Hemp Therapies Wiki / Cannabinoids & Plant Chemistry

CBG (Cannabigerol)

CBG, short for cannabigerol, is a cannabinoid produced by the hemp plant. It is chemically distinct from both CBD (cannabidiol) and THC (tetrahydrocannabinol), though all three trace back to a common origin inside the plant.

Where CBG Comes From

CBG’s starting point is a molecule called CBGA (cannabigerolic acid). CBGA is the principal precursor to most of the other cannabinoids found in cannabis, including THC, CBD, CBN, and CBC — the plant builds each of those compounds out of CBGA. CBGA itself forms from two smaller building blocks, geranyl diphosphate and olivetolic acid, combined by an enzyme called CBGA synthase. CBG is generated from CBGA through a non-enzymatic decarboxylation reaction — a chemical step that does not require an enzyme to occur. In a mature cannabis plant, CBG typically makes up only around 10% of the total cannabinoid content, since most of the CBGA the plant produces has already been converted into other cannabinoids by the time of harvest.

How CBG Interacts With the Body’s Receptors

The body’s endocannabinoid system includes two main receptor types, CB1 and CB2, found throughout the nervous system and elsewhere in the body. Unlike THC and CBD, CBG does not bind directly to CB1 receptors. Laboratory research has measured CBG’s binding affinity (a value called Ki, where a lower number indicates a tighter bind) at CB1 in the range of 440–1045, described in that research as weak agonist activity. At CB2, the same kind of measurement placed CBG’s Ki between 153.4 and 1225, described as partial agonist activity — meaning CBG engages the receptor without fully activating it. Laboratory studies have also reported that CBG may indirectly influence CB1 activity by slowing the body’s reabsorption of anandamide, a naturally-occurring compound the body itself produces.

Beyond CB1 and CB2, laboratory research has identified several other receptor interactions for CBG. One study measured CBG as a potent agonist at the alpha-2 adrenoceptor, reporting an EC50 (a measure of how much compound is needed to produce half of its maximum effect) of 0.2 nanomolar in brain membrane experiments. Separate research has described CBG as a moderately potent antagonist at the serotonin 5-HT1A receptor, an agonist at the PPARγ receptor, and active at two transient receptor potential channels, TRPM8 and TRPA1. Laboratory work in macrophages found lower NF-κB transcriptional activity and inhibited an enzyme called inducible nitric oxide synthase (iNOS) after CBG exposure, an effect that diminished when a CB2 receptor antagonist was introduced alongside it, while separate work found no CB1 involvement in that same pathway. In platelet studies using rabbit and human samples, CBG inhibited platelet aggregation in laboratory conditions, with a measured Ki of 2.7 × 10⁻⁴ M. One comparison in that body of research described CBG’s antioxidant potency as comparable to vitamin E under laboratory conditions.

CBG Levels Change as the Plant Grows

As a hemp plant matures, its CBD content rises while its CBG content falls. By harvest, a typical crop carries ample CBD alongside only trace amounts of CBG, CBN, THC, and other minor cannabinoids — consistent with CBG’s role as an early-stage compound in the plant’s chemistry that mostly converts into other cannabinoids before harvest. Because CBG is present at meaningful levels only earlier in the growth cycle, cultivars bred to carry more CBG are typically harvested earlier than CBD-dominant hemp.

Full-Spectrum and Isolate CBG

CBG is sold both inside full-spectrum hemp extracts, alongside other cannabinoids and terpenes, and as an isolated compound on its own. Broad-spectrum CBG concentrate is typically produced through a three-step process: supercritical CO2 extraction of raw hemp, chromatography to remove impurities and detectable THC, and a final distillation step that removes unwanted compounds while retaining minor cannabinoids.

The Current State of CBG Research

Compared to CBD or THC, CBG has not reached the same stage of clinical research. Most available data comes from laboratory (in vitro) or animal studies rather than human trials. One literature review identified 34 papers on CBG, of which only 6 of 10 registered clinical trials involved administering pure CBG to human participants. One early published clinical result reported lower self-reported stress and anxiety scores and improved memory-task performance among study participants — described in that publication as a first-of-its-kind human result rather than an established finding. No studies have examined how chronic CBG administration affects broader cardiovascular measures in people with high blood pressure.

Animal research has produced mixed findings on CBG at different doses. In one chronic oral-dosing study in animals (0.66–1.33 mg/kg over 90 days), liver tissue examination showed regressive changes, including apoptotic cells. A separate study found dose-dependent liver effects: higher CBG doses (24.6 mg/kg) were associated with pro-inflammatory liver changes in that study, while lower doses (2.46 mg/kg) were associated with protective effects. In one acute-dosing animal study, a single intraperitoneal injection of CBG lowered mean blood pressure by 22 to 28 mmHg, an effect the researchers reported as sensitive to a drug called atipamezole, which blocks the alpha-2 adrenoceptor.

Summary

CBG is an early-stage cannabinoid in hemp’s chemistry, structurally distinct from CBD and THC despite sharing a common precursor, CBGA. Its receptor activity spans CB1, CB2, and several non-cannabinoid receptor targets, most of it characterized in laboratory and animal research rather than large human trials. It is sold both as part of full-spectrum extracts and as an isolate, and hemp cultivars grown for CBG are harvested earlier than those grown for CBD.