Terpenoids and terpenes are aromatic compounds that are found in thousands of plant species. These compounds are responsible for the various flavours and fragrances of each these individual plants. We have known about their presence for decades, but it is only recently that awareness of their potential therapeutic properties has begun to expand.

What are terpenes & terpenoids?

Terpenes are a large class of naturally-occurring organic compounds; they are also known as isoprenes, as their structure is based on repeating isoprene (C5H8) units. Terpenes are major constituents of plant resin and essential oils extracted from such plants.

Terpenes are basic hydrocarbons, whereas terpenoids contain extra functional groups that could be comprised of a range of chemical elements. However, it is common for the term ‘terpene’ to also include terpenoids in many existing writings. Terpenoids, also known as isoprenoids, are the largest group of organic compounds found thus far, comprising at least 20,000 distinct molecules.

How are terpenes produced?

Terpenes are formed through the precursor isopentenyl pyrophosphate (IPP), and give rise to various families of compounds, depending on the number of these molecules that are bound together. In the case of hemiterpenes, these derive from a single IPP; monoterpenes derived from two IPP; sesquiterpenes from six, etc.

Terpenes start to evaporate when they come into contact with the air, especially when exposed to sunlight and high temperatures. For this reason, plants are more aromatic at the start of the day than in the evening.

How do terpenes affect us?

We can smell and taste terpenes, but this is not the only way they affect us. In fact, most people will have heard of aromatherapy, a practice that uses essential oils (rosemary, lavender, rose, etc.) to enhance psychological and physical well-being. These effects are the result of the various terpenes and other compounds present in the plants.

Some terpenes can affect the “grey matter”, since they block the neuronal receptors they modify the permeability of the neuron cell membranes. These terpenes can also have an impact on the levels of serotonin and dopamine, two of the main neurotransmitters responsible for altering a person’s mood and activity. When terpenes are mixed, each affects the brain in its own way. Some complement each another and others cancel each other out. Therefore, every combination is unique.