LAUSR

The kinetics of nitrogen oxide release by binuclear dinitrosyl iron complexes (B-DNICs) with thiolate ligands based on thiophenol and its several oxy, amino, and nitro derivatives was studied using a suspension of red blood cells simulating the internal medium of a blood vessel. The NO donating ability of the complexes was estimated by the kinetic parameters of first-order equation, which described the formation of intra-erythrocytic methemoglobin. Three typical kinetic profiles of NO donation were distinguished: pseudosaturation donation and donation with prolonged and explosive profiles. In the case of first-type NO donation typical of complexes with thiophenol and its nitro derivatives, the curves display a fast coming to saturation long before the complete release of all NO groups contained in the structure of the starting complex into a solution. Such a type of donation is likely due to the formation of long-lived nitrosyl intermediates in the system. The prolonged type of NO donation shown by the complex with hydroxyphenyl ligand is characterized by virtually constant rate of NO release into a solution without pronounced transition to saturation during experiment (10–12 min). In the case of explosive-type donation characteristic of the complex with aminophenyl ligands, a considerable portion of NO was fast released into a solution within 1–3 min. All complexes under study caused hemolysis of a 0.2% suspension of red blood cells. The complex with aminophenyl ligands exhibited the highest hemolytic activity.