ArecolineHow about the fifth most widely used psychoactive drug in the
world? Most likely it is the cannabis plant (genus Cannabis) in its
various forms—marijuana and hashish, smoked and orally ingested
—or, represented by its primary identified psychoactive chemical
component, delta-9-tetrahydrocannabinol (THC). This statement
now becomes sketchier, because there is no good worldwide data on
the prevalence of cannabis use. Because cannabis is prohibited by law
in many countries, determining the prevalence of use is all the more
difficult.
The drug molecules discussed above—caffeine, ethanol, nicotine,
arecoline, and THC—all come, directly or indirectly (in the case of
ethanol), from plants. Importantly, though, plants and chemicals
are very different. Chemicals are single, identified substances, which
may have specific effects on physiology associated with well-defined
molecular interactions. Plants are far more complicated, and we may
not even know the half of it. First of all, plants are extraordinary
chemical factories. In addition to the hundreds of molecular com-
ponents shared with many other life forms, they are well known for
their ability to create weird molecules of many different kinds. Every
plant (and fungus) contains strange molecules, perhaps a handful,
perhaps dozens. Some of these weird molecules are known to have
drug effects in humans.