Terpenoids Commonly Found in Cannabis sativa Do Not Modulate the Actions of Phytocannabinoids or Endocannabinoids on TRPA1 and TRPV1 Channels

Abstract

Introduction: Cannabis sativa produces hundreds of bioactive compounds, including cannabinoids and terpenoids. It has been proposed that cannabinoids act in synergy with terpenoids to produce the entourage effect, a concept used to explain the therapeutic benefits of medicinal cannabis. One molecular explanation for the entourage effect is that the terpenoids augment the actions of cannabinoids at their molecular drug targets in cells. We recently reported that terpenoids commonly found in cannabis do not influence the functional effects of D 9 -tetrahydrocannabinol (D 9 -THC) on cannabinoid 1 and cannabinoid 2 receptors. The present study aimed to extend on this research by examining whether terpenoids influence the effects of phytocannabinoids and endocannabinoids on human transient receptor potential ankyrin 1 (hTRPA1) and human transient receptor potential vanilloid 1 (hTRPV1) channels heterologously expressed in mammalian cells. Materials and Methods: The activity of terpenoids, phytocannabinoids, and endocannabinoids was assessed in inducible HEK Flp-In T-Rex cells transfected with hTRPA1 and hTRPV1 channels, respectively. Real-time changes in intracellular calcium ([Ca] i ) were measured using the Calcium 5 dye and a FlexStation 3 plate reader. Results: a-pinene, b-pinene, b-caryophyllene, linalool, limonene, b-myrcene or a-humulene did not affect [Ca] i in hTRPA1 and hTRPV1 overexpressing cells. Cinnamaldehyde (CA), D 9 -THC, and 2-arachidonoylglycerol (2-AG) activated TRPA1 receptors with high efficacy and similar potency (EC 50 s of *10 lM). Capsaicin and anandamide (AEA) activated TRPV1 receptors with an EC 50 of 61 nM and 4.3 lM, respectively, but TRPV1 showed no response to D 9 -THC, cannabidiol, and other minor cannabinoids. Terpenoids did not significantly affect the responses of TRPA1 and TRPV1 receptors to submaximal and maximal concentrations of CA and D 9 -THC or the endocannabinoids AEA and 2-AG. Discussion: We could not find any evidence that the terpenoids tested here activate TRPA1 and TRPV1 channels or modulate their activation by D 9 -THC and other agonists, including endocannabinoids.

Essential Oils from Monarda fistulosa: Chemical Composition and Activation of Transient Receptor Potential A1 (TRPA1) Channels

“…Further studies need to be conducted to determine the exact EC 50 value of β-myrcene at the TRPA1 channels, but this was beyond the scope of our present study. The only study investigating the "entourage effect" of terpenoids modulating the action of cannabinoids tested 10 µM of β-myrcene on hTRPA1-expressing HEK293 cells [84]. We found that a minimum dose of 125 µM was required to elicit significant increases in [Ca 2+ ] i through rTRPA1 channels in our heterologous cell expression system.…”

Lack of evidence for the effectiveness or safety of over-the-counter cannabidiol products

“… 60 However, experimental studies have consistently failed to provide evidence for such an effect. 61 – 64 Nevertheless, the concept of the ‘entourage effect’ remains popular and is used to promote the health benefits of OTC supplements. 65…”

It Is Our Turn to Get Cannabis High: Put Cannabinoids in Food and Health Baskets

“…Along with their role in photosynthesis, respiration, and plant defense, terpenoids are responsible for the flavor and aroma of different cannabis varieties and are considered as a major crucial factor of preference of the cannabis users. The therapeutic benefit of medicinal cannabis is that to produce a retinue effect, cannabinoids may function in synergy with terpenoids [ 49 ]. Over one hundred monoterpenes and sesquiterpenes have been identified in cannabis [ 50 ].…”