THCA and CBDA: Diverse and Complex

After exploring the four most well-known cannabinoids, it’s time to circle back to the beginning — to the moment when cannabinoids are still present in the plant in their acidic forms. We’ll focus on two well-studied acids: tetrahydrocannabinolic acid (THCA) and cannabidiol acid (CBDA).

THCA and CBDA: Diverse and Complex

Most cannabinoids in the fresh cannabis plant exist primarily in the form of carboxylic acids, also known as precannabinoids. These precannabinoids are primarily formed from two basic precursors: cannabigerolic acid (CBGA) and cannabigerovarinic acid (CBGVA).

CBGA

CBGA is the precursor of all major cannabinoids — or more precisely, their acidic forms: tetrahydrocannabinolic acid (THCA), cannabidiol acid (CBDA), and cannabichromenic acid (CBCA). After decarboxylation, CBGA becomes cannabigerol (CBG).

The therapeutic use of CBD in practice is limited by its ability to reduce liver metabolism of other drugs. This effect has not yet been observed with CBDA.

Since CBGA is converted into the aforementioned acids, its quantity in the plant is usually trace. Higher levels are found only in special cultivars with a genetically blocked CBGA conversion.

CBGVA

CBGVA, whose molecule is two carbon atoms shorter than CBGA, leads to the formation of so-called propyl cannabinoids, such as THCVA (tetrahydrocannabivarinic acid) and CBDVA (cannabidivarinic acid). These compounds are usually present only in tiny amounts, except in some South African (for THCVA) or Afghan cultivars (for CBDVA).

Occurrence of acids in different species

CBDA is the main precannabinoid in “industrial” hemp — the Cannabis sativa species cultivated mainly for fiber. In the psychoactive species Cannabis indica, THCA usually dominates, although in the subspecies Cannabis indica subsp. afghanica (commonly — though incorrectly — referred to as “indica”), both acids are often present in roughly equal amounts.

CBCA is often dominant in both C. indica and C. sativa, but only in young plants, as its amount decreases with plant maturity.

Tendency to Decarboxylation

Compared to their neutral forms, the effects of acidic cannabinoids are much less researched. This is mainly due to their relative instability and their tendency to decarboxylate, making it difficult to isolate them in pure form.

It often happens that the conversion of a precannabinoid to a cannabinoid occurs during the experiment itself, rendering the results unusable.

For a long time, cannabinoid acids were considered biologically inactive, but recent research suggests otherwise. Attention is especially focused on THCA and CBDA, while data on other acids are still lacking.

This article was also published in the magazine KONOPÍ.