The mode of decomposition of Angeli's salt (Na2N2O3) and the effects thereon of oxygen, nitrite, superoxide dismutase, and glutathione

The classical view of the aerobic decomposition of Angeli's salt is that it releases NO2- + NO-/HNO the latter then reacting with O-2 to yield ONOO-. An alternative that has recently been proposed envisions electron transfer to O-2 followed by decomposition to NO2- + NO. The classical view is now strongly supported by the observation that the rates of decomposition of Angeli's salt under 20% O-2 or 100% O-2 were equal. Moreover, NO2-, which inhibits this decomposition by favoring the back reaction, was more effective in the absence of agents that scavenge NO-/HNO. It is thus clear that Angeli's salt is a useful source of NO-/HNO for use in defined aqueous systems. The measurements made in the course of this work allowed approximation of the rate constants for the reactions of NO-/HNO with NO2-, O-2, glutathione, or Cu, Zn superoxide dismutase. The likelihood of the formation of NO-/HNO in vivo is also discussed. (C) 2003 Elsevier Inc.