Fifty Years of Cannabinoid Research: Mechoulam's Retrospective
Plant cannabinoids: a neglected pharmacological treasure trove.
Four decades after isolating THC, the founder of cannabinoid chemistry looked back on his field and argued that most cannabis compounds remained a neglected pharmacological treasure trove.
Jerusalem, 2005. Raphael Mechoulam is 75 years old and still working in the same lab at Hebrew University where he identified THC four decades earlier. The field he started with a two-page chemistry paper now spans thousands of laboratories across six continents. Two cannabinoid receptors have been cloned. Two endocannabinoids discovered. An entire biological system — the endocannabinoid system — has been mapped.
And yet, looking at the cannabis plant itself, Mechoulam sees something that troubles him. Of the roughly 100 cannabinoids identified in Cannabis sativa, the vast majority have never been properly studied. The plant that launched an entire field of neuroscience remains, in pharmacological terms, mostly unexplored.
He calls it a neglected treasure trove.
The Arc of a Field
To understand what Mechoulam was looking back on in 2005, you need to see the trajectory. In 1964, cannabis science didn't exist. By 2005, it had become one of the most active areas in pharmacology — but the path between those two points was anything but smooth.
The timeline reveals something remarkable: one lab in Jerusalem generated a disproportionate share of the field's foundational discoveries. THC isolation. Anandamide. 2-AG. The entourage effect. CBD's anticonvulsant properties. It's difficult to find a parallel in modern pharmacology — one scientist initiating an entire discipline and remaining at its center for six decades.
The Neglected Treasure Trove
The 2005 commentary's central argument was simple and devastating: cannabis contains roughly 100 identified cannabinoids, and the scientific community had only seriously investigated two of them.
~100
cannabinoids identified in Cannabis sativa by 2005 — of which only THC and CBD had been systematically studied for pharmacological activity. The remaining compounds represented what Mechoulam called a 'neglected pharmacological treasure trove.'
For comparison, the opium poppy contains roughly 80 alkaloids, and pharmaceutical development has explored dozens of them. Cannabis, despite being one of the oldest and most widely used medicinal plants, had received a fraction of that attention.
Mechoulam (2005), Br J Pharmacol 146:913-915
To prove his point, Mechoulam highlighted new research published in the same issue of the British Journal of Pharmacology: delta-9-tetrahydrocannabivarin (THCV), a minor cannabinoid that had been sitting in the plant all along, turned out to be a potent antagonist of the CB1 receptor. That meant a cannabis compound could block the same receptor that THC activates. If nobody had bothered to test it, nobody would have known.
How many other surprises were hiding in the unstudied 98?
The Frustration
The gap between Mechoulam's science and its clinical application haunted him. In 1980, his collaborators in Brazil — Cunha, Carlini, and colleagues — published a controlled trial showing CBD reduced seizures in epilepsy patients. The results were clear. Nobody followed up.
For 25 years.
It wasn't that the science was wrong — it was eventually vindicated by the Devinsky trials and the FDA's approval of Epidiolex in 2018. The problem was political. Cannabis was Schedule I in the United States — classified alongside heroin as having "no accepted medical use and a high potential for abuse." Researchers who wanted to study it needed DEA licenses, NIDA-approved cannabis supply (from a single farm at the University of Mississippi), and multiple layers of bureaucratic approval that existed for no other drug class.
The pharmaceutical industry, meanwhile, showed almost no interest. Cannabis couldn't be patented. Its components were difficult to formulate. Its association with recreational use made corporate boards nervous. For decades, the world's most promising source of novel pharmacology was essentially off-limits to the institutions best equipped to develop it.
“We have just scratched the surface. The endocannabinoid system is involved in essentially all human diseases.”
— Raphael Mechoulam
Hebrew University of Jerusalem
Reflecting on 41 years of cannabinoid research, 2005
This wasn't hyperbole. By 2005, the endocannabinoid system had been implicated in pain modulation, appetite regulation, immune function, mood disorders, neurodegeneration, cardiovascular health, bone metabolism, and reproductive biology. It was present in every vertebrate animal studied. Yet the number of approved drugs targeting it could be counted on one hand.
What He Predicted
Mechoulam's "neglected treasure trove" argument proved prophetic on nearly every count.
The compound Mechoulam specifically highlighted — THCV — turned out to have a unique pharmacological profile. At low doses it blocks CB1 (potentially useful for appetite suppression and metabolic disorders). At higher doses it can activate CB1. This biphasic behavior would have been impossible to predict without testing — exactly Mechoulam's point about why the unstudied cannabinoids needed attention.
The Man
Myth vs. Reality
Mechoulam was a cannabis advocate who wanted the drug legalized.
Mechoulam was a chemist and pharmacologist who never used cannabis and never campaigned for legalization. He wanted the compounds studied scientifically and, where evidence supported it, developed into medicines. He was frustrated not by prohibition per se but by the way prohibition prevented research.
The Evidence
In interviews throughout his career, Mechoulam consistently described himself as a scientist, not an advocate. He supported medical cannabis research but did not take public positions on recreational legalization. His famous quote — 'an addiction from which I did not want to be cured' — referred to his research, not to cannabis.
Multiple interviews; Mechoulam obituaries (2023)
What makes the 2005 retrospective compelling isn't just the science — it's the voice. This was a man who had spent 41 years producing discoveries that governments, pharmaceutical companies, and medical institutions had largely ignored. He watched families move across state lines to access a compound his lab had shown was anticonvulsant in 1980. He watched the pharmaceutical industry develop drugs for every receptor system except the one he helped discover.
“Who cared about our findings? No one! Did we have to wait 30 years? We could have helped thousands of children, and we didn't!”
— Raphael Mechoulam
On the decades-long delay between his CBD epilepsy research and the approval of Epidiolex
He never stopped working. In his 80s, he was investigating cannabidiolic acid methyl ester for nausea and anxiety. In his early 90s, he was still publishing. He died on March 9, 2023, at age 92, in Jerusalem — the city where he had arrived as a young immigrant in 1949 and where he would spend the next seven decades quietly building one of the most consequential research programs in modern pharmacology.
He described his life's work as "an addiction from which he did not want to be cured."
The Treasure Trove Today
Twenty years after Mechoulam's commentary, the treasure trove is finally being opened — though unevenly. CBD has become a multibillion-dollar industry. THCV, CBG, CBN, and CBC are finding their way into consumer products and clinical pipelines. The endocannabinoid system is now a target for drug development in dozens of disease areas.
But Mechoulam's core criticism still applies. Of the ~100 plant cannabinoids, the vast majority remain poorly characterized. Most consumer products contain only THC and CBD. The systematic pharmacological investigation Mechoulam called for in 2005 is still incomplete.
The neglected treasure trove is less neglected than it was. But it's far from fully explored.
Frequently Asked Questions
Cite this study
Mechoulam, Raphael. (2005). Plant cannabinoids: a neglected pharmacological treasure trove.. British journal of pharmacology, 146(7), 913-915. https://doi.org/10.1038/sj.bjp.0706415