Chemistry of nitrogen dioxide and its biological implications

Nitrogen dioxide (•NO2) is a radical gas that forms part of air pollution and is produced chemically, photochemically and by ionizing radiation in aqueous and non-aqueous solutions as well as by various endogenous pathways in biological systems. This review describes the: (i) sources of •NO2; (ii) kinetics and mechanism of •NO2 reactions; (iii) •NO2 as a key player in cellular oxidative and nitrosative stress leading to pathological conditions, and (iv) use of diverse antioxidants to reduce •NO2 toxic effects.