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Webb TR, Lvovskiy D, Kim SA, Ji XD, Melman N, Linden J, Jacobson KA. Quinazolines as adenosine receptor antagonists: SAR and selectivity for A2B receptors. Bioorg Med Chem 2003; 11:77-85. [PMID: 12467710 PMCID: PMC3460516 DOI: 10.1016/s0968-0896(02)00323-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We have recently reported the discovery of numerous new compounds that are selective inhibitors of all of the subtypes of the adenosine receptor family via a pharmacophore database searching and screening strategy. During the course of this work we made the unexpected discovery of a potent A(2B) receptor antagonist, 4-methyl-7-methoxyquinazolyl-2-(2'-amino-4'-imidazolinone) (38, CMB 6446), which showed selectivity for this receptor and functioned as an antagonist, with a binding K(i) value of 112 nM. We explored the effects of both substituent- and ring-structural variations on the receptor affinity in this series of derivatives, which were found to be mostly non-selective adenosine receptor ligands with K(i) values in the micromolar range. Since no enhancement of A(2B) receptor affinity of 38 was achieved, the previously reported pharmacophore-based searching strategy yielded the most potent and selective structurally-related hit in the database originally searched.
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Affiliation(s)
- Thomas R. Webb
- ChemBridge Corporation, 16981 Via Tazon, Suite G, San Diego, CA 92127, USA
| | - Dmitriy Lvovskiy
- ChemBridge Corporation, 16981 Via Tazon, Suite G, San Diego, CA 92127, USA
| | - Soon-Ai Kim
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, NIH, Bldg. 8A, Rm. B1A 17, Bethesda, MD 20892-0810, USA
| | - Xiao-duo Ji
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, NIH, Bldg. 8A, Rm. B1A 17, Bethesda, MD 20892-0810, USA
| | - Neli Melman
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, NIH, Bldg. 8A, Rm. B1A 17, Bethesda, MD 20892-0810, USA
| | - Joel Linden
- University of Virginia, Charlottesville, VA, USA
| | - Kenneth A. Jacobson
- ChemBridge Corporation, 16981 Via Tazon, Suite G, San Diego, CA 92127, USA
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, NIH, Bldg. 8A, Rm. B1A 17, Bethesda, MD 20892-0810, USA
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Kim SA, Marshall MA, Melman N, Kim HS, Müller CE, Linden J, Jacobson KA. Structure-activity relationships at human and rat A2B adenosine receptors of xanthine derivatives substituted at the 1-, 3-, 7-, and 8-positions. J Med Chem 2002; 45:2131-8. [PMID: 12014951 PMCID: PMC6927247 DOI: 10.1021/jm0104318] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the search for improved selective antagonist ligands of the A2B adenosine receptor, which have the potential as antiasthmatic or antidiabetic drugs, we have synthesized and screened a variety of alkylxanthine derivatives substituted at the 1-, 3-, 7-, and 8-positions. Competition for 125I-ABOPX (125I-3-(4-amino-3-iodobenzyl)-8-(phenyl-4-oxyacetate)-1-propylxanthine) binding in membranes of stably transfected HEK-293 cells revealed uniformly higher affinity (<10-fold) of these xanthines for human than for rat A2B adenosine receptors. Binding to rat brain membranes expressing A1 and A2A adenosine receptors revealed greater A2B selectivity over A2A than A1 receptors. Substitution at the 1-position with 2-phenylethyl (or alkyl/olefinic groups) and at N-3 with hydrogen or methyl favored A2B selectivity. Relative to enprofylline 2b, pentoxifylline 35 was equipotent and 1-propylxanthine 3 was >13-fold more potent at human A2B receptors. Most N-7 substituents did not enhance affinity over hydrogen, except for 7-(2-chloroethyl), which enhanced the affinity of theophylline by 6.5-fold to 800 nM. The A2B receptor affinity-enhancing effects of 7-(2-chloroethyl) vs 7-methyl were comparable to the known enhancement produced by an 8-aryl substitution. Among 8-phenyl analogues, a larger alkyl group at the 1-position than at the 3-position favored affinity at the human A2B receptor, as indicated by 1-allyl-3-methyl-8-phenylxanthine, with a K(i) value of 37 nM. Substitution on the 8-phenyl ring indicated that an electron-rich ring was preferred for A2B receptor binding. In conclusion, new leads for the design of xanthines substituted in the 1-, 3-, 7-, and 8-positions as A2B receptor-selective antagonists have been identified.
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Hannon JP, Tigani B, Wolber C, Williams I, Mazzoni L, Howes C, Fozard JR. Evidence for an atypical receptor mediating the augmented bronchoconstrictor response to adenosine induced by allergen challenge in actively sensitized Brown Norway rats. Br J Pharmacol 2002; 135:685-96. [PMID: 11834616 PMCID: PMC1573180 DOI: 10.1038/sj.bjp.0704516] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2001] [Accepted: 11/11/2001] [Indexed: 11/09/2022] Open
Abstract
The bronchoconstrictor response to adenosine is markedly and selectively increased following ovalbumin (OA) challenge in actively sensitized, Brown Norway rats. We present a pharmacological analysis of the receptor mediating this response. Like adenosine, the broad-spectrum adenosine receptor agonist, NECA, induced dose-related bronchoconstriction in actively sensitized, OA-challenged animals. In contrast, CPA, CGS 21680 and 2-Cl-IB-MECA, agonists selective for A(1) A(2A) and A(3) receptors, respectively, induced no, or minimal, bronchoconstriction. Neither the selective A(1) receptor antagonist, DPCPX, nor the selective A(2A) receptor antagonist, ZM 241385, blocked the bronchoconstrictor response to adenosine. MRS 1754, which has similar affinity for rat A(2B) and A(1) receptors, failed to block the bronchoconstrictor response to adenosine despite blockade of the A(1) receptor-mediated bradycardia induced by NECA. 8-SPT and CGS 15943, antagonists at A(1), A(2A), and A(2B) but not A(3) receptors, inhibited the bronchoconstrictor response to adenosine. However, the degree of blockade (approximately 3 fold) did not reflect the plasma concentrations, which were 139 and 21 times greater than the K(B) value at the rat A(2B) receptor, respectively. Adenosine and NECA, but not CPA, CGS 21680 or 2-Cl-IB-MECA, induced contraction of parenchymal strip preparations from actively sensitized OA-challenged animals. Responses to adenosine could not be antagonized by 8-SPT or MRS 1754 at concentrations >50 times their affinities at the rat A(2B) receptor. The receptor mediating the bronchoconstrictor response to adenosine augmented following allergen challenge in actively sensitized BN rats cannot be categorized as one of the four recognized adenosine receptor subtypes.
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Affiliation(s)
- J P Hannon
- Research Department, Novartis Pharma AG, CH-4002 Basel, Switzerland
| | - B Tigani
- Research Department, Novartis Pharma AG, CH-4002 Basel, Switzerland
| | - C Wolber
- Research Department, Novartis Pharma AG, CH-4002 Basel, Switzerland
| | - I Williams
- Research Department, Novartis Pharma AG, CH-4002 Basel, Switzerland
| | - L Mazzoni
- Research Department, Novartis Pharma AG, CH-4002 Basel, Switzerland
| | - C Howes
- Novartis Horsham Research Centre, Wimblehurst Road, Horsham RH12 4AB
| | - J R Fozard
- Research Department, Novartis Pharma AG, CH-4002 Basel, Switzerland
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Baraldi PG, Cacciari B, Romagnoli R, Klotz KN, Spalluto G, Varani K, Gessi S, Merighi S, Borea PA. Pyrazolo[4,3-e]1,2,4-triazolo[1,5-c]pyrimidine derivatives as adenosine receptor ligands: A starting point for searching A2B adenosine receptor antagonists. Drug Dev Res 2001. [DOI: 10.1002/ddr.1191] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Ji XD, Kim YC, Ahern DG, Linden J, Jacobson KA. [3H]MRS 1754, a selective antagonist radioligand for A(2B) adenosine receptors. Biochem Pharmacol 2001; 61:657-63. [PMID: 11266650 PMCID: PMC5567772 DOI: 10.1016/s0006-2952(01)00531-7] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
MRS 1754 [N-(4-cyanophenyl)-2-[4-(2,3,6,7-tetrahydro-2,6-dioxo-1,3-dipropyl-1H-purin-8-yl)-phenoxy]acetamide] is a selective antagonist ligand of A(2B) adenosine receptors. This is the least well-defined adenosine receptor subtype, and A(2B) antagonists have potential as antiasthmatic drugs. For use as a radioligand, MRS 1754, a p-cyanoanilide xanthine derivative, was tritiated on the propyl groups in a two-step reaction using a p-carboxamido precursor, which was dehydrated to the cyano species using trifluoroacetic anhydride. [3H]MRS 1754 (150 Ci/mmol) bound to recombinant human A(2B) adenosine receptors in membranes of stably transfected HEK-293 cells. Specific binding was saturable, competitive, and followed a one-site model, with a K(D) value of 1.13 +/- 0.12 nM and a B(max) value of 10.9 +/- 0.6 pmol/mg protein. Specific binding utilizing 0.7 nM [3H]MRS 1754 was > 70% of total binding. The affinity calculated from association and dissociation binding constants was 1.22 nM (N = 4). Binding to membranes expressing rat and human A(1) and A(3) adenosine receptors was not significant, and binding in membranes of HEK-293 cells expressing human A(2A) receptors was of low affinity (K(D) > 50 nM). The effects of cations and chelators were explored. Specific binding was constant over a pH range of 4.5 to 6.5, with reduced binding at higher pH. The pharmacological profile in competition experiments with [3H]MRS 1754 was consistent with the structure-activity relationship for agonists and antagonists at A(2B) receptors. The K(i) values of XAC (xanthine amine congener) and CPX (8-cyclopentyl-1,3-dipropylxanthine) were 16 and 55 nM, respectively. NECA (5'-N-ethylcarboxamidoadenosine) competed for [3H]MRS 1754 binding with a K(i) of 570 nM, similar to its potency in functional assays. Thus, [3H]MRS 1754 is suitable as a selective, high-affinity radioligand for A(2B) receptors.
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Affiliation(s)
- Xiao-duo Ji
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bldg. 8A, Room B1A-19, Bethesda, MD 20892, USA
| | - Yong-Chul Kim
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bldg. 8A, Room B1A-19, Bethesda, MD 20892, USA
| | | | - Joel Linden
- Department of Internal Medicine and Molecular Physiology & Biological Physics, University of Virginia, Box MR4 6012, Health Science Center, Charlottesville, VA 22908, USA
| | - Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bldg. 8A, Room B1A-19, Bethesda, MD 20892, USA
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Harada H, Asano O, Hoshino Y, Yoshikawa S, Matsukura M, Kabasawa Y, Niijima J, Kotake Y, Watanabe N, Kawata T, Inoue T, Horizoe T, Yasuda N, Minami H, Nagata K, Murakami M, Nagaoka J, Kobayashi S, Tanaka I, Abe S. 2-Alkynyl-8-aryl-9-methyladenines as novel adenosine receptor antagonists: their synthesis and structure-activity relationships toward hepatic glucose production induced via agonism of the A(2B) receptor. J Med Chem 2001; 44:170-9. [PMID: 11170626 DOI: 10.1021/jm990499b] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Novel adenosine antagonists, 2-alkynyl-8-aryl-9-methyladenine derivatives, were synthesized as candidate hypoglycemic agents. These analogues were evaluated for inhibitory activity on N-ethylcarboxamidoadenosine (NECA)-induced glucose production in primary cultured rat hepatocytes. In general, aromatic moieties at the 8-position and alkynyl groups at the 2-position had significantly increased activity compared to unsubstituted compounds. The preferred substituents at the 8-position of adenine were the 2-furyl and 3-fluorophenyl groups. In modifying the alkynyl side chain, change of the ring size, cleavage of the ring, and removal of the hydroxyl group were well tolerated. The order of the stimulatory effects of adenosine agonists on rat hepatocytes was NECA > CPA > CGS21680, which is consistent with involvement of the A(2B) receptor. In Chinese hamster ovary cells stably transfected with human A(2B) receptor cDNA, one of the compounds potent in hepatocytes, 15o (IC(50) = 0.42 microM), antagonized NECA-induced stimulation of cyclic AMP production (IC(50) = 0.063 microM). This inhibitory effect was much more potent than those of FK453, KF17837, and L249313 which have been reported to be respectively A(1), A(2A), and A(3) selective antagonists. These findings agree very well with the result that, compared to 15o, these selective antagonists for each receptor subtype showed only marginal effects in rat hepatocytes. These results suggest that adenosine agonist-induced glucose production in rat hepatocytes is mediated through the A(2B) receptor. Furthermore, 15o showed hypoglycemic activity in an animal model of noninsulin-dependent diabetes mellitus, the KK-A(y) mice. It is possible that inhibition of hepatic glucose production via the A(2B) receptor could be at least one of the mechanisms by which 15o exerts its in vivo effects. Further elaboration of this group of compounds may afford novel antidiabetic agents.
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Affiliation(s)
- H Harada
- Tsukuba Research Laboratories, Eisai Company, Ltd., 5-1-3 Tokodai, Tsukuba, Ibaraki 300-2635, Japan.
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Kim YC, Ji XD, Melman N, Linden J, Jacobson KA. Anilide derivatives of an 8-phenylxanthine carboxylic congener are highly potent and selective antagonists at human A(2B) adenosine receptors. J Med Chem 2000; 43:1165-72. [PMID: 10737749 PMCID: PMC9364909 DOI: 10.1021/jm990421v] [Citation(s) in RCA: 149] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
No highly selective antagonists of the A(2B) adenosine receptor (AR) have been reported; however such antagonists have therapeutic potential as antiasthmatic agents. Here we report the synthesis of potent and selective A(2B) receptor antagonists. The structure-activity relationships (SAR) of 8-phenyl-1, 3-di-(n-propyl)xanthine derivatives in binding to recombinant human A(2B) ARs in HEK-293 cells (HEK-A(2B)) and at other AR subtypes were explored. Various amide derivatives of 8-[4-[[carboxymethyl]oxy]phenyl]-1,3-di-(n-propyl)xanthine, 4a, were synthesized. A comparison of aryl, alkyl, and aralkyl amides demonstrated that simple anilides, particularly those substituted in the para-position with electron-withdrawing groups, such as nitro, cyano, and acetyl, bind selectively to human A(2B) receptors in the range of 1-3 nM. The unsubstituted anilide 12 had a K(i) value at A(2B) receptors of 1.48 nM but was only moderately selective versus human A(1)/A(2A) receptors and nonselective versus rat A(1) receptors. Highly potent and selective A(2B) antagonists were a p-aminoacetophenone derivative 20 (K(i) value 1.39 nM) and ap-cyanoanilide 27 (K(i) value 1.97 nM). Compound 27 was 400-, 245-, and 123-fold selective for human A(2B) receptors versus human A(1)/A(2A)/A(3) receptors, respectively, and 8.5- and 310-fold selective versus rat A(1)/A(2A) receptors, respectively. Substitution of the 1,3-dipropyl groups with 1,3-diethyl offered no disadvantage for selectivity, and high affinities at A(2B) receptors were maintained. Substitution of the p-carboxymethyloxy group of 4a and its amides with acrylic acid decreased affinity at A(2B) receptors while increasing affinity at A(1) receptors. 1, 3-Di(cyclohexylmethyl) groups greatly reduced affinity at ARs, although the p-carboxymethyloxy derivative 9 was moderately selective for A(2B) receptors. Several selective A(2B) antagonists inhibited NECA-stimulated calcium mobilization in HEK-A(2B) cells.
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Affiliation(s)
- Yong-Chul Kim
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810
| | - Xiao-duo Ji
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810
| | - Neli Melman
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810
| | - Joel Linden
- Department of Internal Medicine and Molecular Physiology & Biological Physics, University of Virginia, Box MR4 6012, Health Science Center, Charlottesville, Virginia 22908
| | - Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810
- Correspondence to: Dr. K. A. Jacobson, Bldg. 8A, Rm. B1A-19, NIH, NIDDK, LBC, Bethesda, MD 20892-0810. Tel: (301) 496-9024. Fax: (301) 480-8422.
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Webb TR, Melman N, Lvovskiy D, Ji XD, Jacobson KA. The utilization of a unified pharmacophore query in the discovery of new antagonists of the adenosine receptor family. Bioorg Med Chem Lett 2000; 10:31-4. [PMID: 10636237 PMCID: PMC5553072 DOI: 10.1016/s0960-894x(99)00583-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Pharmacophore queries from previously known potent selective A3 antagonists were generated by Chem-X. These queries were used to search a pharmacophore database of diverse compounds (CNS-Set). In vitro assays of 186 'hits' yielded over 30 active compounds, for four adenosine receptor subtypes. This search strategy may also be applicable to the discovery of new ligands via receptor homology data.
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Affiliation(s)
- T R Webb
- ChemBridge Corporation, San Diego, CA 92127, USA.
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de Zwart M, Vollinga RC, Beukers MW, Sleegers DF, von Frijtag Drabbe K�nzel JK, de Groote M, Ijzerman AP. Potent antagonists for the human adenosine A2B receptor. Derivatives of the triazolotriazine adenosine receptor antagonist ZM241385 with high affinity. Drug Dev Res 1999. [DOI: 10.1002/(sici)1098-2299(199911)48:3<95::aid-ddr1>3.0.co;2-b] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Kim YC, Karton Y, Ji XD, Melman N, Linden J, Jacobson KA. Acyl-hydrazide derivatives of a xanthine carboxylic congener (XCC) as selective antagonists at human A2B adenosine receptors. Drug Dev Res 1999; 47:178-188. [DOI: 10.1002/(sici)1098-2299(199908)47:4<178::aid-ddr4>3.0.co;2-l] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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