A terpene from a chemical sense is any hydrocarbon that has the empirical structure consisting of five carbon atoms attached to eight hydrogen atoms (C5H8). Hydrocarbons are the main component of organic chemistry since biological function is built on the existence of this archetype of molecule, meaning that most of the hydrocarbons you find will be of some biological function and commonly come from plants and animals.

Because there can be so many iterations and substructures that fit the C5H8 empirical structure, the approximate number of known terpenes is close to about 55,000 different compounds.


Most of the terpenes we see today are found in plants, and they are responsible for giving them their pleasant or distinct aromas. 


One common misconception is that Terpenes and cannabis are similar or always related, but this is not the case. While it is true that cannabis does tend to have a high concentration of terpenes, they are not mutually exclusive. Many plants such as rosemary, pine, lavender, and orange also have a terpene to thank for their aromatic qualities. 


The chemistry behind terpenes and their pleasant aromas have been harnessed by manufacturers to create the flavors and scents of many everyday products, such as perfumes, body products, and even foods. 


Terpenes are just there for more than just the smells though, they have essential biological function as well. In nature, terpenes may be used to protect some plants from animal grazing, predatory insects, or infectious germs, while in other plants they are meant to attract animals to help them pollinate and reproduce. 


Another misconception that people have is that terpenes and terpenoids are the same, since the two terms are sometimes used interchangeably. However, they are not the same. Terpenes are the
natural form of these compounds when they are in the live plant. As a plant dries and cures — in the production of cannabis, for example — the terpenes oxidize and become terpenoids.

How Do Terpenes Affect People?


Terpenes are found in everyday products for their aromatic properties, but they have a sort of medicinal use as well. One reason that people have the misconception that cannabis and terpenes are the same is because of these medicinal properties. Both these compounds act on the endocannabinoid system in the body in a similar way, but the difference is that the body absorbs and uses these compounds differently.

The endocannabinoid system is one of the key homeostatic systems in the human body. It is responsible for maintaining balance on a molecular level by regulating my biological processes, including immune response, communication between cells, appetite and metabolism, memory, and others. 


Despite the integral role the endocannabinoid system has in human body function, it was discovered relatively recently and much of its importance is only just becoming understood by scientists and the medical community.


One common place you will see terpenes being used for medicinal purposes, other than through cannabis, is through the use of
essential oils.


Terpenes and Essential Oils


In plants, essential oils are usually present in low concentrations ranging from 0.1% to 1%. To extract these essential oils there are many different processes that have been developed depending on the specific plant chemical structures and type of oil that is being extracted.The majority of essential oils have a terpene as their main molecule, the monoterpenes and sesquiterpenes being the most abundant terpene subclasses present.

The use of essential oils with terpenes in the use of aromatherapy is some of the more abundantly explored regions of the topic at the moment. Each specific terpene compound has its therapeutic advantages and disadvantages. Here are just a few example of the some terpenes that have researched therapeutic benefits:

  • Limonene - This terpene is found in several different citrus and cannabis. It has commonly been used as a flavoring agent and orange fragrance, but has been shown to elevate mood and provide stress relief, amongst other beneficial physiological effects. 

  • Pinenes - This terpene is found in plants like lavender and rosemary, but is most common in conifers - trees that bear cones and needles. Oils that have a high concentration of pinene have been shown to have antimicrobial activity and may aid the respiratory system.

  • Eucalyptol - This terpene is present in many different kinds of eucalyptus trees. It has been shown to have many health benefits including some respiratory benefits.

  • Myrcene - This terpene is the main terpene found in cannabis and has been shown to relieve discomfort and it has some mild sedative qualities as well.

  • Linalool - This terpene generally comes from lavender, rose and basil. It is used very commonly in perfumes, and has been shown to have some sedative and antioxidant properties.

  • Camphor - This terpene is found very commonly in Cinnamomum camphora a common “big tree” in california, which is a distant cousin to the Cinnamomum zeylanicum which is the tree that we get the spice cinnamon from. 


While camphor has its roots in ancient asian medicine, it is still very much alive and well showing health benefits to a variety of areas: digestive health, discomfort alleviation, and as a mild sterilizing agent.

    • Terpineol - This terpene comes in a few different chemical forms all originating from the Melaleuca alternifolia plant, more commonly referred to as tea tree. 
    • Citronellol - This terpene is found in the warm humid summer areas on the skin of people enjoying the day and avoiding the bugs. Citronellol is the key ingredient in citronella oil, which is used very commonly as an insect repellant. Citronellol also has therapeutic benefits to relieve some mild discomfort.
    • Chamazulene - This terpene is considered to be quite special due to its unique blue color. It is found in Matricaria chamomilla or more commonly referred to as chamomile. 
    • Humulene - This terpene comes from Humulus lupulus , a plant in the hemp family usually referred to as Hop. 
    • Bergamotene - This terpene comes from the less recognized bergamot citrus, and is one of my personal favorites.
    • Citral - This terpene is coumes in two different forms both found in lemon myrtle (Backhousia citriodora) and lemongrass (Cymbopogon citratus).
    • Bisabolol - This terpene is found most abundantly in chamomile (Matricaria chamomilla) but has been found in a bunch of other species, such as Salvia runcinata, as well. This terpene is quite commonly used in the cosmetic industry and has been shown to relieve discomfort.


Summary


Terpenes are the compounds responsible for many of your favorite and most memorable plant smells. They may play a role in the health and survival of the plants in which they exist, and they may also have health benefits for humans through ingestion, aromatherapy, or otherwise spending time in areas that have a high terpene content. 

The research on the role of the endocannabinoid system and the various plants that affect it - like cannabis - is still very much in the early stages, but researchers continue to study these compounds to more fully understand their therapeutic and medicinal potential.


Sources:

Terpenes in Essential Oils: Bioactivity and Applications | IntechOpen


Terpenes and derivatives as a new perspective  | Expert Opinion on Therapeutic Patents


An introduction to the endogenous cannabinoid system |  Biological Psychiatry


Terpenes and Terpenoids |  IntechOpen