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Poon L, Hum JR, Weiss RG. Effects of cyclic and acyclic amidine side-chains on the properties of polysiloxane ionomers constructed in situ from three uncharged components. SOFT MATTER 2022; 18:5502-5508. [PMID: 35848508 DOI: 10.1039/d2sm00382a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Ionomers, polysiloxanes with imidazolinium dithiocarbamate side chains, have been synthesized in situ from three uncharged components-a polysiloxane with imidazole side chains, CS2, and hexylamine or octadecylamine. Their structural and dynamic properties are compared over a temperature range of 0-50 °C with those of the analogous ionomers in which the polysiloxanes have amidinium side chains. The results, primarily from differential scanning calorimetry, powder X-ray diffraction measurements, and rheology show that the small structural (and smaller electronic) differences between the cyclic 5-membered ring imidazolinium and acyclic amidinium groups have marked effects on the bulk properties of the ionomers. These include their shear strengths and the manner in which the microcrystalline portions of the ionomers with dithiooctadecylcarbamate anions are packed. Thus, it is possible to finely tune the natures of the ionomers from one polysiloxane by changing temperature, the chain length of the alkylamine, and the nature of the base attached to the polysiloxane chain. Why these changes occur to the various properties is discussed.
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Affiliation(s)
- Louis Poon
- Department of Chemistry and Institute for Soft Matter Synthesis and Metrology, Georgetown University, Washington, DC 20057-1227, USA.
| | - Jacob R Hum
- Department of Chemistry and Institute for Soft Matter Synthesis and Metrology, Georgetown University, Washington, DC 20057-1227, USA.
| | - Richard G Weiss
- Department of Chemistry and Institute for Soft Matter Synthesis and Metrology, Georgetown University, Washington, DC 20057-1227, USA.
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Role of intracellular Ca 2+ signaling in the antinociceptive and discriminative stimulus effects of the imidazoline I 2 receptor agonist 2-BFI in rats. Psychopharmacology (Berl) 2017; 234:3299-3307. [PMID: 28825118 PMCID: PMC5660937 DOI: 10.1007/s00213-017-4719-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 08/13/2017] [Indexed: 01/27/2023]
Abstract
RATIONALE Recent research has established the imidazoline I2 receptor as a promising target for the development of novel analgesics. However, despite an increasing understanding of imidazoline I2 receptor-mediated behavioral effects, little is known about post-I2-receptor signaling mechanisms. OBJECTIVE This study examined the effects of several inhibitors of Ca2+ signaling mechanisms on two behavioral effects of the prototypical imidazoline I2 receptor ligand 2-(2-benzofuranyl)-2-imidazoline (2-BFI). METHODS The von Frey filament test was used to examine the antinociceptive effects of 2-BFI in complete Freund's adjuvant (CFA)-induced inflammatory pain in rats. A two-lever drug discrimination paradigm in which rats were trained to discriminate 5.6 mg/kg (intraperitoneally) 2-BFI from its vehicle was used to examine the discriminative stimulus effects of 2-BFI. RESULTS The L-type Ca2+ channel blockers verapamil and nimodipine, the calmodulin antagonist W-7, and the internal Ca2+ release inhibitor ryanodine all attenuated the antinociceptive effects of 2-BFI. Oxycodone- and acetaminophen-induced antinociception was unaffected by pretreatment with the Ca2+ channel blockers. Rats learned to reliably discriminate 5.6 mg/kg 2-BFI from saline. The I2 receptor agonists BU224, RS45041, tracizoline, and CR4056 all fully substituted for 5.6 mg/kg 2-BFI while idazoxan, S22687, 2,5-dimethoxy-4-methylamphetamine (DOM), and phenyzoline produced partial or no substitution. Verapamil, nimodipine, and W-7 did not alter the discriminative stimulus effects of 2-BFI. CONCLUSION These results indicate that the antinociceptive effects of 2-BFI involve intracellular Ca2+ elevation and/or downstream Ca2+/calmodulin signaling, whereas the discriminative stimulus effects of 2-BFI are mediated by a distinct, independent mechanism.
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Del Bello F, Cilia A, Carrieri A, Fasano DC, Ghelardini C, Di Cesare Mannelli L, Micheli L, Santini C, Diamanti E, Giannella M, Giorgioni G, Mammoli V, Paoletti CD, Petrelli R, Piergentili A, Quaglia W, Pigini M. The Versatile 2-Substituted Imidazoline Nucleus as a Structural Motif of Ligands Directed to the Serotonin 5-HT1A
Receptor. ChemMedChem 2016; 11:2287-2298. [DOI: 10.1002/cmdc.201600383] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 08/30/2016] [Indexed: 11/12/2022]
Affiliation(s)
- Fabio Del Bello
- School of Pharmacy; Medicinal Chemistry Unit; University of Camerino; Via S. Agostino 1 62032 Camerino Italy
| | - Antonio Cilia
- Recordati S.p.A.; Drug Discovery; via Civitali 1 20148 Milano (Italy)
| | - Antonio Carrieri
- Department of Pharmacy-Drug Science; University of Bari “Aldo Moro”; Via E. Orabona 4 70125 Bari Italy
| | - Domenico Claudio Fasano
- Department of Pharmacy-Drug Science; University of Bari “Aldo Moro”; Via E. Orabona 4 70125 Bari Italy
| | - Carla Ghelardini
- Department of Neuroscience, Psychology, Drug Research and; Child Health - Neurofarba - Pharmacology and Toxicology Section; University of Florence; Viale Pieraccini 6 50039 Firenze Italy
| | - Lorenzo Di Cesare Mannelli
- Department of Neuroscience, Psychology, Drug Research and; Child Health - Neurofarba - Pharmacology and Toxicology Section; University of Florence; Viale Pieraccini 6 50039 Firenze Italy
| | - Laura Micheli
- Department of Neuroscience, Psychology, Drug Research and; Child Health - Neurofarba - Pharmacology and Toxicology Section; University of Florence; Viale Pieraccini 6 50039 Firenze Italy
| | - Carlo Santini
- School of Science and Technology; University of Camerino; Via S. Agostino 1 62032 Camerino Italy
| | - Eleonora Diamanti
- School of Pharmacy; Medicinal Chemistry Unit; University of Camerino; Via S. Agostino 1 62032 Camerino Italy
| | - Mario Giannella
- School of Pharmacy; Medicinal Chemistry Unit; University of Camerino; Via S. Agostino 1 62032 Camerino Italy
| | - Gianfabio Giorgioni
- School of Pharmacy; Medicinal Chemistry Unit; University of Camerino; Via S. Agostino 1 62032 Camerino Italy
| | - Valerio Mammoli
- School of Pharmacy; Medicinal Chemistry Unit; University of Camerino; Via S. Agostino 1 62032 Camerino Italy
| | - Corinne Dalila Paoletti
- School of Pharmacy; Medicinal Chemistry Unit; University of Camerino; Via S. Agostino 1 62032 Camerino Italy
| | - Riccardo Petrelli
- School of Pharmacy; Medicinal Chemistry Unit; University of Camerino; Via S. Agostino 1 62032 Camerino Italy
| | - Alessandro Piergentili
- School of Pharmacy; Medicinal Chemistry Unit; University of Camerino; Via S. Agostino 1 62032 Camerino Italy
| | - Wilma Quaglia
- School of Pharmacy; Medicinal Chemistry Unit; University of Camerino; Via S. Agostino 1 62032 Camerino Italy
| | - Maria Pigini
- School of Pharmacy; Medicinal Chemistry Unit; University of Camerino; Via S. Agostino 1 62032 Camerino Italy
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Qiu Y, Zhang Y, Li JX. Discriminative stimulus effects of the imidazoline I2 receptor ligands BU224 and phenyzoline in rats. Eur J Pharmacol 2015; 749:133-41. [PMID: 25617792 DOI: 10.1016/j.ejphar.2015.01.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Revised: 01/09/2015] [Accepted: 01/14/2015] [Indexed: 01/25/2023]
Abstract
Although imidazoline I2 receptor ligands have been used as discriminative stimuli, the role of efficacy of I2 receptor ligands as a critical determinant in drug discrimination has not been explored. This study characterized the discriminative stimulus effects of selective imidazoline I2 receptor ligands BU224 (a low-efficacy I2 receptor ligand) and phenyzoline (a higher efficacy I2 receptor ligand) in rats. Two groups of male Sprague-Dawley rats were trained to discriminate 5.6mg/kg BU224 or 32mg/kg phenyzoline (i.p.) from their vehicle in a two-lever food-reinforced drug discrimination procedure, respectively. All rats acquired the discriminations after an average of 18 (BU224) and 56 (phenyzoline) training sessions, respectively. BU224 and phenyzoline completely substituted for one another symmetrically. Several I2 receptor ligands (tracizoline, CR4056, RS45041, and idazoxan) all occasioned>80% drug-associated lever responding in both discriminations. The I2 receptor ligand 2-BFI and a monoamine oxidase inhibitor harmane occasioned>80% drug-associated lever responding in rats discriminating BU224. Other drugs that occasioned partial or less substitution to BU224 cue included clonidine, methamphetamine, ketamine, morphine, methadone and agmatine. Clonidine, methamphetamine and morphine also only produced partial substitution to phenyzoline cue. Naltrexone, dopamine D2 receptor antagonist haloperidol and serotonin (5-HT)2A receptor antagonist MDL100907 failed to alter the discriminative stimulus effects of BU224 or phenyzoline. Combined, these results are the first to demonstrate that BU224 and phenyzoline can serve as discriminative stimuli and that the low-efficacy I2 receptor ligand BU224 shares similar discriminative stimulus effects with higher-efficacy I2 receptor ligands such as phenyzoline and 2-BFI.
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Affiliation(s)
- Yanyan Qiu
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Yanan Zhang
- Research Triangle Institute, Research Triangle Park, NC, USA
| | - Jun-Xu Li
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA.
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Qiu Y, He XH, Zhang Y, Li JX. Discriminative stimulus effects of the novel imidazoline I₂ receptor ligand CR4056 in rats. Sci Rep 2014; 4:6605. [PMID: 25308382 PMCID: PMC4194429 DOI: 10.1038/srep06605] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 09/22/2014] [Indexed: 01/27/2023] Open
Abstract
This study examined whether a novel imidazoline I2 receptor ligand CR4056 could serve as a discriminative stimulus and whether it shares similar discriminative stimulus effects with other reported I2 receptor ligands. Eight male Sprague-Dawley rats were trained to discriminate 10.0 mg/kg CR4056 (i.p.) from vehicle in a two-lever food-reinforced drug discrimination procedure. Once rats acquired the discrimination, substitution and combination studies were conducted to elucidate the underlying receptor mechanisms. All rats acquired CR4056 discrimination after an average of 26 training sessions. Several I2 receptor ligands (phenyzoline, tracizoline, RS45041, and idazoxan, 3.2–75 mg/kg, i.p.) all occasioned > 80% CR4056-associated lever responding. Other drugs that occasioned partial or no CR4056-associated lever responding included methamphetamine, ketamine, the endogenous imidazoline ligand agmatine, the monoamine oxidase (MAO) inhibitor harmane, the α2-adrenoceptor agonist clonidine, the μ-opioid receptor agonists morphine and methadone, and the selective I2 receptor ligands BU224 and 2-BFI. The α1 adrenoceptor antagonist WB4101, α2 adrenoceptor antagonist yohimbine and μ-opioid receptor antagonist naltrexone failed to alter the stimulus effects of CR4056. Together, these results show that CR4056 can serve as a discriminative stimulus in rats, which demonstrates high pharmacological specificity and appears to be mediated by imidazoline I2 receptors.
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Affiliation(s)
- Yanyan Qiu
- 1] Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA [2] Department of Physiology, School of Basic Medical Sciences, Wuhan University, Hubei, China
| | - Xiao-Hua He
- Department of Physiology, School of Basic Medical Sciences, Wuhan University, Hubei, China
| | - Yanan Zhang
- Research Triangle Institute, Research Triangle Park, NC, USA
| | - Jun-Xu Li
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
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Del Bello F, Diamanti E, Giannella M, Mammoli V, Mattioli L, Titomanlio F, Piergentili A, Quaglia W, Lanza M, Sabatini C, Caselli G, Poggesi E, Pigini M. Exploring multitarget interactions to reduce opiate withdrawal syndrome and psychiatric comorbidity. ACS Med Chem Lett 2013; 4:875-9. [PMID: 24900763 DOI: 10.1021/ml400232p] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 07/22/2013] [Indexed: 01/22/2023] Open
Abstract
Opioid addiction is often characterized as a chronic relapsing condition due to the severe somatic and behavioral signs, associated with depressive disorders, triggered by opiate withdrawal. Since prolonged abstinence remains a major challenge, our interest has been addressed to such objective. Exploring multitarget interactions, the present investigation suggests that 3 or its (S)-enantiomer and 4, endowed with effective α2C-AR agonism/α2A-AR antagonism/5-HT1A-R agonism, or 7 and 9-11 producing efficacious α2C-AR agonism/α2A-AR antagonism/I2-IBS interaction might represent novel multifunctional tools potentially useful for reducing withdrawal syndrome and associated depression. Such agents, lacking in sedative side effects due to their α2A-AR antagonism, might afford an improvement over current therapies with clonidine-like drugs.
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Affiliation(s)
- Fabio Del Bello
- School of Pharmacy, Medicinal
Chemistry Unit, University of Camerino,
Via S. Agostino 1, 62032 Camerino, Italy
| | - Eleonora Diamanti
- School of Pharmacy, Medicinal
Chemistry Unit, University of Camerino,
Via S. Agostino 1, 62032 Camerino, Italy
| | - Mario Giannella
- School of Pharmacy, Medicinal
Chemistry Unit, University of Camerino,
Via S. Agostino 1, 62032 Camerino, Italy
| | - Valerio Mammoli
- School of Pharmacy, Medicinal
Chemistry Unit, University of Camerino,
Via S. Agostino 1, 62032 Camerino, Italy
| | - Laura Mattioli
- School of Pharmacy, Pharmacognosy
Unit, University of Camerino, Via Madonna
delle Carceri 9, 62032 Camerino, Italy
| | - Federica Titomanlio
- School of Pharmacy, Pharmacognosy
Unit, University of Camerino, Via Madonna
delle Carceri 9, 62032 Camerino, Italy
| | - Alessandro Piergentili
- School of Pharmacy, Medicinal
Chemistry Unit, University of Camerino,
Via S. Agostino 1, 62032 Camerino, Italy
| | - Wilma Quaglia
- School of Pharmacy, Medicinal
Chemistry Unit, University of Camerino,
Via S. Agostino 1, 62032 Camerino, Italy
| | - Marco Lanza
- Pharmacology & Toxicology
Department, Rottapharm-Madaus, 20052 Monza,
Italy
| | - Chiara Sabatini
- Pharmacology & Toxicology
Department, Rottapharm-Madaus, 20052 Monza,
Italy
| | - Gianfranco Caselli
- Pharmacology & Toxicology
Department, Rottapharm-Madaus, 20052 Monza,
Italy
| | - Elena Poggesi
- Recordati S.pA., Drug Discovery, Via Civitali 1, 20148 Milano, Italy
| | - Maria Pigini
- School of Pharmacy, Medicinal
Chemistry Unit, University of Camerino,
Via S. Agostino 1, 62032 Camerino, Italy
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Geden JV, Pancholi AK, Shipman M. Palladium-Catalyzed Multicomponent Synthesis of 2-Aryl-2-imidazolines from Aryl Halides and Diamines. J Org Chem 2013; 78:4158-64. [DOI: 10.1021/jo400252n] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Joanna V. Geden
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United
Kingdom
| | - Alpa K. Pancholi
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United
Kingdom
| | - Michael Shipman
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United
Kingdom
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Garau C, Miralles A, García-Sevilla JA. Chronic treatment with selective I2-imidazoline receptor ligands decreases the content of pro-apoptotic markers in rat brain. J Psychopharmacol 2013; 27:123-34. [PMID: 22719017 DOI: 10.1177/0269881112450785] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Selective I(2)-imidazoline receptor ligands induce neuroprotection through various molecular mechanisms including blockade of N-methyl-D-aspartate (NMDA) receptors. To investigate new neuroprotective mechanisms associated with I(2)-imidazoline receptors, the effects of selective (2-styryl-2-imidazoline (LSL 61122), 2-(2-benzofuranyl)-2-imidazoline (2-BFI), 2-(4,5-dihydroimidazol-2-yl) quinoline hydrochloride (BU-224)) and non-selective (idazoxan) I(2)-drugs on canonical apoptotic pathways were assessed in rat brain cortex. The acute treatment with LSL 61122 (10 mg/kg) reduced the content of mitochondrial (pro-apoptotic) Bax (-33%) and cytochrome c (-31%), which was prevented by idazoxan, an I(2)-receptor antagonist. The sustained stimulation of I(2)-imidazoline receptors with selective drugs (10 mg/kg, every 12 h for seven days) was associated with down-regulation of key components of the extrinsic (Fas receptor: -20%; Fas associated protein with death domain (FADD) adaptor: -47-54%) and/or intrinsic (Bax: -20-23%; cytochrome c: -22-28%) apoptotic signalling and/or up-regulation of survival anti-apoptotic factors (p-Ser194 FADD/FADD ratio: +1.6-2.5-fold; and/or Bcl-2/Bax ratio: +1.5-fold), which in the long-term could dampen cell death in the brain. Similar chronic treatments with LSL 60101 (the imidazole analogue of 2-BFI) and idazoxan (a mixed I(2)/α(2)-ligand) did not induce significant alterations of pro- or anti-apoptotic proteins. The disclosed anti-apoptotic mechanisms of selective I(2)-imidazoline drugs may work in concert with other molecular mechanisms of neuroprotection (e.g. blockade of NMDA receptors) that are engaged by I(2)-ligands.
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Affiliation(s)
- Celia Garau
- Laboratori de Neurofarmacologia, Institut Universitari d'Investigació en Ciències de la Salut (IUNICS), Universitat de les Illes Balears, Palma de Mallorca, Spain
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Kealey S, Turner EM, Husbands SM, Salinas CA, Jakobsen S, Tyacke RJ, Nutt DJ, Parker CA, Gee AD. Imaging imidazoline-I2 binding sites in porcine brain using 11C-BU99008. J Nucl Med 2012; 54:139-44. [PMID: 23223380 DOI: 10.2967/jnumed.112.108258] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED Changes in the density of imidazoline-I(2) binding sites have been observed in a range of neurologic disorders including Alzheimer's disease, Huntington's chorea, and glial tumor; however, the precise function of these sites remains unclear. A PET probe for I(2) binding sites would further our understanding of the target and may find application as a biomarker for early disease diagnosis. Compound BU99008 has previously been identified as a promising I(2) ligand from autoradiography studies, displaying high affinity and good selectivity toward the target. In this study, BU99008 was radiolabeled with (11)C in order to image the I(2) binding sites in vivo using PET. METHODS (11)C-BU99008 was radiolabeled by N-alkylation of the desmethyl precursor using (11)C-methyl iodide. A series of PET experiments was performed to investigate the binding of (11)C-BU99008 in porcine brains, in the presence or absence of a nonradiolabeled, competing I(2) ligand, BU224. RESULTS (11)C-BU99008 was obtained in good yield and specific activity. In vivo, (11)C-BU99008 displayed good brain penetration and gave a heterogeneous distribution with high uptake in the thalamus and low uptake in the cortex and cerebellum. (11)C-BU99008 brain kinetics were well described by the 1-tissue-compartment model, which was used to provide estimates for the total volume of distribution (V(T)) across brain regions of interest. Baseline V(T) values were ranked in the following order: thalamus > striatum > hippocampus > frontal cortex ≥ cerebellum, consistent with the known distribution and concentration of I(2) binding sites. Administration of a selective I(2) binding site ligand, BU224, reduced the V(T) to near-homogeneous levels in all brain regions. CONCLUSION (11)C-BU99008 appears to be a suitable PET radioligand for imaging the I(2) binding sites in vivo.
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Affiliation(s)
- Steven Kealey
- Institute of Psychiatry, De Crespigny Park, King's College London, London, United Kingdom.
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Thorn DA, An XF, Zhang Y, Pigini M, Li JX. Characterization of the hypothermic effects of imidazoline I₂ receptor agonists in rats. Br J Pharmacol 2012; 166:1936-45. [PMID: 22324428 DOI: 10.1111/j.1476-5381.2012.01894.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Imidazoline I(2) receptors have been implicated in several CNS disorders. Although several I(2) receptor agonists have been described, no simple and sensitive in vivo bioassay is available for studying I(2) receptor ligands. This study examined I(2) receptor agonist-induced hypothermia as a functional in vivo assay of I(2) receptor agonism. EXPERIMENTAL APPROACH Different groups of rats were used to examine the effects of I(2) receptor agonists on the rectal temperature and locomotion. The pharmacological mechanisms were investigated by combining I(2) receptor ligands and different antagonists. KEY RESULTS All the selective I(2) receptor agonists examined (2-BFI, diphenyzoline, phenyzoline, CR4056, tracizoline, BU224 and S22687, 3.2-56 mg·kg(-1) , i.p.) dose-dependently and markedly decreased the rectal temperature (hypothermia) in rats, with varied duration of action. Pharmacological mechanism of the observed hypothermia was studied by combining the I(2) receptor agonists (2-BFI, BU224, tracizoline and diphenyzoline) with imidazoline I(2 ) receptor/ α(2) adrenoceptor antagonist idazoxan, selective I(1) receptor antagonist efaroxan, α(2) adrenoceptor antagonist/5-HT(1A) receptor agonist yohimbine. Idazoxan but not yohimbine or efaroxan attenuated the hypothermic effects of 2-BFI, BU224, tracizoline and diphenyzoline, supporting the I(2) receptor mechanism. In contrast, both idazoxan and yohimbine attenuated hypothermia induced by the α(2) adrenoceptor agonist clonidine. Among all the I(2) receptor agonists studied, only S22687 markedly increased the locomotor activity in rats. CONCLUSIONS AND IMPLICATIONS Imidazoline I(2) receptor agonists can produce hypothermic effects, which are primarily mediated by I(2) receptors. These data suggest that I(2) receptor agonist-induced hypothermia is a simple and sensitive in vivo assay for studying I(2) receptor ligands.
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Affiliation(s)
- David A Thorn
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, the State University of New York, Buffalo, NY, USA
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Tyacke RJ, Fisher A, Robinson ESJ, Grundt P, Turner EM, Husbands SM, Hudson AL, Parker CA, Nutt DJ. Evaluation and initial in vitro and ex vivo characterization of the potential positron emission tomography ligand, BU99008 (2-(4,5-dihydro-1H-imidazol-2-yl)-1- methyl-1H-indole), for the imidazoline₂ binding site. Synapse 2012; 66:542-51. [PMID: 22290740 DOI: 10.1002/syn.21541] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 01/12/2012] [Accepted: 01/23/2012] [Indexed: 11/06/2022]
Abstract
The density of the Imidazoline₂ binding site (I₂BS) has been shown to change in psychiatric conditions such as depression and addiction, along with neurodegenerative disorders such as Alzheimer's disease and Huntington's chorea. The presence of I₂BS on glial cells and the possibility that they may in some way regulate glial fibrillary acidic protein has led to increased interest into the role of I₂BS and I₂BS ligands in conditions characterized by marked gliosis. In addition, it has been suggested that I₂BS may be a marker for human glioblastomas. Therefore, the development of a positron emission tomography (PET) radioligand for the I₂BS would be of major benefit in our understanding of these conditions. We now report the successful synthesis and initial pharmacological evaluation of potential PET radioligands for the I₂BS as well as the tritiation and characterization of the most favorable of the series, BU99008 (6), both in vitro and ex vivo in rat. The series as a whole demonstrated excellent affinity and selectivity for the I₂BS, with BU99008 (6) selected as the lead candidate to be taken forward for in vivo assessment. BU99008 (6) showed very good affinity for the I₂BS (K(i) of 1.4 nM; K(d) = 1.3 nM), good selectivity compared with the α₂ -adrenoceptor (909-fold). In addition, following peripheral administration, [³H]BU99008 demonstrated a heterogenous uptake into the rat brain consistent with the known distribution of the I₂BS in vivo. This, and the amenability of BU99008 (6) to radiolabeling with a positron-emitting radioisotope, indicates its potential as a PET radioligand for imaging the I₂BS in vivo.
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Affiliation(s)
- Robin J Tyacke
- Neuropsychopharmacology Unit, Centre for Pharmacology and Therapeutics, Hammersmith Hospital Campus, Imperial College London, London W12 0NN, United Kingdom.
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Nikolic K, Agbaba D. Imidazoline antihypertensive drugs: selective i(1) -imidazoline receptors activation. Cardiovasc Ther 2011; 30:209-16. [PMID: 21884004 DOI: 10.1111/j.1755-5922.2011.00269.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Involvement of imidazoline receptors (IR) in the regulation of vasomotor tone as well as in the mechanism of action of some centrally acting antihypertensives has received tremendous attention. To date, pharmacological studies have allowed the characterization of three main imidazoline receptor classes, the I(1) -imidazoline receptor which is involved in central inhibition of sympathetic tone to lower blood pressure, the I(2) -imidazoline receptor which is an allosteric binding site of monoamine oxidase B (MAO-B), and the I(3) -imidazoline receptor which regulates insulin secretion from pancreatic β-cells. All three imidazoline receptors represent important targets for cardiovascular research. The hypotensive effect of clonidine-like centrally acting antihypertensives was attributed both to α(2) -adrenergic receptors and nonadrenergic I(1) -imidazoline receptors, whereas their sedative action involves activation of only α(2) -adrenergic receptors located in the locus coeruleus. Since more selective I(1) -imidazoline receptors ligands reduced incidence of typical side effects of other centrally acting antihypertensives, there is significant interest in developing new agents with higher selectivity and affinity for I(1) -imidazoline receptors. The selective imidazoline receptors agents are also more effective in regulation of body fat, neuroprotection, inflammation, cell proliferation, epilepsy, depression, stress, cell adhesion, and pain. New agonists and antagonists with high selectivity for imidazoline receptor subtypes have been recently developed. In the present review we provide a brief update to the field of imidazoline research, highlighting some of the chemical diversity and progress made in the theoretical studies of imidazoline receptor ligands.
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Affiliation(s)
- K Nikolic
- Faculty of Pharmacy, Institute of Pharmaceutical Chemistry, University of Belgrade, Vojvode Stepe, Belgrade, Serbia.
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14
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Li JX, Zhang Y. Imidazoline I2 receptors: target for new analgesics? Eur J Pharmacol 2011; 658:49-56. [PMID: 21371460 DOI: 10.1016/j.ejphar.2011.02.038] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2010] [Revised: 01/19/2011] [Accepted: 02/15/2011] [Indexed: 12/22/2022]
Abstract
Pain remains a major clinical challenge because there are no effective analgesics for some pain conditions and the mainstay analgesics for severe pain, opioids, have serious unwanted effects. There is a dire need for novel analgesics in the clinic. Imidazoline receptors are a family of three receptors (I(1), I(2) and I(3)) that all can recognize compounds with an imidazoline structure. Accumulating evidence suggests that I(2) receptors are involved in pain modulation. Ligands acting at I(2) receptors are effective for tonic inflammatory and neuropathic pain but are much less effective for acute phasic pain. When studied in combination, I(2) receptor ligands enhance the analgesic effects of opioids in both acute phasic and chronic tonic pain. During chronic use, patients can develop tolerance to and dependence on opioids. Imidazoline I(2) receptor ligands can attenuate the development of tolerance to opioid analgesia and inhibit drug withdrawal or antagonist precipitation induced abstinence syndrome in animals. Taken together, drugs acting on I(2) receptors may be useful as a monotherapy or combined with opioids as an adjuvant for treating pain. Future studies should focus on understanding the relative efficacy of I(2) receptor ligands and developing new compounds to fill the gap in intrinsic efficacy continuum of I(2) receptors.
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Affiliation(s)
- Jun-Xu Li
- Department of Pharmacology and Toxicology, University at Buffalo, State University of New York, Buffalo, NY 14214, USA.
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15
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Imaging of I2-imidazoline receptors by small-animal PET using 2-(3-fluoro-[4-11C]tolyl)-4,5-dihydro-1H-imidazole ([11C]FTIMD). Nucl Med Biol 2010; 37:625-35. [DOI: 10.1016/j.nucmedbio.2010.02.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Revised: 02/26/2010] [Accepted: 02/28/2010] [Indexed: 11/23/2022]
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16
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New analogues of agmatine with higher affinity to imidazoline receptors. Bioorg Med Chem Lett 2009; 19:1009-11. [DOI: 10.1016/j.bmcl.2008.11.055] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Revised: 11/14/2008] [Accepted: 11/17/2008] [Indexed: 11/20/2022]
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17
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Gentili F, Cardinaletti C, Vesprini C, Ghelfi F, Farande A, Giannella M, Piergentili A, Quaglia W, Mattioli L, Perfumi M, Hudson A, Pigini M. Novel Ligands Rationally Designed for Characterizing I2−Imidazoline Binding Sites Nature and Functions. J Med Chem 2008; 51:5130-4. [DOI: 10.1021/jm800400k] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Francesco Gentili
- Dipartimento di Scienze Chimiche, Università degli Studi di Camerino, via S. Agostino 1, 62032 Camerino, Italy, Dipartimento di Medicina Sperimentale e Sanità Pubblica, Università degli Studi di Camerino, via Madonna delle Carceri, 62032 Camerino, Italy, Department of Pharmacology, Medical Sciences Building, University of Alberta, Edmonton, Alberta, Canada
| | - Claudia Cardinaletti
- Dipartimento di Scienze Chimiche, Università degli Studi di Camerino, via S. Agostino 1, 62032 Camerino, Italy, Dipartimento di Medicina Sperimentale e Sanità Pubblica, Università degli Studi di Camerino, via Madonna delle Carceri, 62032 Camerino, Italy, Department of Pharmacology, Medical Sciences Building, University of Alberta, Edmonton, Alberta, Canada
| | - Cristian Vesprini
- Dipartimento di Scienze Chimiche, Università degli Studi di Camerino, via S. Agostino 1, 62032 Camerino, Italy, Dipartimento di Medicina Sperimentale e Sanità Pubblica, Università degli Studi di Camerino, via Madonna delle Carceri, 62032 Camerino, Italy, Department of Pharmacology, Medical Sciences Building, University of Alberta, Edmonton, Alberta, Canada
| | - Francesca Ghelfi
- Dipartimento di Scienze Chimiche, Università degli Studi di Camerino, via S. Agostino 1, 62032 Camerino, Italy, Dipartimento di Medicina Sperimentale e Sanità Pubblica, Università degli Studi di Camerino, via Madonna delle Carceri, 62032 Camerino, Italy, Department of Pharmacology, Medical Sciences Building, University of Alberta, Edmonton, Alberta, Canada
| | - Aniket Farande
- Dipartimento di Scienze Chimiche, Università degli Studi di Camerino, via S. Agostino 1, 62032 Camerino, Italy, Dipartimento di Medicina Sperimentale e Sanità Pubblica, Università degli Studi di Camerino, via Madonna delle Carceri, 62032 Camerino, Italy, Department of Pharmacology, Medical Sciences Building, University of Alberta, Edmonton, Alberta, Canada
| | - Mario Giannella
- Dipartimento di Scienze Chimiche, Università degli Studi di Camerino, via S. Agostino 1, 62032 Camerino, Italy, Dipartimento di Medicina Sperimentale e Sanità Pubblica, Università degli Studi di Camerino, via Madonna delle Carceri, 62032 Camerino, Italy, Department of Pharmacology, Medical Sciences Building, University of Alberta, Edmonton, Alberta, Canada
| | - Alessandro Piergentili
- Dipartimento di Scienze Chimiche, Università degli Studi di Camerino, via S. Agostino 1, 62032 Camerino, Italy, Dipartimento di Medicina Sperimentale e Sanità Pubblica, Università degli Studi di Camerino, via Madonna delle Carceri, 62032 Camerino, Italy, Department of Pharmacology, Medical Sciences Building, University of Alberta, Edmonton, Alberta, Canada
| | - Wilma Quaglia
- Dipartimento di Scienze Chimiche, Università degli Studi di Camerino, via S. Agostino 1, 62032 Camerino, Italy, Dipartimento di Medicina Sperimentale e Sanità Pubblica, Università degli Studi di Camerino, via Madonna delle Carceri, 62032 Camerino, Italy, Department of Pharmacology, Medical Sciences Building, University of Alberta, Edmonton, Alberta, Canada
| | - Laura Mattioli
- Dipartimento di Scienze Chimiche, Università degli Studi di Camerino, via S. Agostino 1, 62032 Camerino, Italy, Dipartimento di Medicina Sperimentale e Sanità Pubblica, Università degli Studi di Camerino, via Madonna delle Carceri, 62032 Camerino, Italy, Department of Pharmacology, Medical Sciences Building, University of Alberta, Edmonton, Alberta, Canada
| | - Marina Perfumi
- Dipartimento di Scienze Chimiche, Università degli Studi di Camerino, via S. Agostino 1, 62032 Camerino, Italy, Dipartimento di Medicina Sperimentale e Sanità Pubblica, Università degli Studi di Camerino, via Madonna delle Carceri, 62032 Camerino, Italy, Department of Pharmacology, Medical Sciences Building, University of Alberta, Edmonton, Alberta, Canada
| | - Alan Hudson
- Dipartimento di Scienze Chimiche, Università degli Studi di Camerino, via S. Agostino 1, 62032 Camerino, Italy, Dipartimento di Medicina Sperimentale e Sanità Pubblica, Università degli Studi di Camerino, via Madonna delle Carceri, 62032 Camerino, Italy, Department of Pharmacology, Medical Sciences Building, University of Alberta, Edmonton, Alberta, Canada
| | - Maria Pigini
- Dipartimento di Scienze Chimiche, Università degli Studi di Camerino, via S. Agostino 1, 62032 Camerino, Italy, Dipartimento di Medicina Sperimentale e Sanità Pubblica, Università degli Studi di Camerino, via Madonna delle Carceri, 62032 Camerino, Italy, Department of Pharmacology, Medical Sciences Building, University of Alberta, Edmonton, Alberta, Canada
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18
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One-pot synthesis of imidazolines from aldehydes: detailed study about solvents and substrates. Tetrahedron 2007. [DOI: 10.1016/j.tet.2006.11.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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19
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Gentili F, Pizzinat N, Ordener C, Marchal-Victorion S, Maurel A, Hofmann R, Renard P, Delagrange P, Pigini M, Parini A, Giannella M. 3-[5-(4,5-dihydro-1H-imidazol-2-yl)-furan-2-yl]phenylamine (Amifuraline), a promising reversible and selective peripheral MAO-A inhibitor. J Med Chem 2006; 49:5578-86. [PMID: 16942031 DOI: 10.1021/jm060605r] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
On the basis of the observation that the central side effects of MAO inhibitors may represent a major limit for their use in pathological processes involving peripheral MAOs, we investigated the possibility of generating novel inhibitors able to target specifically peripheral MAOs. To address this issue, we designed compounds 7-28. From biological results, the 2-(5-phenyl-furan-2-yl)-4,5-dihydro-1H-imidazole (Furaline, 17) proved to be a suitable lead. In fact, in enzyme assays on homogenate preparation from rat liver and HEK cells expressing MAO-A or MAO-B, compounds possessing the frame of 17 behaved as selective and reversible MAO-A inhibitors. Interestingly, in in vivo studies the amino derivative 21 (Amifuraline), endowed with good hydrophilic character, was able to significantly inhibit liver but not brain MAO-A.
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Affiliation(s)
- Francesco Gentili
- Dipartimento di Scienze Chimiche, Università degli Studi di Camerino, via S. Agostino 1, 62032 Camerino, Italy
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20
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Saczewski F, Tabin P, Tyacke RJ, Maconie A, Saczewski J, Kornicka A, Nutt DJ, Hudson AL. 2-(4,5-Dihydroimidazol-2-yl)benzimidazoles as highly selective imidazoline I2/adrenergic α2 receptor ligands. Bioorg Med Chem 2006; 14:6679-85. [PMID: 16782348 DOI: 10.1016/j.bmc.2006.05.062] [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: 03/05/2006] [Revised: 05/19/2006] [Accepted: 05/31/2006] [Indexed: 11/25/2022]
Abstract
2-(4,5-Dihydroimidazol-2-yl)benzimidazoles have been identified as selective imidazoline I2/alpha2-adrenoceptor ligands. 4-Methyl (2) and 4-chloro (4) derivatives display I2 affinity at nanomolar concentration (Ki=4.4 and 17.7 nM, respectively) and high I2/alpha2 selectivity ratio=4226 and 5649, respectively. An evidence has been obtained that pKa value influences considerably the I2/alpha2-selectivity ratio of this class of imidazoline I2 receptor ligands.
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Affiliation(s)
- Francieszek Saczewski
- Department of Chemical Technology of Drugs, Medical University of Gdańsk, 80-416 Gdańsk, Poland.
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21
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Gentili F, Cardinaletti C, Carrieri A, Ghelfi F, Mattioli L, Perfumi M, Vesprini C, Pigini M. Involvement of I2-imidazoline binding sites in positive and negative morphine analgesia modulatory effects. Eur J Pharmacol 2006; 553:73-81. [PMID: 17081513 DOI: 10.1016/j.ejphar.2006.09.031] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2006] [Revised: 09/05/2006] [Accepted: 09/07/2006] [Indexed: 11/26/2022]
Abstract
Some studies, suggesting the involvement of I(2)-imidazoline binding sites (I(2)-IBS) in morphine analgesia modulation, prompted us to examine on mice antinociceptive assays the effect produced by 1 (phenyzoline), that in view of its high I(2)-IBS affinity and high I(2)-IBS selectivity with regard to I(1)-IBS, alpha(2)-adrenoreceptors and mu-opioid receptors might be considered the first interesting I(2)-IBS ligand. The study was also applied to its ortho phenyl derivative 2 (diphenyzoline), designed and prepared in order to produce a possible modification of the biological profile of 1. Diphenyzoline (2) retains a significant I(2)-IBS selectivity with regard to I(1)-IBS, alpha(2)-adrenoreceptors and mu-opioid receptors. Moreover, by the functional assays 1 and 2 proved inactive at all alpha(2)-adrenoreceptors subtypes up to 10(-3) M. As expected, phenyzoline and diphenyzoline, which are structurally related, highlighted an interesting "positive" or "negative", respectively, morphine analgesia modulatory effect. In fact, 1 (s.c. 10 mg/kg) enhanced morphine analgesia (60% and 40% in mouse tail-flick and mouse hot-plate, respectively), while 2 (s.c. 10 mg/kg) decreased it (-41% and -20%, respectively). The ability to decrease morphine analgesia had never been observed before in I(2)-IBS ligands. These effects were not affected by i.p. treatment of animals with yohimbine (a selective alpha(2)-adrenoreceptor antagonist, 0.625 mg/kg) or efaroxan (an I(1)-IBS/alpha(2)-adrenoreceptor antagonist, 1.0 mg/kg). In contrast, they were completely reversed by i.p. treatment of animals with idazoxan (an I(2)-IBS/alpha(2)-adrenoreceptor antagonist, 2 mg/kg). Moreover, compound 2, in mouse tail-flick test, was able to potentiate by 23% the naloxone-induced decrease of morphine analgesia. Therefore, the results of this study indicate the crucial involvement of I(2)-IBS in the morphine analgesia modulatory effects of 1 and 2.
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Affiliation(s)
- Francesco Gentili
- Dipartimento di Scienze Chimiche, Università degli Studi di Camerino, via S. Agostino 1, 62032 Camerino, Italy
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22
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Mustafa SM, Bavadekar SA, Ma G, Moore BM, Feller DR, Miller DD. Synthesis and biological studies of yohimbine derivatives on human α2C-adrenergic receptors. Bioorg Med Chem Lett 2005; 15:2758-60. [PMID: 15911252 DOI: 10.1016/j.bmcl.2005.03.116] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2005] [Revised: 03/29/2005] [Accepted: 03/30/2005] [Indexed: 11/25/2022]
Abstract
A series of yohimbine derivatives was synthesized and evaluated for binding affinity at the human alpha(2C)-adrenergic receptors expressed in Chinese hamster ovary cells. It has been found that compound 5 shows a higher affinity for alpha(2C)-AR than the parent compound yohimbine 1, thereby illustrating that the nature of the linkers affect binding potencies on these receptors.
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Affiliation(s)
- Suni M Mustafa
- Department of Pharmaceutical Sciences, University of Tennessee, Health Science Center, Memphis, 38163, USA
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23
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Fujioka H, Murai K, Ohba Y, Hiramatsu A, Kita Y. A mild and efficient one-pot synthesis of 2-dihydroimidazoles from aldehydes. Tetrahedron Lett 2005. [DOI: 10.1016/j.tetlet.2005.02.025] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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24
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Dragan U, Stephan S, Jean-Daniel E, Pascal B, Hugues G. LNP 906, the first high-affinity photoaffinity ligand selective for I1 imidazoline receptors. Br J Pharmacol 2005; 142:609-17. [PMID: 15178642 PMCID: PMC1574957 DOI: 10.1038/sj.bjp.0705784] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1 The hypotensive effect of imidazoline-like drugs, such as clonidine, was attributed both to alpha2-adrenergic receptors and nonadrenergic imidazoline receptors, which are divided into I1, I2 and I3 subtypes. 2 We have recently synthesized a derivative of (2-(2-chloro-4-iodo-phenylamino)-5-methyl-pyrroline (LNP 911), the first high-affinity and selective ligand for I1 receptors (I1R), with a photoactivable function (LNP 906). 3 This work aims to test whether this derivative retained the binding properties of LNP 911 and bound irreversibly to I1R. 4 Binding studies showed that LNP 906 exhibited nanomolar affinity for I1R and was selective for I1R over I2 receptors and alpha2-adrenergic receptors (alpha2Ars). 5 Upon exposure to u.v. light, LNP 906 irreversibly blocked the binding of [125I]-paraiodoclonidine (PIC) to I1R, time- and dose-dependently, on PC12 cell membranes and interacted with I1R in a reversible and competitive manner in the absence of light. Pharmacological studies showed that this blockade was prevented by the concomitant presence of rilmenidine (a well-known I1 agonist), but not by rauwolscine (an alpha2 antagonist). 6 Finally, LNP 906 clearly antagonized the decrease in forskolin-stimulated cAMP level induced by rilmenidine, but not by melatonin. 7 These results indicate that LNP 906 is the first high-affinity and selective photoaffinity ligand for I1R and that it behaves as an I1R antagonist.
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Affiliation(s)
- Urosevic Dragan
- Laboratoire de Neurobiologie et Pharmacologie Cardiovasculaire, INSERM E 0333, Faculté de Médecine, Université Louis Pasteur, 11 rue Humann, 67000 Strasbourg, France
| | - Schann Stephan
- Laboratoire de Neurobiologie et Pharmacologie Cardiovasculaire, INSERM E 0333, Faculté de Médecine, Université Louis Pasteur, 11 rue Humann, 67000 Strasbourg, France
| | - Ehrhardt Jean-Daniel
- Laboratoire de Neurobiologie et Pharmacologie Cardiovasculaire, INSERM E 0333, Faculté de Médecine, Université Louis Pasteur, 11 rue Humann, 67000 Strasbourg, France
| | - Bousquet Pascal
- Laboratoire de Neurobiologie et Pharmacologie Cardiovasculaire, INSERM E 0333, Faculté de Médecine, Université Louis Pasteur, 11 rue Humann, 67000 Strasbourg, France
| | - Greney Hugues
- Laboratoire de Neurobiologie et Pharmacologie Cardiovasculaire, INSERM E 0333, Faculté de Médecine, Université Louis Pasteur, 11 rue Humann, 67000 Strasbourg, France
- Author for correspondence:
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25
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Dardonville C, Rozas I. Imidazoline binding sites and their ligands: an overview of the different chemical structures. Med Res Rev 2004; 24:639-61. [PMID: 15224384 DOI: 10.1002/med.20007] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Since Bousquet et al. discovered the imidazoline binding sites (IBS) two decades ago, when they realized that the antihypertensive drug clonidine interacts not only with the alpha2-adrenenoceptors (alpha2-AR) but also with a distinct imidazoline preferring binding site, these receptors have been paid a great deal of attention. At least two subtypes, I1 and I2, have been characterised based on their binding affinity for different radioligands, but their structures still remain unknown. The pharmacological profile of these IBSs has been the objective of several and very thorough reviews. However, a medicinal chemistry overview of the different IBS ligands prepared to date has never been attempted. In this study, we attempt to compile all the different chemical structures reported to date as IBS ligands and classify them in function of their chemical structure and binding affinity for the different IBS subtypes. Thus, we comment on the different endogenous IBS ligands known as well as the drugs described to interact with the I1-IBS which have found application as antihypertensive drugs. Then, we review those compounds described in the literature to interact with the I2-IBS, classifying them by their chemical families (imidazolines, guanidines, 2-aminoimidazolines, beta-carbolines). Finally, some conclusions are drawn.
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26
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Gentili F, Ghelfi F, Giannella M, Piergentili A, Pigini M, Quaglia W, Vesprini C, Crassous PA, Paris H, Carrieri A. α2-Adrenoreceptors Profile Modulation. 2. Biphenyline Analogues as Tools for Selective Activation of the α2C-Subtype. J Med Chem 2004; 47:6160-73. [PMID: 15566287 DOI: 10.1021/jm0408215] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of derivatives structurally related to biphenyline (3) was designed with the aim to modulate selectivity toward the alpha(2)-AR subtypes. The results obtained demonstrated that the presence of a correctly oriented function with positive electronic effect (+sigma) in portion X of the ligands is an important factor for significant alpha(2C)-subtype selectivity (imidazolines 5, 13, 16, and 19). Homology modeling and docking studies support experimental data and highlight the crucial role for the hydrogen bond between the pyridine nitrogen in position 3 of 5 and the NH-indole ring of Trp6.48, which is favorably oriented in the alpha(2C)-subtype, only.
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Affiliation(s)
- Francesco Gentili
- Dipartimento di Scienze Chimiche, Università degli Studi di Camerino, Via S. Agostino 1, 62032 Camerino, Italy
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27
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Sabetkasaie M, Vala S, Khansefid N, Hosseini AR, Sadat Ladgevardi MAR. Clonidine and guanfacine-induced antinociception in visceral pain: possible role of α2/I2 binding sites. Eur J Pharmacol 2004; 501:95-101. [PMID: 15464067 DOI: 10.1016/j.ejphar.2004.08.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2004] [Revised: 07/30/2004] [Accepted: 08/04/2004] [Indexed: 01/15/2023]
Abstract
Visceral pain is one of the most common forms of pain which is poorly understood. We now studied the influence of imidazoline/guanidinium compounds such as clonidine and guanfacine on visceral pain in the presence or absence of yohimbine and benazoline. To produce visceral pain-related behaviours, formalin (10%) was administered by inserting a fine cannula into the colon via the anus. Each experiment took 1 h. Clonidine (0.001, 0.01 and 0.1 mg/kg, i.p.) and guanfacine (2.5, 5 and 10 mg/kg, i.p.) produced analgesia dose dependently. The clonidine response was inhibited by yohimbine (0.2 mg/kg, i.p.). On the other hand, benazoline (5 mg/kg, i.p.) blocked the antinociceptive effect of guanfacine (5 mg/kg). Benazoline (2.5 and 5 mg/kg) itself also induced analgesia in inflammatory colonic pain. In this study, we used morphine to ensure that the behavioural responses were pain-related. Our results showed that morphine (2.5, 5 and 10 mg/kg, s.c.) produced a dose-dependent antinociception. The morphine (7 mg/kg, s.c.) response was reduced by naloxone (2 mg/kg, i.p.). However, we concluded that both imidazoline (I(2)) and alpha(2)-adrenoceptors may play a role in producing analgesia in visceral pain.
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Affiliation(s)
- Masoumeh Sabetkasaie
- Department of Pharmacology and Neuroscience Research Center, School of Medicine, Shaheed Beheshti University of Medical Sciences, P.O. Box 19835-355, Tehran, Iran.
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28
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Glennon RA, Grella B, Tyacke RJ, Lau A, Westaway J, Hudson AL. Binding of an imidazopyridoindole at imidazoline I2 receptors. Bioorg Med Chem Lett 2004; 14:527-9. [PMID: 14698196 DOI: 10.1016/j.bmcl.2003.09.092] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
3,5,6,11-Tetrahydro-2H-imidazo[1',2':1,2]pyrido[3,4-b]indole (10) might be viewed as a fusion structure of two classes of I(2) imidazoline receptor ligands: 2-(2-benzofuranyl)-2-imidazolines and beta-carbolines. Its high affinity (K(i)=7.3 nM) provides insight to how the two classes of agents might bind relative to one another at I(2) receptors.
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Affiliation(s)
- Richard A Glennon
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA 23298, USA.
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29
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Saczewski F, Hudson AL, Tyacke RJ, Nutt DJ, Man J, Tabin P, Saczewski J. 2-(4,5-Dihydro-1H-imidazol-2-yl)indazole (indazim) derivatives as selective I2 imidazoline receptor ligands. Eur J Pharm Sci 2003; 20:201-8. [PMID: 14550886 DOI: 10.1016/s0928-0987(03)00182-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of variously substituted 2-(4,5-dihydro-1H-imidazol-2-yl)indazoles 3a-j and 2-(4,5-dihydro-1H-imidazol-2-yl)-4,5,6,7-tetrahydroindazole 6 were prepared by the regiospecific heteroalkylation of corresponding indazoles 1a-k with 2-chloro-4,5-dihydroimidazole (2). Their affinity to imidazoline I(2) receptors and alpha(2)-adrenergic receptors was determined by radioligand binding assay carried out on P(2) membrane preparations obtained from rat whole brains. 4-Chloro-2-(4,5-dihydro-1H-imidazol-2-yl)indazole (3f, 4-Cl-indazim) showed a 3076-fold difference in affinity for the [(3)H]2BFI-labeled imidazoline I(2) receptors relative to the [(3)H]RX821001-labeled alpha(2)-adrenergic receptors. This highly selective compound should prove to be useful tool in further understanding the functions of the imidazoline I(2) receptors.
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Affiliation(s)
- F Saczewski
- Department of Chemical Technology of Drugs, Medical University of Gdańsk, Al Gen Hallera 107, 80-416 Gdańsk, Poland.
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30
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Roeda D, Hinnen F, Dollé F. Radiosynthesis of a 2-substituted 4,5-dihydro-1H-[2-11C] imidazole: the I2imidazoline receptor ligand [11C] benazoline. J Labelled Comp Radiopharm 2003. [DOI: 10.1002/jlcr.746] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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31
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Gentili F, Bousquet P, Brasili L, Dontenwill M, Feldman J, Ghelfi F, Giannella M, Piergentili A, Quaglia W, Pigini M. Imidazoline binding sites (IBS) profile modulation: key role of the bridge in determining I1-IBS or I2-IBS selectivity within a series of 2-phenoxymethylimidazoline analogues. J Med Chem 2003; 46:2169-76. [PMID: 12747788 DOI: 10.1021/jm021113r] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The alpha- and beta-methyl derivatives of 2-phenylethylimidazoline (compounds 7 and 8) and the corresponding enantiomers were prepared and tested with the purpose of studying the role played by the ethylene bridge in modulating I(1)- and I(2)-IBS selectivity. The alpha-methylation appeared to be extremely critical regarding the affinity and selectivity for the I1-IBS subtypes (I1/I2 = 186 for imidazoline 7) and the stereospecificity of interaction (eudismic ratio (S)-(-)-7/(R)-(+)-7 = 5888). Instead, even if in a more limited fashion, the -methylation tended toward I2-IBS selectivity (I2/I1 = 50 for imidazoline 8). The unsubstituted compound 4 (I2/I1 = 1479) proved to be considerably more potent and selective with respect to I2-IBS subtypes.
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Affiliation(s)
- Francesco Gentili
- Dipartimento di Scienze Chimiche, Università degli Studi di Camerino, via S. Agostino 1, 62032 Camerino, Italy
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32
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Touzeau F, Arrault A, Guillaumet G, Scalbert E, Pfeiffer B, Rettori MC, Renard P, Mérour JY. Synthesis and biological evaluation of new 2-(4,5-dihydro-1H-imidazol-2-yl)-3,4-dihydro-2H-1,4-benzoxazine derivatives. J Med Chem 2003; 46:1962-79. [PMID: 12723959 DOI: 10.1021/jm021050c] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
2-(4,5-Dihydro-1H-imidazol-2-yl)-3,4-dihydro-2H-1,4-benzoxazine derivatives and tricyclic analogues with a fused additional ring on the nitrogen atom of the benzoxazine moiety have been prepared and evaluated for their cardiovascular effects as potential antihypertensive agents. The imidazoline ring was generated by reaction of the corresponding ethyl ester with ethylenediamine. Affinities for imidazoline binding sites (IBS) I(1) and I(2) and alpha(1) and alpha(2) adrenergic receptors were evaluated as well as the effects on mean arterial blood pressure (MAP) and heart rate (HR) of spontaneously hypertensive rats. With few exceptions the most active compounds on MAP were those with high affinities for IBS and alpha(2) receptor. Among these, compound 4h was the most interesting and is now, together with its enantiomers, under complementary pharmacological evaluation.
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MESH Headings
- Adrenal Medulla/metabolism
- Animals
- Antihypertensive Agents/chemical synthesis
- Antihypertensive Agents/chemistry
- Antihypertensive Agents/pharmacology
- Binding Sites
- Blood Pressure/drug effects
- Cattle
- Frontal Lobe/drug effects
- Frontal Lobe/metabolism
- Heart Rate/drug effects
- Imidazoles/chemical synthesis
- Imidazoles/chemistry
- Imidazoles/pharmacology
- Imidazoline Receptors
- In Vitro Techniques
- Kidney/drug effects
- Kidney/metabolism
- Oxazines/chemical synthesis
- Oxazines/chemistry
- Oxazines/pharmacology
- Rabbits
- Radioligand Assay
- Rats
- Rats, Inbred SHR
- Rats, Wistar
- Receptors, Adrenergic, alpha-1/drug effects
- Receptors, Adrenergic, alpha-1/metabolism
- Receptors, Adrenergic, alpha-2/drug effects
- Receptors, Adrenergic, alpha-2/metabolism
- Receptors, Drug/drug effects
- Receptors, Drug/metabolism
- Stereoisomerism
- Structure-Activity Relationship
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Affiliation(s)
- Frédérique Touzeau
- Institut de Chimie Organique et Analytique, UMR-CNRS 6005, BP 6759, Université d'Orléans, 45067 Orléans Cedex 2, France
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33
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Hulme C, Bienaymé H, Nixey T, Chenera B, Jones W, Tempest P, Smith AL. Library Generation via Postcondensation Modifications of Isocyanide-Based Multicomponent Reactions. Methods Enzymol 2003; 369:469-96. [PMID: 14722968 DOI: 10.1016/s0076-6879(03)69024-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Christopher Hulme
- Amgen Inc., Department of Small Molecule Drug Discovery, One Amgen Center Drive, 29-1-B, Thousand Oaks, California 91320, USA
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34
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Dardonville C, Rozas I, Callado LF, Meana JJ. I(2)-imidazoline binding site affinity of a structurally different type of ligands. Bioorg Med Chem 2002; 10:1525-33. [PMID: 11886814 DOI: 10.1016/s0968-0896(01)00420-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Two families of compounds with affinity towards the I(2) imidazoline binding sites are reported. The first is a family of compounds structurally related to agmatine with two guanidine or 2-aminoimidazoline groups at each end of an aliphatic chain of six, eight, nine or 12 methylene groups. Second, and following the model of clonidine, we propose another family of compounds also with two guanidine or 2-aminoimidazoline groups at each end of a chain consisting of two phenyl rings connected by groups such as CH(2), CO, NH and SO(2). The affinity of the compounds towards the I(2) imidazoline binding sites was then evaluated in human brain tissues. In order to determine their pharmacological selectivity versus alpha(2)-adrenoceptors, the affinity for these receptors was also evaluated for the compounds with the highest affinities at I(2) imidazoline binding sites. The results obtained show that many of the compounds exhibit a considerable affinity towards the I(2) imidazoline binding sites. The aliphatic derivatives, in particular, present a very interesting selectivity for the I(2) imidazoline binding sites versus the alpha(2) adrenoceptors. To better understand these findings, mono-guanidinium analogues of the aliphatic derivatives were synthesised and tested showing poor affinity for I(2) imidazoline binding sites. The importance of these results lies in the novelty of the chemical structures studied (dicationic aliphatic compounds particularly) because they are significantly different to those of the I(2) imidazoline binding site ligands reported to date.
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35
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Gentili F, Bousquet P, Brasili L, Caretto M, Carrieri A, Dontenwill M, Giannella M, Marucci G, Perfumi M, Piergentili A, Quaglia W, Rascente C, Pigini M. Alpha2-adrenoreceptors profile modulation and high antinociceptive activity of (S)-(-)-2-[1-(biphenyl-2-yloxy)ethyl]-4,5-dihydro-1H-imidazole. J Med Chem 2002; 45:32-40. [PMID: 11754577 DOI: 10.1021/jm0110082] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A number of derivatives structurally related to cirazoline (1) were synthesized and studied with the purpose of modulating alpha2-adrenoreceptors selectivity versus both alpha1-adrenoreceptors and I2 imidazoline binding sites. The most potent alpha2-agonist was 2-[1-(biphenyl-2-yloxy)ethyl]-4,5-dihydro-1H-imidazole (7), whose key pharmacophoric features closely matched those found in the alpha2-agonist 2-(3-exo-(3-phenylprop-1-yl)-2-exo-norbornyl)amino-2-oxazoline (15). (S)-(-)-7 was the most potent of the two enantiomers, confirming the stereospecificity of the interaction with alpha2-adrenoreceptors. This eutomer was tested on two algesiometric paradigms and, because of the interaction with alpha2-adrenoreceptors, showed a potent and long-lasting antinociceptive activity, since it was abolished by the selective alpha2-antagonist RX821002.
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Affiliation(s)
- Francesco Gentili
- Dipartimento di Scienze Chimiche, Università degli Studi di Camerino, Via S. Agostino 1, 62032 Camerino, Italy
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36
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Bruban V, Feldman J, Greney H, Dontenwill M, Schann S, Jarry C, Payard M, Boutin J, Scalbert E, Pfeiffer B, Renard P, Vanhoutte P, Bousquet P. Respective contributions of alpha-adrenergic and non-adrenergic mechanisms in the hypotensive effect of imidazoline-like drugs. Br J Pharmacol 2001; 133:261-6. [PMID: 11350862 PMCID: PMC1572786 DOI: 10.1038/sj.bjp.0704080] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The hypotensive effect of imidazoline-like drugs, such as clonidine, was first attributed to the exclusive stimulation of central alpha2-adrenoceptors (alpha2ARs). However, a body of evidence suggests that non-adrenergic mechanisms may also account for this hypotension. This work aims (i) to check whether imidazoline-like drugs with no alpha2-adrenergic agonist activity may alter blood pressure (BP) and (ii) to seek a possible interaction between such a drug and an alpha2ARs agonist alpha-methylnoradrenaline (alpha-MNA). We selected S23515 and S23757, two imidazoline-like drugs with negligible affinities and activities at alpha2ARs but with high affinities for non-adrenergic imidazoline binding sites (IBS). S23515 decreased BP dose-dependently (-27+/-5% maximal effect) when administered intracisternally (i.c.) to anaesthetized rabbits. The hypotension induced by S23515 (100 microg kg(-1) i.c.) was prevented by S23757 (1 mg kg(-1) i.c.) and efaroxan (10 microg kg(-1) i.c.), while these compounds, devoid of haemodynamic action by themselves, did not alter the hypotensive effect of alpha-MNA (3 and 30 microg kg(-1) i.c.). Moreover, the alpha2ARs antagonist rauwolscine (3 microg kg(-1) i.c.) did not prevent the effect of S23515. Finally, whilst 3 microg kg(-1) of S23515 or 0.5 microg kg(-1) of alpha-MNA had weak hypotensive effects, the sequential i.c. administration of these two drugs induced a marked hypotension (-23+/-2%). These results indicate that an imidazoline-like drug with no alpha2-adrenergic properties lowers BP and interacts synergistically with an alpha(ARs agonist.
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Affiliation(s)
- Véronique Bruban
- Laboratoire de Neurobiologie et Pharmacologie Cardiovasculaire, Faculté de Médecine, Université Louis Pasteur, 11 rue Humann, 67000 Strasbourg, France
| | - Josiane Feldman
- Laboratoire de Neurobiologie et Pharmacologie Cardiovasculaire, Faculté de Médecine, Université Louis Pasteur, 11 rue Humann, 67000 Strasbourg, France
| | - Hugues Greney
- Laboratoire de Neurobiologie et Pharmacologie Cardiovasculaire, Faculté de Médecine, Université Louis Pasteur, 11 rue Humann, 67000 Strasbourg, France
| | - Monique Dontenwill
- Laboratoire de Neurobiologie et Pharmacologie Cardiovasculaire, Faculté de Médecine, Université Louis Pasteur, 11 rue Humann, 67000 Strasbourg, France
| | - Stephan Schann
- Laboratoire de Neurobiologie et Pharmacologie Cardiovasculaire, Faculté de Médecine, Université Louis Pasteur, 11 rue Humann, 67000 Strasbourg, France
| | - Christian Jarry
- Laboratoire de Chimie Physique, Faculté des Sciences Pharmaceutiques, Université Bordeaux 2, 146 rue Leo Saignat, 33076 Bordeaux cedex, France
| | - Marc Payard
- Laboratoire de Chimie Pharmaceutique, Faculté de Pharmacie, 35 chemin des Maraîchers, 31400 Toulouse, France
| | - Jean Boutin
- Institut de Recherches Internationales Servier, 6 place des Pléiades, 92415 Courbevoie cedex, France
| | - Elizabeth Scalbert
- Institut de Recherches Internationales Servier, 6 place des Pléiades, 92415 Courbevoie cedex, France
| | - Bruno Pfeiffer
- Institut de Recherches Internationales Servier, 6 place des Pléiades, 92415 Courbevoie cedex, France
| | - Pierre Renard
- Institut de Recherches Internationales Servier, 6 place des Pléiades, 92415 Courbevoie cedex, France
| | - Paul Vanhoutte
- Institut de Recherches Internationales Servier, 6 place des Pléiades, 92415 Courbevoie cedex, France
| | - Pascal Bousquet
- Laboratoire de Neurobiologie et Pharmacologie Cardiovasculaire, Faculté de Médecine, Université Louis Pasteur, 11 rue Humann, 67000 Strasbourg, France
- Author for correspondence:
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37
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Schann S, Bruban V, Pompermayer K, Feldman J, Pfeiffer B, Renard P, Scalbert E, Bousquet P, Ehrhardt JD. Synthesis and biological evaluation of pyrrolinic isosteres of rilmenidine. Discovery of cis-/trans-dicyclopropylmethyl-(4,5-dimethyl-4,5-dihydro-3H-pyrrol-2-yl)-amine (LNP 509), an I1 imidazoline receptor selective ligand with hypotensive activity. J Med Chem 2001; 44:1588-93. [PMID: 11334568 DOI: 10.1021/jm001111b] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To find new compounds selective for purported I1 imidazoline receptors (I1Rs) over I2 imidazoline binding sites (I2BS) and alpha2-adrenoceptors (alpha2ARs), a series of pyrrolinic isosteres of rilmenidine has been prepared and their biological activity at I1Rs, I2BS, and alpha2ARs evaluated. This isosteric replacement provided us with compounds which still bound to I1Rs but not to I2BS nor to alpha2ARs. A limited structure-affinity relationship was generated around the heterocyclic moiety of these ligands. One compound in this series, LNP 509 (1e) [cis-/trans-dicyclopropylmethyl-(4,5-dimethyl-4,5-dihydro-3H-pyrrol-2-yl)-amine], had no detectable affinity at alpha2ARs yet was capable of lowering blood pressure after central administration. These pyrrolinic analogues constitute a new chemical class of imidazoline related compounds with high selectivity for the I1Rs. They could be used as new tools in the study of I1Rs and in the conception of new centrally acting hypotensive drugs.
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Affiliation(s)
- S Schann
- Laboratoire de Neurobiologie et Pharmacologie Cardiovasculaire, Université Louis Pasteur, Faculté de Médecine, 11, rue Humann, 67000 Strasbourg, France
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38
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Anastassiadou M, Danoun S, Crane L, Baziard-Mouysset G, Payard M, Caignard DH, Rettori MC, Renard P. Synthesis and pharmacological evaluation of imidazoline sites I1 and I2 selective ligands. Bioorg Med Chem 2001; 9:585-92. [PMID: 11310592 DOI: 10.1016/s0968-0896(00)00280-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Several series of 2-aryl or heterocyclic-imidazoline compounds have been prepared and evaluated in vitro as imidazoline sites (I1 and I2) and alpha-adrenergic (alpha1 and alpha2) receptor ligands. Their pKi values indicate that linkage of the imidazoline moiety at the 2-position with an aromatic substituent dramatically decreases alpha-adrenergic affinity. I1 sites are more accessible by phenyl imidazolines substituted by a methyl or a methoxy group at the ortho or meta position. Indeed, 2-(2'-methoxyphenyl)-imidazoline (17) is one of the best I1 ligands ever reported (pKi = 8.53 and I1/I2 > 3388). On the other hand, I2 selectivity increases in the presence of a methyl group in the para position. The original compound, 2-(3'-fluoro-4'-tolyl)-imidazoline (31) is a new potent ligand for the I2 sites with high selectivity (pKi = 8.53 and I2/I1 > 3388).
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Affiliation(s)
- M Anastassiadou
- Laboratoire de Chimie Pharmaceutique, Université Paul Sabatier, Faculté de Pharmacie 35, Toulouse, France
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39
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Pigini M, Quaglia W, Gentili F, Marucci G, Cantalamessa F, Franchini S, Sorbi C, Brasili L. Structure-activity relationship at alpha-adrenergic receptors within a series of imidazoline analogues of cirazoline. Bioorg Med Chem 2000; 8:883-8. [PMID: 10882000 DOI: 10.1016/s0968-0896(00)00030-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Several analogues of cirazoline (2), a selective alpha1-adrenoreceptor agonist, were prepared and their pharmacological profiles studied. Although at the alpha1-adrenoreceptor all the compounds displayed a significant agonist activity, at the alpha2-adrenoreceptor they showed either agonist or antagonist activity depending on the nature of the phenyl substituent. The qualitative structure-activity relationship led us to the conclusion that the oxygen atom in the side-chain is essential for alpha1-agonist activity, while the cyclopropyl ring is not, and may be replaced by several groups. Of the groups studied, isopropoxy appears to be the best. Instead, the same substitution (i.e., isopropoxy for the cyclopropyl ring) at alpha2-adrenoreceptors causes a reversal of activity. On the other hand, the cyclopropyl ring seems to be important for alpha1-selectivity. Compound 20 is the most potent alpha1-agonist of the series, being equiactive with cirazoline on rat vas deferens and in pithed rat.
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Affiliation(s)
- M Pigini
- Dipartimento di Scienze Chimiche, Università degli Studi di Camerino, Italy
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40
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Polidori C, Gentili F, Pigini M, Quaglia W, Panocka I, Massi M. Hyperphagic effect of novel compounds with high affinity for imidazoline I(2) binding sites. Eur J Pharmacol 2000; 392:41-9. [PMID: 10748271 DOI: 10.1016/s0014-2999(00)00014-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Previous studies have suggested that imidazoline I(2) receptors play a role in feeding control in rats. The effect of subcutaneous (s.c.) injections of four novel imidazoline I(2) ligands, 2-naphthalen-2yl-4,5-dihydro-1H-imidazole hydrochloride (benazoline), 2-styryl-4,5-dihydro-1H-imidazole oxalate (tracizoline), o-nitro-tracizoline and o-methyl-tracizoline (metrazoline) on food intake during the light phase was now evaluated in freely feeding male Wistar rats. Their effect was compared to that of idazoxan, a high-affinity ligand at imidazoline I(2) binding sites, but also a potent alpha(2)-adrenoceptor antagonist. Compared to idazoxan, metrazoline exhibits a higher pK(i) for imidazoline I(2) binding sites in rat liver, while the other compounds have a slightly lower pK(i); on the other hand, the novel compounds have much lower affinity than idazoxan at alpha(2)-adrenoceptors. Idazoxan stimulated drinking at a dose as low as 1 mg/kg, and evoked feeding at a higher dose (30 mg/kg). The selective alpha(2)-adrenoceptor antagonist 2-methoxy-idazoxan (RX821002), with negligible affinity at imidazoline I(2) binding sites, significantly increased drinking but failed to stimulate feeding at doses of 10-50 mg/kg. Metrazoline induced hyperphagia and water drinking at doses of 50 mg/kg or higher. Its dipsogenic effect was secondary to the hyperphagic effect, since it was not observed in rats without access to food. Benazoline significantly increased feeding only in response to 30 mg/kg, but its effect was less pronounced than that of metrazoline. Tracizoline and o-nitro-tracizoline were inactive. Following injection into the lateral cerebroventricle at doses up to 100 microgram/rat, and into the third or fourth brain ventricle at doses up to 50 microgram/rat, neither idazoxan nor metrazoline induced hyperphagia. The present results support the idea that imidazoline I(2) ligands influence feeding in rats, and suggest that their site of action is not in the central nervous system. The finding that idazoxan elicits a more potent hyperphagic effect than metrazoline and benazoline, although its affinity for imidazoline I(2) binding sites is lower than that of metrazoline and similar to that of benazoline, raises the question whether its hyperphagic effect might also be due to interaction with other receptors.
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Affiliation(s)
- C Polidori
- Department of Pharmacological Sciences, University of Camerino, 62032, Camerino, Italy.
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41
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Baurin N, Vangrevelinghe E, Morin-Allory L, Mérour JY, Renard P, Payard M, Guillaumet G, Marot C. 3D-QSAR CoMFA study on imidazolinergic I(2) ligands: a significant model through a combined exploration of structural diversity and methodology. J Med Chem 2000; 43:1109-22. [PMID: 10737743 DOI: 10.1021/jm991124t] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Displaying an unprecedented structural diversity, 119 I(2) ligands, and their pK(i) values, were collected and submitted to a comparative molecular fields analysis (CoMFA) study. They were discerned into three structural subsets (A, B, C), to explore the I(2) 3D-QSARs from finite structural systems (A, B, C) to more complex ones (AB, AC, BC, ABC). In addition, various key steps of the CoMFA methology were explored. The applied method used two pharmacophore templates and seven molecular field combinations (electrostatic, lipophilic, steric), as well as eight alignment methods (two point-by-point and six similarity-based variations). That way, 644 CoMFA models were obtained and further selected according to their predictive ability through two filters. The first filter was mainly based on the q(2), which internally evaluates the predictive ability from the training set. For the second filter, the predictive ability was externally evaluated through the prediction of test sets. Finally, one model was extracted from the whole data as the best. Indeed, it combines three features of upmost importance for the further design of ligands endowed with high I(2) affinity: structural diversity (n = 73), robustness (N = 9, r(2) = 0.96, s = 0. 28, F = 148), and a great fully assessed predictive ability (q(2) = 0.50, r(2)(test set) = 0.81, n(test set) = 46). On the basis of structural data and CoMFA isocontours, some elements of the I(2) tridimensional pharmacophore are also suggested.
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Affiliation(s)
- N Baurin
- Institut de Chimie Organique et Analytique, associé au CNRS, Université d'Orléans, BP-6759, 45067 Orléans Cedex 2, France
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42
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Abstract
The identification of new binding sites raises the problem of defining their role, if any. At times they are shown to be pharmacological receptors, in a strict sense, as they fulfill certain requirements, and a precise physiological role and function, and an endogenous ligand (neurotransmitter) are discovered. At other times, however, neither a clear physiological role nor an endogenous ligand are found, but the term "receptor" is still used, although it may not be a proper one in the conventional pharmacological sense. Furthermore, no clear intracellular signalling transduction pathway is defined and, as a consequence, it is not possible to determine whether drugs binding to these receptors act as agonists or antagonists. What their structure and biological function are and how they mediate the pharmacological effects of ligands may remain for a long time an enigma. The matter, in any case, is of great interest to researchers of different areas, especially to medicinal chemists who foresee novel potential targets for therapeutic interventions. In this meeting one section is dedicated to two examples of this kind of receptors: imidazoline (I) and sigma (sigma) receptors.
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Affiliation(s)
- L Brasili
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Modena, Italy
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43
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Hulme C, Ma L, Kumar N, Krolikowski PH, Allen AC, Labaudiniere R. Novel applications of resin bound α-amino acids for the synthesis of benzodiazepines (via Wang resin) and ketopiperazines (via hydroxymethyl resin). Tetrahedron Lett 2000. [DOI: 10.1016/s0040-4039(99)02326-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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44
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Hulme C, Ma L, Romano J, Morrissette M. Remarkable three-step-one-pot solution phase preparation of novel imidazolines utilizing a UDC (Ugi/de-Boc/cyclize) strategy. Tetrahedron Lett 1999. [DOI: 10.1016/s0040-4039(99)01580-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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45
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Quaglia W, Bousquet P, Pigini M, Carotti A, Carrieri A, Dontenwill M, Gentili F, Giannella M, Maranca F, Piergentili A, Brasili L. 2-(2-Phenylcyclopropyl)imidazolines: reversed enantioselective interaction at I(1) and I(2) imidazoline receptors. J Med Chem 1999; 42:2737-40. [PMID: 10425083 DOI: 10.1021/jm991049m] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- W Quaglia
- Dipartimento di Scienze Chimiche, Università di Camerino, Via S. Agostino 1, 62032 Camerino, Italy
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46
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Farsang C, Kapocsi J. Imidazoline receptors: from discovery to antihypertensive therapy (facts and doubts). Brain Res Bull 1999; 49:317-31. [PMID: 10452352 DOI: 10.1016/s0361-9230(99)00057-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The hypothesis and indirect evidence of imidazoline receptors has been promoted since some 15 years ago and it gave a substantial impetus for research in this field, resulting in a better understanding of neuronal and cardiovascular regulatory processes. The nomenclature of the imidazoline receptors has been accepted by international forums but no direct proof for the existence of these receptors has been published. Authors summarise the most important available data, including facts and doubts as far as the discovery, characterisation, and function of imidazoline receptors and their subtypes, the differences between imidazoline receptors and alpha-2 adrenoceptors, and also on their participation in regulatory processes.
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Affiliation(s)
- C Farsang
- First Department of Internal Medicine, St. Imre Teaching Hospital, Budapest, Hungary
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Pigini M, Bousquet P, Brasili L, Carrieri A, Cavagna R, Dontenwill M, Gentili F, Giannella M, Leonetti F, Piergentili A, Quaglia W, Carotti A. Ligand binding to I2 imidazoline receptor: the role of lipophilicity in quantitative structure-activity relationship models. Bioorg Med Chem 1998; 6:2245-60. [PMID: 9925287 DOI: 10.1016/s0968-0896(98)80005-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A series of 2-trans-styryl-imidazoline (tracizoline) congeners were designed and tested to develop 2-D and 3-D QSAR models for their binding to imidazoline (I2) receptor. The important role of lipophilicity was assessed by classical 2-D QSAR study (Hansch approach) and by comparative molecular field analysis (CoMFA) with the inclusion of the molecular lipophilicity potential (MLP), as an additional descriptor, besides standard steric and electrostatic fields. Results from these studies were compared to those obtained in a previous modeling study of I2 receptor ligands and integrated into a new, comprehensive model, based on about sixty I2 receptor ligands. This model revealed, at the three-dimensional level, the most significant steric, electrostatic, and lipophilic interactions accounting for high I2 receptor affinity.
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Affiliation(s)
- M Pigini
- Dipartimento di Scienze Chimiche, Università di Camerino, MC, Italy
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King PR, Suzuki S, Hosseini AR, Iakovidis D, Nero TL, Jackman GP, Louis WJ, Gundlach AL. [3H]Rilmenidine-labelled imidazoline-receptor binding sites co-localize with [3H]2-(benzofuranyl)-2-imidazoline-labelled imidazoline-receptor binding sites and monoamine oxidase-B in rabbit, but not rat, kidney. JOURNAL OF THE AUTONOMIC NERVOUS SYSTEM 1998; 72:118-28. [PMID: 9851560 DOI: 10.1016/s0165-1838(98)00096-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The distribution and relative densities of imidazoline-receptor binding sites (I-RBS) and monoamine oxidase (MAO)-A and -B enzyme(s) in rat and rabbit kidney were compared autoradiographically using fixed nanomolar concentrations of [3H]rilmenidine and [3H]2-(benzofuranyl)-2-imidazoline ([3H]2-BFI) to label I-RBS, and [3H]RO41-1049 and [3H]RO19-6327 to label MAO-A and -B isoenzymes, respectively. In rat kidney, high densities of I-RBS labelled by [3H]rilmenidine were observed in the cortex and outer stripe (120-280 fmol/mg tissue), in contrast to low I-RBS densities labelled by [3H]2-BFI (<4 fmol/mg). A relatively high density of [3H]RO41-1049 binding to MAO-A enzyme was present in all regions of the rat kidney (160-210 fmol/mg) compared with a low density of [3H]RO19-6327 binding to MAO-B (< 25 fmol/mg). Comparison of MAO-A and -B distributions with that of [3H]rilmenidine-labelled I-RBS strongly suggests a lack of association in rat kidney. Similarly, the extremely low densities of [3H]2-BFI-labelled I2-RBS in rat kidney contrasts with the density of MAO-A, but is consistent with the low density of MAO-B. Rabbit kidney cortex and outer stripe contained high relative densities of [3H]rilmenidine-labelled I-RBS (200-215 fmol/mg) and [3H]2-BFI-labelled I2-RBS (45-60 fmol/mg) with lower densities in the inner stripe and inner medulla (< or = 100 and 30 fmol/mg respectively). A high density of MAO-A binding was observed in the inner stripe (515 fmol/mg) with lower levels in the cortex and outer stripe (100-240 fmol/mg), while high densities of MAO-B binding were observed in the cortex and outer stripe (290-450 fmol/mg) with lower levels in the inner stripe (65 fmol/mg). The correlation between the localization of [3H]rilmenidine-labelled I-RBS and [3H]RO19-6327-labelled MAO-B in rabbit kidney (r = 0.87, P = 0.057) suggest that [3H]rilmenidine may label a binding site co-existent with MAO-B, but not MAO-A (n.s.), in this tissue, but rilmenidine did not inhibit [3H]RO41-1049 or [3H]RO19-6327 binding. The distribution of [3H]2-BFI-labelled I2-RBS overlapped the combined distributions of both MAO-A and -B isoenzymes, suggesting that [3H]2-BFI may label sites on both enzymes in the rabbit, but [3H]2-BFI binding only correlated with [3H]RO19-6327 (r = 0.84, P = 0.07), not [3H]RO41-1049 binding (n.s.). Moreover, 2-BFI only inhibited [3H]RO19-6327, not [3H]RO41-1049 binding. These data are consistent with reports that I2-RBS are located on MAO-B and allosterically influence the catalytic site. The relationship of [3H]rilmenidine- and [3H]2-BFI-labelled I-RBS and the identity of non-MAO-associated [3H]rilmenidine-labelled I-RBS requires further investigation.
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Affiliation(s)
- P R King
- The University of Melbourne, Department of Medicine, Austin and Repatriation Medical Centre, Heidelberg, Victoria, Australia.
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Kaul PN. Drug discovery: past, present and future. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 1998; 50:9-105. [PMID: 9670776 DOI: 10.1007/978-3-0348-8833-2_1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
New drug discovery from early on involved a trial-and-error approach on naturally derived materials and substances until the end of the nineteenth century. The first half of the twentieth century witnessed systematic pharmacological evaluations of both natural and synthetic compounds. However, most new drugs until the 1970s were discovered by serendipity. With the exponential development of molecular biology on one hand and computer technology on the other, it became possible from 1980 onwards to place drug discovery on a rational basis. Cloning of genes has led to the development of methodologies for specific receptor-directed and enzyme-directed drug discoveries. Advances in recombinant DNA and transgenic technologies have enabled the production of human hormonal and other endogenous biomolecules as new drugs. As we understand more about the co-ordinating and regulating powers of the cerebral cortex during the next century, especially of the frontal lobe, man may be able to use bio-feedback training to voluntarily regulate the release of neurotransmitters, hormones, and other molecules involved in the regulation of various physiological processes in health as well as in disease.
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Affiliation(s)
- P N Kaul
- Clark Atlanta University, GA 30314, USA
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