Cannabis contains a large variety of different chemical compounds. With already well over 500 known constituents, cannabis is one of the chemically best studied plants. But because most of these constituents have not yet been properly characterized for biological activity, the cannabis plant could be called a “neglected pharmacological treasure trove”. Many of the cannabis constituents can also be found in other plant species. However, the cannabinoids are unique to the cannabis plant alone.
The most interesting constituents are those found in the secretions of resin glands (trichomes) distributed across the surface of the Cannabis plant. Although trichomes can be found all over the male and female plants, they are particularly concentrated in the area of the female flowers. The excreted resinous material is made up of a mixture of different chemicals, the most important of which are the cannabinoids and terpenes. The outer layer of the excreted material is made up of a wax layer, which protects the other chemicals from oxidation and degradation. Because of its sparkly appearance under strong light, the resin glands are often referred to as ‘crystals’.
Cannabinoids are unique chemical structures that can only be found in the cannabis plant. They are generally accepted as the main medicinal ingredients of cannabis. The most commonly known cannabinoid is tetrahydrocannabinol (THC), which is also the compound that is responsible for getting high after consuming larger amounts of cannabis. Because of this psychotropic effect, THC is often referred to as the active constituent of cannabis.
However, already more than 70 different cannabinoids have been identified so far. These compounds have a chemical structure that is much related to THC, but their biological effects are quite different and they have (virtually) no psychotropic potential. It is becoming increasingly clear that such lesser known cannabinoids may have therapeutic use for certain medical conditions. The most important example of this is cannabidiol (CBD), which has shown potent anti-cancer and anti-psychotic effects. Other cannabinoids which are under investigation include cannabigerol (CBG) and tetrahydrocannabivarin (THCV).
For those who enjoy chemistry, it should be noted that THC and CBD are present in the plant in their so-called acid-form. Only during heating of the flowers to high temperatures (such as during vaporizing, smoking, or baking) these ‘precursors’ are rapidly transformed into the more active compounds.
The terpenes are the chemicals that give cannabis its distinct smell. Cannabis contains a large number as well as a significant amount of terpenes. These compounds can be easily evaporated and are consequently inhaled by smoking or vaporizing. Already more than 120 different terpenes have been identified in cannabis, and there relative composition can be very different between cannabis strains. In fact, drug search dogs are trained to recognize specific terpenes in order to find cannabis. The cannabis terpenes have a wide range of known biological effects, such as anti-inflammatory, antibiotic or analgesic. Some terpenes may also be involved in regulating and/or changing the effects of THC and other cannabinoids.
Different strains of cannabis produce a different spectrum of chemical constituents. Some constituents may be only produced by very specific strains, or the same constituents may be present, but in different relative amounts. As a result, the medicinal properties of cannabis strains may vary widely. Because of the large number of constituents to be considered, it is still very hard to study scientifically how the chemical composition of a cannabis strain is related to its effect on different medical conditions.
The Dutch official cannabis grower Bedrocan is developing chemically distinct cannabis varieties with a different profile of cannabinoids and terpenes. At this moment, 4 different cannabis varieties are available through Dutch pharmacies. New varieties are being developed as part of Bedrocan’s ongoing Research and Development program. Any new variety needs to be fully standardized to guarantee a reproducible and reliable chemical composition.