Enzymatic hydrolysis of ester groups of mixed-ligand oxorhenium(V) and oxotechnetium(V) complexes

In order to elucidate the potential and limitation of ester groups as a tool in designing 99mTc radiopharmaceuticals, the enzymatic hydrolysis of 17 anionic Tc and Re complexes with systematically altered ester functionality was studied by incubation with pig liver esterase, rat plasma and human plasma and characterization of the products by HPLC and FAB-mass spectrometry. The effects of molecular parameters such as the charge of the mostly mixed-ligand S-coordinate complexes, the denticity of ligands and the neighbouring group are described.