Investigations on redox-active pyridinium-salt/dihydropyridine bearing Tc- and Re-complexes

Potentially redox-active NAD⁺/NADH-analogous pyridinium- and quinolinium-salt bearing Re- and ^99mTc-mixed-ligand complexes were synthesized. The complexes vary in the chelate type, the oxidation state of the metal, the spacer length to the chelate and the substituent at the pyridine/quinoline nitrogen. The complexes were reduced to dihydropyridines and dihydroquinolines respectively and investigations concerning their stability against reoxidation were performed. In competition experiments with NADH the quinoliniuni-salt/dihydroquinoline bearing complexes display enzymatic inhibition of the lactate dehydrogenase.