Have you ever smelled a cannabis chemovar that reminds you of hops? If so you’ve likely encountered the terpene Humulene. It is a terpene found in many plants including hops and cannabis plants. A terpene is one of several aromatic molecules that give plants their unique effects. Terpenes are found in the resinous glands of cannabis plants (trichomes) and contribute to a chemovar’s distinct properties. Humulene is also an isomer (compounds with the same molecular formula but different compositions) of another common terpene, beta-caryophyllene. In fact they are so close, that another name for Humulene is actually alpha-caryophyllene.
The scent is characterized as earthy, spicy, herbal, and, of course, is reminiscent of that peppery hops scent. Humulene can be found in high concentrations in hops essential oils as well. Other naturally rich sources include cloves, basil, sage, spearmint, black pepper, balsam fir trees, ginseng, and ginger.
It is also an insect repellant with a wide range of therapeutic applications. Its benefits include anti-inflammatory and antinociceptive (painkilling) properties, antibacterial effects and potentially anticancerous activity.
What are its effects? What else is it used for?
Terpenes are thought to be a defense mechanism secreted by plants to deter insects. In Humulene’s case this is especially true as studies show this terpene is an effective insect repellent.
A 2015 paper sought out to analyze the efficiency of Commiphora leptophloeos leaf oil against “the yellow fever mosquito,” A. aegypti. The researchers identified α-Humulene as one of the major constituents in the oil. They concluded that its presence in conjunction with other terpenes was, “…responsible, at least in part, for the deterrent effect of the oil.” They added that the deterrent activity of the oil was, “…one of the most potent reported so far, suggesting that it could represent an interesting alternative to synthetic insecticides.”
Humulene has been used throughout history as an herbal medicine. It has also demonstrated promise with respect to cancer treatment. One 2003 study analyzing the antitumor activity of fir balsam oil found it to be active against all the solid tumor cell lines tested. Interestingly enough the researchers noted, “all the compounds tested were inactive…except for alpha-Humulene…which thus seems responsible for the cytotoxicity of the oil.”
How common is it in cannabis?
Humulene (along with its isomer, beta-caryophyllene) is thought to be one of eight primary terpenes found in cannabis plants. As such it is fairly common in chemovars, though its concentration may vary. Since chemovars can vary in terpene content from grower to grower and even batch to batch, it’s a good idea to check out a flower’s certificate of analysis whenever possible.
One study analyzed 233 samples representing 30 cultivars to identify terpene content. Concentrations of terpenes in each chemovar — including that of Humulene — was used as one of the characteristics that set particular chemovar classes apart. As such one of the major groups was characterized by the presence of β-Caryophyllene-dominant, alcohol-substituted terpenoids. Chemovars in this class typically demonstrated a 1:1 or 2:1 ratio of Limonene to Humulene and included varieties from the Sherbert and Cookies families. Some Cookie chemovars listed were: Animal Cookies, Blue Cookies, Girl Scout Cookies, and Thin Mints.
Other chemovars that are colloquially believed to have high levels include Headband, White Widow, OG Kush, and Candyland.
Humulene’s clinical applications are still being evaluated. One promising potential use is as an anti-inflammatory/steroidal drug. A 2009 study found α-Humulene showed anti-inflammatory properties in a murine model of airways’ allergic inflammation. Another 2007 study compared its anti-inflammatory effects to the steroidal drug dexamethasone.
Another keen area of popular interest is Humulene’s purported effects on appetite. Many cite the terpene to be an appetite suppressant, though this claim has yet to be empirically tested and reviewed.
Humulene is also thought to act as an antioxidative agent involved in the production of reactive oxygen species (ROS). Imbalances in ROS are implicated in disease states such as aging and diabetes.