THC

2 Pages 480 Words

Tetrahydrocannabinol (THC) is the active chemical in cannabis and is one of the oldest hallucinogenic drugs known. There is evidence that cannabis extracts were used by the Chinese as a herbal remedy since the first century AD. Cannabis comes from the flowering tops and leaves of the hemp plant, Cannabis sativa (shown in the picture on the right). For centuries this plant has been widely cultivated around the world for its fibers, and indeed the word canvas, which is a material made from woven hemp fibers, takes its name from cannabis. However, cannabis is more commonly known as the source of the marijuana drug, although the word marijuana applies both to the whole plant, and to the resin from it (although this is sometimes also called hashish).
Cannabis contains approximately 60 different psychoactive chemicals called cannabinoids, of which the most important one is tetrahydrocannabinol (THC). The mode of action of THC is still not properly understood, although it is known that of the two stereoisomers (mirror images), the (-)-form (the left-handed form of the molecule) is 10-15 times more potent than the (+)-form.
The cannabinoids belong to a class of chemicals called terpenoids, meaning terpene-like. These compounds occur as essential oils within many plants and some are involved in the formation of vitamins, steroids, pigments and odors. The perfume industry relies on compounds such as these, and they also find a variety of uses in the food and pharmaceutical industry as flavor and odor improvers. Terpenes can be linear (such as geraniol or citronella) or cyclic as in THC. Examples of some other simple cyclic terpenes are shown below.
The cannabinoids are basically non-polar molecules, with low solubility in water, so they are normally self-administered by smoking. The volatilized fractions are inhaled as a vapor and give rise to a number of physiological effects. These effects depend very much upon the expectations and mood of t...