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Kelderman CAA, Maclean RC, Hungnes IN, Davey PRWJ, Salimova E, de Veer M, Patel N, Ma MT, Paterson BM. Technetium Nitrido Complexes of Tetradentate Thiosemicarbazones: Kit-Based Radiolabeling, Characterization, and In Vivo Evaluation. Inorg Chem 2023; 62:20791-20805. [PMID: 37855107 DOI: 10.1021/acs.inorgchem.3c02650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2023]
Abstract
Bis(thiosemicarbazone) and pyridylhydrazone-thiosemicarbazone chelators have demonstrated utility in nuclear medicine. In particular, the 64Cu2+ complexes have been extensively developed for hypoxia imaging and molecular imaging of peptide and protein markers of disease. However, the chemistry and application of bis(thiosemicarbazone) and pyridylhydrazone-thiosemicarbazone chelators in combination with 99mTc, the most widely used radionuclide in nuclear medicine, is underexplored. Herein, a series of bis(thiosemicarbazone) and pyridylhydrazone-thiosemicarbazone chelators were radiolabeled with nitrido-technetium-99m in an optimized one-pot synthesis from [99mTc]TcO4-. Optimization of the radiochemical syntheses allowed for production of the complexes in >90% radiochemical conversion with apparent molar activities of 3.3-5 GBq/μmol. Competition experiments demonstrated the excellent stability of the complexes. The nitrido-technetium-99 complexes were synthesized, and the chemical identities were investigated using mass spectrometry, spectroscopy, and density functional theory calculations. Complexation of nitrido-rhenium(V) was achieved with the N4-dialkylated bis(thiosemicarbazones). Planar imaging and ex vivo biodistribution studies of the five 99mTc complexes were conducted on healthy BALB/c mice to determine in vivo behavior. The lipophilic nature of the complexes resulted in uptake of 1.6-5.7% ID g-1 in the brain at 2 min postinjection and retention of 0.4-1.7% ID g-1 at 15 min postinjection. The stability of the complexes and the biodistribution data demonstrate that these chelators are ideal platforms for future production of radiopharmaceutical candidates.
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Affiliation(s)
| | - Rachel C Maclean
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
- Centre for Advanced Imaging, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Ingebjørg N Hungnes
- School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London SE1 7EH, United Kingdom
| | - Patrick R W J Davey
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Ekaterina Salimova
- Monash Biomedical Imaging, Monash University, Clayton, Victoria 3800, Australia
| | - Michael de Veer
- Monash Biomedical Imaging, Monash University, Clayton, Victoria 3800, Australia
| | - Natasha Patel
- School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London SE1 7EH, United Kingdom
| | - Michelle T Ma
- School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London SE1 7EH, United Kingdom
| | - Brett M Paterson
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
- Centre for Advanced Imaging, The University of Queensland, St. Lucia, Queensland 4072, Australia
- Monash Biomedical Imaging, Monash University, Clayton, Victoria 3800, Australia
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Modern Developments in Bifunctional Chelator Design for Gallium Radiopharmaceuticals. MOLECULES (BASEL, SWITZERLAND) 2022; 28:molecules28010203. [PMID: 36615397 PMCID: PMC9822085 DOI: 10.3390/molecules28010203] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/19/2022] [Accepted: 12/19/2022] [Indexed: 12/28/2022]
Abstract
The positron-emitting radionuclide gallium-68 has become increasingly utilised in both preclinical and clinical settings with positron emission tomography (PET). The synthesis of radiochemically pure gallium-68 radiopharmaceuticals relies on careful consideration of the coordination chemistry. The short half-life of 68 min necessitates rapid quantitative radiolabelling (≤10 min). Desirable radiolabelling conditions include near-neutral pH, ambient temperatures, and low chelator concentrations to achieve the desired apparent molar activity. This review presents a broad overview of the requirements of an efficient bifunctional chelator in relation to the aqueous coordination chemistry of gallium. Developments in bifunctional chelator design and application are then presented and grouped according to eight categories of bifunctional chelator: the macrocyclic chelators DOTA and TACN; the acyclic HBED, pyridinecarboxylates, siderophores, tris(hydroxypyridinones), and DTPA; and the mesocyclic diazepines.
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Kelderman CAA, Davey PRWJ, Ma MT, de Veer M, Salimova E, Donnelly PS, Paterson BM. Hexadentate technetium-99m bis(thiosemicarbazonato) complexes: synthesis, characterisation and biodistribution. Dalton Trans 2022; 51:14064-14078. [PMID: 35822662 DOI: 10.1039/d2dt01264b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The syntheses of non-oxido/non-nitrido bis(thiosemicarbazonato)technetium(V) complexes featuring a series of alkyl and ether substituents is presented. The bis(thiosemicarbazones) were radiolabelled with technetium-99m using an optimised one-pot synthesis from [99mTc][TcO4]-. Mass spectrometry and computational chemistry data suggested a distorted trigonal prismatic coordination environment for the bis(thiosemicarbazonato)technetium(V) complexes by way of a bis(thiosemicarbazone)technetium(V)-oxido intermediate complex. The lipophilicities of the complexes were estimated using distribution ratios and three of the new complexes were investigated in mice using kinetic planar imaging and ex vivo biodistribution experiments and were compared to [99mTc][TcO4]-. Modification of the technetium complexes with various lipophilic functional groups altered the biodistributions of the complexes in mice despite evidence suggesting limited stability of the complexes to biologically relevant conditions. The most hydrophilic complex had higher uptake in the kidneys compared to the most lipophilic, which had higher liver uptake, suggesting modification of the excretion pathways.
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Affiliation(s)
| | | | - Michelle T Ma
- School of Biomedical Engineering and Imaging Sciences, King's College London, St Thomas' Hospital, London SE1 7EH, UK
| | - Michael de Veer
- Monash Biomedical Imaging, Monash University, Clayton, Victoria 3800, Australia
| | - Ekaterina Salimova
- Monash Biomedical Imaging, Monash University, Clayton, Victoria 3800, Australia
| | - Paul S Donnelly
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Brett M Paterson
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia. .,Monash Biomedical Imaging, Monash University, Clayton, Victoria 3800, Australia
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Parrilha GL, dos Santos RG, Beraldo H. Applications of radiocomplexes with thiosemicarbazones and bis(thiosemicarbazones) in diagnostic and therapeutic nuclear medicine. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2022.214418] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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