Nicotine is a potent parasympathomimetic stimulant and an alkaloid found in the nightshade family of plants. Nicotine acts as an agonist at most nicotinic acetylcholine receptors (nAChRs), except at two nicotinic receptor subunits (nAChRα9 and nAChRα10) where it acts as a receptor antagonist. Nicotine is found in the leaves of Nicotiana rustica, in concentrations of 2–14%; in the tobacco plant, Nicotiana tabacum; in Duboisia hopwoodii; and in Asclepias syriaca.
Nicotine constitutes approximately 0.6–3.0% of the dry weight of tobacco. It also occurs in edible plants, such as those in the Solanaceae...