The Cytostatic Action of Dinitrosyl Iron Complexes with Glutathione on Escherichia coli Cells Is Mediated by Nitrosonium Cations Released from These Complexes

This study demonstrates a bacteriostatic effect of binuclear dinitrosyl iron complexes with glutathione on Escherichia coli TN300 cells. It has been quantified by the colony formation assay. The bacteriostatic effect exerted by these complexes increases considerably in the presence of diethyldithiocarbamate. Our results suggest that this effect is caused by the intense release of nitrosonium cations, NO(+), from the complexes, which decompose under the action of diethyldithiocarbamate. A similar effect is observed when E. coli cells are treated with diethyldithiocarbamate 40 min after the addition of sodium nitrite or S-nitrosoglutathione. Notably, the level of dinitrosyl iron complexes observed in the bacterial cells due to the effects of sodium nitrite or S-nitrosoglutathione is almost the same as that obtained after treatment with glutathione-containing complexes. The bacteriostatic effects of the NO molecules released from nitrite or S-nitrosoglutathione during their brief interaction with bacteria were significantly smaller than the bacteriostatic effect of NO(+). We deduce therefrom that the nitrosonium cations released from DNICs are responsible for the observed bacteriostatic effect of these complexes in E. coli cells.