Development of Cobinamide as Potential Antidote for Azide Poisoning

Sodium azide, referred to as “NaN3” or “azide” in this thesis, is a common pesticide, laboratory preservative, and propellent in vehicular airbags due to its explosive properties. Despite its practical utilities, azide is highly toxic. Ingestion of several grams can cause death in 1-2 hours. Azide’s high toxicity in conjunction to its commercial availability are causes for concern and the chemical is listed as a potential terrorism threat (Holstege et al. 2007). There are two proposed mechanisms of azide toxicity: inhibition of cellular respiration via cytochrome C oxidase inhibition and generation of nitric oxide. Inhibition of cytochrome C by azide is well documented but generation of nitric oxide has only recently been found in vivo. Since there is no FDA-approved antidote for azide poisoning, development of an antidote for azide poisoning is a public health priority. Members of the Boss Lab have shown that cobinamide (Cbi), a vitamin B12 analog, scavenges azide and nitric oxide. We hypothesized that cobinamide could antagonize azide poisoning based on azide’s mechanism of toxicity and how cobinamide functions. We determined that azide inhibited cell growth and cobinamide offered protection. We saw that D. melanogaster (fruit flies) raised on food containing cobinamide were partially protected from azide toxicity, with survival as a readout. We found that azide induced nitric oxide generation in mice. Finally, we observed that cobinamide rescued mice poisoned with a lethal dose of azide. Altogether our results demonstrated azide toxicity in vitro and in vivo and that cobinamide could reverse these toxic effects