The synthesis of [Ru(NO2)L(bpy)2]+ (bpy = 2,2′-bipyridine and L = pyridine (py) and pyrazine (pz)) can be accomplished by addition of [Ru(NO)L(bpy)2](PF6) 3 to aqueous solutions of physiological pH. The electrochemical processes of [Ru(NO2)L(bpy)2]+ in aqueous solution were studied by cyclic voltammetry and differential pulse voltammetry. The anodic scan shows a peak around 1.00 V vs. Ag/AgCl attributed to the oxidation process centered on the metal ion. However, in the cathodic scan a second peak around -0.60 V vs. Ag/AgCl was observed and attributed to the reduction process centered on the nitrite ligand. The controlled reduction potential electrolysis at -0.80 V vs. Ag/AgCl shows NO release characteristics as judged by NO measurement with a NO-sensor. This assumption was confirmed by ESI/MS+ and spectroelectrochemical experiment where cis-[Ru(bpy) 2L(H2O)]2+ was obtained as a product of the reduction of cis-[RuII(NO2)L(bpy)2] +. The vasorelaxation observed in denuded aortic rings pre-contracted with 0.1 μmol L-1 phenylephrine responded with relaxation in the presence of cis-[RuII(NO2)L(bpy)2]+. The potential of rat aorta cells to metabolize cis-[RuII(NO 2)L(bpy)2]+ was also followed by confocal analysis. The obtained results suggest that NO release happens by reduction of cis-[RuII(NO2)L(bpy)2]+ inside the cell. The maximum vasorelaxation was achieved with 1 × 10-5 mol L-1 of cis-[RuII(NO2)L(bpy)2] + complex.
ASJC Scopus subject areas