Nicotine, one of the
major constituents in cigarette smoking is known to be a major
risk factor in the development of chronic obstructive lung
diseases, cardiovascular disorders, and lung cancer.It also augments both free fatty acid release fromthe liver and the hepatic synthesis of very low-density lipoproteins,
resulting in genotoxicity . In addition, nicotine provokes oxidative stress
by stimulating intracellular production of reactive oxygen species
(ROS) .
ROS damage on the mitochondrial and nuclear DNA, proteins,
and lipids has been identified as one of the most important deleterious
mechanisms of nicotine . 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)