What is Nicotine?

by Phyllis Pugh, PhD

Nicotine is an alkoloid (a substance with a basic charge) contained in the leaves of several species of plants. The primary commercial source of nicotine is by extraction from the dried leaves of tobacco plant (Nicotinia tabaum and N. rustica).

The chemical formula for nicotine is C10H14N2, with a molecular mass of 162.23 . In proper nomenclature, nicotine is 3-(1-Methyl-2-pyrrolidinyl)pyridine. Nicotine's structure was deduced by Pinner (Berichte der Deutschen Chemischen Gesellschaft 29: 294), and looks like this:

nicotine structural diagram

Since there are several other compounds which act in similar manners to nicotine, I thought I would include their information here as well.

The first other compound is acetylcholine (ACh), the natural agonist for the receptors which also bind nicotine (c.f., nicotine's mode of action). ACh is synthesized in the body from choline and acetylCoA by the enzyme choline acetylase (also referred to as choline acetyltransferase, or CAT). In the laboratory, AChCl (acetylcholine chloride) can be synthesized from trimethylame and beta-chloroethyl acetate.

The chemical formula for AChCl is C7H16ClNO2, for a molecular mass of 181.68 . In proper nomenclature, AChCl is 2-(Acetyloxy)-N,N,N-trimethylethanamium chlorode. ACh is also known by the names Acecoline, Arterocolin, Miochol, and Ovisot. The structure of ACh is:

ACh structural diagram

Lobeline is another plant alkaloid which acts in some of the same ways as nicotine. Lobeline is extracted from the herb and seeds of Lobelia inflata, (Indian tobacco), a plant found in Canada and the US. [Interestingly, the plant's other names are "wild tobacco," "emetic herb," "asthma weed," "bladder bod," and "vomit wart," which should give you a hint as to some of the other effects of nicotine on the body.

The chemical formula of lobeline is C22H27NO2, for a molecular mass of 337.47 . In proper nomenclature, lobeline is 2-[6-(2-Hydroxy-2-phenylethyl)-1-methyl-2-piperidinyl]-1-phenylethanone. The absolute configuration of lobeline was determined by Schöpf and Müller [Ann. 687:241 (1965)] to be:

lobeline structural diagram

Finally, d-Tubocurarine chloride, or curare, (dTC) is yet another plant alkaloid which acts in the opposite manner of nicotine. dTC is extracted from Chondodendron tomentosum, a South American vine. Widely used as a muscle relaxant during surgery, curare was reportedly used by the Indians of Brazil, Peru, Ecuador and Colombia on the tips of their arrows.

The chemical formula of dTC is C37H43Cl2N2O6, for a molecular mass of 681.66 . In proper nomenclature, tubocurare is 7',12'-Dihydroxy-6,6'-dimethoxy-2,2',2'-trimethyltubocuraranium chloride hydrochloride. The structue was shown by Everett et al. [Chem Commun. 1070:1020] and Chodding and James et al. [Chem Commun. 1072:1174] to be:

dTC structural diagram

Something that is worth noting at this point is that all of those above structures interact with the same structure, although with differing affinities. That tells us that there are very specific parts of the molecules which are needed. In this case, the amine (N) is one of the necessities.