Voltammetric redox behavior of nitrofuryl 1,4-dihydropyridine derivatives: Interdependence between two redox centers

To investigate new chemotherapeutics alternatives to Chagas’ disease, three 4-(5′-nitro-2′-furyl)-1,4-dihydropyridine derivatives were synthesized and electrochemically investigated in order to clarify their redox behavior. The redox behavior of these compounds is very attractive as they share a reducible (nitrofuryl) and an oxidizable (1,4-DHP) moiety, the interdependence of these two redox centers will be our current challenge. The reduction of the nitrofuryl derivatives was studied in two different protogenic aqueous-organic media (Britton–Robinson buffer/ethanol: 70/30 and citrate buffer/DMF: 60/40) and working at two different experimental time windows (i.e., Polarographic and cyclic voltammetric experiments). The current work reveals that both redox centers showed a great interdependence and electronic communication, determining its electrochemical properties. The reduction potential of the nitrofuryl moiety can be modulated at both fine tuning (tens of mV) by changing the electronic properties of the 3,5 substituents in the 1,4-DHP ring, and coarse tuning (cents of mV) by changing the oxidation state of the 1,4-DHP ring into a pyridine ring, thus producing nitrofuryl derivatives with very low reduction potentials, i.e., good candidates to be reduced by nitroreductases.