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Optimization of the labeling yield by determination of the Cu+–acetonitrile complex constant in Cu+-catalyzed nucleophilic exchange reactions in mixed solvent conditions. J Radioanal Nucl Chem 2010. [DOI: 10.1007/s10967-010-0956-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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[123/131I]Iodometomidate as a radioligand for functional diagnosis of adrenal disease: synthesis, structural requirements and biodistribution. RADIOCHIM ACTA 2009. [DOI: 10.1524/ract.92.4.297.35598] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
Metomidate [(R)-1-(1-phenylethyl)-1H-imidazole-5-carboxylic acid methyl ester] (MTO, 1, Fig. 1) is a potent and selective inhibitor of the cytochrome P-450 enzyme system in the adrenal cortex. Labelled in the 4-position with radioiodine, (R)-4-[131I]iodometomidate, 2, [131I]IMTO has been evaluated by in-vitro studies and also ex-vivo in rats. [131I]IMTO was synthesized by oxidative radioiododestannylation using a suitable precursor which was prepared by a new stereoselective synthesis. Optimization of the labelling reaction was performed by systematic variation of the most important reaction parameters. Under optimum reaction conditions, a labelling yield of 95% was obtained. In-vitro-stability of the tracer was studied over 8 days, indicating slow deiodination (0.27%/h). Displacement studies using [131I]IMTO and rat adrenal membranes revealed the structural requirements for high affinity binding, namely an intact ester group and (R)-configuration of the radioligand. Pharmacokinetic studies in rats showed fast accumulation of [131I]IMTO in the adrenals (approx. 10% ID/g tissue) with an activity plateau for 2 hours. Metabolic degradation was indicated by a steady increase of renal activity up to 4 hours post injection. Based on target to non-target ratios the highest contrast for imaging of the adrenals was observed between 30 and 60 min post injection of [131I]IMTO. We conclude that SPECT using [123I]IMTO will be a promising method for the characterization of adrenal incidentalomas.
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Zolle IM, Berger ML, Hammerschmidt F, Hahner S, Schirbel A, Peric-Simov B. New Selective Inhibitors of Steroid 11β-Hydroxylation in the Adrenal Cortex. Synthesis and Structure–Activity Relationship of Potent Etomidate Analogues. J Med Chem 2008; 51:2244-53. [DOI: 10.1021/jm800012w] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ilse M. Zolle
- Department of Medicinal/Pharmaceutical Chemistry and Institute of Organic Chemistry, University of Vienna, 1090 Vienna, Austria, Center for Brain Research, Medical University of Vienna, 1090 Vienna, Austria, and Department of Medicine and Department of Nuclear Medicine, University of Wuerzburg, 97080 Wuerzburg, Germany
| | - Michael L. Berger
- Department of Medicinal/Pharmaceutical Chemistry and Institute of Organic Chemistry, University of Vienna, 1090 Vienna, Austria, Center for Brain Research, Medical University of Vienna, 1090 Vienna, Austria, and Department of Medicine and Department of Nuclear Medicine, University of Wuerzburg, 97080 Wuerzburg, Germany
| | - Friedrich Hammerschmidt
- Department of Medicinal/Pharmaceutical Chemistry and Institute of Organic Chemistry, University of Vienna, 1090 Vienna, Austria, Center for Brain Research, Medical University of Vienna, 1090 Vienna, Austria, and Department of Medicine and Department of Nuclear Medicine, University of Wuerzburg, 97080 Wuerzburg, Germany
| | - Stefanie Hahner
- Department of Medicinal/Pharmaceutical Chemistry and Institute of Organic Chemistry, University of Vienna, 1090 Vienna, Austria, Center for Brain Research, Medical University of Vienna, 1090 Vienna, Austria, and Department of Medicine and Department of Nuclear Medicine, University of Wuerzburg, 97080 Wuerzburg, Germany
| | - Andreas Schirbel
- Department of Medicinal/Pharmaceutical Chemistry and Institute of Organic Chemistry, University of Vienna, 1090 Vienna, Austria, Center for Brain Research, Medical University of Vienna, 1090 Vienna, Austria, and Department of Medicine and Department of Nuclear Medicine, University of Wuerzburg, 97080 Wuerzburg, Germany
| | - Biljana Peric-Simov
- Department of Medicinal/Pharmaceutical Chemistry and Institute of Organic Chemistry, University of Vienna, 1090 Vienna, Austria, Center for Brain Research, Medical University of Vienna, 1090 Vienna, Austria, and Department of Medicine and Department of Nuclear Medicine, University of Wuerzburg, 97080 Wuerzburg, Germany
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Mertens J, Kersemans V, Bauwens M, Joos C, Lahoutte T, Bossuyt A, Slegers G. Synthesis, radiosynthesis, and in vitro characterization of [125I]-2- iodo-L-phenylalanine in a R1M rhabdomyosarcoma cell model as a new potential tumor tracer for SPECT. Nucl Med Biol 2004; 31:739-46. [PMID: 15246364 DOI: 10.1016/j.nucmedbio.2004.03.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2004] [Revised: 03/08/2004] [Accepted: 03/14/2004] [Indexed: 10/26/2022]
Abstract
[125I]-2-iodo-L-phenylalanine, a new radioiodinated phenylalanine analog was evaluated as a potential specific tumor tracer for SPECT. The tracer is obtained with an overall radiochemical yield of at least 98%, a purity of > 99%, and a specific activity of 11 MBq/mmol in one pot Kit conditions using the Cu1+ assisted isotopic exchange. The tracer is evaluated in vitro using R1M rat rabdomyosarcoma cells in HEPES buffer with and without Na+ ions and in MEM buffer. The uptake of [125I]-2-iodo-L-phenylalanine follows a reversible pseudo-first-order reaction which is the same in presence and absence of Na+ ions, but the compound is not incorporated into the cell proteins. The reversible uptake is proven to occur with the same affinity as L-henylalanine by a saturable transport system which is competitively inhibited by BCH, an L transport type selective molecule. Trans-stimulation of the efflux by BCH and typical L transported amino acids shows that the transporter is of the antiport type and fulfils all the properties of the LAT1 heterodimer transport system. [125I]-2-iodo-L-phenylalanine is thus a phenylalanine analog that for the uptake uses for the major part the LAT1 transport system which is known to be over-expressed in tumor cells. This, together with the easy Kit preparation, makes [123I]-2-iodo-L-phenylalanine a promising tumor specific tracer for SPECT.
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Affiliation(s)
- J Mertens
- Nuclear Medicine Department/BEFY, Vrije Universiteit Brussel, Belgium.
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Guarna A, Menchi G, Berti G, Cini N, Bottoncetti A, Raspanti S, Politi A, Pupi A. Synthesis and preliminary biological characterization of a new potential (125)I-radioligand for dopamine and serotonin receptors. Bioorg Med Chem 2001; 9:3197-206. [PMID: 11711295 DOI: 10.1016/s0968-0896(01)00229-2] [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: 11/18/2022]
Abstract
The synthesis and a preliminary biological characterization of a new class of N-benzyl-aminoalcohols which have serotonin (5-HT(2)) and dopamine (D(2)) receptor affinity is described. In vitro competition binding studies were conducted with the new molecules and (3)H-spiperone on crude membrane preparation from rat striatum and frontal cortex. One of these compounds, 3-benzylamino-1-(4-fluoro-2-iodophenyl)-propan-1-ol (6f), whose IC(50) values are in the micromolar range for both the D(2) and 5-HT(2) receptors, was prepared in iodine-125 labelled form (6i) by nucleophilic substitution of the bromine atom of 3-benzylamino-1-(2-bromo-4-fluorophenyl)-propan-1-ol (6d). In the in vivo studies, conducted on rats, the radiolabelled molecule 6i shows a good capacity to cross the blood-brain barrier (BBB) with a mean value of first pass cerebral extraction (E) of ca. 50% when the regional cerebral blood flow, measured with microsphere technique, is in the experimental animal's physiologic range (0.8-1 mL/min/g). A preliminary in vitro autoradiographic distribution on coronal rat brain slices of the radioiodinated molecule showed that it was preferentially localized in the striatum and in the cerebral regions rich in dopamine- and serotonin receptors, even if a high non-specific binding was observed.
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Affiliation(s)
- A Guarna
- Dipartimento di Chimica Organica U. Schiff, e Centro di Studio sulla Chimica e la Struttura dei Composti Eterociclici e loro Applicazioni, CNR, Università di Firenze, Via G. Capponi 9, Firenze I-50121, Italy.
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Ho YP, Lin G, Damani LA, Mitterhauser M, Zolle I. Spectral and chromatographic properties of 2-methoxyphenylmetyrapone and its potential metabolites. J Pharm Biomed Anal 1997; 15:479-86. [PMID: 8953491 DOI: 10.1016/s0731-7085(96)01861-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In the search for new metyrapone derivatives as radioligands for the functional diagnosis of adrenal pathology, 2-methoxyphenylmetyrapone [2-MPMP, 1-(2-methoxyphenyl)-2-methyl-2-(3-pyridyl)-1-propanone] (1), and related 2-substituted phenylmetyrapone derivatives, have been separated as potent inhibitors of adrenal 11 beta-hydroxylase, with high affinity for adrenal mitochondrial binding sites. Surprisingly, 2-[11C]MPMP showed a rapid loss of the radioactive label, which prompted investigation of its metabolism. Synthetic 2-MPMP (1) and its seven potential metabolites (2-8) have been identified spectroscopically (1H- and 13C-NMR and mass spectrometry) and further characterised by chromatography (TLC and gradient reversed-phase HPLC). Chromatographic and mass analysis of urinary extracts from rats dosed with 2-MPMP have confirmed the major metabolites as 2-hydroxyphenylmetyrapone (2-OHPMP), 2) and its N-oxide (2-OHPMP-NO, 6), which are present predominantly as conjugates.
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Affiliation(s)
- Y P Ho
- Department of Pharmacy, Faculty of Medicine, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong
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Schirbel A, Coenen HH. Comparison of non-isotopic exchange methods for n.c.a. labelling of 2-iodophenyl-metyrapone. Nucl Med Biol 1995; 22:1075-9. [PMID: 8998470 DOI: 10.1016/0969-8051(95)02033-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The Cu(I)-assisted aromatic halogen exchange proved useful for preparation of macroscopic amounts of 2-iodophenyl-metyrapone as well as for the n.c.a. radioiodinated analogue. Semi-preparative HPLC-isolation provided the compound with high purity for use as chromatographic standard and for the determination of the inhibition constant of the 2-iodo-analogue. The non-isotopic exchange led to a high specific activity (> 5000 GBq/mumol) of 2-[123I]iodophenyl-metyrapone. A reaction in acetic acid at elevated temperatures proved superior to an exchange in aqueous solution with in-situ reduction of Cu2+. Even without Cu+ high radiochemical yields of > 80% were obtained, while addition of Cu+ provided the radiotracer with 95% radiochemical yield within 5 minutes in acetic acid.
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Affiliation(s)
- A Schirbel
- Klinik und Poliklinik für Nuklearmedizin, Universitätsklinikum, Essen, FRG
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