Terpenes – a new understanding
Cannabis derives many of its most pleasant flavors and aromas from terpenes, a large class of organic molecules. But what exactly are terpenes, and why do they exist in nature?
Originally thought only to be produced in plants to serve as a deterrent to herbivores by imparting an undesirable smell or taste to the plant, terpenes are now understood to function in a number of interesting ways. One function is facilitating communication between plants and bacteria through the language of ‘smells’. Terpenes serve an adaptive purpose for the cannabis plant too, distinct from their potential effects on humans. In flowers, the sticky consistency of terpenes can trap would-be insect herbivores while other phytocannabinoids are directly insecticidal. In the lower leaves, higher concentrations of bitter sesquiterpenoids act as a deterrent to grazing animals.
These examples from across biology illustrate that terpenes are involved in a wide range of biological functions throughout the tree of life and should be thought of as key signaling and communication molecules and not just as ‘nice smelling’ molecules with only peripheral or secondary importance to their parent organisms. Perhaps this knowledge should also reframe how we should consider the role of terpenes in cannabis, and in the humans that consume cannabis for therapeutic purposes.
Cannabis contains hundreds of compounds – each with the potential to exert some pharmacological effect on the patient. Studies dating back to the 1970s indicate that whole cannabis extracts produce much stronger effects than administering THC alone. Of the many potentially therapeutic molecules found in cannabis, over 200 are terpenes, of which to date are understudied with respect to their potential role in modulation of THC and other cannabinoids. That being said, terpenes are known to exhibit a wide range of effects in animals, including humans. Effects of terpenes on humans, or in animal models studied with regards to human health, include alleviation of depression, inhibition of cancer cell growth, limiting the growth of skin disease, changing the level of mouse neuronal activity, anti-inflammatory properties, and performing free radical scavenging to prevent oxidative stress and cell damage. Given that synergy has been observed among various cannabinoids and other compounds extracted from cannabis, and that we know terpenes can exhibit effects on animal health, behavior, and cognition, it’s important to consider that terpenes may be key players in modulating the effects of THC and other active compounds found in cannabis. Yet, despite this knowledge, most cannabis preparations contain no more than 1% terpenes, even though terpenes comprise around 10% of trichome content. Clearly most of the existing harvest, preparation, and extraction techniques are not well optimized to retain terpenes, a potential lost opportunity for therapeutic value.
Taking all of this into account, it’s time to more carefully consider the role of cannabis terpenes on their own and as they relate to the effects of cannabinoids on human biology. Understanding how cannabis terpenes and other compounds may modulate the efficacy of cannabis in preventing or treating disease could facilitate the next leap forward in cannabis science.