Nicotine is an alkaloid found in the nightshade family of plants (Solanaceae), predominantly in tobacco and coca, and in lower quantities in tomato, potato, eggplant (aubergine), and green pepper. Nicotine has been found to constitute approximately 0.6-3% of dry weight of tobacco,[1] with biosynthesis taking place in the roots, and accumulating in the leaves. It functions as an antiherbivore chemical, being a potent neurotoxin with particular specificity to insects; therefore nicotine was widely used as an insecticide in the past, and currently nicotine derivatives such as imidacloprid continue to be widely used.
In low concentrations (an average cigarette yields about 1 mg of absorbed nicotine), the substance acts as a stimulant in mammals and is one of the main factors responsible for the dependence-forming properties of tobacco smoking. According to the American Heart Association, "Nicotine addiction has historically been one of the hardest addictions to break." The pharmacological and behavioral characteristics that determine tobacco addiction are similar to those that determine addiction to drugs such as heroin and cocaine.[2]
Tobacco smoking is the act of burning dried or cured leaves of the tobacco plant and inhaling the smoke for pleasure, for ritualistic or social purposes, self-medication, as well as to satisfy a physiological dependence on nicotine. Tobacco use by Native Americans throughout North and South America dates back to 2000BC. The practice was brought back to Europe by the crew of Christopher Columbus. Tobacco smoking took hold in Spain and was introduced to the rest of the world, via trade. Tobacco is an agricultural product processed from the fresh leaves of plants in the genus Nicotiana. Tobacco has been growing on the northern continents since about 6000 BC and began being used by native cultures at about 3000 BC. It has been smoked in one form or another since about 2000 BC. There are pictoral drawings of ancient Mayans smoking crude cigars from 1400 BC.
Tobacco smoke contains nicotine and harmane (a MAO inhibitor), which combined give rise to addictive stimulant and euphoriant properties. The effect of nicotine in first time or irregular users is an increase in alertness and memory, and mild euphoria. Nicotine also disturbs metabolism and suppresses appetite. This is because nicotine, like many stimulants, increases blood sugar.
Medical research has determined that chronic tobacco smoking can lead to many health problems, particularly lung cancer, emphysema, and cardiovascular disease.[1][2]
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