Terpenes and their importance in medical cannabis

What are terpenes?

Terpenes are aromatic organic compounds derived from isoprene (hydrocarbon 5 carbon atoms), they are found in all kinds of vegetation and are important in numerous biotic interactions (Goodwin 1971). They exercise primary functions such as protection against various factors like high temperatures, insects or herbivore predators. They have also been found as part of chlorophyll and some carotenoid pigments.

The functions of terpenes at the plant level are varied and are responsible for highly specialised processes that allow plants to have a protection against the elements around it. Among its functions are the colouring, repellent or aromatization that facilitates the pollination of the plants.

Effects of terpenes

Terpenes in cannabis

The terpene entourage effect

The presence of such a high quantity of different compounds in the cannabis plant can lead to pharmacological interactions, either synergistically or antagonistically. Studying these interactions has shown that, both in terms of efficacy and tolerability, treatments with whole plant preparations have been more promising than the use of isolated cannabinoids. This effect, called the “entourage” effect, was first described by Raphael Mechoulam in 1998 (Ben-Shabat, 1998; Russo and Taming, 2011). The best example described so far is the THC-CBD couple whose combination makes THC better distributed, increases bioavailability (our body uses the available amount in the most efficient way) and reduces possible side effects (McPartland et al, 2014). Although there are few studies on the subject, it is believed that the entourage effect is not only due to interactions between different phytocannabinoids, but also to the functional interaction between cannabinoids and noncannabinoid plant components such as terpenes and flavonoids.

If terpenes are combined with cannabinoids, the effects of the latter can be more powerful. Two essential oils composed mainly of limonene have been shown to inhibit the bacteria Propionibacterium acnes, the key pathogen that causes acne, more effectively than triclosan. Similarly, linalool demonstrated a complementary anti-inflammatory effect, while pinene was the most powerful component of the tea tree and eucalyptus in suppressing acne-producing bacteria.

Some studies have also focused on the ability of terpenes to combat methicillin-resistant staphylococcal (MRSA) infections. This is a strain of Staphylococcus aureus bacteria that is resistant to different antibiotics. Pineapple has been shown to be effective in fighting this type of infection and other bacteria that are resistant to antibiotics. In addition, the ability of terpenes to improve skin permeability and the entry of other drugs can further enhance antibiotic benefits.

It was the lack of information on the entourage effect that led Dr Ethan Russo of the University of Massachusetts to publish an essay on the synergy of phytocannabinoids and terpenes in 2011.

Similarly, these two terpenes and pinene may help to increase the effect of THC on dementia in Alzheimer’s patients. Linalool, together with caryophyllene and myrcene, can increase the effects of several cannabinoids on sleep problems. Finally, caryophyllene, myrcene and pinene may be useful in providing adjuvant support in treating addictions

Four basic synergy mechanisms have recently been proposed (Wagner and Ulrich-Merzenich, 2009):

Multi-target effects
Pharmacokinetic effects such as improved solubility or bioavailability
Interactions of agents affecting bacterial resistance
Modulation of the adverse effects that can be achieved by the entourage

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