The majority of people who purchase medical marijuana report that they are treating chronic pain associated with injuries, neuropathies or arthritis. The sensation of chronic pain is often due to the presence of inflammation in the effected tissues. My laboratory demonstrated that stimulation of cannabinoid receptors contributes to the anti-inflammatory effects of medical marijuana. In contrast, there are only anecdotal reports that cannabidiol (CBD) has anti-inflammatory effects. This is likely because CBD cannot stimulate cannabinoid receptors. CBD does modestly reduce anxiety; this action at serotonin receptors might reduce some cognitive aspects of the pain.
A pair of recent studies investigated whether there are other chemicals in the cannabis plant that contribute to the pain-relieving actions of medicinal marijuana. Their purpose was to identify molecules in the cannabis plant that might be useful treatments for chronic pain without producing any psychoactive side-effects. Many older patients report that the psychoactive effects are unpleasant. One study examined the anti-inflammatory properties of oil-extracts of the leaves while a second study examined the anti-inflammatory chemicals found in an aqueous extract of cannabis roots.
The oil-soluble chemicals in cannabis leaves and stems include the alkaloids, flavonoids, stilbenoids, various fatty acids, cannabinoids, and terpenofenoids. These molecules have antifungal, anti-inflammatory, anti-bacterial, and psychotropic effects. In contrast, aqueous extracts of cannabis roots contain very low levels the psychoactive molecule THC, consistent with the low psychotropic potential of this part of the plant.
The aqueous extract of the roots of C. sativa contained detectable levels tetrahydrocannabiorcolic acid, cannabisatavine, cannabichromenic acid and anyhydrocannabisatavine. The recent study using mice demonstrated that the aqueous extract of the C. sativa root exhibited an anti-inflammatory effect that was due to the reduction of vascular extravasation and the inhibition of migration of inflammatory cells (primarily leukocytes), without effects on the central nervous system.
The second study evaluated the anti-inflammatory properties of an oil extract from cannabis flowers. The oil extract contained CBD and THC (the two most abundant cannabinoids) as well as the monoterpenes (alpha-Pinene, Camphene, beta-Myrecene and D-Limonene) and sesquiterpenes (beta-Caryophyllene, alpha-Bergamotene, alpha-Humelene, Humulene epoxide II, and Caryophyllene oxide).
The oil extract of cannabis flowers markedly suppressed the release of the pro-inflammatory cytokine TNF-alpha as well as many other indicators of inflammation. The oil extract also significantly reduced the level of edema in injured tissues. These data likely underlie why arthritis patients find medicinal marijuana effective.
It was once thought that the cannabis plant contained no aqueous-soluble chemicals that have therapeutic use. This is obviously not the case. There is much more to learn about the contents of the cannabis roots. Dr. Gary L. Wenk serves on the Ohio Governor’s Medical Marijuana Advisory Committee.
Wenk GL (2019) Your Brain on Food: How chemicals control your thoughts and feelings, Oxford University Press, U.K., 3rd Edition.
Shebaby W et al (2021) In vivo and in vitro anti-inflammatory activity evaluation of Lebanese Cannabis sativa L. ssp. indica (Lam.) Journal of Ethnopharmacology, Vol 270, Article Number: 113743
Marchalant Y…Wenk GL (2009) Cannabinoids attenuate the effects of aging upon neuroinflammation and neurogenesis. Neurobiology of Disease, Vol 34, p 300. PMID: 19385063
Zagozen M et al (2021) Cannabigerol and cannabichromene in Cannabis sativa L.
ACTA Pharmaceutica, Vol 71, p 355.
Lima KSB et al (2021) Cannabis roots: Pharmacological and toxicological studies in mice. Journal of Ethnopharmacology, Vol 271, Article Number: 113868
Declan R et al (2021) Pharmacokinetics and effects on arachidonic acid metabolism of low doses of cannabidiol following oral administration to horses. Drug Testing and Analysis, Early Access: MAR 2021