Those Pungent Smells Oozing Out of Marijuana Buds Are Actually Giving You Clues About What Their Effects Will Be Like
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How do terpenoids exert effects within the body? Citing the relevant studies, Russo explains that they are “lipophilic, interact with cell membranes, neuronal and muscle ion channels, neurotransmitter receptors, G-protein coupled (odorant) receptors, second messenger systems and enzymes.”
The beneficial effects are wide-ranging and, in many cases, well established. Limonene, for example, has been shown to decrease anxiety in mice via the serotonin receptors. “Compelling confirmatory evidence in humans,” Russo writes, was provided by a Japanese study of severely depressed hospital patients whose moods improved when exposed to citrus fragrance. (Nine of 12 were able to get off antidepressants.)
Limonene, inhaled, is an immunostimulant. In lab experiments it has killed breast cancer cells and acne bacteria. It is a potential treatment for gastro-esophageal reflux.
Alpha-pinene —as anyone who has walked into piney woods and breathed deeply can sense— is a bronchodilator. It also has anti-bacterial and antibiotic properties. α-Pinene inhibits the enzyme that breaks down acetylcholine, a neurotransmitter involved in memory. “This feature could counteract short-term memory deficits induced by THC intoxication,” Russo notes.
Myrcene, another monoterpene common in cannabis, is also abundant in the flowers of humulus lupulus —hops— the only other member of the Cannabinacae family. In addition to its anti-inflammatory effect, Russo writes, “Myrcene is a recognized sedative as part of hops preparations, employed to aid sleep in Germany... Myrcene acted as a muscle relaxant in mice, and potentiated barbiturate sleep time at high doses.
“Together, these data would support the hypothesis that myrcene is a prominent sedative terpenoid in cannabis, and combined with THC, may produce the ‘couch-lock’ phenomenon of certain chemotypes that is alternatively decried or appreciated by recreational cannabis consumers.”
Linalool, which is abundant in lavender, affects serotonin neurotransmission and counters anxiety, according to a study cited by Russo. Linalool has sedative and anti-convulant properties, and is also “the likely suspect in the remarkable therapeutic capabilities of lavender essential oil to alleviate skin burns without scarring.”
Beta-caryophyllene, which is found in black pepper, Echinacea, and marigolds, “is frequently the predominant terpenoid in cannabis extracts, particularly if they have been processed under heat.” β-caryophyllene is anti-inflammatory and, unlike other anti-inflammatories, protective of the stomach lining.
In 2008 Swiss investigators led by Jurg Gertsch showed that β-caryophyllene activates the CB2 receptor —making it “the first proven phytocannabinoid beyond the cannabis genus,” Russo proclaims. “Given the lack of psychoactivity attributed to CB2 agonists, caryophyllene offers great promise as a therapeutic compound, whether systemically or in dermatological applications.”
Other terpenoids with therapeutic potential mentioned by Russo in his BJP paper are nerolidol (found in citrus, it may have sedative and anti-fungal effects); caryophyllene oxide (found in the herb lemon balm, it repels insects); and phytol (a breakdown product of chlorophyll with relaxant properties that may be the reason that green tea, despite its caffeine content, doesn’t jangle the nerves).
In their landmark 2001 paper in the Journal of Cannabinoid Therapeutics, Russo and lead author John McPartland touched on the beneficial effects of eucalypytol, pulegone, alpha-terpineol and other possibly efficacious terpenoids. These compounds were not discussed in Russo’s 2011 BJP paper.
Russo describes several mechanisms by which terpenoids and/or cannabinoids can act synergistically.
• They can work on separate targets. For example, if CBD were combined with limonene as an acne treatment, the cannabinoid could penetrate the skin and induce the cells that produce sebum to self-destruct, while the terpenoid could inhibit production of the key pathogen, Propionbacterium acnes. (Linalool and alpha-pinene also suppress P. acnes.)
• They can interact to overcome bacterial resistance. For example, CBD and CBG “powerfully inhibit MRSA,” according to one study cited by Russo, while in another study, an essential oil rich in pinene proved “as effective against MRSA and other antibiotic resistant bacterial strains as vancomycin.”