Selinene blog header, single leaf cannabis terpene structure

What is Selinene? The Cannabis Terpene You’ve Never Heard of

by | Dec 5, 2023

Selinene blog header, single leaf cannabis terpene structure

Written by Jessica McKeil

Jessica McKeil is a cannabis writer and B2B content marketer living in British Columbia, Canada. Her focus on cannabis tech, scientific breakthroughs, and extraction has led to bylines with Cannabis & Tech Today, Terpenes and Testing, Analytical Cannabis, and Grow Mag among others. She is the owner and lead-writer of Sea to Sky Content, which provides content and strategy to the industry’s biggest brands.

Across the commercial cannabis sector, there has been a slow yet noticeable shift away from an obsession with cannabinoid content toward a new obsession with terpenes. But how many of us obsessed with terpenes have heard about selinene? 

Selinene is a rarely mentioned terpene, technically a sesquiterpene, that can rank high enough in a terpene panel that it will hit the top ten. Yet, it’s a cannabis terpenoid that is mysteriously missing from the industry conversation on terpenes writ-large. 

What is Selinene?

“Selinenes are a group of closely related isomeric chemical compounds which are classified as sesquiterpenes. The selinenes all have the molecular formula C15H24 and they have been isolated from a variety of plant sources. α-Selinene and β-selinene are the most common and are two of the principal components of the oil from celery seeds. γ-Selinene and δ-selinene are less common.”

Selinene cannabis terpene structure
Selinene is a terpene that is never tested for, and therefore never found. But it’s more prevalent than you might think in todays most popular cultivars.

Several preliminary studies have uncovered evidence of antimicrobial, anti-inflammatory, and neuroprotective properties, and (+) δ-selinene has exhibited antitumor activity. But, unlike other terpenes, selinene has never been tested for its pharmacological or even botanical properties. 

Pinene smells like pine trees, linalool like lavender — but what about selinene? It remains so underreported that there is very little information online about what this family of terpenes smells like. At best, I could find only a vague reference to it smelling herbal.

Despite the lack of aromatic information, selinene is found in many herbs and spices, including allspice, basil, celery seeds, galangal root, and others. It’s prevalent in aromatic wood oils, including cedar and Amyris. And while you’ll never see it on a lab test, selinene also frequently appears in common cannabis cultivars.

Selinene Terpenes in Cannabis

In a recent interview with Cannabis Tech, Hubert Marceau, ​​directeur de développement at Laboratoire PhytoChemia in Quebec, Canada, mentioned selinene. Although our interview was about his work on terpene clusters, our conversation quickly pivoted to this mysterious compound.

According to Marceau, selinene is far from one of the rarest cannabis terpenes. He has found it can be attributed to up to one percent of the most volatile fraction. Yet, this family of sesquiterpenes is almost entirely ignored by the cannabis industry. Why is that?

To date, few studies even name selinene and cannabis together in the same paper. Current research has been more focused on listing and categorizing terpenes derived from cannabis rather than diving into the mysteries of individual compounds. This means selinene, in relation to cannabis, has largely ended up as a list item and nothing more.

In 2020, “Terpenes/Terpenoids in Cannabis: Are They Important?” tested the abundance of main terpenes/terpenoids in 54 samples, discovering γ-selinene ranked within the main 13 terpenes/terpenoids uncovered, including one variety that was predominantly selinene.

In 2021, “Metabolomic Analysis of Cannabinoid and Essential Oil Profiles in Different Hemp (Cannabis sativa L.) Phenotypes” found a positive correlation between the prevalence of γ-selinene and β-selinene (among several other terpenoids), and THC-A with a negative correlation to CBD-A.

A 2022 publication found that selinene was more pronounced in male CBD flowers than in females. But in the male flowers, it made up 3.4 percent of the essential oil tested.

Despite the often high concentration and frequency of occurrence of selinene in cannabis, generally speaking, few people have paid much mind to this little-known terpenoid. 

Selinene Missing from the Cannabis Terpenes Conversation

Part of the problem, as Marceau outlined, is that selinene isn’t available commercially. It’s only possible to purchase through a chemical provider, from the likes of EvitaChem of sMolecule. 

Marceau explains, “Because they are not available commercially, if you are going target analysis, meaning that you need to buy a standard and compare to the sample, you will more often or not just get them, or not see them.” 

Scott Holden, founder and CEO of Lab Effects & CBD Global, elaborated that it is usually pulled from celery seed, and “it’s difficult to extract and isolate naturally in high concentrations, which may be why it is not commonly available.”

According to Holden, “The natural forms are typically around 40 to 60 percent purity, which is very low. It’s not chemically pure enough for most applications. Certainly not for analytical chemistry, but even far too low for use in formulation like we do at Lab Effects. Our Isolated terpenes are all around 98+ percent purity, so sub-60 percent is too low for our standards.”

While Lab Effects may be one of the only terpene brands committed to 100 percent natural terpenes, they aren’t the only company without selinene. None of the major terpene companies sell even synthetic selinene, nor do they include it in their blends.

It’s an interesting catch-22. Yes, selinene is one of the more prevalent cannabis terpenes from a list that has now reached well over 150. Still, achieving high purity from a natural source is challenging, while synthetic versions remain prohibitively expensive and/or impossible to source. Furthermore, labs don’t set standards for selinene, which means without testing, the cannabis sector doesn’t talk about it.

Selinene’s Role and Safety Profile Remains a Mystery

Without data beyond those buried in scientific publications and in the databases of labs like Marceau’s, selinene’s properties remain largely a mystery. Even Marceau can only speculate about its potential properties. According to his testing, he sees it exhibited like an on-off switch, leading him to hypothesize it may serve as a proxy for other systems, genetic or metabolic.

Is selinene even safe for human consumption? Holden is wary of including rare terpenes just for the sake of novelty. When he reads a label with a list of rare terpenes, he knows most, if not all, of these are impossible to source on the open market. In his experience, “Many of the rare terpenes we have seen come from very woody essential oils which are known to be unsafe for human consumption or inhalation.” 

Unlike almost all the other common terpenes attributed to cannabis, selinene is one of the least studied. It has no history of use in perfumery, as a flavor additive, or in the pharmaceutical sector. Nobody tests for selinene and, therefore, nobody finds it — even if it commonly occurs in many popular cultivars. Its botanical characteristics and safety profile remain shrouded in mystery.