The Science Behind Terpenes and Their Role in Cannabis

Terpenes are significant to how humans experience cannabis. Besides being responsible for our natural attraction to the plant’s appearance and aroma, terpenes also contribute to the plant’s therapeutic and medicinal effects. While ongoing scientific research into the potential healing properties of these powerful compounds is expanding along with legalization, brands have already started embracing terpenes as a more nuanced and reliable way to describe their cultivars and promote their products. And terpenes’ therapeutical potential could someday have a bigger role to play in both the cannabis industry and the future of medicine.

In this article, we’ll explore…

• Terpenes and their chemical properties 
• Cannabis terpenes and their effects
• Terpenes and their role in the entourage effect
• Terpenes and their potential health benefits
• Terpenes and consumption methods

Understanding Terpenes: Chemical Properties and Biosynthesis

Terpenes are volatile organic compounds responsible for the scent, flavor, and color of plants and have a natural ability to deter insects and mitigate microorganisms. They are a key component of essential oils, highly concentrated and complex liquid compounds derived from plants and proven to offer multiple health benefits. In addition to the vital role terpenes play in repelling predators and attracting pollinators, they are also behind the plant’s anti-inflammatory, antiviral, antimicrobial, antiparasitic, and other properties. 

Terpenes are part of the most extensive and varied class of volatile organic compounds known as isoprenoids, which are comprised of two or more units of the hydrocarbon isoprene. During terpene biosynthesis, a single enzyme creates a reaction linking one part of a molecule to another, forming a closed ring and causing a variety of modifications. Secondary metabolites are among such modifications and include terpenoids, which result from the introduction of oxygen, and flavonoids which also use scent, color, and flavor to attract insect pollinators and regulate cell growth in plants.

The majority of terpenes identified in cannabis fall under the two classes of monoterpenes and sesquiterpenes. Monoterpenes have two isoprene units and are considered the smallest and most fragrant terpene classification. Because their primary function is to attract pollinators or repel predators through scent, monoterpenes are used commercially in fragrances and repellants and are the primary ingredient in essential oils.  Sesquiterpenes are larger and more stable than monoterpenes and are characterized by three isoprene units. Beyond contributing to plant growth and serving as either a defense or attraction mechanism in response to environmental factors, sesquiterpenes are also used to treat migraines and bacterial infections. 

The variability of chemical compounds made possible through terpenes gives each cultivar its own unique flavor and aromatic profile, but adding cannabinoids into the mix takes that variety further, offering customers and producers alike plenty to play with when it comes to effects.

Read more about terpenes and their chemical properties here.

Cannabis Terpenes: Effects and Benefits

Research indicates that terpenes show the potential to treat a broad range of illnesses due to their therapeutic properties. In this section, we break down the terpenes that occur most frequently across cannabis cultivars, and their reported effects:

• β-Caryophyllene is a sesquiterpene that brings spice to black pepper and is a recurring ingredient in essential oils. Like ∆9-tetrahydrocannabinol (THC) and cannabidiol (CBD), caryophyllene can selectively bind to CB2 receptors, and provide relief through the body’s opioid and endocannabinoid systems. Caryophyllene is shown to be effective in treating pain, neuropathy, and inflammation, and is considered to have anti-cancer, anti-inflammatory, and antioxidant benefits.
• α-humulene is an isomer of β-caryophyllene and the monoterpene that contributes to the distinctly woody and spicy flavors in beer, and the floral-spicy aromas in the cannabis plant. Findings show humulene to exhibit analgesic, appetite-suppressive, and anti-inflammatory properties, and the potential to reduce the expression of bacteria that cause inflammatory bowel disease.
• D-Limonene is a monoterpene found abundantly in citrus fruit peels. Cannabis cultivars high in limonene are known to energize and uplift moods and soothe anxiety. A known anti-inflammatory and antioxidant, limonene could potentially play a neuroprotective role in the treatment of multiple neurodegenerative diseases and may also offer antimicrobial, antidepressant, anxiolytic, antifungal, and neuroprotective benefits to the immune system. 
• Linalool is an abundant monoterpene in basil, lavender, and other aromatic plants. Its floral, woody scent is used in a variety of consumer products including shampoos and soaps. Scientific research suggests linalool’s potential anti-anxiety, anti-inflammatory, antioxidant, and neuroprotective benefits. Linalool’s ability to mitigate oxidative stress and inflammation may also yield anti-cancer effects. 
• β-Myrcene is a monoterpene that occurs naturally in more than 200 plants and is the smallest yet most prevalent terpene found in cannabis varieties. Due to its sedative and relaxing properties, myrcene is the terpene largely attributed to “couch lock”. Multiple studies show myrcene to have analgesic. antioxidant, anti-cancer, and anti-inflammatory properties, as well as the potential ability to facilitate the passage of cannabinoids across the blood-brain barrier.
• Pinene is one of the most plentiful monoterpenes in nature and appears in pine trees, dill, and rosemary. Pinene is known to produce alleviating effects on pain, and calming effects on mood including anxiety. Findings indicate pinene’s potential analgesic, anti-anxiety, and anti-inflammatory properties, and the ability to promote antioxidant activity and neuroprotection in seizures and strokes.
• α-Terpineol is a monoterpene found in over 150 plants and is widely used in cosmetics and as a flavoring agent.  Terpineol is known to reduce inflammatory effects on the skin, and its antioxidant properties may also show potential anti-cancer benefits.
• Terpinolene is a monoterpene that appears in small concentrations in cannabis. Terpinolene’s use in essential oils indicates potential anti-inflammatory and analgesic properties. Research indicates terpinolene may have a synergistic effect with other terpenes, producing anti-inflammatory and analgesic relief without causing negative effects. 

Read more about cannabis terpenes and their effects here.

The Entourage Effect: Synergistic Interactions of Terpenes and Cannabinoids

Cannabis terpenes are packed with medicinal potential, but they‘re not alone. In this section we dig into the relationship between terpenes and cannabinoids, and how they collaborate to produce what’s known as the “entourage effect”.

Over 100 cannabinoids have been identified in the cannabis plant, and research shows they play a role in regulating multiple bodily functions including metabolic activity and digestion. Within the endocannabinoid system, cannabinoids are able to produce myriad therapeutic outcomes by binding to CB1 and CB2 receptors throughout the body and central nervous system.

Professors Raphael Mechoulam and Shimon Ben-Shabat hypothesized in 1998 that the greatest therapeutic benefit from cannabis comes not from one individual compound, but from the interaction between different cannabinoids and the combination of cannabinoids and terpenes. This hypothesis became the entourage effect theory.

Δ9-Tetrahydrocannabinol (THC) is the principal chemical component in cannabis the cannabinoid attributed to its psychoactive and analgesic properties. The second most prevalent cannabinoid is cannabidiol or CBD, which is known to have anti-anxiety, anti-inflammatory, and analgesic properties. Considered non-psychoactive, CBD contributes to the entourage effect by potentially mitigating the potency of and intoxication from THC in high doses. In low doses, CBD shows the potential to enhance THC’s effects. The consumer market’s embrace of the entourage effect has opened the door to full-spectrum products that blend extracts of CBD with terpenes, essential oils, flavonoids, and other cannabinoids including THC in low amounts, and broad-spectrum products high in CBD and other plant constituents with little or no THC.

Here’s how other chemical compounds in cannabis factor into the entourage effect:

• Cannabichromene (CBC): Non-psychoactive CBC contributes to the plant’s anti-inflammatory effects and reportedly demonstrates antimicrobial, analgesic, and antidepressant properties. CBC’s influence over the endocannabinoid system centers on its ability to inhibit anandamide uptake. It was also found to enhance THC’s cytotoxic properties and increase the effectiveness of CBD extracts.
• Cannabichromene (CBG): Considered “the mother of all cannabinoids”, CBG shares THC’s ability to work as a partial agonist of CB1 and CB2 receptors. Like CBD, it’s non-psychoactive and offers potential relief against pain, insomnia, anxiety, and depression. While preliminary research shows CBG to be ineffective against inflammation on its own, it reportedly enhances CBD’s ability to soothe inflammation.
• Cannabinol (CBN): An oxidized metabolite of THC, CBN demonstrates potential sedative, anti-inflammatory, antibiotic, and anticonvulsant properties. CBN has about ¼ the potency of THC and some research indicates it may increase the sedative properties of both THC and CBD.
• Δ9- Tetrahydrocannabivarin (THCV): THCV is a non-psychoactive cannabinoid that shows potential appetite-suppressing and neuroprotective properties. While research is limited, one study found that THCV may inhibit THC’s psychoactive effects.

Read more about terpenes and their role in the entourage effect here.

Terpenes and Consumption Methods

While the entourage effect boils down to terpenes and cannabinoids joining forces to produce a variety of therapeutic outcomes, the method in which cannabis is consumed can directly impact the way consumers absorb these volatile compounds. In this section, we explore how terpenes interact with different cannabis consumption methods.

Inhalation 

The most common cannabis consumption method is inhalation. This is typically achieved when the plant material is combusted – via rolled cigarettes like joints or blunts, or through bongs and other pipes – resulting in smoke that’s inhaled through the lungs. Inhalation through vaporizers, or vaping, has also become popular with consumers and involves heating the plant material without causing combustion. Vaping is largely considered to be the safer option since consumers inhale vapor instead of smoke, which is more likely to be carcinogenic.

As volatile compounds, terpenes are particularly susceptible to heat and start to evaporate and even degrade at temperatures between 70°-100°F – which makes smoking the less optimal way to consume terpenes. Because vaping doesn’t lead to combustion, terpenes are better preserved through heating which enables consumers to experience the flavors while also reaping greater benefits from the entourage effect. 

Oral Ingestion

Oral ingestion is the consumption of food or drinks that have been infused with cannabis. The effects are felt through sublingual applications – strips, lozenges, and drops for example – in which absorption is achieved in the mucous membranes under the tongue and throughout the mouth, typically within minutes. Eating cookies, gummies, and other infused foods leads to absorption through the digestive tract and metabolization through the liver before releasing into the bloodstream and the brain. This method involves a slower onset time, but effects can last for hours. Mimicking their role in nature, terpenes contribute to the aroma and flavors of infused food and drinks, but whether consumers experience the entourage effect when consuming them depends greatly on the manufacturing process.

Concentrates 

Trichomes, the microscopic resinous bearers of cannabinoids from the cannabis plant, are extracted then used to create the overarching product category known as concentrates. Containing high levels of THC, concentrates like hash, rosin, and shatter also have high amounts of terpenes and are largely considered the best way to experience the flavors of these volatile compounds. 

How they are processed and consumed, however, can impact their availability. A study on dabbing for example, in which the smoke from high-THC concentrates is inhaled after combustion, showed increased instances of the terpene β-myrcene – but also a greater exposure to harmful or potentially harmful components (HPHCs).

Topicals (Balm, Lotion, Salve, Cream)

When applied to the skin, cannabis topicals can provide localized relief against pain and a variety of skin conditions. Cannabis-infused topicals including lotions and balms penetrate the outer epidermal layer and are absorbed by interacting with CB1 and CB2 receptors in the skin, but don’t get reach the bloodstream, which is why they’re generally considered to be non-psychoactive for the user. 

Depending on how they’re produced, topicals can exhibit the analgesic, antifungal, anti-inflammatory and other therapeutic properties inherent to the plant’s most abundant cannabinoids and terpenes – enabling consumers to reap the benefits of the entourage effect in the potential treatment of various skin conditions.

Read more about terpenes and their potential health benefits here.

Conclusion

In summary…

• Terpenes are volatile organic compounds that appear abundantly in plants and are known to offer a variety of health benefits. They’re part of the most extensive and varied class of volatile organic compounds known as isoprenoids.
• The process of terpene biosynthesis links one part of a molecule to another to create a variety of modifications that include the secondary metabolites: terpenoids and flavonoids.
• The majority of terpenes identified in cannabis fall under two classes: monoterpenes and sesquiterpenes.
• Cannabis terpenes are attributed to the plant’s anti-inflammatory, antiviral, antimicrobial, antiparasitic, and other therapeutic properties. 
• Caryophyllene, humulene, limonene, linalool, myrcene, pinene, terpineol, and terpinolene are the most frequently occurring terpenes in cannabis.
• The entourage effect theory coined by Professors Raphael Mechoulam and Shimon Ben-Shabat 1998 hypothesized that the greatest therapeutic benefit from cannabis comes from the interaction between different cannabinoids and the combination of cannabinoids and terpenes. 
• How well terpenes are absorbed varies by consumption method.

As legalization continues, further scientific study has started supporting what many have discovered anecdotally about terpenes: that volatile compounds from the cannabis plant may very well hold the key to countless medical and therapeutic applications.

References

• Healthline.com: How Long Do Edibles Take to Kick In?
• Hopkinsmedicine.org: Vaping Cannabis Produces Stronger Effects Than Smoking Cannabis For Infrequent Users, December 4, 2018, hopkinsmedicine.org
• Makhakhe L. Topical cannabidiol (CBD) in skin pathology - A comprehensive review and prospects for new therapeutic opportunities. S Afr Fam Pract (2004). 2022 May 30;64(1):e1-e4. doi: 10.4102/safp.v64i1.5493. PMID: 35695447; PMCID: PMC9210160.
• Meehan-Atrash J, Luo W, McWhirter KJ, Dennis DG, Sarlah D, Jensen RP, Afreh I, Jiang J, Barsanti KC, Ortiz A, Strongin RM. The influence of terpenes on the release of volatile organic compounds and active ingredients to cannabis vaping aerosols. RSC Adv. 2021 Mar 23;11(19):11714-11723. doi: 10.1039/d1ra00934f. PMID: 35423635; PMCID: PMC8695911.
• NIDA. 2019, December 24. Cannabis (Marijuana) DrugFacts. Retrieved from https://nida.nih.gov/publications/drugfacts/cannabis-marijuana
• Raz N, Eyal AM, Davidson EM. Optimal Treatment with Cannabis Extracts Formulations Is Gained via Knowledge of Their Terpene Content and via Enrichment with Specifically Selected Monoterpenes and Monoterpenoids. Molecules. 2022 Oct 15;27(20):6920. doi: 10.3390/molecules27206920. PMID: 36296511; PMCID: PMC9608144.