Synthesis, characterisation and cytotoxicity of rhenium complexes with Bis(2-pyridylmethyl)amine and two of its derivatives

Abstract

The three ligands showed relatively good cytotoxicity with IC 50 values ranging from 10±2 to 16±1 µM, while the cytotoxicity of the rhenium complexes was less with IC 50 values ranging from 26±1 to 38±1 µM. Similar results have been reported before, where the presence of the metal appears to show a dilutive effect on the cytotoxicity of the ligand. This makes these complexes ideal for use as theranostic agents, since the ligand provides cytotoxicity, while a radioactive metal center can offer diagnostic properties. The synthesis, characterisation, crystal structures and cytotoxicity against HeLa cells of three rhenium complexes fac -[Re(CO) 3 (PMA)] + (PMA = bis(2-pyridylmethyl)amine), fac -[Re(CO) 3 (PMAEth)] + (PMAEth = bis(2-pyridylmethyl)-2-aminoethanol), and fac -[Re(CO) 3 (PMAProp)] + (PMAProp = bis(2-pyridylmethyl)-2-aminopropanol) are reported. The tripodal ligands showed slightly higher cytotoxicity than the coordinated complexes with IC 50 values ranging from 10 µM to 38 µM. These values, together with the fact that the ligand backbones can be easily modified to introduce higher toxicity, supports the possible use of Rhenium(I) as a theranostic radiopharmaceutical.