Synthesis and biodistribution of new oxo and nitrido 99mTc complexes with asymmetrical potentially dianionic or trianionic tetradentate SNNO ligands derived from methyl-2-aminocyclopentene-1-dithiocarboxylic acid.

In this work, 10 new asymmetrical tetradentate SNNO ligands were prepared by reaction of the amine function of methyl 2-[(beta-aminoethyl)amino]cyclopentene-1-dithiocarboxylate with various bifunctional substituents bearing hydroxyl/ketone and hydroxyl/aldehyde functional groups and with diethyl oxalate. 99mTc labeling efficiency was optimized by adjusting temperature and pH conditions. Seven nitrido and two oxo 99mTc complexes were isolated. Six of them proved to be stable near physiological conditions. Biodistribution studies in the rat showed a significant heart uptake for four of them and strong kidney and liver uptake for the other two.