What are terpenes?

By Andrew Megahy • 2月 11, 2020 • 3 min read

Anyone who has experience with the Cannabis plant will be familiar with the word ‘terpenes’. They’re an integral part of the functioning of the plant as well as how we use it, in regards to its smell, therapeutic properties and appearance of cannabis oils. For those of us who might be less informed, I intend to cover what I consider to be the most important things to know about terpenes. Topics ranging from what they do in the plant, an overview of the ‘entourage effect’, how they’re produced and where you can find them in nature. Before getting into the complex stuff we’ll start with the basics.

Terpenes are a class of organic compounds (they are composed primarily of carbon). It’s important to note that terpenes are inherently different to ‘terpenoids’, which are chemically different molecules. While most notable for contributing to the distinctive smell of the Cannabis plant, terpenes can be found in a vast variety of plants – conifers particularly are known for their terpene production – and even some insects (Pichersky et al. 2006). They are the main components of rosin and turpentine, two industrial products sourced from pine resin, as well as being important building blocks for biosynthesis of other organic compounds such as steroids. Terpenes are also the primary constituents of essential oils, which are commonly used as fragrances in perfumes or for aromatherapy. Clearly there are a number of applications that humans can use terpenes for, but what purpose do they serve in the organisms that produce them?

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The entourage effect is a synergistic relationship between all the compounds in the Cannabis plant, where the effect of one molecule is enhanced by the presence of others. It can be thought of as an example of the phrase, ‘the whole is greater than the sum of its parts’.

There is a consensus that in many plants terpenes are produced to protect them by aiding in defence against herbivores (Martin et al. 2003). The two methods through which this is achieved are either by deterring the herbivore directly – often by making the plant smell unappetising or rotten – or by releasing an aroma that actively attracts either predators or parasites of the herbivore, perhaps one that smells like meat. There is also research suggesting that pine trees in northern boreal forests release terpenes into the air to ‘thicken’ cloud formations, reflecting sunlight and regulating the temperature of the forest as a whole (Faiola et al. 2018). These terpenes are also responsible for the characteristic smell associated with walking through a pine forest. One final notable usage of terpenes in nature is by Nasutitermitinae termites. Through the use of a specialised appendage called a ‘fontanellar gun’ on their head, they can spray a mix of certain chemicals to protect themselves from predatory insects. I highly recommend looking this up because it is genuinely one of the most incredible things I’ve read about (Nutting et al. 1974).

To get back onto the topic of terpenes, there is a lot of interest regarding including them in Cannabis-based products because of a phenomenon referred to as the ‘entourage effect’. The entourage effect is a synergistic relationship between all the compounds in the Cannabis plant, where the effect of one molecule is enhanced by the presence of others. It can be thought of as an example of the phrase, ‘the whole is greater than the sum of its parts’. The entourage effect is of great interest in both the supplement and medical communities for Cannabis, as it may prove an easy method to make Cannabis-based products more effective at their stated uses; pain relief cream may be more efficacious simply by including other chemicals from the plant. This concept doesn’t just apply to cannabinoids, as terpenes are proving to be of interest to the scientific community too (Blasco-Benito et al. 2018).

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Finally, I’d like to go into a little of the chemistry behind terpenes. This part is going to get a bit dense so I’ll keep it short. Ignoring terpenoids, there are at least 10 different chemical forms that terpenes can take. The name of each type depends on the number of isoprene units it contains, which are a specific type of hydrocarbon molecule. In the same way that sugars like maltose and sucrose are made up of different numbers of monosaccharides, so terpenes are made up of different numbers of isoprenes. They are named accordingly; Monoterpenes have two, Diterpenes four, Triterpenes have six etc.

I’ll end with a couple examples of terpenes for you to have a guess where they first came from/are most known for. This isn’t really a knowledge test, more of a demonstration as to how unimaginative scientists can be when it comes to naming things. Hopefully you learned a few new things over the course of this blog, even if they weren’t directly related to CBD products.