Get to Know a Cannabis Terpene: Limonene

The fresh citrus smell of the cleaner I used this morning inspired the research behind today’s terpene, limonene. Limonene helps explain terpenes to the uninitiated. The zesty citrus smell emanating from flower helps demonstrate that different plants can share the same terpenoids. A monoterpene, limonene can be found in citrus (obviously), and there are two isomers — D-Limonene (with a citrus smell) and L-Limonene (with a piney smell).

D-Limonene, which is the terpene that is also found in cannabis, is the isomer that is found in citrus peels. This versatile terpene isomer is not only found in perfumes and foods, but also regularly used as an industrial degreaser, is a key ingredient in some cleansers, and is in use in many insecticides. The bright, citrus smell can be found in a variety of natural sources, and limonene is present across cannabis strains in varying amounts.

Because there are so many uses for limonene, it stars in a lot of patent applications. One of my favorites describes a cannabis chewing gum. Another one is for a limonene-based flame retardant. Because limonene has such versatile and long-standing uses in perfumes and food , there are a variety of patents leveraging limonene in those areas. This includes laundry detergents, perfumes, household cleaners, shampoos, conditioners, pet products, and more. Limonene’s power as a cleanser should not be forgotten , nor should its inherent usefulness as a natural insecticide.

Limonene has been studied along with other terpenes in their effectiveness to assist the percutaneous absorption of some poorly-absorbed drugs. That study demonstrated that terpenes like limonene and nerolidol were increased the effectiveness of topical medications — limonene was particularly adept at helping the absorption of lipophilic medications.

Because limonene is found in so many consumer products and has been available outside of cannabis for years, it has already come under some amount of scrutiny. While male lab rats might have issues with limonene in the liver, the reasons are

A study in 1998 found limonene was well-tolerated and worthy of further study for its impact against cancer. Further studies have showed a distinct in vitro impact against cancer.

The oral administration of limonene was found to reduce inflammation due to colitis in rats in a study conducted in 2013, with the recommendation to move forward to human subjects. Limonene is a solvent for both cholesterol and gallstones. Limonene was present in an essential oil found to be effective in the treatment of IBS. Limonene was suggested for further study in the clinical context of COVID-19 due to its other clinical uses. Limonene has a gastric-acid neutralizing effect and is used in the treatment of GERD.

The advantages of limonene don’t all require a direct contact with the chemical itself. Forest bathing and high exposure to limonene aerosols contribute to lower blood pressure and better mood.

Limonene was identified as one of the anxiolytic / antidepressive therapeutic compounds and it has been studied and found to be effective as an inhaled anti-emetic.

Limonene has an variety of uses, and this little powerhouse of a terpene is found in every strain of cannabis I’ve encountered (and that’s a lot!).

Boiling Point: 352° F ( 176 °C)

Other Sources: Oranges, lemons, limes, grapefruit, bay leaf, cardamom, celery, dill, pepper, rosemary, tea tree. While its name comes from lemons, the highest concentration of natural limonene is found in orange rind, whose oil is up to 97% limonene.

Article Sources:

http://www.chm.bris.ac.uk/motm/limonene/limoneneh.htm

https://en.wikipedia.org/wiki/Limonene

https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/limonene

https://www.ewg.org/skindeep/ingredients/702113-LIMONENE/

https://pubchem.ncbi.nlm.nih.gov/compound/___-Limonene#section=Taste

Originally published at https://oregoncannabisgazette.com.