Novel Roussin's red salt esters as cardiovascular protectors: "Structure-activity" correlations, properties in solid state and solutions.

A novel binuclear neutral tetranitrosyl iron complexes (NICs) with phenylmethanethiolyl and phenylethanethiolyl ligands were synthesized, and their properties were compared with known phenylthiolyl NIC. It has been shown that in this series of compounds, the complex with phenylethanethiolyls demonstrates a prolonged release of nitric oxide (NO) in aqueous solutions, which is unusual for the class of Roussin's red salt esters. The combination of data on NO generation with the results of biological activity (based on changes in the level of cyclic nucleotides and their cytotoxicity on Vero cells) allows us to conclude that the complex with phenylethanethiolyls is of greatest interest among the studied compounds and is promising for further use in the treatment of cardiovascular diseases. The article describes the mechanism of decomposition of this complex in various model systems. For aerobic and oxygen-free systems in DMSO and Tris-HCl buffer, the substitution of NO ligands occurs with the preservation of the binuclear diamagnetic structure, in contrast to the phenylthiolyl complexes. Additionally, the complex can bind to serum albumin and mucin. In the latter case, an increase in the concentration of NO groups and the appearance of an EPR signal from mononuclear complexes is observed.