Nicotine is an alkaloid found in the nightshade family of plants (Solanaceae), predominantly in tobacco, and in lower quantities in tomato, potato, eggplant (aubergine), and green pepper.
Nicotine alkaloids are also found in the leaves of the coca plant.
Nicotine constitutes 0.3 to 5 percent of the tobacco plant by dry weight, with biosynthesis taking place in the roots, and accumulates in the leaves.
It is a potent neurotoxin and is included in many insecticides. In lower concentrations, the substance acts as a stimulant and is one of the main factors responsible for the dependence-forming properties of tobacco smoking..
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