Nicotine is a natural alkaloid obtained from the dried leaves and stems of the nightshade family of pants, such as Nicotiana tabacum and Nicotiana rustica, where it occurs in concentrations of 0.5-8%. Cigarette tobacco varies in its nicotine content, but common blends contain 15-25 mg per cigarette, with a current trend towards lower levels. Nicotine is highly addictive substance, it exhibits a stimulant effect when adsorbed at 2 mg. Administration of higher doses could be harmful. Action of nicotine is mediated by nicotinic cholinergic receptors. Nicotine binds to the interface between two subunits of the receptors, opens the channel and allows the entry of sodium or calcium. The principal mediator of nicotine dependence is α4β2 nicotine receptor.

Myosmine (3-(1-pyrrolin-2-yl)pyridine) is a minor tobacco alkaloid widely occurring in food products of plant and animal origin. Myosmine expresses significant genotoxic effects in human target cells of carcinogenesis. After nitrosation and/or peroxidation, myosmine gives rise to reactive pyridyloxobutylating species which are capable of forming pyridyloxobutylated DNA adducts.

Anabasine, a tobacco alkaloid, was used as a biomarker of active tobacco use. Anabasine is a selective alpha7-nicotinic acetylcholine receptor agonist. Anabasine antagonized MK-801-elicited mouse popping behavior, an animal model of schizophrenia.