Terpenes and their role in medicinal cannabis
Terpenes and Medicinal Cannabis
When discussing the active ingredients of medicinal cannabis, tetrahydrocannabinol (THC) and cannabidiol (CBD) are two cannabinoids that often receive the lion’s share of attention. While these two molecules (alongside other cannabinoids) have demonstrated therapeutic potential, medicinal cannabis is more than simply a ratio of THC to CBD.
Medicinal cannabis is complex. Beyond THC and CBD, the cannabis plant produces an array of natural compounds (over 480) that may hold therapeutic value. To understand the full scope of medicinal cannabis’ potential, it is important to acknowledge how these other molecules contribute to the plant’s effects.
Terpenes have been identified as an important chemical component of the cannabis plant that may influence outcomes. In fact, each cannabis strain has a unique terpene profile that is composed of a selection of more than 100 different terpenes. But what exactly are they?
What are terpenes?
Terpenes are aromatic compounds that are abundant in nearly all plants.
They play a key role in the growth and survival of plants and originally evolved to attract pollinators and repel predators. They achieve this by producing the distinct aromas, flavours, and pigments commonly associated with certain plants. Terpenes are also responsible for plant regeneration and protection from environmental stressors.
Female cannabis plants are covered in glands called trichomes, which secrete high concentrations of terpenes, in addition to cannabinoids and other chemicals. Beyond strain genetics, terpene levels can be influenced by environmental factors, such as light exposure, temperature changes, and the presence of nutrients.
The benefits of terpenes aren’t just limited to the plants they inhabit. Humans have a long history of including terpene-rich plants such as ginger, lemon, and mint in natural remedies to improve wellness and soothe ailments. Today, terpenes are used within essential oils, which can be used for aromatherapy (e.g. lavender oil containing linalool) or topical application (e.g. tea tree oil containing terpineol).
Terpenes are the subject of ongoing research to determine how they can be used to manage various conditions. Scientific research has discovered that certain terpenes possess anti-inflammatory, anti-bacterial, anti-microbial, anti-cancer, antioxidant, and sedative properties, amongst others.1 As cannabis plants are a rich source of terpenes, it is important to further understand how these molecules interact and influence medicinal cannabis outcomes.
The importance of terpenes in medicinal cannabis
From a scientific perspective, the current understanding of cannabis terpenes is that they can potentially enhance the effects of cannabinoids. This phenomenon has been described as the “Entourage Effect”. This effect explains how these molecules (in addition to other cannabis-derived chemicals) can work together to affect the body’s endocannabinoid system (ECS). For example, certain terpenes may inhibit the psychoactive effects of THC to increase its therapeutic benefits.2
Other studies have also supported the claim that terpenes can enhance the activity of cannabinoids.3 Coupled with the effects of terpenes, this synergy suggests that full-spectrum cannabis products (e.g. medicinal-grade dried cannabis flower) could provide a wider range of health benefits than isolated cannabinoids alone.
Learning more about the influence of terpenes on the effects of medicinal cannabis may lead us to reconsider how we currently classify cannabis plants. Traditionally, medicinal cannabis plants have been categorised by their species names: either Cannabis sativa or Cannabis indica (i.e. Sativa and Indica strains). These terms are commonly used to differentiate cannabis plants by their physical appearance and botanical properties. Sativa plants are tall and sparse with thin leaves, while Indica plants are short and bushy with wide leaves.
While these labels are useful to some researchers and cultivators, they may prove outdated from an outcome perspective. The terms Indica and Sativa do not consider the modern chemical analysis of cannabis plants. As such, they are not as predictive of a specific plant’s effects as once thought.
As such, this framework may not be the most accurate predictor of outcomes for patients and healthcare professionals using it for guidance. Most medicinal cannabis plants today are “hybrid strains”, which are created by cross-breeding two or more different strains to enhance certain traits or to produce specific effects - further reducing the utility of the indica/sativa framework.
Medicinal cannabis strains should instead be evaluated holistically by their THC content, CBD content and terpene profile, as their remedial effects are associated with their unique chemical composition.4 By mapping out the terpene profile of individual strains, we have a better understanding of their predicted effects and medical applications. This offers unlimited opportunities to cultivate, manufacture and prescribe high-quality medicinal cannabis products for specific indications and conditions.
Overview of cannabis terpenes
Terpenes are incredibly abundant in cannabis plants, with researchers identifying more than 150 different types. The majority of these terpenes exist in low concentrations and are unlikely to contribute to any aromas, flavours or effects.
However, there is a small number of cannabis terpenes that have a large presence across a wide range of different cannabis strains. The two most prominent terpenes are myrcene and caryophyllene. Either of these terpenes are likely to be found in high concentrations across most full-spectrum medicinal cannabis products, along with some others in varying proportions.
Myrcene (β-Myrcene)
Myrcene is responsible for the characteristic earthy aroma and herbal flavour of cannabis. High concentrations of myrcene can also be found in mangoes, hops, lemongrass parsley, and thyme. In regards to medicinal benefits, antibacterial, antimicrobial and antioxidant properties are common amongst myrcene and the other cannabis terpenes mentioned below. Myrcene may also hold potential in contributing to anti-inflammatory, analgesic, sedative, and muscle-relaxing effects.5
Caryophyllene (β-Caryophyllene)
Caryophyllene is responsible for the spicy aromas and flavours of spices such as black pepper and cinnamon. High concentrations of caryophyllene can also be found in cloves, basil, oregano and hops. Caryophyllene may also hold potential in contributing to anti-inflammatory, analgesic, neuroprotective, and gastoprotective effects.6
Limonene (D-Limonene)
Limonene is responsible for the fresh aroma and flavour of all citrus fruits, such as lemons, limes and oranges. Due to its pleasant scent and taste, limonene is also commonly used as an additive in food products, beverages, fragrances, cosmetics, and cleaning products. Limonene may also hold potential in contributing to anti-inflammatory, antifungal, antidiabetic, anticancer, neuroprotective, and gastroprotective effects.7
Pinene (α-Pinene)
Pinene is responsible for the distinct and refreshing aroma associated with pine and conifer trees. High concentrations of pinene can also be found in rosemary, dill, basil and parsley. Similar to limonene, pinene is also included as an additive in some cleaning products and fragrances due to its refreshing forest scent. Pinene may also hold potential in contributing to anti-inflammatory, bronchodilator, and antiallergic effects.8
Humulene
Humulene is responsible for the herbal aroma of hops and the bitter flavour of beer. Moderate concentrations of humulene can also be found in ginseng, sage, basil, and coriander. Humulene may also hold potential in contributing to anti-inflammatory and anticancer effects.9
Linalool
Linalool is responsible for the floral aromas and flavours of flowers, such as lavender and rose. High concentrations of linalool can also be found in bergamot, jasmine, and mint. This terpene is also commonly included in cosmetics, fragrances and cleaning products due to its pleasant scent. Linaloolmay also hold potential in contributing to anti-inflammatory, anticonvulsant, anxiolytic, and sedative effects.10
The future of terpenes in medicinal cannabis
As medicinal cannabis becomes more widely accepted, it is important to acknowledge the need for further research on the potential effects and interactions of terpenes within humans. Currently, the base of evidence to support the therapeutic potential of terpenes consists mainly of animal studies and pre-clinical models. It is also apparent that high concentrations of terpenes are required to contribute towards any significant effects.
Despite this, there is growing interest in the benefits of terpenes and their potential clinical applications. The discovery of terpene synergy with other cannabis-derived molecules is promising and will open pathways for future research on medicinal cannabis products and patient outcomes.
References
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2. Russo, E. (2011). Taming THC: potential cannabis synergy and phytocannabinoid-terpenoid entourage effects. British Journal of Pharmacology [online]. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3165946/ [accessed 9th of Feb 2022].
3. LaVigne, J., et al. (2021). Cannabis sativa terpenes are cannabimetric and selectively enhance cannabinoid activity. Scientific Reports [online]. Available from: https://www.nature.com/articles/s41598-021-87740-8 [accessed 9th of Feb 2022].
4. Piomelli, D., Russo, E. (2016). The Cannabis sativa Versus Cannabis indica Debate: An Interview with Ethan Russo, MD. Cannabis and Cannabinoid Research [online]. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5576603/ [accessed 9th of Feb 2022].
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7. Anandakumar, P., Kamaraj, P., Vanitha, MK. (2020). D-limonene: A multifunctional compound with potent therapeutic effects. Journal of Food Biochemistry [online]. Available from: https://pubmed.ncbi.nlm.nih.gov/33289132/ [accessed 19th of Feb 2022].
8. Salehi, B., et al. (2019). Therapeutic Potential of α- and β-Pinene: A Miracle Gift of Nature. Biomolecules [online]. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6920849/ [accessed 19th of Feb 2022].
9. Mendes de Lacerda, G., et al. (2021). Pharmacological and toxicological activities of α-humulene and its isomers: A systematic review. Trends in Food Science & Technology [online]. Available from: https://www.sciencedirect.com/science/article/abs/pii/S0924224421004234 [accessed 19th of Feb 2022].
10. Aprotosoaie, AC., et al. (2014). Linalool: a review on a key odorant molecule with valuable biological properties. Available from: https://onlinelibrary.wiley.com/doi/10.1002/ffj.3197 [accessed 19th of Feb 2022].
