Dinitrosyl iron complexes with thiol-containing ligands as sources of universal cytotoxins - nitrosonium cations

Abstract

It was shown that the release of a half of nitrosyl ligands from dinitrosyl iron units in the form of nitrosonium cation (NO+) from binuclear dinitrosyl iron complexes with thiol-containing ligands (B-DNIC) during DNIC decomposition in acid solutions is increased with the decrease of the stability of these complexes and completely blocked with the increase of the concentrations of free thiols (non-included into B-DNIC) up to the level that was two times and more than that of dinitrosyl iron units. It was demonstrated that the less stable B-DNIC with mercaptosuccinate degrade in an acidic environment at ambient temperature, while the decomposition of more stable B-DNIC with glutathione was only marked when the solution was heated at 80°C. The inhibition of NO+ release from B-DNIC in the presence of elevated free thiol level in the solution was due to the ability of free thiols to induce the reduction of NO+ to NO.