In Defense of the “Entourage Effect”: Terpenes Found in Cannabis sativa Activate the Cannabinoid Receptor 1 In Vitro
Authors: Hecksel Ryan , LaVigne Justin , Streicher John M. 
Published: April 2020

Marijuana has been understudied for decades, primarily due to social stigma and legal restrictions. However, as legal restrictions begin to loosen among states, the potential medical benefits and pharmacological properties of marijuana are beginning to be explored. Terpenes, an expansive group of organic chemicals that impart odor and taste, are found in the Cannabis sativa plant and may work synergistically with cannabinoids, such as THC and CBD, in a term deemed the “entourage effect”. Anecdotally among the recreational and medical use community, terpenes have been reported to enhance the potency and physiological effects of marijuana. However, scientific evidence for the “entourage effect” is very limited. To evaluate this hypothesis, we obtained the C. sativa‐relevant terpenes: β‐pinene, α‐humulene, geraniol, and linalool. Utilizing Chinese hamster ovary cells (CHO) expressing the human cannabinoid receptor type 1 (CB1, CB1‐CHO) we screened these terpenes for CB1‐dependent phosphorylation of extracellular signal‐regulated kinase 1/2 (ERK1/2), a well‐known downstream target of CB1 activation, using Western blot. We observed that pERK levels were efficaciously stimulated by all four terpenes when compared to positive control, the selective CB1 agonist WIN 55,212‐2. These results appeared to be CB1‐dependent, as pre‐treatment of these cells with a selective CB1 antagonist, rimonabant (SRI141716), blocked ERK phosphorylation by each of the terpenes. We further verified the CB1‐dependent nature of these effects by examining ERK phosphorylation by the terpenes in wild type CHO (WT CHO) cells, which do not express the CB1 receptor. In these cells, β‐pinene and α‐humulene treatment resulted in ERK phosphorylation while linalool or geraniol treatment did not. In WT CHO cells, the ERK phosphorylation induced by β‐pinene and α‐humulene was not CB1‐dependent, as rimonabant pre‐treatment did not block it. These results thus suggest that geraniol and linalool could be CB1‐selective agonists, whereas β‐pinene and α‐humulene are non‐selective and may also activate one or more receptors besides CB1. Follow‐up studies will examine other measures of CB1 activity (binding, cAMP signaling, GTPgS coupling) to characterize the binding and functional properties of these terpenes at the CB1 receptor, as well as identifying the other targets of β‐pinene and α‐humulene.
Once we’ve characterized these terpenes individually, we aim to investigate their role in the “entourage effect”, by testing their modulation of typical cannabinoid (THC, etc.) pharmacology. Translationally, these findings could have implications in marijuana cultivar breeding and
could help produce strains optimized for specific terpene profiles, which could be more efficacious for chronic pain management and other therapeutic uses.

Support or Funding Information

This study was supported by institutional funds from the University of Arizona. JMS has received research funding from Botanical Results, LLC, a company that develops cannabidiol products (not related to current study).