CBDA, cannabidiolic acid, is the form in which the plant stores CBD. CBDA synthase cyclises CBGA into CBDA in the trichome head, competing with THCA synthase for the same CBGA supply. Decarboxylation by heat or time turns CBDA into CBD.
In practice
Plants with two functional CBDA synthase alleles and no functional THCA synthase make mostly CBDA; plants with one of each tend toward a balanced 1:1 profile. A breeder crossing a THCA-type with a CBDA-type parent typically sees a mix of THC-type, balanced and CBD-type offspring in the F2, roughly following simple Mendelian ratios at that locus, though real data are messier. Feeding, light or stress do not switch a plant from THCA to CBDA.
1 g of CBDA can yield at most 0.877 g of CBD. Total CBD = CBD + 0.877 × CBDA.
Don't confuse with
- CBD: the neutral product of decarboxylation.
- CBGA: the shared precursor of both CBDA and THCA.
- THCA: the alternative product of the same precursor, from a different enzyme.
CBD (cannabidiol) is a non-intoxicating neutral cannabinoid formed when CBDA decarboxylates; hemp-type and CBD-dominant cannabis make it mainly as CBDA in their trichomes.CBDA synthase is the trichome enzyme that converts CBGA into CBDA; it competes with THCA synthase, and its alleles largely decide whether a plant is CBD-dominant.CBGA (cannabigerolic acid) is the precursor cannabinoid that the plant converts into THCA, CBDA or CBCA, formed by joining olivetolic acid to geranyl pyrophosphate.Trichome heads are the bulbous resin-filled tops of capitate glandular trichomes, where cannabis makes and stores nearly all its cannabinoids and terpenes; they are the raw material of hash.THCA synthase is the trichome enzyme that converts CBGA into THCA; which alleles of its gene a plant carries largely decides whether it is THC-dominant.Decarboxylation is the loss of a carboxyl group as CO2 that turns acid cannabinoids such as THCA and CBDA into neutral THC and CBD, quickly with heat, slowly with time.THCA (tetrahydrocannabinolic acid) is the acid cannabinoid that drug-type cannabis makes in its trichomes; heat or time decarboxylates it into THC, losing about 12% of its mass.Total THC is a calculated figure, Δ9-THC plus 0.877 × THCA, estimating the maximum THC a sample could yield after full decarboxylation.The chemotype ratio is the balance of a plant's main cannabinoids, usually THC to CBD, classing plants as type I (THC-dominant), II (mixed), III (CBD-dominant), IV (CBG) or V (near-zero).Total CBD is a calculated figure, CBD plus 0.877 × CBDA, estimating the maximum CBD a sample could yield after full decarboxylation.
