The metabolism and degradation of nicotine during senescence, curing and aging give rise to nicotine metabolites and reactive nicotine derived intermediates in air-cured tobacco. The major metabolite is nornicotine followed by cotinine and pseudooxynicotine (PON). All three products involve oxidation of the carbon alpha to the pyrrolidine nitrogen of the nicotine moiety. Nornicotine and cotinine are formed predominantly by metabolism during curing. We have observed that these three products can be formed by auto-oxidation in the tobacco matrix.
Both nornicotine and PON are intermediates for the formation of N'-nitrosonicotine (NNN) and 4-(N'-methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). One of the many questions posed for the accumulation of these nitrosamines, is nornicotine and PON concentrations limiting their accumulation? A study has recently been completed on analyzing 17 varieties of air-cured tobaccos for nicotine, PON, nornicotine, nitrate, nitrite, and TSNA. Data will be presented to show that these varieties contain different levels of alkaloids, nitrate, nitrite and PON. The results from these analyses will be compared to accumulation of NNN and NNK in the tobaccos.