N-Nitrosamine Research Paper

The carcinogenic nature of N-nitrosamines depends on the organs. For example, their targets for cancer in rodents include thyroid, pancreas, urinary bladder, trachea, lung, oral and nasal cavities, esophagus, kidney and liver. With respect to N-nitrosamides, skin, bone, peripheral nervous system, brain, small intestine and glandular stomach are targeted organs for cancers. Besides cancer, acute myelocytic leukemia and T and B cell lymphoma have also been triggered by N-nitrosamides. In table 8.1, some N-nitrosamines and their main targets organs are summarized. Another property of the carcinogenicity of N-nitrosamines is that a single dose in large amount is less effective than multiple doses in small amount (Pegg & Shahidi 2000). The carcinogenesis of N-nitrosamines requires several steps shown in figure 1. As N-nitrosamines are biochemically stable, they firstly need to be activated to form alpha-hydroxynitrosamines. This is done by cytochrome P450-dependent
Moreover, carcinogenesis of N-nitrosamines differs from that of N-nitrosamides in that N-nitrosamides induce regional and systemic tumors whereas N-nitrosamines only induce systemic tumors which occur far away from the place of application (Tricker & Preussmann 1990).
However, according to DNA studies, tumors were found only in some organs where methylated DNA was recognized. This indicates that cancerous cells cannot be initiated by DNA alkylation alone. The primary factor that comes into play has been suggested as the role of cyclic nitrosamines since cyclic nitrosamines are structurally hindered to induce DNA alkylation, but have also exhibited carcinogenicity (Tricker & Preussmann