Terpenes form a large group of phytochemicals, with more than 200 molecules identified in Cannabis sativa L. Terpenes are responsible for the organoleptic characteristics (aromas and flavours) of different strains and have therefore contributed to the selection of strains under human domestication. Terpenes are classified in diverse families according to the number of repeating units of 5-carbon building blocks (isoprene units), such as monoterpenes with 10 carbons, sesquiterpenes with 15 carbons and triterpenes derived from a 30-carbon skeleton.
Terpene yield and distribution in the plant varies according to numerous parameters, such as processes for obtaining essential oil, environmental conditions, maturity of the plant. Mono- and sesquiterpenes have been detected in flowers, roots and leaves of Cannabis, with the secretory glandular hairs as the main production site. Monoterpenes generally dominate the volatile terpene profile (from 3.1-28.3 mg flower dry weight) and include mainly D-limonene, β-myrcene, α- and β-pinene, terpinolene and linalool. Sesquiterpenes, β-caryophyllene and α-humulene in particular, occur to a large extent in Cannabis extracts (from 0.5-10.1 mg flower dry weight). Triterpenes have also been detected in hemp roots, as friedelin and epifriedelanol, in hemp fibres as β-amyrin and in hemp seed oil as cycloartenol, β-amyrin and dammaradienol.
Terpenes are secondary metabolites, secreted alongside cannabinoids, which are a class of terpenophenolic (part terpenoid, part phenol) compound, which provide plants with aromas and flavours. Both types of compounds are biosynthesised in the glandular trichomes of leaves and flowers of the Cannabis plants and are accumulated in large proportions in the exuded resin. It seems certain non-capitular glandular trichomes, which are more abundant in the leaf surface, are specialised in synthesising terpenes. It has been shown the ratio between monoterpenes and sesquiterpenes in leaves and flowers is rather different due to the dominance of sessile trichomes in leaves, which are more specialised in synthesising terpenes, while capitate trichomes are more abundant in flowers and are specialised in the synthesis of monoterpenes and cannabinoids. The proportion of terpenes in the plant is normally less than 1%, potentially achieving up to 10% of the resin composition.
Terpenes play a vital role in the plant kingdom; they deter insect predation, protect plants from environmental stresses and act as building blocks for more complex molecules, such as cannabinoids. Many terpenes act synergistically with other varieties of terpenes and some either catalyse or inhibit formation of different compounds within a plant. While much research has yet to be done on terpenes, their potential to offer unique benefits to medical patients has heightened the interest of both medicine and science. Understanding how terpenes function allows scientists to manipulate cannabinoids to desired ratios.
There are around ten primary and twenty secondary terpenes that occur naturally in significant concentrations. Alphabetically, the first three of the primary terpenes found in Cannabis are caryophyllene, geraniol and α-humulene.
Caryophyllene is a sesquiterpene, made of three isoprene units, which makes it larger than the monoterpenes, pinene, limonene and myrcene (made up of only two isoprene units). α-caryophyllene (α-humulene), β-caryophyllene (BCP, the main component of essential oil of black pepper and Copaiba balsam) and caryophyllene oxide which resists decarboxylation (the terpene most commonly found in Cannabis extracts and detected by sniffer dogs).
This sesquiterpene is found in many other plants including Thai basil, cinnamon, cloves (known remedy for toothache), hops, oregano and rosemary. With a rich spicy odour and flavour it is present in all Cannabis strains. Caryophyllene oxide takes part in the defence system of plants, functioning as an insecticide and an anti-fungal. BCP is the only terpene known to interact with the body’s Endocannabinoid System (ECS) via cannabinoid receptor 2 (CB2).
- Alcohol craving reduction
- Analgaesic – pain relief.
- Anti-bacterial – Slows bacterial growth.
- Anti-coagulant properties
- Anti-depressant – Relieves symptoms of depression.
- Anti-fungal – Caryophyllene and Cannabichromene (CBC) join in defence against fungi and caryophyllene oxide has shown clinical effectiveness against certain fungal infections
- Anti-inflammatory on two levels, one is blocking prostaglandins’ inflammatory pathway (also occurs with myrcene and pinene), the other is as a CB2 agonist
- Anti-oxidant – Prevents oxidation damage to other molecules in the body.
- Anti-proliferative – Inhibits cancer cell growth.
- Anxiolytic – Helps relieves anxiety.
- Gastric protection effects
- Neuroprotective – Slows damage to the nervous system and brain.
What makes caryophyllene chemically unique is the inclusion of a cyclobutane ring, a rarity in nature making it an attractive candidate for biotech research. As BCP has also been shown to have cancer fighting properties it could be a viable candidate for a new chemotherapy drug. Caryophyllene isn’t only unique for being a cyclobutane, but for being both a terpene and a ‘dietary cannabinoid‘, a food-stuff which acts as a cannabinoid and binds to CB2 receptors.
Cannabinoids as a terpenophenolic compound, trigger the body’s endocannabinoid receptors. A 2008 study, which first identified caryophyllene as a cannabinoid, found it had numerous medicinal benefits. Some sources speculate BCP is so powerful it could threaten existing pharmaceuticals and synthetic cannabinoids currently being developed, which could be why BCP is being so heavily studied.
Geraniol is a monoterpene alcohol that boils at about 230˚C (447˚F) and frequently occurs in strains that also produce linalool. It is used frequently as a fruity flavouring agent and shows up in an array of bath and body products. Geraniol, like valencene, is known to repel mosquitoes. Potential therapeutic benefits include:
- Topical drug enhancer
A few strains said to test high in geraniol include indica Lavender, sativa’s Amnesia Haze and Great White Shark, Afghani, Headband, Island Sweet Skunk, OG Shark and Master Kush currently test highest in geraniol.
Humulene, also commonly called α-humulene or α-caryophyllene is one of the predominant terpenes in Humulus lupulus (common hops), from which it gets its name. Also found in basil, Cannabis, clove, coriander, ginger, ginseng, common sage and spearmint. While humulene is related to β-caryophyllene it is a different isomer with distinct properties and it has yet to be recognised as a dietary cannabinoid. Like caryophyllene, humulene is a sesquiterpene. Humulene is unique because, like THCv, it acts as an appetite suppressant, making it promising for weight loss treatments.
Humulene exhibits potent anti-inflammatory and analgesic activity. It also displays anti-cancer properties. It carries a subtle earthy, woody aroma with spicy herbal notes. Humulene’s potential therapeutic effects include:
- Analgesic – Relieves pain.
- Anorectic – Appetite suppressant, promotes weight loss.
- Anti-bacterial – long been known and used in folk medicines but little research had been done to verify claims. 2006 study looked at the essential oil of balsam fir trees and humulene was one of the compounds in the oil which fought bacterial infections.
- Anti-cancer/tumour – first highlighted in a 2003 study, may have to do with ability to produce Reactive Oxygen Species (ROS). ROS have various roles in cancer, contributing to death of cancer cells through apoptosis. A wonderful demonstration of the Entourage Effect can be seen in this 2007 study, which showed β-caryophyllene potentiates the anti-cancer effects of humulene.
- Anti-inflammatory – 2007 study found anti-inflammatory properties of humulene comparable to dexamethasone, a steroidal anti-inflammatory. A 2008 study found topical and systemic anti-inflammatory properties and found it to be an antinociceptive (has analgesic properties). This 2009 study looked closer at the anti-inflammatory properties and found them quite notable and present when taken either orally or by aerosol. This research, taken as a whole, shows humulene as a powerful anti-inflammatory in all forms tested, whether topical or internal.
- Anti-Proliferative – Inhibits cancer cell growth.
- Interleukin-8 (IL-8) Secretion – 2004 study, humulene shown to increase rate of IL-8 secretion. IL-8 is a chemokine (a signalling protein) secreted by human cells which has various functions in the body. One major role of IL-8 is promoting angiogenesis (blood cells split to form new ones; core component in cancer, particularly transition from benign to malignant tumours). The greater the level of angiogenesis, the faster the cancer grows, so generally angiogenesis is inhibited to fight cancer. It is possible that these effects on angiogenesis are tied in to humulene’s ability to promote ROS production, which also has effects on angiogenesis. More research is required to know for certain.
- Pharmacokinetic – the study of the movement of drugs in the body, including the processes of absorption, distribution, localisation in tissues, bio-transformation and excretion.
Expanded from Benefits of Cannabis Terpenes: Terpineol, Valencene, and Geraniol, Cannabis Terpenes: The Benefits of Humulene, Caryophyllene, and Trans-Nerolidol, Terpenes, Infographic: What are Cannabis Terpenes and How Do They Affect You?, Terpenes, Chemistry and analysis of phytocannabinoids and other cannabis constituents, Evolution and Classification of Cannabis sativa (Marijuana, Hemp) in Relation to Human Utilization, Cannabinoids and Terpenes as Chemotaxonomic Markers in Cannabis, Plant terpenes: defense responses, phylogenetic analysis, regulation and clinical applications, Terpene.info