His research helped break down the chemical compounds of THC, the primary psychoactive cannabinoid (compound) in cannabis, to figure out how cannabis stimulates a euphoric effect or high.

In the 1960s, a Bulgarian-born researcher named Raphael Mechoulam was caught in possession of five kilograms of, as he referred, “superb, smuggled Lebanese hashish” on a bus en route from Tel Aviv to Rehovot. But the purpose of this journey was purely scientific.

Mechoulam was a fledgling scientist focused on investigating the chemistry behind cannabis, a stigmatized plant whose distinct medical properties were not yet identified. Over the decades, he became a trailblazer in marijuana research. His discoveries about the psychoactive compound found in cannabis helped ease the acceptance of the plant into the mainstream from the counterculture.

Mechoulam passed away last week in his native country of Israel at 92. His passing was reported Friday by the American Friends of the Hebrew University, where Dr. Mechoulam helped establish, The Hebrew University Multidisciplinary Center for Cannabinoid Studies in early 2017.

According to Hebrew University President Asher Cohen, most of the human and scientific understanding of cannabis was amassed thanks to the research of Prof. Mechoulam. He pioneered groundbreaking research and initiated scientific cooperation between scientists around the globe.

At the Hebrew University School of Pharmacy, Prof. Mechoulam and his research team isolated Tetrahydrocannabinol, or THC, the psychoactive compound found in marijuana, and cannabidiol, or CBD, an active component in cannabis with a multitude of medicinal benefits.

He also spearheaded research on the body’s endocannabinoid system, which produces compounds similar to THC to help manage pain, regulate appetite, and operate the immune system.

At the same time Dr. Mechoulam was revolutionizing cannabis science and discovering its efficacy in easing symptoms of multiple diseases, he was at odds with the strict drug laws in the United States and elsewhere that suppressed any substantial studies and lobbied to keep any derivatives of marijuana off the market.

In 2017, Prof. Mechoulam told the New York Times, The industry and science of medical cannabis “have to follow logical, medical lines of thought and development and modern medical routes,” “Israel has more [clinical trials] than the US at the moment, which is ridiculous.”

Dr. Mechoulam was a founding fellow of the International Cannabinoid Research Society (ICRS). In 1994, he was selected to join the Israel Academy of Sciences & Humanities.

Mechoulam was born in 1930 in Bulgaria and resettled with his family to Israel in 1949, where he later majored in chemistry. He received his doctorate at the Weizmann Institute (Rehovot,) eventually writing a thesis on the chemistry of steroids.

After further studies at the Rockefeller Institute in New York, he joined the Weizmann Institute of Science scientific staff. There, he began to read about the pharmacology of cannabis and was surprised to learn that an active compound had never been isolated in pure form.

Because cannabis was illegal in Israel, Prof. Mechoulam developed contacts within law enforcement to procure a supply for his research.

Throughout Prof. Mechoulam’s illustrious career, he was a tireless champion of research into the potential medical benefits of marijuana.

Professor Mechoulam is often referred to as the grandfather of marijuana, and once asked about it, he smiled and stated, “Well, I am a grandfather; okay, I have seven grandkids.” In addition to them, he is survived by his wife, Dalia, his son, Roy, and his daughters, Dafna and Hadas.