N-nitrosation and N-nitration of morpholine by nitrogen dioxide: inhibition by ascorbate, glutathione and alpha-tocopherol.

Ascorbate anion and glutathione were found to inhibit the aqueous reaction between nitrogen dioxide (NO2) and morpholine (MOR) and thereby prevented the formation of N-nitrosomorpholine (NMOR) and N-nitromorpholine (NTMOR) at both pH 7.4 and 12.5. These antioxidants are approximately 3 orders of magnitude more reactive towards NO2 than is MOR and may play an important role in the prevention of carcinogen formation in the lung due to inhaled NO2. Ammonium sulfamate was ineffective at preventing nitrosation or nitration by NO2 at either pH 7.4 or 12.5.