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Issue 33, 2016
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Evaluation of H2CHXdedpa, H2dedpa- and H2CHXdedpa-N,N′-propyl-2-NI ligands for 64Cu(II) radiopharmaceuticals

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Abstract

The chiral acyclic “pa” ligand (pa = picolinic acid) H2CHXdedpa (N4O2) and two NI-containing dedpa analogues (H2CHXdedpa-N,N′-propyl-2-NI, H2dedpa-N,N′-propyl-2-NI, NI = nitroimidazole) were studied as chelators for copper radiopharmaceuticals (CHX = cyclohexyl, H2dedpa = 1,2-[[carboxypyridin-2-yl]methylamino]ethane). The hexadentate ligand H2CHXdedpa was previously established as a superb system for 67/68Ga radiochemistry. The solid state X-ray crystal structures of [Cu(CHXdedpa-N,N′-propyl-2-NI)] and [Cu(dedpa-N,N′-propyl-2-NI)] reveal the predicted hexadentate, distorted octahedral binding of the copper(II) ion. Cyclic voltammetry of [Cu(dedpa-N,N′-propyl-2-NI)] shows that there is one reversible couple associated with the NI redox, and one irreversible but reproducible couple attributed to the Cu(II)/Cu(I) redox cycle. Quantitative radiolabeling (>99%) of CHXdedpa2− and (dedpa-N,N′-propyl-2-NI)2− with 64Cu was achieved under fast and efficient labeling conditions (10 min, RT, 0.5 M sodium acetate buffer, pH 5.5) at ligand concentrations as low as 10−6 M. In vitro kinetic inertness studies of the 64Cu labelled complexes were studied in human serum at 37 °C over 24 hours; [64Cu(CHXdedpa)] was found to be 98% stable compared to previously investigated [64Cu(dedpa)] which was only 72% intact after 24 hours.

Graphical abstract: Evaluation of H2CHXdedpa, H2dedpa- and H2CHXdedpa-N,N′-propyl-2-NI ligands for 64Cu(ii) radiopharmaceuticals

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Publication details

The article was received on 08 Mar 2016, accepted on 30 Apr 2016 and first published on 02 May 2016


Article type: Paper
DOI: 10.1039/C6DT00932H
Citation: Dalton Trans., 2016,45, 13082-13090
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    Evaluation of H2CHXdedpa, H2dedpa- and H2CHXdedpa-N,N′-propyl-2-NI ligands for 64Cu(II) radiopharmaceuticals

    C. F. Ramogida, E. Boros, B. O. Patrick, S. K. Zeisler, J. Kumlin, M. J. Adam, P. Schaffer and C. Orvig, Dalton Trans., 2016, 45, 13082
    DOI: 10.1039/C6DT00932H

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