Oxidation of Amines to Nitroso Compounds
Oxidation of Amines to N-Nitrosamines: Biological Importance
In an acidic medium, for example in the human stomach, nitrite is being transformed into nitrosyl cation. This intermediate subsequently reacts with an amine, taken up with food, to form a N-nitrosamine.
N-Nitrosamines can also be generated by exposing cured food to heat.
N-Nitrosamines per se are pro-carcinogens, i.e. precursors which have to be activated in the human body. The activating step is enzymatic α-C-hydroxylation by microsomal cytochrome P-450-dependent monoxygenase. In a multistep sequence involving several reactive intermediates, a labile diazohydroxide or diazotic acid is generated. This electrophile reacts with nucleophilic centers of DNA to form stable adducts which might cause genotoxic effects.