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Bondarenko SP, Podobii EV, Frasinyuk MS, Vinogradova VI, Khilya VP. Synthesis of Flavonoid Derivatives of Cytisine. 4. Synthesis of 3-aryl-7-[2-(cytisin-12-yl)ethoxy]Coumarins. Chem Nat Compd 2014. [DOI: 10.1007/s10600-014-0975-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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52
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Jasiewicz B, Malczewska-Jaskóła K, Kowalczyk I, Warżajtis B, Rychlewska U. Chalcogen analogues of nicotine lactam studied by NMR, FTIR, DFT and X-ray methods. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2014; 128:773-780. [PMID: 24699296 DOI: 10.1016/j.saa.2014.02.158] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 02/19/2014] [Accepted: 02/21/2014] [Indexed: 06/03/2023]
Abstract
The selenoanalogue of nicotine has been synthesized and characterized by spectroscopic and X-ray diffraction methods. The crystals of selenonicotine are isomorphic with the thionicotine homologue and consist of molecules engaged in columnar π⋯π stacking interactions between antiparallely arranged pyridine moieties. These interactions, absent in other crystals containing nicotine fragments, seem to be induced by the presence of a lactam group. The molecular structures in the vacuum of the oxo-, thio- and selenonicotine homologues have been calculated by the DFT method and compared with the available X-ray data. The delocalized structure of thionicotine is stabilized by intramolecular C-H⋯S hydrogen bond, which becomes weaker in the partial zwitterionic resonance structure of selenonicotine in favor of multiple C-H⋯Se intermolecular hydrogen-bonds. The calculated data allow a complete assignment of vibration modes in the solid state FTIR spectra. The (1)H and (13)C NMR chemical shifts were calculated by the GIAO method with B3LYP/6-311G(3df) level. A comparison between experimental and calculated theoretical results indicates that the density functional B3LYP method provided satisfactory results for predicting FTIR, (1)H, (13)C NMR spectra properties.
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Affiliation(s)
- Beata Jasiewicz
- Faculty of Chemistry, A. Mickiewicz University, Umultowska 89b, 61-614 Poznań, Poland.
| | | | - Iwona Kowalczyk
- Faculty of Chemistry, A. Mickiewicz University, Umultowska 89b, 61-614 Poznań, Poland.
| | - Beata Warżajtis
- Faculty of Chemistry, A. Mickiewicz University, Umultowska 89b, 61-614 Poznań, Poland
| | - Urszula Rychlewska
- Faculty of Chemistry, A. Mickiewicz University, Umultowska 89b, 61-614 Poznań, Poland.
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53
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Xia L, Idhayadhulla A, Lee YR, Kim SH, Wee YJ. Microwave-assisted synthesis of diverse pyrrolo[3,4-c]quinoline-1,3-diones and their antibacterial activities. ACS COMBINATORIAL SCIENCE 2014; 16:333-41. [PMID: 24749663 DOI: 10.1021/co500002s] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
With the aim of developing a general and practical method for library production, a novel and efficient two-phase microwave-assisted cascade reaction between isatins and β-ketoamides in [Bmim]BF4/toluene was developed for the synthesis of pyrrolo[3,4-c]quinoline-1,3-diones. The features of this methodology are, the use of microwave-assisted rapid synthesis, mild reaction conditions, high yields, operational simplicity, facile product separation, and recyclability. Furthermore, the antibacterial activities of the pyrrolo[3,4-c]quinoline-1,3-dione derivatives produced were evaluated against Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, and Enterobacter aerogenes) and Gram-positive bacteria (Bacillus cereus and Staphylococcus aureus). These derivatives showed antibacterial activities against Gram-positive strains that were at least equivalent to that against Gram-negative strains. Compound 7{3,5} displayed the most potent antibacterial activity against P. aeruginosa (MIC = 0.5 μg/mL) and greater activity than standard ampicillin (MIC = 1 μg/mL). Compound 7{4,7} exhibited the best inhibitory activity against E. coli and E. aerogenes (MIC = 1 and 0.5 μg/mL), compared with the standard ampicillin (both MICs = 1 μg/mL). The synthesized pyrrolo[3,4-c]quinoline-1,3-diones are expected to be widely used as lead compounds for the development of new antibacterial agents.
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Affiliation(s)
- Likai Xia
- School
of Chemical Engineering, Yeungnam University, Gyeongsan 712-749, Republic of Korea
| | - Akber Idhayadhulla
- School
of Chemical Engineering, Yeungnam University, Gyeongsan 712-749, Republic of Korea
| | - Yong Rok Lee
- School
of Chemical Engineering, Yeungnam University, Gyeongsan 712-749, Republic of Korea
| | - Sung Hong Kim
- Analysis
Research Division, Daegu Center, Korea Basic Science Institute, Daegu 702-701, Republic of Korea
| | - Young-Jung Wee
- Department
of Food Science and Technology, Yeungnam University, Gyeongsan 712-749, Republic of Korea
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54
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Yoshida T, Farone WA, Xantheas SS. Isomers and conformational barriers of gas-phase nicotine, nornicotine, and their protonated forms. J Phys Chem B 2014; 118:8273-85. [PMID: 24654683 DOI: 10.1021/jp501646p] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report extensive conformational searches of the gas-phase neutral nicotine, nornicotine, and their protonated analogs and the pathways and barriers for the interconversion between their various isomers that are based on ab initio second-order Møller-Plesset perturbation (MP2) electronic structure calculations. Initial searches were performed with the 6-31G(d,p), and the energetics of the most important structures were further refined from geometry optimizations with the larger aug-cc-pVTZ basis set. On the basis of the calculated free energies at T = 298 K for the gas-phase molecules, neutral nicotine has two dominant trans conformers, whereas neutral nornicotine is a mixture of several conformers. For nicotine, the protonation on both the pyridine and the pyrrolidine sites is energetically competitive, whereas nornicotine prefers protonation on the pyridine nitrogen. The protonated form of nicotine is mainly a mixture of two pyridine-protonated trans conformers and two pyrrolidine-protonated trans conformers, whereas the protonated form of nornicotine is a mixture of four pyridine-protonated trans conformers. Nornicotine is conformationally more flexible than nicotine; however, it is less protonated at the biologically important pyrrolidine nitrogen site. The lowest energy isomers for each case were found to interconvert via low (<6 kcal/mol) rotational barriers around the pyridine-pyrrolidine bond. These barriers are much lower than previous estimates based on lower levels of theory obtained without relaxation of the structure along the path. Nicotine was found to bind more strongly to tryptophan (Trp) than nornicotine, a finding that is consistent with nicotine's enhanced affinity in the nicotinic acetylcholide receptor.
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Affiliation(s)
- Tomoki Yoshida
- Center for Quantum Life Sciences and Department of Chemistry, Graduate School of Science, Hiroshima University , 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan
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55
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Jasiewicz B, Mrówczyńska L, Malczewska-Jaskóła K. Synthesis and haemolytic activity of novel salts made of nicotine alkaloids and bile acids. Bioorg Med Chem Lett 2014; 24:1104-7. [PMID: 24461290 DOI: 10.1016/j.bmcl.2014.01.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 01/03/2014] [Accepted: 01/05/2014] [Indexed: 11/18/2022]
Abstract
A series of novel salts made of nicotine alkaloids and bile acids were synthesized and their haemolytic activity was examined in vitro using human erythrocytes. All compounds were characterized by spectroscopic methods. The novel salts show membrane-perturbing properties inducing the erythrocyte shape alterations and haemolysis in dose-dependent manner. Nicotine decreases the membrane interacting potential of bile acids in the novel compounds. The presence of sulfur or selenium atom in the nicotine molecule affects the haemolytic activity of its novel salts depending on the hydrophobicity of bile acids.
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Affiliation(s)
- Beata Jasiewicz
- Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznań, Poland.
| | - Lucyna Mrówczyńska
- Department of Cell Biology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland.
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Autonomic Nervous System Mediates the Hypotensive Effects of Aqueous and Residual Methanolic Extracts of Syzygium polyanthum (Wight) Walp. var. polyanthum Leaves in Anaesthetized Rats. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:716532. [PMID: 24454508 PMCID: PMC3878421 DOI: 10.1155/2013/716532] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 10/22/2013] [Accepted: 10/30/2013] [Indexed: 11/21/2022]
Abstract
Syzygium polyanthum (Wight) Walp. var. polyanthum leaves are consumed as a traditional Malay treatment of hypertension. This study investigates hypotensive potential of aqueous (AESP) and residual methanolic (met-AESP) extracts of S. polyanthum leaves and possible involvement of autonomic receptors. AESP and met-AESP (20 to 100 mg/kg) were intravenously administered into anaesthetized Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats. Blood pressure and heart were monitored for 20 min. AESP and met-AESP induced significant dose-dependent hypotension, but only 100 mg/kg AESP caused mild bradycardia (n = 5). AESP-induced hypotension was more potent than that of met-AESP in WKY. AESP has a faster onset time than that of met-AESP in both WKY and SHR. However, met-AESP-induced hypotension was more sustained than that of AESP in SHR. Blockages of autonomic ganglion and α-adrenergic receptors using hexamethonium and phentolamine (n = 5 for each group) partially attenuated AESP-induced hypotension, suggesting involvement of α-adrenergic receptors. Blockages of autonomic ganglion, β-adrenergic, cholinergic receptors, and nitric oxide production using hexamethonium, propranolol, atropine, and N-ω-nitro-l arginine methyl ester (L-NAME) (n = 5 for each group) partially attenuated met-AESP-induced hypotension, suggesting involvement of β-adrenergic and cholinergic receptors via nitric oxide production.
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Rouden J, Lasne MC, Blanchet J, Baudoux J. (−)-Cytisine and Derivatives: Synthesis, Reactivity, and Applications. Chem Rev 2013; 114:712-78. [DOI: 10.1021/cr400307e] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Jacques Rouden
- Laboratoire de Chimie Moléculaire
et Thioorganique, ENSICAEN-Université de Caen, CNRS, Institut Normand de Chimie Moléculaire, Médicinale et Macromoléculaire (INC3M), 6 Boulevard du Maréchal Juin, 14050 Caen, France
| | - Marie-Claire Lasne
- Laboratoire de Chimie Moléculaire
et Thioorganique, ENSICAEN-Université de Caen, CNRS, Institut Normand de Chimie Moléculaire, Médicinale et Macromoléculaire (INC3M), 6 Boulevard du Maréchal Juin, 14050 Caen, France
| | - Jérôme Blanchet
- Laboratoire de Chimie Moléculaire
et Thioorganique, ENSICAEN-Université de Caen, CNRS, Institut Normand de Chimie Moléculaire, Médicinale et Macromoléculaire (INC3M), 6 Boulevard du Maréchal Juin, 14050 Caen, France
| | - Jérôme Baudoux
- Laboratoire de Chimie Moléculaire
et Thioorganique, ENSICAEN-Université de Caen, CNRS, Institut Normand de Chimie Moléculaire, Médicinale et Macromoléculaire (INC3M), 6 Boulevard du Maréchal Juin, 14050 Caen, France
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Wong DF, Kuwabara H, Kim J, Brasic JR, Chamroonrat W, Gao Y, Valentine H, Willis W, Mathur A, McCaul ME, Wand G, Gean EG, Dannals RF, Horti AG. PET imaging of high-affinity α4β2 nicotinic acetylcholine receptors in humans with 18F-AZAN, a radioligand with optimal brain kinetics. J Nucl Med 2013; 54:1308-14. [PMID: 23801676 DOI: 10.2967/jnumed.112.108001] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED We evaluated (-)-2-(6-[(18)F]fluoro-2,3'-bipyridin-5'-yl)-7-methyl-7-aza-bicyclo[2.2.1]heptane ((18)F-AZAN), a novel radiotracer that binds to α4β2 nicotinic acetylcholine receptors (α4β2-nAChRs) and shows high specific binding and rapid and reversible kinetics in the baboon and human brain. METHODS We tested safety tolerability and test-retest reliability (n = 5) and proposed initial quantification of (18)F-AZAN receptors in 3 healthy human subjects who had nicotine exposure and 9 who did not. We also present a receptor blocking study in a nicotine subject dosed with the α4β2-nAChR-selective partial agonist varenicline. RESULTS Radiation dosimetry PET/CT experiments indicated that most human organs received doses between 0.008 and 0.015 mSv/MBq, with an effective dose of approximately 0.014 mSv/MBq. The tracer rapidly entered the brain, and the peak was reached before 20 min, even for thalamus. Ninety-minute scans were sufficient for (18)F-AZAN to obtain the ratio at equilibrium of specifically bound radioligand to nondisplaceable radioligand in tissue (BPND) using plasma reference graphical analysis, which showed excellent reproducibility of BPND (test-retest variability < 10%) in the nAChR-rich brain regions. Regional plasma reference graphical analysis BP(ND) values exceeded 2 in the midbrain tegmental nuclei, lateral geniculate body, and thalamus for nonsmokers (n = 9) but were less than 1 in the nAChR-poor brain regions. There was a dramatic reduction of (18)F-AZAN brain uptake in smokers and varenicline-treated subjects. CONCLUSION (18)F-AZAN is a highly specific, safe, and effective PET radioligand for human subjects that requires only 90 min of PET scanning to estimate high-affinity α4β2-nAChR in the living human brain.
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Affiliation(s)
- Dean F Wong
- Department of Radiology, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.
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59
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Johnston TH, Huot P, Fox SH, Koprich JB, Szeliga KT, James JW, Graef JD, Letchworth SR, Jordan KG, Hill MP, Brotchie JM. TC-8831, a nicotinic acetylcholine receptor agonist, reduces L-DOPA-induced dyskinesia in the MPTP macaque. Neuropharmacology 2013; 73:337-47. [PMID: 23770260 DOI: 10.1016/j.neuropharm.2013.06.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 05/25/2013] [Accepted: 06/04/2013] [Indexed: 11/29/2022]
Abstract
Long-term L-DOPA treatment for Parkinson's disease (PD) is limited by motor complications, particularly L-DOPA-induced dyskinesia (LID). A therapy with the ability to ameliorate LID without reducing anti-parkinsonian benefit would be of great value. We assessed the ability of TC-8831, an agonist at nicotinic acetylcholine receptors (nAChR) containing α6β2/α4β2 subunit combinations, to provide such benefits in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine- (MPTP) lesioned macaques with established LID. Animals were treated orally for consecutive 14-day periods with twice-daily vehicle (weeks 1-2) or TC-8831 (0.03, 0.1 or 0.3 mg/kg, weeks 3-8). L-DOPA was also administered, once-daily, (weeks 1-12, median-dose 30 mg/kg, p.o.). For the following two-weeks (weeks 9-10), TC-8831 was washed out, while once-daily L-DOPA treatment was maintained. The effects of once-daily amantadine (3 mg/kg, p.o.) were then assessed over weeks 11-12. LID, parkinsonism, duration and quality of ON-time were assessed weekly by a neurologist blinded to treatment. TC-8831 reduced the duration of 'bad' ON-time (ON-time with disabling dyskinesia) by up to 62% and decreased LID severity (median score 18 cf. 34 (vehicle), 0.1 mg/kg, 1-3 h period). TC-8831 also significantly reduced choreiform and dystonic dyskinesia (median scores 6 and 31 cf. 19 and 31 respectively (vehicle), both 0.03 mg/kg, 1-3 h). At no time did TC-8831 treatment result in a reduction in anti-parkinsonian benefit of L-DOPA. By comparison, amantadine also significantly reduced dyskinesia and decreased 'bad' ON-time (up to 61%) but at the expense of total ON-time (reduced by up to 23%). TC-8831 displayed robust anti-dyskinetic actions and improved the quality of ON-time evoked by L-DOPA without any reduction in anti-parkinsonian benefit.
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Affiliation(s)
- Tom H Johnston
- Toronto Western Research Institute, Toronto Western Hospital, University Health Network, Toronto, ON, Canada
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60
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Armanino N, Carreira EM. Ruthenium-Catalyzed Intramolecular Hydrocarbamoylation of Allylic Formamides: Convenient Access to Chiral Pyrrolidones. J Am Chem Soc 2013; 135:6814-7. [DOI: 10.1021/ja4026787] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Nicolas Armanino
- Laboratorium für
Organische Chemie, ETH Zürich, CH-8093
Zürich, Switzerland
| | - Erick M. Carreira
- Laboratorium für
Organische Chemie, ETH Zürich, CH-8093
Zürich, Switzerland
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61
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Horti AG, Kuwabara H, Holt DP, Dannals RF, Wong DF. Recent PET radioligands with optimal brain kinetics for imaging nicotinic acetylcholine receptors. J Labelled Comp Radiopharm 2013; 56:159-66. [DOI: 10.1002/jlcr.3020] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 11/27/2012] [Accepted: 12/07/2012] [Indexed: 01/28/2023]
Affiliation(s)
- Andrew G. Horti
- Division of Nuclear Medicine, Department of Radiology; Johns Hopkins University; Baltimore; MD; USA
| | - Hiroto Kuwabara
- Division of Nuclear Medicine, Department of Radiology; Johns Hopkins University; Baltimore; MD; USA
| | - Daniel P. Holt
- Division of Nuclear Medicine, Department of Radiology; Johns Hopkins University; Baltimore; MD; USA
| | - Robert F. Dannals
- Division of Nuclear Medicine, Department of Radiology; Johns Hopkins University; Baltimore; MD; USA
| | - Dean F. Wong
- Division of Nuclear Medicine, Department of Radiology; Johns Hopkins University; Baltimore; MD; USA
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62
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Wang J, Li X, Yuan Q, Ren J, Huang J, Zeng B. Synthesis and Pharmacological Properties of 5-Alkyl Substituted Nicotine Analogs. CHINESE J CHEM 2012. [DOI: 10.1002/cjoc.201200952] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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63
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Strachan JP, Farias JJ, Zhang J, Caldwell WS, Bhatti BS. Diazaspirocyclic compounds as selective ligands for the α4β2 nicotinic acetylcholine receptor. Bioorg Med Chem Lett 2012; 22:5089-92. [DOI: 10.1016/j.bmcl.2012.05.108] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 05/24/2012] [Accepted: 05/29/2012] [Indexed: 11/16/2022]
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64
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Barbacci D, Jackson SN, Muller L, Egan T, Lewis EK, Schultz JA, Woods AS. Cellular membrane phospholipids act as a depository for quaternary amine containing drugs thus competing with the acetylcholine/nicotinic receptor. J Proteome Res 2012; 11:3382-9. [PMID: 22506649 PMCID: PMC4144022 DOI: 10.1021/pr300184g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We previously demonstrated that ammonium- or guanidinium-phosphate interactions are key to forming noncovalent complexes (NCXs) through salt bridge formation with G-protein coupled receptors (GPCR), which are immersed in the cell membrane's lipids. The present work highlights MALDI ion mobility coupled to orthogonal time-of-flight mass spectrometry (MALDI IM oTOF MS) as a method to determine qualitative and relative quantitative affinity of drugs to form NCXs with targeted GPCRs' epitopes in a model system using, bis-quaternary amine based drugs, α- and β- subunit epitopes of the nicotinic acetylcholine receptor' (nAChR) and phospholipids. Bis-quaternary amines proved to have a strong affinity for all nAChR epitopes and negatively charged phospholipids, even in the presence of the physiological neurotransmitter acetylcholine. Ion mobility baseline separated isobaric phosphatidyl ethanolamine and a matrix cluster, providing an accurate estimate for phospholipid counts. Overall this technique is a powerful method for screening drugs' interactions with targeted lipids and protein respectively containing quaternary amines and guanidinium moieties.
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Affiliation(s)
- Damon Barbacci
- Integrative Neuroscience, NIDA IRP, NIH, Baltimore, MD 21224, USA
- Ionwerks Inc., Houston, Texas, 77002, USA
| | | | - Ludovic Muller
- Integrative Neuroscience, NIDA IRP, NIH, Baltimore, MD 21224, USA
| | | | | | | | - Amina S. Woods
- Integrative Neuroscience, NIDA IRP, NIH, Baltimore, MD 21224, USA
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Pujeri SS, Khader AMA, Seetharamappa J. Stress degradation studies on varenicline tartrate and development of a validated stability-indicating HPLC method. Sci Pharm 2012; 80:115-26. [PMID: 22396908 PMCID: PMC3293356 DOI: 10.3797/scipharm.1109-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2011] [Accepted: 12/05/2011] [Indexed: 11/22/2022] Open
Abstract
A simple, rapid and stability-indicating reversed-phase liquid chromatographic method was developed for the assay of varenicline tartrate (VRT) in the presence of its degradation products generated from forced decomposition studies. The HPLC separation was achieved on a C18 Inertsil column (250 mm × 4.6 mm i.d. particle size is 5 μm) employing a mobile phase consisting of ammonium acetate buffer containing trifluoroacetic acid (0.02M; pH 4) and acetonitrile in gradient program mode with a flow rate of 1.0 mL min(-1). The UV detector was operated at 237 nm while column temperature was maintained at 40 °C. The developed method was validated as per ICH guidelines with respect to specificity, linearity, precision, accuracy, robustness and limit of quantification. The method was found to be simple, specific, precise and accurate. Selectivity of the proposed method was validated by subjecting the stock solution of VRT to acidic, basic, photolysis, oxidative and thermal degradation. The calibration curve was found to be linear in the concentration range of 0.1-192 μg mL(-1) (R(2) = 0.9994). The peaks of degradation products did not interfere with that of pure VRT. The utility of the developed method was examined by analyzing the tablets containing VRT. The results of analysis were subjected to statistical analysis.
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Affiliation(s)
- Sudhakar S Pujeri
- Department of Chemistry, Mangalore University, Mangalagangotri, India
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66
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Ho YS, Lee CH, Wu CH. The Alpha 9-Nicotinic Acetylcholine Receptor Serves as a Molecular Target for Breast Cancer Therapy. ACTA ACUST UNITED AC 2011. [DOI: 10.1016/j.jecm.2011.10.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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67
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Kroker KS, Rast G, Rosenbrock H. Differential effects of subtype-specific nicotinic acetylcholine receptor agonists on early and late hippocampal LTP. Eur J Pharmacol 2011; 671:26-32. [PMID: 21968142 DOI: 10.1016/j.ejphar.2011.09.167] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 09/13/2011] [Accepted: 09/15/2011] [Indexed: 01/14/2023]
Abstract
Brain nicotinic acetylcholine receptors are involved in several neuropsychiatric disorders, e.g. Alzheimer's and Parkinson's diseases, Tourette's syndrome, schizophrenia, depression, autism, attention deficit hyperactivity disorder, and anxiety. Currently, approaches selectively targeting the activation of specific nicotinic acetylcholine receptors are in clinical development for treatment of memory impairment of Alzheimer's disease patients. These are α4β2 and α7 nicotinic acetylcholine receptor agonists which are believed to enhance cholinergic and glutamatergic neurotransmission, respectively. In order to gain a better insight into the mechanistic role of these two nicotinic acetylcholine receptors in learning and memory, we investigated the effects of the α4β2 nicotinic acetylcholine receptor agonist TC-1827 and the α7 nicotinic acetylcholine receptor partial agonist SSR180711 on hippocampal long-term potentiation (LTP), a widely accepted cellular experimental model of memory formation. Generally, LTP is distinguished in an early and a late form, the former being protein-synthesis independent and the latter being protein-synthesis dependent. TC-1827 was found to increase early LTP in a bell-shaped dose dependent manner, but did not affect late LTP. In contrast, the α7 nicotinic acetylcholine receptor partial agonist SSR180711 showed enhancing effects on both early and late LTP in a bell-shaped manner. Furthermore, SSR180711 not only increased early LTP, but also transformed it into late LTP, which was not observed with the α4β2 nicotinic acetylcholine receptor agonist. Therefore, based on these findings α7 nicotinic acetylcholine receptor (partial) agonists appear to exhibit stronger efficacy on memory improvement than α4β2 nicotinic acetylcholine receptor agonists.
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Affiliation(s)
- Katja S Kroker
- Boehringer Ingelheim Pharma GmbH & Co KG, Department of CNS Diseases Research, Birkendorfer Strasse 65, 88397 Biberach, Germany.
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Simoni D, Rondanin R, Marchetti P, Rullo C, Baruchello R, Grisolia G, Barbato G, Giovannini R, Marchioro C, Capelli AM, Virginio C, Bozzoli A, Borea PA, Merighi S, Donati D. Synthesis and biological activity of a novel class nicotinic acetylcholine receptors (nAChRs) ligands structurally related to anatoxin-a. Bioorg Med Chem Lett 2011; 21:5423-7. [PMID: 21824774 DOI: 10.1016/j.bmcl.2011.06.127] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 06/28/2011] [Accepted: 06/30/2011] [Indexed: 11/17/2022]
Abstract
The introduction of the isoxazole ring as bioisosteric replacement of the acetyl group of anatoxin-a led to a new series of derivatives binding to nicotinic acetylcholine receptors. Bulkier substitutions than methyl at the 3 position of isoxazole were shown to be detrimental for the activity. The binding potency of the most interesting compounds with α1, α7 and α3β4 receptor subtypes, was, anyway, only at micromolar level. Moreover, differently from known derivatives with pyridine, isoxazole condensed to azabicyclo ring led to no activity.
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Affiliation(s)
- Daniele Simoni
- Department of Pharmaceutical Sciences, University of Ferrara, Via Fossato di Mortara 17/19, 44121 Ferrara, Italy.
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69
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Nirogi R, Jabaris SL, Jayarajan P, Abraham R, Shanmuganathan D, Rasheed MA, Royapalley PK, Goura V. Antinociceptive activity of α4β2* neuronal nicotinic receptor agonist A-366833 in experimental models of neuropathic and inflammatory pain. Eur J Pharmacol 2011; 668:155-62. [PMID: 21756895 DOI: 10.1016/j.ejphar.2011.06.032] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 06/02/2011] [Accepted: 06/15/2011] [Indexed: 01/12/2023]
Abstract
Nerve injury, diabetes and cancer therapies are often associated with painful neuropathy. The mechanism underlying neuropathic pain remains poorly understood. The current therapies have limited efficacy and are associated with dose-limiting side effects. Compounds which act at nicotinic acetylcholine receptors have also been reported to show antinociceptive activity. Among those, tebanicline (ABT-594) a potent nicotinic acetylcholine receptor agonist demonstrated analgesic effects across a broad range of preclinical models of nociceptive and neuropathic pain. Another nicotinic acetylcholine receptor agonist, 5-[(1R,5S)-3,6-Diazabicyclo[3.2.0]heptan-6-yl]nicotinonitrile (A-366833) from the same group produced significant antinociceptive effects in writhing pain (abdominal constriction), acute thermal pain (hot box), persistent chemical pain (formalin induced) and neuropathic pain. In the present study, we have demonstrated the efficacy of A-366833 in rat models of chronic constriction injury, partial sciatic nerve ligation, spinal nerve ligation, diabetes, chemotherapy induced neuropathic pain and complete Freund's adjuvant induced inflammatory pain. A-366833 (1, 3 and 6 mg/kg) produced significant antihyperalgesic effects in partial sciatic nerve ligation, chronic constriction injury and spinal nerve ligation models. In the diabetic and chemotherapy induced neuropathic models compound exerted antinociceptive activity and reduction in the mechanical hyperalgesia was observed. A-366833 dose dependently attenuated mechanical hyperalgesia in complete Freund's adjuvant induced inflammatory pain model. These results demonstrated broad-spectrum antinociceptive properties of A-366833 in both neuropathic and inflammatory pain models.
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Affiliation(s)
- Ramakrishna Nirogi
- Department of Pharmacology, Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road No 5, Avenue-7, Banjara Hills, Hyderabad, 500034, India.
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70
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From smoking to cancers: novel targets to neuronal nicotinic acetylcholine receptors. JOURNAL OF ONCOLOGY 2011; 2011:693424. [PMID: 21772846 PMCID: PMC3136181 DOI: 10.1155/2011/693424] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 02/18/2011] [Accepted: 03/17/2011] [Indexed: 12/11/2022]
Abstract
Cigarette smoking bears a strong etiological association with many neovascularization-related diseases, including cancer, cardiovascular disease, and age-related macular degeneration. Cigarette smoke is a complex mixture of many compounds, including nicotine, which is the major active and addictive component of tobacco. Nicotine and its specific metabolized carcinogens directly bind to nicotinic acetylcholine receptors (nAChRs) on cell membranes and trigger the nAChR signal cascade. The nAChRs were originally thought to be ligand-gated ion channels that modulate physiological processes ranging from neurotransmission to cancer signaling. For several decades, the nAChRs served as a prototypic molecule for neurotransmitter receptors; however, they are now important therapeutic targets for various diseases, including Alzheimer's and Parkinson's diseases, schizophrenia, and even cancer. This paper describes recent advances in our understanding of the assembly, activity, and biological functions of nicotinic receptors, as well as developments in the therapeutic application of nicotinic receptor ligands.
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71
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Wu CH, Lee CH, Ho YS. Nicotinic acetylcholine receptor-based blockade: applications of molecular targets for cancer therapy. Clin Cancer Res 2011; 17:3533-41. [PMID: 21444681 DOI: 10.1158/1078-0432.ccr-10-2434] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The nicotinic acetylcholine receptor (nAChR) was first characterized in 1970 as a membrane receptor of a neurotransmitter and an ion channel. nAChRs have been shown to be involved in smoking-induced cancer formation in multiple types of human cancer cells. In vitro and in vivo animal studies have shown that homopentameric nAChR inhibitors, such as methyllycaconitine and α-Bgtx, can attenuate nicotine-induced proliferative, angiogenic, and metastatic effects in lung, colon, and bladder cancer cells. Recent publications have shown that α9-nAChR is important for breast cancer formation, and in many in vivo studies, α9-nAChR-specific antagonists (e.g., α-ImI, α-ImI, Vc1.1, RgIA, and It14a) produced an analgesic effect. Vc1.1 functions in a variety of animal pain models and currently has entered phase II clinical trials. For cancer therapy, natural compounds such as garcinol and EGCG have been found to block nicotine- and estrogen-induced breast cancer cell proliferation through inhibition of the α9-nAChR signaling pathway. A detailed investigation of the carcinogenic effects of nAChRs and their specific antagonists would enhance our understanding of their value as targets for clinical translation.
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Affiliation(s)
- Chih-Hsiung Wu
- Department of Surgery, School of Medicine, and Graduate Institute of Medical Sciences, College of Medicine, Taipei, Taiwan
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72
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Pretze M, Große-Gehling P, Mamat C. Cross-coupling reactions as valuable tool for the preparation of PET radiotracers. Molecules 2011; 16:1129-65. [PMID: 21270732 PMCID: PMC6259626 DOI: 10.3390/molecules16021129] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 01/17/2011] [Accepted: 01/21/2011] [Indexed: 11/16/2022] Open
Abstract
The increasing application of positron emission tomography (PET) in nuclear medicine has stimulated the extensive development of a multitude of new radiotracers and novel radiolabeling procedures with the most prominent short-lived positron emitters carbon-11 and fluorine-18. Radiolabeling with these radionuclides represents a remarkable challenge. Special attention has to be paid to synthesis time and specific labeling techniques due to the short physical half life of the respective radionuclides 11C (t1/2 = 20.4 min) and 18F (t1/2 = 109.8 min). In the past, numerous transition metal-catalyzed reactions were employed in organic chemistry, even though only a handful of these coupling reactions were adopted in radiochemical practice. Thus, the implementation of modern synthesis methods like cross-coupling reactions offers the possibility to develop a wide variety of novel radiotracers. The introduction of catalysts based on transition metal complexes bears a high potential for rapid, efficient, highly selective and functional group-tolerating incorporation of carbon-11 and fluorine-18 into target molecules. This review deals with design, application and improvement of transition metal-mediated carbon-carbon as well as carbon-heteroatom cross-coupling reactions as a labeling feature with the focus on the preparation of radiolabeled compounds for molecular imaging.
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Affiliation(s)
- Marc Pretze
- Institut für Radiopharmazie, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, D-01328 Dresden, Germany
| | - Philipp Große-Gehling
- OncoRay – National Center for Radiation Research in Oncology, Medical Faculty Carl Gustav Carus, Dresden University of Technology, Fetscherstraße 74, P.O. Box 41, D-01307 Dresden, Germany
| | - Constantin Mamat
- Institut für Radiopharmazie, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, D-01328 Dresden, Germany
- Author to whom correspondence should be addressed; ; Tel.: +49-351-260 2805; Fax: +49-351-260 3232
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73
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Identification of 9-fluoro substituted (−)-cytisine derivatives as ligands with high affinity for nicotinic receptors. Bioorg Med Chem Lett 2010; 20:6667-70. [DOI: 10.1016/j.bmcl.2010.09.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Revised: 09/02/2010] [Accepted: 09/02/2010] [Indexed: 10/19/2022]
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74
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Wu J, Toyohara J, Tanibuchi Y, Fujita Y, Zhang J, Chen H, Matsuo M, Wang RF, Hashimoto K. Pharmacological characterization of [125I]CHIBA-1006 binding, a new radioligand for α7 nicotinic acetylcholine receptors, to rat brain membranes. Brain Res 2010; 1360:130-7. [DOI: 10.1016/j.brainres.2010.08.095] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Revised: 08/27/2010] [Accepted: 08/27/2010] [Indexed: 11/26/2022]
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75
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76
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Abstract
Activation of nicotinic acetylcholine receptors (nAChRs) is known to modulate various forms of learning and memory, including contextual fear conditioning. Although numerous studies have shown that high-affinity beta2-containing nAChRs are necessary for the nicotine-induced enhancement of contextual fear conditioning, it is unknown whether other high-affinity nAChR agonists are capable of enhancing this learning. To examine this issue, ABT-418, a high-affinity nAChR agonist with greater selectivity for high-affinity receptors than nicotine, was administered before acquisition and/or recall of contextual fear memories. ABT-418 enhanced acquisition of contextual fear memories in a dose-dependent manner.
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77
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Toyohara J, Hashimoto K. α7 Nicotinic Receptor Agonists: Potential Therapeutic Drugs for Treatment of Cognitive Impairments in Schizophrenia and Alzheimer's Disease. THE OPEN MEDICINAL CHEMISTRY JOURNAL 2010; 4:37-56. [PMID: 21249164 PMCID: PMC3023065 DOI: 10.2174/1874104501004010037] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Revised: 10/23/2009] [Accepted: 10/30/2009] [Indexed: 01/19/2023]
Abstract
Accumulating evidence suggests that α7 nicotinic receptors (α7 nAChRs), a subtype of nAChRs, play a role in the pathophysiology of neuropsychiatric diseases, including schizophrenia and Alzheimer's disease (AD). A number of psychopharmacological and genetic studies shown that α7 nAChRs play an important role in the deficits of P50 auditory evoked potential in patients with schizophrenia, and that (α nAChR agonists would be potential therapeutic drugs for cognitive impairments associated with P50 deficits in schizophrenia. Furthermore, some studies have demonstrated that α7 nAChRs might play a key role in the amyloid-β (Aβ)-mediated pathology of AD, and that α7 nAChR agonists would be potential therapeutic drugs for Aβ deposition in the brains of patients with AD. Interestingly, the altered expression of α7 nAChRs in the postmortem brain tissues from patients with schizophrenia and AD has been reported. Based on all these findings, selective α7 nAChR agonists can be considered potential therapeutic drugs for cognitive impairments in both schizophrenia and AD. In this article, we review the recent research into the role of α7 nAChRs in the pathophysiology of these diseases and into the potential use of novel α7 nAChR agonists as therapeutic drugs.
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Affiliation(s)
- Jun Toyohara
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba, Japan
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78
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Ondachi PW, Comins DL. Synthesis of fused-ring nicotine derivatives from (S)-nicotine. J Org Chem 2010; 75:1706-16. [PMID: 20141225 DOI: 10.1021/jo9026929] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The synthesis of novel fused-ring bicyclic (4-6) and tricyclic (7-10) nicotine derivatives from natural (S)-nicotine are described. Enantiopure bicyclic dioxino, dihydrofuro, and dihydropyranol nicotine derivatives as well as tricylic benzofuro and benzopyran derivatives were synthesized from simple alkoxy or halonicotine intermediates. Attempts to synthesize furonicotines (11, 12) resulted in formation of the furonicotine dimers 42 and 49.
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Affiliation(s)
- Pauline W Ondachi
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA
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79
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Liu LT, Haddadian EJ, Willenbring D, Xu Y, Tang P. Higher susceptibility to halothane modulation in open- than in closed-channel alpha4beta2 nAChR revealed by molecular dynamics simulations. J Phys Chem B 2010; 114:626-32. [PMID: 20014754 DOI: 10.1021/jp908944e] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The neuronal alpha4beta2 nicotinic acetylcholine receptor (nAChR) is a potential molecular target for general anesthetics. It is unclear, however, whether anesthetic action produces the same effect on the open and closed channels. Computations parallel to our previous open channel study (J. Phys. Chem. B 2009, 113, 12581) were performed on the closed-channel alpha4beta2 nAChR to investigate the conformation-dependent anesthetic effects on channel structures and dynamics. Flexible ligand docking and over 20 ns molecular dynamics simulations revealed similar halothane-binding sites in the closed and open channels. The sites with relatively high binding affinities (approximately -6.0 kcal/mol) were identified at the interface of extracellular (EC) and transmembrane (TM) domains or at the interface between alpha4 and beta2 subunits. Despite similar sites for halothane binding, the closed-channel conformation showed much less sensitivity than the open channel to the structural and dynamical perturbations from halothane. Compared to the systems without anesthetics, the amount of water inside the pore decreased by 22% in the presence of halothane in the open channel but only by 6% in the closed channel. Comparison of the nonbonded interactions at the EC/TM interfaces suggested that the beta2 subunits were more prone than the alpha4 subunits to halothane binding. In addition, our data support the notion that halothane exerts its effect by disturbing the quaternary structure and dynamics of the channel. The study concludes that sensitivity and global dynamics responsiveness of alpha4beta2 nAChR to halothane are conformation dependent. The effect of halothane on the global dynamics of the open-channel conformation might also account for the action of other inhaled general anesthetics.
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Affiliation(s)
- Lu Tian Liu
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA
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80
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Albertí FM, Fiol JJ, García-Raso A, Torres M, Terrón A, Barceló-Oliver M, Prieto MJ, Moreno V, Molins E. Ruthenium(III) and iridium(III) complexes with nicotine. Polyhedron 2010. [DOI: 10.1016/j.poly.2009.05.082] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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81
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Ghandi M, Taheri A, Abbasi A. Diastereoselective synthesis of nicotine derivatives via 1,3-dipolar cycloaddition reactions. J Heterocycl Chem 2010. [DOI: 10.1002/jhet.366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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82
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Pasikanti S, Srinivasa Reddy D, Venkatesham B, Dubey P, Iqbal J, Das P. An efficient synthesis of varenicline. Tetrahedron Lett 2010. [DOI: 10.1016/j.tetlet.2009.10.107] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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83
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Huang K, Ortiz-Marciales M, De Jesús M, Stepanenko V. A New and Efficient Approach to the Synthesis of Nicotine and Anabasine Analogues. J Heterocycl Chem 2009; 46:1252-1258. [PMID: 20161612 DOI: 10.1002/jhet.233] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A straightforward and practical approach was established for the synthesis of nicotine and anabasine analogues by the cyclization of mesylated 1-(3-pyridinyl)-1,4, and 1,5-diol derivatives to form the pyrrolidino or piperidino fragments. Nicotine analogue (S)-15 was prepared with good enantioselectivity using the developed azacyclization procedure of nonracemic (R)-1-pyridin-3-yl-butane-1,4-diol, which was obtained by the borane-mediated reduction of ketone 12 in the presence of the spiroborate ester derived from diphenyl prolinol and ethylene glycol.
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Affiliation(s)
- Kun Huang
- Department of Chemistry, University of Puerto Rico-Humacao, CUH Station, Humacao, Puerto Rico 00791-4300, USA
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84
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Gómez E, Marco-Contelles J, Soriano E, Jimeno ML. N-Arylmethyl-7-azabicyclo[2.2.1]heptane derivatives: synthesis and reaction mechanisms. Tetrahedron 2009. [DOI: 10.1016/j.tet.2009.09.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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85
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Kozikowski AP, Eaton JB, Bajjuri KM, Chellappan SK, Chen Y, Karadi S, He R, Caldarone B, Manzano M, Yuen PW, Lukas RJ. Chemistry and pharmacology of nicotinic ligands based on 6-[5-(azetidin-2-ylmethoxy)pyridin-3-yl]hex-5-yn-1-ol (AMOP-H-OH) for possible use in depression. ChemMedChem 2009; 4:1279-91. [PMID: 19569163 DOI: 10.1002/cmdc.200900079] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AMOP-H-OH (sazetidine-A; 6-[5-(azetidin-2-ylmethoxy)pyridin-3-yl]hex-5-yn-1-ol) and some sulfur-bearing analogues were tested for their activities in vitro against human alpha4beta2-, alpha4beta4-, alpha3beta4*- and alpha1*-nicotinic acetylcholine receptors (nAChRs). AMOP-H-OH was also assessed in an antidepressant efficacy model. AMOP-H-OH and some of its analogues have high potency and selectivity for alpha4beta2-nAChRs over other nAChR subtypes. Effects are manifested as partial agonism, perhaps reflecting selectivity for high sensitivity (alpha4)(3)(beta2)(2)-nAChRs. More prolonged exposure to AMOP-H-OH and its analogues produces inhibition of subsequent responses to acute challenges with full nicotinic agonists, again selectively for alpha4beta2-nAChRs over other nAChR subtypes. The inhibition is mediated either via antagonism or desensitization of nAChR function, but the degree of inhibition of alpha4beta2-nAChRs is limited by the partial agonist activity of the drugs. Certain aspects of the in vitro pharmacology suggest that AMOP-H-OH and some of its analogues have a set of binding sites on alpha4beta2-nAChRs that are distinct from those for full agonists. The in vitro pharmacological profile suggests that peripheral side effects of AMOP-H-OH or its analogues would be minimal and that their behavioral effects would be dominated by central nAChR actions. AMOP-H-OH also has profound and high potency antidepressant-like effects in the forced swim test. The net action of prolonged exposure to AMOP-H-OH or its analogues, as for nicotine, seems to be a selective decrease in alpha4beta2-nAChR function. Inactivation of nAChRs may be a common neurochemical endpoint for nicotine dependence, its treatment, and some of its manifestations, including relief from depression.
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Affiliation(s)
- Alan P Kozikowski
- Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois 60612, USA.
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86
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Holtman JR, Crooks PA, Johnson-Hardy JK, Wala EP. The analgesic and toxic effects of nornicotine enantiomers alone and in interaction with morphine in rodent models of acute and persistent pain. Pharmacol Biochem Behav 2009; 94:352-62. [PMID: 19800911 DOI: 10.1016/j.pbb.2009.09.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Revised: 09/01/2009] [Accepted: 09/24/2009] [Indexed: 11/25/2022]
Abstract
Neuronal nicotinic acetylcholinic receptors (nAChR) are promising targets for the development of novel analgesics. Nicotine and other nAChR-agonists produce profound analgesia in rodent models of acute and persistent pain. However, significant side-effects are of concern. Nornicotine (N-desmethyl-nicotine) appears to activate different nAChR subtypes, has a better pharmacokinetic profile, and produces less toxicity than nicotine. Little is known about its analgesic properties. In the present study, the S(-)- and R(+)-enantiomers of nornicotine were characterized with regard to analgesia and side-effects profile. Efficacy was demonstrated in rat models of pain where central sensitization is involved: i.e. the chronic constriction nerve injury model of peripheral neuropathy and the formalin model of tonic inflammatory pain. The desirable (analgesic) properties resided predominantly in the S(-)- rather than the R(+)-enantiomer. In contrast, undesirable effects (motor in-coordination, reduced locomotor activity, ataxia) were more pronounced with the R(+)-enantiomer. This is an interesting finding, which may suggest separation of toxicity from analgesia by utilization of S(-)-enantiomer of nornicotine. Maximum analgesic effectiveness without significant side-effects was achieved when S(-)-nornicotine (sub-analgesic dose) was combined with a low-dose of the micro-opioid, morphine. These preclinical data suggest that S(-)-nornicotine may be of value, either alone or in combination with an opioid, for treatment of a broad-spectrum of pain (i.e. nociceptive, neuropathic, and mixed pain).
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Affiliation(s)
- Joseph R Holtman
- Anesthesiology/Pain Medicine, College of Medicine, University of Kentucky, Lexington KY 40536, United States.
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87
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Andreasen JT, Olsen GM, Wiborg O, Redrobe JP. Antidepressant-like effects of nicotinic acetylcholine receptor antagonists, but not agonists, in the mouse forced swim and mouse tail suspension tests. J Psychopharmacol 2009; 23:797-804. [PMID: 18583432 DOI: 10.1177/0269881108091587] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Current literature suggests involvement of nicotinic acetylcholine receptors (nAChRs) in major depression. However, it is controversial whether the antidepressant-like effect of nAChR modulation is induced by activation, desensitization or inhibition of central nAChRs. In addition, the specific nAChR subtype/s involved remains unknown. In this study, we systematically compared the effects of non-selective and selective nicotinic agonists and antagonists in two different tests for antidepressant effects in mice: the tail suspension test and the forced swim test. Compounds: nicotine, RJR-2403 (alpha4beta2-selective agonist), PNU-282987 (alpha7-selective agonist), mecamylamine (non-selective antagonist), dihydro-beta-erythroidine (DHbetaE; alpha4beta2-selective antagonist), methyllycaconitine (MLA; alpha7-selective antagonist) and hexamethonium (non-brain-penetrant non-selective antagonist). All compounds were tested in a locomotor activity paradigm to rule out non-specific stimulant effects. The data show that blockade of nAChRs with mecamylamine, or selective antagonism of alpha4beta2 or alpha7 nAChRs with DHbetaE or MLA, respectively, has antidepressant-like effects. These effects were not confounded by motor stimulation. Hexamethonium did not show antidepressant-like activity, supporting the involvement of central nAChRs. At the dose levels tested, none of the nAChR agonists displayed antidepressant-like profiles. In conclusion, antagonism of central alpha4beta2 and/or alpha7 nAChRs induced antidepressant-like effects in mice. A strategy involving antagonism of central nAChRs could potentially lead to the development of novel antidepressant therapeutics.
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Affiliation(s)
- J T Andreasen
- Department of Affective Disorders, Neurosearch A/S, Ballerup, Denmark.
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88
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Breining SR, Bencherif M, Grady SR, Whiteaker P, Marks MJ, Wageman CR, Lester HA, Yohannes D. Evaluation of structurally diverse neuronal nicotinic receptor ligands for selectivity at the alpha6( *) subtype. Bioorg Med Chem Lett 2009; 19:4359-63. [PMID: 19560354 PMCID: PMC6107347 DOI: 10.1016/j.bmcl.2009.05.085] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Revised: 05/15/2009] [Accepted: 05/20/2009] [Indexed: 11/15/2022]
Abstract
Direct comparison of pyridine versus pyrimidine substituents on a small but diverse set of ligands indicates that the pyrimidine substitution has the potential to enhance affinity and/or functional activity at alpha6 subunit-containing neuronal nicotinic receptors (NNRs) and decrease activation of ganglionic nicotinic receptors, depending on the scaffold. The ramifications of this structure-activity relationship are discussed in the context of the design of small molecules targeting smoking cessation.
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Affiliation(s)
- Scott R Breining
- Department of Medicinal Chemistry, Targacept, Inc., 200 East First St., Suite 300, Winston-Salem, NC 27101, USA
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89
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Tasso B, Canu Boido C, Terranova E, Gotti C, Riganti L, Clementi F, Artali R, Bombieri G, Meneghetti F, Sparatore F. Synthesis, Binding, and Modeling Studies of New Cytisine Derivatives, as Ligands for Neuronal Nicotinic Acetylcholine Receptor Subtypes. J Med Chem 2009; 52:4345-57. [DOI: 10.1021/jm900225j] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Bruno Tasso
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Genova, Viale Benedetto XV 3, 16139 Genova, Italy
| | - Caterina Canu Boido
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Genova, Viale Benedetto XV 3, 16139 Genova, Italy
| | - Emanuela Terranova
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Genova, Viale Benedetto XV 3, 16139 Genova, Italy
| | - Cecilia Gotti
- Dipartimento di Farmacologia “E. Trabucchi”, Università degli Studi di Milano, via Vanvitelli 32, 20129 Milano, Italy, Istituto di Neuroscienze del CNR, via Vanvitelli 32, 20129 Milano, Italy
| | - Loredana Riganti
- Dipartimento di Farmacologia “E. Trabucchi”, Università degli Studi di Milano, via Vanvitelli 32, 20129 Milano, Italy, Istituto di Neuroscienze del CNR, via Vanvitelli 32, 20129 Milano, Italy
| | - Francesco Clementi
- Dipartimento di Farmacologia “E. Trabucchi”, Università degli Studi di Milano, via Vanvitelli 32, 20129 Milano, Italy, Istituto di Neuroscienze del CNR, via Vanvitelli 32, 20129 Milano, Italy
| | - Roberto Artali
- Dipartimento di Scienze Farmaceutiche “P. Pratesi”, Università degli Studi di Milano, Via Mangiagalli 25, 20133 Milano, Italy
| | - Gabriella Bombieri
- Dipartimento di Scienze Farmaceutiche “P. Pratesi”, Università degli Studi di Milano, Via Mangiagalli 25, 20133 Milano, Italy
| | - Fiorella Meneghetti
- Dipartimento di Scienze Farmaceutiche “P. Pratesi”, Università degli Studi di Milano, Via Mangiagalli 25, 20133 Milano, Italy
| | - Fabio Sparatore
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Genova, Viale Benedetto XV 3, 16139 Genova, Italy
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90
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Soriano E, Marco-Contelles J. Mechanistic analysis of intramolecular free radical reactions toward synthesis of 7-azabicyclo[2.2.1]heptane derivatives. J Org Chem 2009; 74:4061-7. [PMID: 19402620 DOI: 10.1021/jo900225f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mechanisms for the formation of conformationally constrained epibatidine analogues by intramolecular free radical processes have been computationally addressed by means of DFT methods. The mechanism and the critical effect of the 7-nitrogen protecting group on the outcome of these radical-mediated cyclizations are discussed. Theoretical findings account for unexpected experimental results and can assist in the selection of proper precursors for a successful cyclization.
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Affiliation(s)
- Elena Soriano
- Laboratorio de Radicales Libres y Química Computacional, IQOG (CSIC), C/Juan de la Cierva 3, 28006 Madrid, Spain.
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91
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Gao Y, Ravert HT, Kuwabara H, Xiao Y, Endres CJ, Hilton J, Holt DP, Kumar A, Alexander M, Wong DF, Dannals RF, Horti AG. Synthesis and biological evaluation of novel carbon-11 labeled pyridyl ethers: candidate ligands for in vivo imaging of alpha4beta2 nicotinic acetylcholine receptors (alpha4beta2-nAChRs) in the brain with positron emission tomography. Bioorg Med Chem 2009; 17:4367-77. [PMID: 19481945 DOI: 10.1016/j.bmc.2009.05.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Revised: 05/05/2009] [Accepted: 05/09/2009] [Indexed: 10/20/2022]
Abstract
The most abundant subtype of cerebral nicotinic acetylcholine receptors (nAChR), alpha4beta2, plays a critical role in various brain functions and pathological states. Imaging agents suitable for visualization and quantification of alpha4beta2 nAChRs by positron emission tomography (PET) would present unique opportunities to define the function and pharmacology of the nAChRs in the living human brain. In this study, we report the synthesis, nAChR binding affinity, and pharmacological properties of several novel 3-pyridyl ether compounds. Most of these derivatives displayed a high affinity to the nAChR and a high subtype selectivity for alpha4beta2-nAChR. Three of these novel nAChR ligands were radiolabeled with the positron-emitting isotope (11)C and evaluated in animal studies as potential PET radiotracers for imaging of cerebral nAChRs with improved brain kinetics.
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Affiliation(s)
- Yongjun Gao
- Department of Radiology, Division of Nuclear Medicine, PET Center, The Johns Hopkins University School of Medicine, Baltimore, MD 21287-0816, USA
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92
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Development of radioligands with optimized imaging properties for quantification of nicotinic acetylcholine receptors by positron emission tomography. Life Sci 2009; 86:575-84. [PMID: 19303028 DOI: 10.1016/j.lfs.2009.02.029] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Revised: 02/05/2009] [Accepted: 02/12/2009] [Indexed: 11/20/2022]
Abstract
AIMS There is an urgent need for positron emission tomography (PET) imaging of the nicotinic acetylcholine receptors (nAChR) to study the role of the nicotinic system in Alzheimer's and Parkinson's diseases, schizophrenia, drug dependence and many other disorders. Greater understanding of the underlying mechanisms of the nicotinic system could direct the development of medications to treat these disorders. Central nAChRs also contribute to a variety of brain functions, including cognition, behavior and memory. MAIN METHODS Currently, only two radiotracers, (S)-3-(azetidin-2-ylmethoxy)-2-[(18)F]fluoropyridine (2-[(18)F]FA) and (S)-5-(azetidin-2-ylmethoxy)-2-[(18)F]fluoropyridine (6-[(18)F]FA), are available for studying nAChRs in human brain using PET. However, the "slow" brain kinetics of these radiotracers hamper mathematical modeling and reliable measurement of kinetic parameters since it takes 4-7 h of PET scanning for the tracers to reach steady state. The imaging drawbacks of the presently available nAChR radioligands have initiated the development of radioligands with faster brain kinetics by several research groups. KEY FINDINGS This minireview attempts to survey the important achievements of several research groups in the discovery of PET nicotinic radioligands reached recently. Specifically, this article reviews papers published from 2006 through 2008 describing the development of fifteen new nAChR (11)C-and (18)F-ligands that show improved imaging properties over 2-[(18)F]FA. SIGNIFICANCE The continuous efforts of radiomedicinal chemists led to the development of several interesting PET radioligands for imaging of nAChR including [(18)F]AZAN, a potentially superior alternative to 2-[(18)F]FA.
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93
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Zhang S, Cheng J, Liu Y, Xu L, Trudell ML, Izenwasser S, Wade D. Synthesis and nicotinic acetylcholine receptor affinity of bivalent tropane-3-carboxylates. J Heterocycl Chem 2009. [DOI: 10.1002/jhet.5570440629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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94
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Cheng J, Xu L, Stevens ED, Trudell ML, Izenwasser S, Wade D. Stereoselective synthesis of conformationally constrained tropane analogues: 6-Chloro-2,5-diazatetracyclo[8.5.0.02,13.04,9]pentadeca-4,6,8-triene-11-one and 6-chloro-2,7-diazatetracyclo-[8.5.0.02,13.04,9]pentadeca-4,6,8-triene-11-one. J Heterocycl Chem 2009. [DOI: 10.1002/jhet.5570410414] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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95
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Effects of subunit selective nACh receptors on operant ethanol self-administration and relapse-like ethanol-drinking behavior. Psychopharmacology (Berl) 2009; 203:99-108. [PMID: 18987848 DOI: 10.1007/s00213-008-1375-5] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Accepted: 10/08/2008] [Indexed: 10/21/2022]
Abstract
RATIONALE AND OBJECTIVES The sensitivity to ethanol central effects is partially determined by the subunit composition of brain nicotinic acetylcholine receptors (nAChRs). Thus, the effects of intraventral tegmental area (VTA) administration of the nicotinic subunit-specific antagonist, alpha-conotoxin MII (alphaCtxMII, alpha(3)beta(2)*, beta(3)*, alpha(6)*), were compared to those of systemic mecamylamine (MEC, an allosteric negative modulator of the nAChR), dihydro-beta-erythroidine (DHbetaE, alpha(4)beta(2)*), and methyllycaconitine (MLA, alpha(7)*) to elucidate involvement of different subunits of nAChRs in operant ethanol self-administration and relapse-like activation of ethanol consumption after ethanol deprivation in rats. METHODS The effects of drugs were studied in rats trained for operant oral self-administration of ethanol (FR = 1). For ethanol deprivation, trained animals were subjected to a period of alcohol deprivation for 10 days. alphaCtxMII was given directly into the VTA through implanted permanent intracranial cannulae, whereas MEC, DHbetaE, and MLA were administered systemically. RESULTS alphaCtxMII reduced operant ethanol self-administration and blocked the deprivation-induced relapse-like ethanol consumption. MEC reduced operant ethanol self-administration and inhibited the deprivation-induced increase in alcohol consumption. DHbetaE did not alter ethanol self-administration in the lower-dose range but inhibited ethanol intake at a higher dose (4 mg/kg), although this effect might have been nonspecific. MLA failed to block self-administration of ethanol and relapse-like drinking after deprivation. CONCLUSIONS Our results indicate that nAChRs are involved in the modulation of operant alcohol self-administration and relapse-like alcohol drinking behavior in rats. Our observations support the working hypothesis that systemically active selective ligands for nAChR alpha(3)beta(2)*, beta(3), and/or alpha(6)* receptor subunits might be of therapeutic value for the treatment of alcoholism.
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96
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Williams M, Martin Garraffo H, F. Spande T. Epibatidine: From Frog Alkaloid to Analgesic Clinical Candidates. A Testimonial to “True Grit”! HETEROCYCLES 2009. [DOI: 10.3987/rev-08-sr(d)5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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97
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Grazioso G, Cavalli A, De Amici M, Recanatini M, De Micheli C. Alpha7 nicotinic acetylcholine receptor agonists: prediction of their binding affinity through a molecular mechanics Poisson-Boltzmann surface area approach. J Comput Chem 2008; 29:2593-602. [PMID: 18478580 DOI: 10.1002/jcc.21019] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A group of agonists for the alpha7 neuronal nicotinic acetylcholine receptors (nAChRs) was investigated, and their free energies of binding DeltaG(bind) were calculated by applying the molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) approach. This method, based on molecular dynamics simulations of fully solvated protein-ligand complexes, allowed us to estimate the contribution of both polar and nonpolar terms as well as the entropy to the overall free energy of binding. The calculated results were in a good agreement with the experimentally determined DeltaG(bind) values, thereby pointing to the MM-PBSA protocol as a valuable computational tool for the rational design of specific agents targeting the neuronal alpha7 nAChR subtypes.
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Affiliation(s)
- Giovanni Grazioso
- Istituto di Chimica Farmaceutica e Tossicologica "Pietro Pratesi", Università degli Studi di Milano, Via Mangiagalli 25, 20133 Milano, Italy
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98
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Patel AB, Malpass JR. Potential Nicotinic Acetylcholine Receptor Ligands from 2,4-Methanoproline Derivatives. J Med Chem 2008; 51:7005-9. [DOI: 10.1021/jm800537a] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Anup B. Patel
- Department of Chemistry, University of Leicester, Leicester LE1 7RH, United Kingdom
| | - John R. Malpass
- Department of Chemistry, University of Leicester, Leicester LE1 7RH, United Kingdom
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99
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Maciuk A, Moaddel R, Haginaka J, Wainer IW. Screening of tobacco smoke condensate for nicotinic acetylcholine receptor ligands using cellular membrane affinity chromatography columns and missing peak chromatography. J Pharm Biomed Anal 2008; 48:238-46. [PMID: 18187282 PMCID: PMC2605108 DOI: 10.1016/j.jpba.2007.11.024] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Revised: 11/16/2007] [Accepted: 11/19/2007] [Indexed: 11/23/2022]
Abstract
This manuscript reports an approach to the screening of natural product extracts for compounds which are active at membrane-bound receptors, ion channels and transporters. The technique is based upon cellular membrane affinity chromatography (CMAC) columns created through the immobilization of cellular membrane fragments on liquid chromatography stationary phases. In this study a CMAC(nAChR(+)) column was created out of membranes from a transfected cell line expressing the alpha3beta4 neuronal nicotinic acetylcholine receptor (nAChR) and the column was used to screen tobacco smoke condensates. A strategy involving parallel screening with a CMAC column created from a non-transfected form of the same cell line, CMAC(nAChR(-)) was adopted. The condensate was chromatographed on both columns, timed fractions collected and concentrated. Each fraction was analyzed on a C18 column in order to establish a chromatographic fingerprint of each fraction and a differential elution profile of each compound. Comparison of the elution profiles from the CMAC(nAChR(+)) and CMAC(nAChR(-)) columns identified patterns that could be associated with high affinity ligands and with low-affinity/non-binding compounds. Known strong ligands ((S)-nicotine, (R,S)-anatabine, N'-nitrosonornicotine), weak ligands ((R,S)-nornicotine, anabasine) as well as known non-ligands (N-methyl-gamma-oxo-3-pyridinebutanamide, (1'S,2'S)-nicotine 1'-oxide) have been identified in the complex extract. The results demonstrate that CMAC-based screens can be used in the identification of compounds within natural product extracts that bind to membrane-based targets.
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Affiliation(s)
- Alexandre Maciuk
- Gerontology Research Center, National Institute on Aging, National Institutes of Health, Baltimore, MD
| | - Ruin Moaddel
- Gerontology Research Center, National Institute on Aging, National Institutes of Health, Baltimore, MD
| | - Jun Haginaka
- Mukogawa Women’s University, Nishinomiya 663-8179, Japan
| | - Irving W. Wainer
- Gerontology Research Center, National Institute on Aging, National Institutes of Health, Baltimore, MD
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100
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Gómez-Sánchez E, Soriano E, Marco-Contelles J. Synthesis of heterocyclic analogues of epibatidine via 7-azabicyclo[2.2.1]hept-2-yl radical intermediates. 1. Intermolecular reactions. J Org Chem 2008; 73:6784-92. [PMID: 18656981 DOI: 10.1021/jo8011094] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis and reactivity of the 7-azabicyclo[2.2.1]hept-2-yl radical has been extensively investigated in inter- and intramolecular reaction processes for the first time. In this work we will present the preparation of the radical and its successful intermolecular reaction with radical acceptors such as tert-butylisocyanide and acrylonitrile. Computational analyses have been carried out to show and explain the mechanisms and stereochemical outcome of these transformations. Overall and from the chemical point of view, a new and convenient synthetic approach has been developed for the synthesis of exo-2-(cyano)alkyl substituted 7-azabicyclo[2.2.1]heptane derivatives, a series of compounds of wide interest for the synthesis of heterocyclic analogues of epibatidine. As a result, we describe here the synthesis of the tetrazoloepibatidines (8 and 15) and the oxadiazoloepibatidine (10).
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Affiliation(s)
- Elena Gómez-Sánchez
- Laboratorio de Radicales Libres, IQOG (CSIC), C/Juan de la Cierva 3, 28006-Madrid, Spain
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