Particularly,
nicotine-derived nitrosamine ketone, or 4-(methylnitrosamino)-
1-(3-pyridyl)-1-butanone (NNK), carcinogen derived from nicotine, serves as a cause for etiology of lung cancer .
In contrast, cotinine [(5S)-1-methyl-5-(3-pyridyl)-pyrrolidin-2-
one], another main metabolite of nicotine, does not provide cardiovascular
or addictive side effects in humans . It is converted from nicotine in the
liver by enzymes such as cytochrome P450 2A6 (CYP2A6) and cytochrome
P450 2A5 (CYP2A5), eventually excreted in the urine
of humans (Moran 2012). A recent study reported that cotinine
has beneficial therapeutic properties . In addition, cotinine has revealed to improve both
memory and attention, resulting in the prevention of Alzheimer’s
disease (AD)