NNK (Nicotine-derived nitrosamine ketone) is a procarcinogen and a major tobacco-specific toxicant. It inhibits the expression of lysyl oxidase which is a tumor suppressor.

Hydroxycotinine is the main nicotine metabolite detected in smokers' urine.

Cotinine (NIH-10498) is an alkaloid found in tobacco and is also the predominant metabolite of nicotine.

R-(+)-Cotinine ((+)-Cotinine), a metabolite of Nicotine, demonstrates minimal activity across numerous pharmacological targets. However, it is capable of enhancing the acetylcholine (Ach)-evoked current in human α7 nicotinic acetylcholine receptors (nAChRs) [1].

beta-Nicotyrine is a tobacco alkaloids Metabolite in the liver.

(2'S)-Nicotine-1-oxide, a nicotine metabolite, arises from the liver's metabolism of nicotine via the cytochrome P450 (CYP) isoform CYP2A6. It has been identified in human sperm and semen.