What Are Terpenes?

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What Are Terpenes?

The hemp plant is a promising therapeutic agent for ailments like anxiety, pain, and inflammatory conditions. These potential benefits are accented and potentiated by terpenes, one of 700 chemicals found in the cannabis plants, including hemp. 

While research on terpenes is still growing, there’s evidence that they are powerful compounds that enhance the benefits of cannabis products for both pets and humans. 

The Definition of Terpenes: What Are They?

Plant terpenes are essentially fragrant oils composed of hydrogen and carbon molecules (AKA hydrocarbons). They’re what give plants—from lavender and pepper to cinnamon and pine—their distinctive fragrances and flavors. 

Terpenes are the largest family of natural compounds with over 55,000 identified to date and at least half are synthesized by plants. In nature, plants produce terpenes to attract pollinators like bees, ward off predators, and protect themselves from disease-causing microorganisms. In addition, they act as building blocks (called isoprene units) for more complex compounds, such as steroids, hormones, vitamins and even cannabinoids. All living organisms manufacture terpenes for certain essential physiological functions. 

dog in lavender field

Some organic terpenes, like bisabolol (present in the chamomile plant) were used in ancient times as health preventatives and remedies for a variety of maladies. Today, manufacturers use terpenes as additives in foods, cosmetics, insect repellants, household cleaners and essential oils, and they’re increasingly being investigated for their therapeutic properties.

The cannabis plant (including hemp) contains more than 200 different terpenes.

Each variety of the hemp plant (Cannabis sativa) has a unique terpene profile, consisting of different types of terpenes in varying concentrations. These distinct profiles give each plant variety, a unique scent, and a set of physiologic properties. 

The specific terpene profile is based on factors such as plant genetics and environment (humidity, quality of soil, light and temperature). 

What Are Terpenoids?

The terms terpene and terpenoid are used interchangeably, but they are slightly different compounds. 

Terpenes are unaltered, consisting solely of organic hydrocarbons. 

Terpenoids are a derivative of terpenes, modified when the hemp plant is processed by drying and preserving (curing) or by chemical means. This results in oxidation, or the addition of atoms (usually an oxygen).

Differences (and Similarities) Between Phytocannabinoids and Terpenes

One important distinction between phytocannabinoids and terpenes is that phytocannabinoids are found predominantly in the cannabis plant, while terpenes are contained in all plants. 

It was recently discovered that other plants besides cannabis contain similar chemical compounds that interact with our endocannabinoid system. These compounds—called cannabimimetics—are more prevalent than you might think and include echinacea, curcumin and the cocoa tree. 

Another interesting fact is that terpenes are responsible for the aroma and flavor of the cannabis plant, while cannabinoids have no scent at all. The cannabis plant contains more than 100 phytocannabinoids, two of which are tetrahydrocannabinol (THC) and cannabidiol (CBD).

CBD and THC share the same chemical composition and even have essentially identical molecular weights, but their atomic arrangements differ. Despite the slight variance in atomic structure, the physiologic effects of both compounds vary greatly. 

A good example is that both CBD and THC bind to receptors in the brain and impact factors like sleep, mood, and anxiety, but only THC produces intoxicating effects that have been associated with high THC marijuana varieties. 

What Are Terpenes Used For?

hemp plant with water droplets

Terpenes have a wide range of commercial uses—in food, personal care items, and household products. You’ll find terpenes in chewing gum, cleaning products, soaps, perfumes, and cosmetics. 

Terpenes are also key compounds found in the cannabis plant and have physiologic effects on their own. In addition, they enhance the absorption of cannabinoids. Some of the terpenes found in hemp plants have therapeutic properties that vary depending on a plant’s terpene profile and concentration, according to the European Journal of Medicinal Chemistry.  

These benefits include: 

  • Anti-inflammatory
  • Analgesic (pain reduction)
  • Antioxidant 
  • Neuroprotective (protects the nervous system: brain and spinal cord)
  • Anticonvulsant (controls seizures)
  • Anticancer (controls cancer)
  • Anti-allergic (controls allergies)

One great example of a well-known terpene is a chemotherapeutic drug called paclitaxel, which is derived from the bark of the Pacific yew tree (Taxus brevifolia). It was originally used in traditional Chinese medicine for the treatment of a variety of types of cancers (1).

Terpenes also work in concert with the other compounds within the plant. This herbal synergy between cannabinoids, terpenes and flavonoids is what is referred to as the entourage effect. This theory is typically exemplified by the amplifying effects of the multiple compounds, however another example of entourage effect is evidenced by the ability of CBD to reduce the side effects of THC. 

Common Types of Terpenes

The hemp plant contains over 200 different terpenes. The following—also present in other plants—are some of the more commonly found and well-researched terpenes:

Myrcene

mangos in bowl

Myrcene is a terpene that is common in plants like lemongrass, mangoes, eucalyptus, and thyme. It’s also the most common terpene in the cannabis plant, and responsible for producing its earthy smell. 

There’s evidence that myrcene can reduce inflammation and pain, relax muscles, act as a sedative, and induce sleep (2). Its sedative properties are enhanced when combined with THC.

In a study published in Chemico-Biological Reactions, myrcene was shown to help prevent gastric and duodenal peptic ulcers. 

β-Caryophyllene 

picture of black pepper on table

βCaryophyllene is found in many herbs and vegetables like basil, cinnamon leaves, cloves, and black pepper. 

β-Caryophyllene is a potent anti-inflammatory, analgesic (acting to relieve pain), gastrointestinal tract protectant, and it also shows promise as an application for contact dermatitis (2). The greatest revelation regarding β-caryophyllene is its ability to bind directly to the cannabinoid receptor 2 (CB2) which is one of the ways it works to reduce inflammation. 

Limonene 

lemons in a box

A major component in citrus fruit rinds (like lemons), limonene is also present in rosemary, juniper, peppermint, and pine needles. Hemp varieties with high concentrations of limonene have a citrusy scent and provide an uplifting effect. It is the second most widely distributed terpene in nature and is also the precursor to all other terpenes. 

Limonene has been shown to have anti-anxiety, anti-depressive, gastroprotective, and antitumor properties. In fact, in one human study, hospitalized depressed patients exposed to citrus fragrances in ambient air showed improvement and discontinuation of antidepressant medication was noted in 9 out of 12 patients (2).

Terpinolene 

picture of rosemary

Common in plants like sage and rosemary, this terpene tends to have an herbal aroma. 

Terpinolene has been shown to induce drowsiness and sedation, according to a study published in the Journal of Natural Medicines. According to Oncology Letters, it can also prevent cancer growth by inhibiting specific survival pathways.

Humulene 

ginger root on table

Humulene is present in plants like clove and ginger, as well as in hops, which is what gives beer its earthy smell. It has a similar structure to beta-caryophyllene and is sometimes referred to as alpha-caryophyllene.

Humulene has strong anti-inflammatory properties (3). Also, this terpene may be helpful to combat allergies. A study published in British Journal of Pharmacology, found that humulene resulted in marked reduction in inflammatory allergic airway disease in mice models. Research also shows that humulene inhibits tumor growth by producing reactive oxygen species, chemicals that help destroy cancer cells (4).

Lastly, humulene also has antibacterial properties (5), and may work as an appetite suppressant.

Alpha-Pinene 

pine tree

Alpha-pinene is the most common terpene found in the natural world and is found in pine woods and balsamic resin, and produces a scent of pine needles. 

Alpha-pinene has anti-inflammatory, bronchodilator (relaxes and opens airways), antitumor and antibacterial properties. It also aids in memory retention, which can be very helpful to counteract the short-term memory loss induced by THC intoxication (2). 

Linalool 

lavender sprigs on table

Linalool is most abundant in the lavender plant. It’s most notable for its use as a sleep aid, sedative, and anti-anxiety agent and is widely used for aromatherapy. Linalool is the key to lavender’s therapeutic properties.

Linalool demonstrates potent anti-inflammatory, analgesic and local anesthetic properties. Interestingly, the local anesthetic effects of linalool are equal to commonly used agents such as procaine and menthol (6).

Another important property of linalool is its powerful ability to promote anticonvulsant effects. Therefore, finding strains rich in this particular terpene may potentially aid in seizure control (2).  

Bisabolol 

chamomile flower in field

Bisabolol is found primarily in the chamomile plant and has anti-inflammatory, antitumor and antibacterial properties (7). Two studies published in Anticancer Research found that alpha-bisabolol has multiple antitumor effects on pancreatic cancer cells (8) (9).

German chamomile also relieves anxiety and many other conditions, according to a study published in Molecular Medicine Reports, which is why chamomile tea is widely used to promote stress relief.

Keep in mind that the terpenes studied for medicinal properties are more concentrated than the terpenes contained in food and commercial products. Eating a mango, for example, will not impart the same health benefits as a hemp CBD product extracted from a plant with high levels of myrcene. 

Possible Terpene Benefits for Pets

While studies pointing specifically to the benefits of terpenes for pets are lacking, based on the studies performed in the laboratory and in rodent and human models, there is evidence to support the therapeutic usefulness of these compounds.   

Some of the roles we believe terpenes can play, typically in conjunction with key cannabinoids, in supporting pets health include:

  • Reduction in anxiety
  • Reduction in pain and inflammation
  • Reduction in seizure activity 
  • Overall nervous system support
  • Reduction in tumor growth
  • Potent antioxidant

As mentioned above, one of the most impressive benefits of terpenes is their ability to work harmoniously with the other plant compounds and there is an intricate synergy that occurs to boost the therapeutic effect. The general rule is there is a greater effect on the body when exposed to a combination of compounds versus individual ones.

A good example of this concept is a 2015 Israeli study where researchers demonstrated that a larger therapeutic impact was achieved when using a whole plant extract over purified CBD. It concluded that it is likely that other components (minor cannabinoids and terpenes) found in the extract created an additive or synergistic interaction with CBD and was found to be superior in reducing inflammation compared to a CBD isolate (10). 

Are Terpenes Safe for Pets?

happy dog outside in yard

Holistic veterinary practitioners have been incorporating terpenes safely into their practices for centuries.

Without thorough clinical trials, we do not know all the details regarding safety parameters for pets, but dogs and cats are already exposed to terpenes on a regular basis. If you give your pet food or treats flavored with mango, citrus, black pepper or rosemary or bathe your dog using a lavender-based shampoo, you’re essentially using products containing terpenes.

In fact, terpenes have been widely used in commercial products as additives and flavorings in the human diet and are generally recognized as safe (GRAS) to consume by the U.S. Food & Drug Administration. If in doubt about giving products containing terpenes to your pet, check with your veterinarian.  

While there is still much research needed to elucidate the various mechanisms of terpenes and the specific dosing needed to treat different disease processes, it is evident that cannabis terpenes have enormous potential for medicinal benefit, both on their own, and when used in combination with the other components of the cannabis plant.   

References Cited in This Article

  1. Cox-Georgian D., Ramadoss N., Dona C., Basu C. (2019) Therapeutic and Medicinal Uses of Terpenes. In: Joshee N., Dhekney S., Parajuli P. (eds) Medicinal Plants. Springer, Cham. https://doi.org/10.1007/978-3-030-31269-5_15
  2. Russo E. B. (2011). Taming THC: potential cannabis synergy and phytocannabinoid-terpenoid entourage effects. British journal of pharmacology, 163(7), 1344–1364. https://doi.org/10.1111/j.1476-5381.2011.01238.x
  3. Fernandes ES, Passos GF, Medeiros R, et al. Anti-inflammatory effects of compounds alpha-humulene and (-)-trans-caryophyllene isolated from the essential oil of Cordia verbenacea. Eur J Pharmacol. 2007;569(3):228‐236.https://doi.org/10.1016/j.ejphar.2007.04.059
  4. Legault J, Dahl W, Debiton E, Pichette A, Madelmont JC. Antitumor activity of balsam fir oil: production of reactive oxygen species induced by alpha-humulene as possible mechanism of action. Planta Med. 2003;69(5):402‐407. https://doi.org/10.1055/s-2003-39695
  5. Pichette, A., Larouche, P.‐L., Lebrun, M. and Legault, J. (2006), Composition and antibacterial activity of Abies balsamea essential oil. Phytother. Res., 20: 371-373. https://doi.org/10.1002/ptr.1863
  6. Ghelardini, Carla, Galeotti, Nicoletta, Salvatore, Giuseppe, Mazzanti, Gabriela. Local Anaesthetic Activity of the Essential Oil of Lavandula angustifolia. Planta Med. 1999; 65(8): 700-703. https://doi.org/10.1055/s-1999-14045
  7. Kamatou, G.P.P. and Viljoen, A.M. (2010), A Review of the Application and Pharmacological Properties of α ‐Bisabolol and α ‐Bisabolol‐Rich Oils. J Am Oil Chem Soc, 87: 1-7. https://doi.org/10.1007/s11746-009-1483-3
  8. Uno, M., Kokuryo, T., Yokoyama, Y., Senga, T., & Nagino, M. (2016). α-Bisabolol Inhibits Invasiveness and Motility in Pancreatic Cancer Through KISS1R Activation. Anticancer research, 36(2), 583–589.
  9. Murata, Y., Kokuryo, T., Yokoyama, Y., Yamaguchi, J., Miwa, T., Shibuya, M., Yamamoto, Y., & Nagino, M. (2017). The Anticancer Effects of Novel α-Bisabolol Derivatives Against Pancreatic Cancer. Anticancer research, 37(2), 589–598.https://doi.org/10.21873/anticanres.11352  
  10. Gallily, R. , Yekhtin, Z. and Hanuš, L. (2015) Overcoming the Bell-Shaped Dose-Response of Cannabidiol by Using Cannabis Extract Enriched in Cannabidiol. Pharmacology & Pharmacy, 6, 75-85. https://doi.org/10.4236/pp.2015.62010
Dr. Trina Hazzah, DVM, DACVIM (Oncology), CVCH