding is demonstrated for bis(ammonio)alkane-type compounds.
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Affiliation(s)
- Alexandra Raasch
- Pharmacology and Toxicology, Institute of Pharmacy, University of Bonn, An der Immenburg 4, 53121 Bonn, Germany
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16
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Gharagozloo P, Lazareno S, Miyauchi M, Popham A, Birdsall NJM. Substituted pentacyclic carbazolones as novel muscarinic allosteric agents: synthesis and structure-affinity and cooperativity relationships. J Med Chem 2002; 45:1259-74. [PMID: 11881995 DOI: 10.1021/jm010946z] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two series of pentacyclic carbazolones, 22 and 23, have been synthesized utilizing a facile intramolecular Dielsminus signAlder reaction and are allosteric modulators at muscarinic acetylcholine receptors. Their affinities and cooperativities with acetylcholine and the antagonist N-methylscopolamine (NMS) at M(1)minus signM(4) receptors have been analyzed and compared. All of the synthesized compounds are negatively cooperative with acetylcholine. In contrast, the majority of the compounds exhibit positive cooperativity with NMS, particularly at M(2) and M(4) receptors. The subtype selectivity, in terms of affinity, was in general M(2) > M(1) > M(4) > M(3). The largest increases in affinity produced by a single substitution of the core structure were given by the 1-OMe (22b) and 1-Cl (22d) derivatives. The position of the N in the ring did not appear to be important for binding affinity or cooperativity. Two compounds 22y and 23i, both trisubstituted analogues, were the most potent compounds synthesized, with dissociation constants of 30minus sign100 nM for the M(2) NMS-liganded and unliganded receptor, respectively. The results indicate that the allosteric site, like the primary binding site, is capable of high-affinity interactions with molecules of relatively low molecular weight.
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Affiliation(s)
- Parviz Gharagozloo
- MRC Technology Research Division, 1-3 Burtonhole Lane, Mill Hill, London, NW7 1AD, UK.
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17
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Daiss JO, Duda-Johner S, Burschka C, Holzgrabe U, Mohr K, Tacke R. N+/Si Replacement as a Tool for Probing the Pharmacophore of Allosteric Modulators of Muscarinic M2 Receptors: Synthesis, Allosteric Potency, and Positive Cooperativity of Silicon-Based W84 Derivatives. Organometallics 2002. [DOI: 10.1021/om010847j] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Jürgen O. Daiss
- Institut für Anorganische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany, Institut für Pharmazie und Lebensmittelchemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany, and Pharmakologie und Toxikologie, Pharmazeutisches Institut, Universität Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Seraina Duda-Johner
- Institut für Anorganische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany, Institut für Pharmazie und Lebensmittelchemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany, and Pharmakologie und Toxikologie, Pharmazeutisches Institut, Universität Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Christian Burschka
- Institut für Anorganische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany, Institut für Pharmazie und Lebensmittelchemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany, and Pharmakologie und Toxikologie, Pharmazeutisches Institut, Universität Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Ulrike Holzgrabe
- Institut für Anorganische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany, Institut für Pharmazie und Lebensmittelchemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany, and Pharmakologie und Toxikologie, Pharmazeutisches Institut, Universität Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Klaus Mohr
- Institut für Anorganische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany, Institut für Pharmazie und Lebensmittelchemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany, and Pharmakologie und Toxikologie, Pharmazeutisches Institut, Universität Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Reinhold Tacke
- Institut für Anorganische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany, Institut für Pharmazie und Lebensmittelchemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany, and Pharmakologie und Toxikologie, Pharmazeutisches Institut, Universität Bonn, An der Immenburg 4, D-53121 Bonn, Germany
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18
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Li R, Tränkle C, Mohr K, Holzgrabe U. Hexamethonium-type allosteric modulators of the muscarinic receptors bearing lateral dibenzazepine moieties. Arch Pharm (Weinheim) 2001; 334:121-4. [PMID: 11382147 DOI: 10.1002/1521-4184(200104)334:4<121::aid-ardp121>3.0.co;2-t] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Alkane-bisammonium compounds carrying lateral phthalimido substituents are known to have a high affinity for the allosteric binding site of the acetylcholine M2 receptor. The purpose of this study was to replace the lateral phthalimido moieties with rigid tricyclic skeletons of a large volume in order to learn more about the function of the lateral heterocycles. In addition, methyl groups were introduced into the lateral connecting chains. Allosteric inhibition of the dissociation of [3H]N-methylscopolamine from the M2 receptors in porcine cardiac homogenates served to indicate binding of the test compounds to the allosteric site. The phthalimido groups could be replaced with dibenzazepine moieties without any loss in potency. Interestingly, the additional methyl group in the lateral spacer seems to have a significant influence on the allosteric behaviour.
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Affiliation(s)
- R Li
- Department of Organic Chemistry, School of Pharmaceutical Sciences, Beijing Medical University, Beijing 100083, P.R. China
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19
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Zlotos DP, Buller S, Tränkle C, Mohr K. Bisquaternary caracurine V derivatives as allosteric modulators of ligand binding to M2 acetylcholine receptors. Bioorg Med Chem Lett 2000; 10:2529-32. [PMID: 11086722 DOI: 10.1016/s0960-894x(00)00509-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The allosteric effect on muscarinic acetylcholine M2 receptors of 11 bisquaternary salts of the Strychnos alkaloid caracurine V was determined. The effect was indicated by the concentration which retarded the rate of dissociation of the antagonist [3H]-N-methylscopolamine from porcine cardiac cholinoceptors by a factor of 2 (EC50). The most potent compounds carry allyl and propargyl substituents, respectively. Introduction of more bulky substituents (e.g., benzyl groups) resulted in a considerably reduced allosteric potency. The wide range of EC50 values (3 nM for R = allyl. 1750 nM for R = 2-naphthyl) suggests a sterically restricted binding pocket. Molecular modeling studies indicated that the caracurine V ring system satisfies the pharmacophore model for the allosteric interaction.
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Affiliation(s)
- D P Zlotos
- Pharmaceutical Institute, University of Würzburg, Germany.
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20
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Bender W, Staudt M, Tränkle C, Mohr K, Holzgrabe U. Probing the size of a hydrophobic binding pocket within the allosteric site of muscarinic acetylcholine M2-receptors. Life Sci 2000; 66:1675-82. [PMID: 10809164 DOI: 10.1016/s0024-3205(00)00490-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Hexane-bisammonium-type compounds containing lateral phthalimide moieties are known to have a rather high affinity for the allosteric site of muscarinic M2 receptors. In order to get more insight into the contribution of the lateral substituents for alloster binding affinity, a series of compounds with unilaterally varying imide substituents were synthesized and tested for their ability to retard allosterically the dissociation of [3H]N-methylscopolamine from the receptor protein (control t1/2 = 2 min; 3 mM MgHCO4, 50 mM Tris, pH 7.3, 37 degrees C). Among the test compounds, the naphthalimide containing agent (half maximum effect at ECs5,diss = 60 nM) revealed the highest potency. Apparently, its affinity for the allosteric site in NMS-occupied receptors is 20fold higher compared with the phthalimide containing parent compound W 84. Analysis of quantitative structure-activity relationships yielded a parabolic correlation between the volume of the lateral substituents and the allosteric potency. The maximal volume was determined to be approximately 600 A3 suggesting that the allosteric binding site contains a binding pocket of a defined size for the imide moiety.
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Affiliation(s)
- W Bender
- Department of Pharmaceutical Chemistry, Institute of Pharmacy, University of Würzburg, Germany
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Holzgrabe U, Bender W, Cid HM, Staudt M, Pick R, Pfletschinger C, Balatková E, Tränkle C, Mohr K. Ligands for the common allosteric site of acetylcholine M2-receptors: development and application. PHARMACEUTICA ACTA HELVETIAE 2000; 74:149-55. [PMID: 10812952 DOI: 10.1016/s0031-6865(99)00028-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ligands for the allosteric site of acetylcholine M2 receptors are able to retard the dissociation of simultaneously bound ligands for the orthosteric site. This effect promotes receptor occupation by the orthosteric ligand. The allosteric effect opens various therapeutic perspectives, e.g., in organophosphorus poisoning. The aim of our studies was to optimize the affinity of the modulators for the common allosteric binding site of muscarinic M2 receptors, the orthosteric site of which was liganded with the N-methylscolopamine. The phthalimido substituted hexane-bisammonium compound W84 served as a starting point. Previous molecular modelling studies revealed two positive charges and two aromatic imides in a sandwich-like arrangement to be essential for a high allosteric potency. A three-dimensional quantitative structure activity relationship (3D QSAR) analysis predicted compounds with substituents of increasing size on the lateral imide moieties to enhance the affinity for the allosteric binding site. Thus, we synthesized and pharmacologically evaluated compounds bearing "saturated" phthalimide moieties as well as phthalimidines with substituents of systematically increasing size in position 3 or on the aromatic ring at one or both ends of the molecule. Within each series, QSAR could be derived: 1. "Saturation" of the aromatic ring of the phthalimide moiety results in less potent compounds. 2. Increasing the size of the substituents in position 3 of the phthalimide enhances the potency. 3. Putting substituents on the aromatic part of the phthalimide increases the potency more effectively: the introduction of a methyl group in position 5 gave a compound with a potency in the nanomolar concentration range which was subsequently developed as the first radioligand for the allosteric binding site.
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Affiliation(s)
- U Holzgrabe
- Department of Pharmaceutical Chemistry, University of Würzburg, Germany.
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