Bis(4-nitrobenzenethiolato)tetranitrosyldiiron: synthesis, structure, and pharmacological activity of a new nitric oxide (NO) donor

Abstract

A preparative procedure was developed for the synthesis of new binuclear tetranitrosyl iron complex of the “μ-S” structural type, [Fe₂(SC₆H₄NO₂)₂(NO)₄] (1), comprising the replacement of the thiosulfate ligands in Na₂[Fe₂(S₂O₃)₂(NO)₄]•4H₂O by anions of the 4-nitrobenzenethiolate hydrazinium salt. The salt was obtained by the reduction of bis(4-nitrophenyl) disulfide with hydrazine hydrate in ethanol. The physicochemical properties of the complex in the solid state were studied by IR and Mössbauer spectroscopy. According to amperometric measurements in aqueous solutions, the complex generates NO in a protic medium without additional photo, thermal, or redox activation, providing prolonged release of NO, since the para-positioned nitro group in the aromatic ligand functions as an additional NO source. A study of the pharmacological activity by the MTT assay showed that the complex possesses a high cytotoxic activity against the MCF7 human breast cancer cells (IC₅₀ = 47 μmol L^–1) and an antibacterial activity against gram-negative (E. coli, BB strain) and gram-positive (M. luteus, 21/26 strain) microorganisms.