The classical cannabinoids are concentrated in a viscous resin produced in structures known as glandular trichomes. At least 113 different cannabinoids have been isolated from the Cannabis plant. To the right, the main classes of cannabinoids from Cannabis are shown. The best studied cannabinoids include tetrahydrocannabinol (THC), cannabidiol (CBD) and cannabinol (CBN).
All classes derive from cannabigerol-type compounds and differ mainly in the way this precursor is cyclized. The classical cannabinoids are derived from their respective 2-carboxylic acids(2-COOH) by decarboxylation (catalyzed by heat, light, or alkaline conditions).