Synthesis and evaluation of new mixed “2 + 1” Re, 99mTc and 186Re tricarbonyl dithiocarbamate complexes with different monodentate ligands

Bifunctional chelators for radiorhenium: past, present and future outlook

“…Due to the slower kinetics of rhenium during radiolabelling, the [ 186 Re]Re-complexes were obtained in lower radiochemical yields than their 99m Tc equivalents. 152 They did, however, remain stable at room temperature over 48 hours and showed high resistance to transchelation in vitro during histidine and cysteine challenge assays (>95% complex intact). 152 These dithiocarbamate-containing [ 186 Re]Recomplexes with isocyanide, phosphine and arsine monodentate ligands also provide the opportunity for biomolecule conjugation, as the ligands are amenable to derivatisation.…”

“…152 They did, however, remain stable at room temperature over 48 hours and showed high resistance to transchelation in vitro during histidine and cysteine challenge assays (>95% complex intact). 152 These dithiocarbamate-containing [ 186 Re]Recomplexes with isocyanide, phosphine and arsine monodentate ligands also provide the opportunity for biomolecule conjugation, as the ligands are amenable to derivatisation. In particular, these highly lipophilic complexes could be conjugated with biomolecules which require the penetration of the cell membrane to reach their desired target.…”

“…This "2 + 1" approach of a combination of monodentate and bidentate ligands has been shown to afford complexes with high in vitro stability with a decent level of flexibility. 152 There is also a good opportunity to design very versatile complexes as the pharmacokinetics can be fine-tuned using one ligand while the targeting ligand may be incorporated with the other. While this approach has been used extensively in the preparation of 99m Tc-labelled biomolecules, it has less commonly been used to produce "2 + 1" complexes of radiorhenium.…”

“…In particular, these highly lipophilic complexes could be conjugated with biomolecules which require the penetration of the cell membrane to reach their desired target. 152 Another recent example in the search for radiorheniumtricarbonyl complexes for use in targeted radionuclide therapy is the [ 188 Re]Re-tricarbonyl tamoxifen compound synthesised by Chhabra et al in 2021 (Fig. 23b).…”

“…Shegani et al in 2021 synthesised a series of “2 + 1” tricarbonyl complexes with the general formula fac -[Re/ 99m Tc/ 186 Re(CO) 3 (DDTC)(L)] which contained a bidentate diethyldithiocarbamate (DDTC) ligand and a variety of monodentate ligands (L). 152 One of the [ 186 Re]Re-tricarbonyl complexes evaluated by this group is shown in Fig. 23a.…”