Chi hong B. Chen

Chemical Studies on Tobacco Smoke: LI: Studies on Non-Volatile Nitrosamines in Tobacco

Abstract Various factors which might contribute to the presence of or reflect on the formation of N-nitrosonornicotine (NNN) or related nitrosamines in tobacco were studied. Using high-performance liquid chromatography (HPLC), the E- and Z-isomers of NNN were clearly separated and the rates of interconversion were determined. The E/Z ratio in tobacco approximated that observed in solution at similar pH and temperature. The influence of curing and stalk position on NNN levels in tobacco was determined. NNN was not detected in green tobacco but was detected in air-cured leaves from the same crop. No significant correlation was observed among stalk position and NNN levels in one variety of bright tobacco. Since NNN may derive from nicotine, two new nitrosamines, a nitrosamino ketone and a nitrosamino aldehyde, which could theoretically arise from nicotine, were synthesized. Analysis of tobacco for these components is currently in progress

α-Hydroxylation of N-nitrosopyrrolidine and N′-nitrosonornicotine by human liver microsomes

The environmental carcinogens N-nitrosopyrrolidine (NPYR) and N-nitrosonornicotine (NNN) were incubated with human liver microsomes to test for the presence of enzymes catalyzing alpha-hydroxylation, which is likely to be an activation mechanism for these compounds. Both nitrosamines underwent alpha-hydroxylation; rates were higher for NPYR than for NNN, as observed in rats. The results indicate that both NPYR and NNN can be metabolically activated by human liver microsomes.

Mass Spectra of Tobacco Alkaloid - Derived Nitrosamines, their Metabolites, and Related Compounds

Abstract The mass spectra of the tobacco alkaloid - derived nitrosamines NNN, NNK, NNA, NAB and NAtB and of known mammalian metabolites of NNN and NNK are presented. Mass spectra of synthetic derivatives related to these nitrosamines and their metabolites are also included. These spectra will be useful in studies on the occurrence and metabolism of the tobacco alkaloid - derived nitrosamines and in investigations of other compounds related to the tobacco alkaloids.