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Rotstein BH, Liang SH, Belov VV, Livni E, Levine DB, Bonab AA, Papisov MI, Perlis RH, Vasdev N. Practical Radiosynthesis and Preclinical Neuroimaging of [11C]isradipine, a Calcium Channel Antagonist. Molecules 2015; 20:9550-9. [PMID: 26016546 PMCID: PMC4870226 DOI: 10.3390/molecules20069550] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 05/19/2015] [Accepted: 05/20/2015] [Indexed: 11/30/2022] Open
Abstract
In the interest of developing in vivo positron emission tomography (PET) probes for neuroimaging of calcium channels, we have prepared a carbon-11 isotopologue of a dihydropyridine Ca2+-channel antagonist, isradipine. Desmethyl isradipine (4-(benzo[c][1,2,5]oxadiazol-4-yl)-5-(isopropoxycarbonyl)-2,6-dimethyl-1,4-dihydropyridine-3-carboxylic acid) was reacted with [11C]CH3I in the presence of tetrabutylammonium hydroxide in DMF in an HPLC injector loop to produce the radiotracer in a good yield (6 ± 3% uncorrected radiochemical yield) and high specific activity (143 ± 90 GBq·µmol−1 at end-of-synthesis). PET imaging of normal rats revealed rapid brain uptake at baseline (0.37 ± 0.08% ID/cc (percent of injected dose per cubic centimeter) at peak, 15–60 s), which was followed by fast washout. After pretreatment with isradipine (2 mg·kg−1, i.p.), whole brain radioactivity uptake was diminished by 25%–40%. This preliminary study confirms that [11C]isradipine can be synthesized routinely for research studies and is brain penetrating. Further work on Ca2+-channel radiotracer development is planned.
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Affiliation(s)
- Benjamin H Rotstein
- Department of Radiology, Harvard Medical School, Division of Nuclear Medicine and Molecular Imaging and Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA.
| | - Steven H Liang
- Department of Radiology, Harvard Medical School, Division of Nuclear Medicine and Molecular Imaging and Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA.
| | - Vasily V Belov
- Department of Radiology, Harvard Medical School, Division of Nuclear Medicine and Molecular Imaging and Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA.
- Department of Research, Shriners Hospitals for Children-Boston, 51 Blossom Street, Boston, MA 02114, USA.
| | - Eli Livni
- Department of Radiology, Harvard Medical School, Division of Nuclear Medicine and Molecular Imaging and Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA.
| | - Dylan B Levine
- Department of Radiology, Harvard Medical School, Division of Nuclear Medicine and Molecular Imaging and Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA.
- Department of Research, Shriners Hospitals for Children-Boston, 51 Blossom Street, Boston, MA 02114, USA.
| | - Ali A Bonab
- Department of Radiology, Harvard Medical School, Division of Nuclear Medicine and Molecular Imaging and Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA.
- Department of Research, Shriners Hospitals for Children-Boston, 51 Blossom Street, Boston, MA 02114, USA.
| | - Mikhail I Papisov
- Department of Radiology, Harvard Medical School, Division of Nuclear Medicine and Molecular Imaging and Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA.
- Department of Research, Shriners Hospitals for Children-Boston, 51 Blossom Street, Boston, MA 02114, USA.
| | - Roy H Perlis
- Department of Psychiatry and Center for Experimental Drugs and Diagnostics, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA.
| | - Neil Vasdev
- Department of Radiology, Harvard Medical School, Division of Nuclear Medicine and Molecular Imaging and Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA.
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Dolle F, Valette H, Hinnen F, Demphel S, Bramoulle Y, Peglion JL, Crouzel C. Highly efficient synthesis of [11C]S12968 and [11C]S12967, for thein vivo imaging of the cardiac calcium channels using PET. J Labelled Comp Radiopharm 2001. [DOI: 10.1002/jlcr.476] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Dollé F, Valette H, Hinnen F, Fuseau C, Péglion JL, Crouzel C. Synthesis and characterization of a 11C-labelled derivative of S12968: an attempt to image in vivo brain calcium channels. Nucl Med Biol 1998; 25:339-42. [PMID: 9639294 DOI: 10.1016/s0969-8051(97)00211-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
[11C]S11568 (3-ethyl-5-methyl 2-[2-(2-aminoethoxy)ethoxymethyl]-4-(2,3-dichlorophenyl)-6-methyl- 1,4-dihydropyridine-3,5-dicarboxylate) is a powerful ligand for the visualization of the cardiac calcium channel in vivo using PET. The aim of the present study was to synthesize a lipophilic, nonionized derivative of S11568 to facilitate its penetration into the brain. To increase the lipophilicity and to remove simultaneously the ionic nature of our ligand, the N-tert-butoxycarbonyl (N-Boc) derivative of S11568 was synthesized. An IC50 value of 1.7 nM for this derivative confirmed that both the affinity and selectivity for the calcium channel was unaltered by this chemical modification (S11568 with IC50 value of 9.9 nM). The biologically more active enantiomer of S11568, the levogyre isomer S12968, was labelled with 11C using [11C]iodomethane. The lipophilicity of the N-Boc derivative was increased by a factor of three to four when compared to the parent compound (as determined by the measurement of the octanol/buffer partition coefficients). In vivo, this derivative slightly crosses the blood-brain barrier, as demonstrated by a 4-fold increase (with respect to the parent compound S12968) of the radioactivity in the brain using the 11C-labelled N-Boc S12968. This uptake remained too low to be suitable for imaging calcium channels.
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Affiliation(s)
- F Dollé
- Service Hospitalier Frédéric Joliot, Département de Recherche Médicale, Commissariat à l'Energie Atomique, Orsay, France
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Dollé F, Hinnen F, Valette H, Fuseau C, Duval R, Péglion JL, Crouzel C. Synthesis of two optically active calcium channel antagonists labelled with carbon-11 for in vivo cardiac PET imaging. Bioorg Med Chem 1997; 5:749-64. [PMID: 9158874 DOI: 10.1016/s0968-0896(97)00024-2] [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: 02/04/2023]
Abstract
(+/-)-S11568 (1, 3-ethyl-5-methyl-(+/-)-2-[(2-(2-aminoethoxy)ethoxy) methyl]-4-(2,3-dichlorophenyl)-6-methyl-1,4-dihydropyridine-3, 5-dicarboxylate), has an in vitro profile of high potency and of high selectivity for the low-voltage dependent. L-type calcium channel. In in vitro binding studies, it displaced specifically bound (-)-[3H]PN 200-110 (isradipine (2), the reference molecule for in vitro studies) from cardiac and vascular smooth muscle preparations with potencies of 5.6 and 51 nM, respectively. It also appears as a pure pharmacological antagonist acting at a single channel L-type and free of any interaction at the benzothiazepine binding site such as amlodipine (3). Both enantiomers of S11568 have in vitro activities, the dextro isomer S12967 ((+)-1) being 6 to 18-fold less potent than the levo one S12968 ((-)-1). Two couples of optically active labelling precursors of S11568, ((-)-10/(+)-10 and (-)-14/(+)-14) have been synthesized using a modified Hantzsch's dihydropyridine synthesis. In both cases, the enantiomers were separated by preparative chiral HPLC. They both have been independently labelled with carbon-11, using [11C]diazomethane or [11C]iodomethane to give multimilliCurie quantities of (-)-1 (S12968) and (+)-1 (S12967) with high specific activities (500-1000 mCi/mumol, 18.5-37.0 GBq/mumol). Both enantiomers appear suitable for PET experiments: their myocardial concentration increases after a bolus injection to reach a maximum in 2 min and then remains on a plateau with a slight downslope while the blood concentration falls rapidly. Myocardial uptake was threefold higher than lung uptake, leading to a good contrast on PET images. The present preliminary biological results obtained in Beagle dogs showed that both enantiomers have similar myocardial kinetics and in vivo affinity for the left ventricular myocardium.
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Affiliation(s)
- F Dollé
- Service Hospitalier Frédéric Joliot, CEA, Orsay, France
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