Nicotine is an alkaloid found in the nightshade family of plants (Solanaceae) that acts as a nicotinic acetylcholine agonist and a monoamine oxidase inhibitor. The biosynthesis takes place in the roots and accumulation occurs in the leaves of the Solanaceae. It constitutes approximately 0.6–3.0% of the dry weight of tobacco and is present in the range of 2–7 μg/kg of various edible plants. It functions as an antiherbivore chemical; therefore, nicotine was widely used as an insecticide in the past and nicotine analogs such as imidacloprid are currently widely used.