Most everyone knows that THC is the psychoactive component of cannabis, while CBD is billed as a non-psychoactive cannabinoid. Let’s talk chemistry for a bit. THC and CBD share the same chemical core, and are in fact chemical isomers: both are composed of 21 carbon, 30 hydrogen and 2 oxygen atoms. In the plant, both compounds are carboxylated on the phenyl ring, giving CBDA and THCA. Heating converts the acid forms to base CBD and THC.
Both THCA and CBDA are derived from cannabigerolic acid (CBGA), thus explaining their common core. CBGA is converted into THCA in the plant via the enzyme THCA synthase, while a separate enzyme, CBDA synthase converts the CBGA to CBDA. Again, heat, or simply time will decarboxylate the acid forms to the parent cannabinoids. Hemp is a cultivar of cannabis that contains the enzyme needed to produce CBD, while “marijuana” cultivars are high in THCA synthase. Thus, one of the main differences between hemp and “marijuana” is the expression of genes encoding the two disparate synthases. Hemp and cannabis are the same plant, except for the relatively small differences in synthase production. Think about the differences between yellow and red roses: the plants are nearly identical genetically, yet produce different color flowers.
Most folks are surprised to learn that CBD can be isomerized to THC in the presence of acid and heat. While not a clean and easy conversion, hemp processors need to maintain a neutral pH to prevent this transformation from increasing THC levels in their extract.
CBD vs THC – What is the difference?
In the next post we’ll discuss how the minor chemical differences between the two cannabinoids lead to major differences in their biochemical interactions with the human body.