Opinion

Isolating CBG: The Problem

Lance Griffin
Written by Lance Griffin

Cannabigerol (CBG) is the neutral form of cannabigerolic acid (CBGA). [1] CBGA is the precursor molecule for tetrahydrocannabinolic acid (THCA), cannabidiolic acid (CBDA), and cannabichromenic acid (CBCA), which are differentiated by their respective synthases. [1] For this reason, CBG is often referred to as the “mother” cannabinoid. It is non-intoxicating and may confer unique and desirable therapeutic benefits. Nonetheless, isolating CBG poses several challenges.

CBG has demonstrated preliminary evidence for reducing inflammation in inflammatory bowel disease [2], exerting neuroprotective effects in Huntington’s disease [3],  stimulating appetite [4], decreasing bladder contractions [5], exerting antidepressant effects, and relieving pain [6], among other benefits. Thus, there is significant demand for CBG.

Plants first undergo extraction, usually with hydrocarbon solvents, ethanol, or supercritical carbon dioxide (CO2). Plant oil is winterized to remove lipids and waxes and distilled to fractionate the chemical compounds. Distillation pushes purity into the arena of 80%; further purification is achieved by chromatography, which is capable of near-complete isolation to 99.9% purity.  Chromatography separates compounds in a mixture based on affinity for either a stationary phase (solid or liquid) or a mobile phase (liquid or gas). Supercritical fluid chromatography—which uses supercritical gas (usually CO2) as the liquid mobile phase—is considered a relatively environmentally friendly technique for this purpose.

Nonetheless, CBG is usually a minor constituent in Cannabis sativa L. by the time of harvest. It requires large amounts of biomass to extract and isolate, making it costly. Alternatively, crops may be harvested earlier, sacrificing other cannabinoids (like cannabidiol, CBD) for CBG. Some companies have developed seed genetics that amplify CBG concentrations in plants significantly. Hemp chemovars that maximize minor cannabinoids are fairly limited but represent a major opportunity for breeders.

There is also the question as to whether an isolated cannabinoid is ideal for therapeutic benefits compared to combinations of cannabinoids and terpenes. CBD, for example, appears to exert greater anticonvulsive benefits in treatment-resistant epilepsy patients when administered as full spectrum CBD (an extract rich in hemp phytochemicals) rather than as CBD isolate. [7] As research expands our knowledge of CBG, its popularity in both forms is likely to increase.

References

  1. ElSohly MA, et al. “Phytochemistry of Cannabis sativa L. Phytocannabinoids, 2017, pp.1–36,doi:10.1007/978-3-319-45541-9_1.
  2. Borrelli F, et al. “Beneficial Effect of the Non-Psychotropic Plant Cannabinoid Cannabigerol on Experimental Inflammatory Bowel Disease.” Biochem Pharmacol., vol. 85, no. 9, 2013, pp. 1306-16.
  3. Valdeolivas S, et al. “Neuroprotective Properties of Cannabigerol in Huntington’s Disease: Studies in R6/2 mice and 3-Nitropropionate-Lesioned Mice.” Neurotherapeutics, vol.12, no.1, 2015, pp.185-199.
  4. Brierley D, et al. “Cannabigerol is a Novel, Well-Tolerated Appetite Stimulant in Pre-Satiated Rats.” Psychopharmacology (Berl), vol. 233, no. 19-20, 2016, pp. 3603-3613.
  5. Pagano E, et al. “Effect of Non-Psychotropic Plant-Derived Cannabinoids on Bladder Contractility: Focus on Cannabigerol.” Nat Prod Commun, vol. 10, no. 6, 2015, pp. 1009-1012.
  6. Russo EB, Marcu J. “Cannabis Pharmacology: The Usual Suspects and a Few Promising Leads. Advances in Pharmacology, 2017, pp.67–134,doi:10.1016/bs.apha.2017.03.004.
  7. Pamplona F, et al. “Potential Clinical Benefits of CBD-Rich Cannabis Extracts Over Purified CBD in Treatment-Resistant Epilepsy: Observational Data Meta-analysis.” Frontiers in Neurology, vol.9, no.759, 2018.

About the author

Lance Griffin

Lance Griffin

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