The Mapping of Physiological Conversion Pathways from the Major Acidic Cannabinoids

The acidic cannabinoids tetrahydrocannabinolic acid (THCA), cannabidiolic acid (CBDA), and cannabigerolic acid (CBGA) serve as primary precursors in cannabis phytochemistry. They undergo physiological conversion through decarboxylation, isomerization, degradation, and hepatic metabolism, yielding diverse neutral cannabinoids and phase I/II metabolites. Key Conversion Pathways THCA → Predominantly conjugated intact to THCA-glucuronide via UGT1A9; a minority fraction decarboxylates to Δ9-THC (with minor Δ8-THC, Δ10-THC, THCV if varin precursors present, CBN via oxidation, and traces of CBL/CBT). Active metabolites include 11-OH-THC (psychoactive) and oxidative derivatives; inactive metabolites feature THC-COOH (primary urinary marker), glucuronides, and carboxy analogs. CBDA → Directly glucuronidated through its own carboxyl group, a pathway that may dominate over oxidative metabolism; the remainder decarboxylates to CBD (with traces of CBDV). Active metabolites include 7-OH-CBD (equipotent to CBD) and cannabielsoin (CBE), recently characterized as a biased CB1 agonist; inactive metabolites include 7-COOH-CBD (dominant circulating metabolite), glucuronides, and carboxy variants. CBGA → Serves as the class's central biosynthetic precursor; CBG is rapidly oxidized to cyclo-CBG, its major human metabolite, with 6′,7′-epoxy-CBG as a secondary product — both well-characterized, not speculative. Hepatic cytochrome P450 enzymes (CYP2J2, 3A4, 2C9, and others) drive this and related hydroxylation across the CBG/CBC class, followed by glucuronidation for excretion. As the second in a three-part series on cannabis dietary inputs, this review maps these conversion cascades in parallel, revealing that all three acids retain a documented capacity for intact, non-decarboxylated processing alongside conventional conversion to their neutral forms — a pattern not previously stated in the literature reviewed here. Integration with companion works on hemp seed nutrition and ECS mechanisms positions acidic cannabinoids as plausible contributors to endocannabinoid system modulation, warranting targeted clinical investigation.