Synthesis and nitric oxide release study of dinitrosyl cobalt complexes

Three dinitrosyl cobalt complexes (DNCCs) [(Dppe)Co(NO)(2)]Cl, [(Dppp)Co(NO)(2)]Cl and [(TMEDA)Co (NO)(2)]BPh4 were synthesized using CoCl2 center dot 6H(2)O as a starting material and were isolated via fast column chromatography with final yields ranging from 53% to 67%. These EPR silent DNCCs each showed only one pair of redox events ({Co(NO)(2)}10/11) in the cyclic voltammograms. In comparison with sodium nitroprusside (SNP), the DNCCs' NO release amount and duration significantly enhanced, and were related closely to their hydrolytic stability. Additionally, DNCCs have demonstrated significantly higher NO cellular uptake rates in the first 5 h than SNP by human umbilical vein endothelial cells (HUVEC), to which the DNCCs also showed low cytotoxicity. Based on the fact that DNCCs could hydrolyze yielding ligands as the remaining products and the possible formation of [(Dppp)Co(NO)(2)] and [(Dppp)Co(PPh3)(NO)] in the reduction of [(Dppp)Co(NO)(2)]Cl, a plausible NO release mechanism via a one electron reduction process was proposed.

Automated summary

Three dinitrosyl cobalt complexes (DNCCs) were synthesized from CoCl2 center dot 6H(2)O, with final yields ranging from 53% to 67%, and isolated via fast column chromatography. These EPR silent DNCCs showed only one pair of redox events in the cyclic voltammograms. Compared to sodium nitroprusside (SNP), the DNCCs exhibited significantly enhanced NO release amount and duration, which were closely related to their hydrolytic stability. Additionally, the DNCCs showed higher NO cellular uptake rates in the first 5 hours than SNP by HUVEC, and had low cytotoxicity. A plausible NO release mechanism via a one electron reduction process was proposed based on the hydrolysis of DNCCs and the possible formation of [(Dppp)Co(NO)(2)] and [(Dppp)Co(PPh3)(NO)] in the reduction of [(Dppp)Co(NO)(2)]Cl.