Phytocannabinoids are cannabinoids that occur naturally in the cannabis plant. The classical cannabinoids are formed through decarboxylation of their respective 2-carboxylic acids (2-COOH), a process which is catalyzed by heat, light or alkaline conditions.
These cannabinoids are abundant in the viscous resin that is produced by glandular structures in the cannabis plant called trichomes. This resin is also rich in terpenes, which are responsible for the characteristic smell of the cannabis plant. The phytocannabinoids are mostly insoluble in water but are soluble in alcohol and fat and other non-polar organic solvents. In alkaline conditions, they can form water-soluble phenolate salts, being essentially phenols.
Of over 480 different compounds present in the cannabis plant, only around 66 have been identified as cannabinoids The most well known of these compounds is the delta-9-tetrahydrocannabinol (Δ9-THC), the main psychoactive ingredient in the plant. Other common cannabinoids include cannabidiol (CBD) and cannabinol (CBN).
Classes of cannabinoids
The cannabinoids are separated into subclasses that include:
- Cannabigerols (CBG)
- Cannabichromenes (CBC)
- Cannabidiols (CBD)
- Tetrahydrocannabinols (THC)
- Cannabinol (CBN)
- Cannabinodiol (CBDL)
- Cannabicyclol (CBL)
- Cannabielsoin (CBE)
- Cannabitriol (CBT)
- Cannabivarin (CBV)
- Tetrahydrocannabivarin (THCV)
- Cannabidivarin (CBDV)
- Cannabichromevarin (CBCV)
- Cannabigerovarin (CBGV)
- Cannabigerol Monoethyl Ether (CBGM)
Of these, THC is the main psychoactive component in the plant. This compound reduces pain perception in the brain and is also neuroprotective. THC has a similar affinity for the CB1 and CB2 receptors.
Cannabidiol (CBD), on the other hand, is not psychoactive and has been found to act as a CB1 receptor antagonist. CBN is effective at relieving convulsions or seizures, anxiety, nausea and inflammatory changes. Cannabigerol is also not psychoactive and acts as a CB1 receptor antagonist.
Reviewed by Sally Robertson, BSc