Understanding Terpinene

Updated: Jul 10, 2022

Terpenes are one of the three major families of wellness molecules produced by cannabis/hemp/marijuana, which also includes cannabinoids and flavonoids. As one of the most abundant types of chemical in nature, more than 40,000 varieties of terpenes exist, with the most common in cannabis being myrcene.

Collectively, the 200 terpenes contained in the cannabis species genome (only a small subset of which manifests in an individual chemotype or sample of the plant) offer a wide range of medical properties to the humans who consume them. These include antioxidant, antibacterial, anti-inflammatory, antianxiety, antifungal, neuroprotective, anticancer, and analgesic (pain reducing) properties.

Terpinene is a minor terpene that has demonstrated a number of wellness benefits, including anticancer efficacy. This monoterpene is produced by betel, cannabis, cardamom, eucalyptus, juniper, marjoram, peppermint, tea tree, and verbena, among other plant species.

In isolation, terpinene emits an aroma that is piney, with heavy notes of smoke and wood, and delivers a spicy flavor. Terpinene is the primary chemical component of tea tree oil and is employed in many industrial applications where odor neutralization is required.

The terpinene molecular isomers

The medicinal benefits of terpinene beyond cancer efficacy (in which it inhibits cancer cell growth) are many, including antibacterial, antifungal, and antioxidant effects. It has also been shown to serve as a sleep aid, of value to those suffering social anxiety and anxiety-related conditions such a Post-traumatic Stress Disorder.

Terpinene is produced in volume at the industrial level via conversion from alpha-pinene (the most common terpene in nature that is produced by 400+ plant species) by the method of acid-catalyzed rearrangement.

Terpinene actually encompasses a small family of related compounds involving four analogs (α-terpinene, β-terpinene, γ-terpinene, and δ-terpinene). These molecular analogs, or isomers as they are sometimes called, are so similar that they possess the identical molecular formula. They differ only with respect to the position of their carbon-carbon double bonds (just as the delta-8 and delta-9 THC cannabinoids differ only in the location of their carbon double bond).

α-terpinene is found in natural sources and produced by many plant species, including hemp. β-terpinene has no known natural source, but can be derived from the terpene sabinene. The other two analogs occur naturally and are commonly categorized not as analogs of terpinene, but as the terpene terpinolene. While naturally occurring, α-terpinene can also be derived from α-pinene.

A 2017 study entitled "Inhibition of the TetK Efflux-pump by the Essential Oil of Chenopodium Ambrosioides L. and α-Terpinene Against Staphylococcus Aureus"

that was published in the journal Food and Chemical Toxicology explored the ability of α-terpinene to treat bacterial infections and act as an antibacterial agent.

The efficacy of α-terpinene was investigated for the specific treatment of the Staphylococcus bacteria (an organism with the ability to cause a number of diseases and infections of the skin in human and animals, including lesions, abscesses, and deep infections. Unfortunately, Staphylococcus is known for its ability to form resistance to conventional antibiotic treatments.

α-terpinene alone was not found to display statistically relevant efficacy. However, it was shown to "significantly decrease" the presence of the bacterial infection when combined with tetracycline and ethidium bromide. The study's authors concluded that α-terpinene demonstrates that the C. ambrosioides L. essential oil may effectively inhibit the growth of this type of bacteria.

A 2012 study entitled "α-Terpinene, an Antioxidant in Tea Tree Oil, Autoxidizes Rapidly to Skin Allergens on Air Exposure" that was published in Chemical Research in Toxicology investigated the potential medicinal efficacy of terpinene, including its antioxidant properties.

The study found α-terpinolene to be the compound responsible for the antioxidant efficacy of tea tree oil and revealed that it is structurally similar to limonene, another terpene that exhibits antioxidant behavior.

Reported the study, "From a technical perspective, α-terpinene is a true antioxidant since it autoxidizes rapidly compared with many other compounds." The study's authors noted that this terpene also "easily autoxidizes to form allergens," and, thus, "its suitability can be questioned when used in products for topical applications" such as cosmetics and skin care products containing tea tree oil.

A 2006 study entitled "Tea Tree Oil: A Review of Antimicrobial and Other Medicinal Properties" that was published in the journal Clinical Microbiology Reviews explored "recent developments in our understanding of the antimicrobial and anti-inflammatory activities of the oil and its components, as well as clinical efficacy."

The study noted that the primary uses of tea tree oil have "historically capitalized on the antiseptic and anti-inflammatory actions of the oil." It noted that tea tree oil "has been used for almost 100 years in Australia but is now available worldwide, both as neat oil and as an active component in an array of products."

The study's authors concluded that the body of research data available about terpinene shows true medicinal value and a need for additional research, including human clinical trials. "A wealth of in vitro data now supports the long-held beliefs that [terpinene] has antimicrobial and anti-inflammatory properties."

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