Researchers at Stellenbosch University have identified a class of rare chemical compounds in cannabis leaves that were never known to exist in the plant before, potentially opening new avenues for medical research and challenging the notion that certain plant material is waste.
The discovery centers on flavoalkaloids, a group of phenolic compounds so uncommon in nature that their presence in cannabis came as a surprise to the research team. Phenolic compounds, particularly flavonoids, have long been valued in medicine for their antioxidant, anti-inflammatory, and cancer-fighting properties. The identification of flavoalkaloids in cannabis suggests the plant harbors even more medically relevant compounds than science has previously recognized.
The team analyzed three commercially grown cannabis strains sourced in South Africa and cataloged 79 phenolic compounds in total. Twenty-five of those compounds had never been documented in cannabis before. Most striking was the tentative identification of 16 flavoalkaloid compounds, a finding that marks the first time this rare class has been detected in the species.
Dr. Magriet Muller, the study's lead author and an analytical chemist at the university's Central Analytical Facility, stressed how challenging it is to detect such compounds. Plant phenolics occur in minute quantities and vary widely in structure, making them difficult to isolate and identify. Cannabis itself contains more than 750 distinct metabolites, far exceeding what researchers anticipated in terms of chemical variation between strains.
"We did not expect such high variation in phenolic profiles between only three strains, nor to detect so many compounds for the first time in the species," Muller said. "Especially the first evidence of flavoalkaloids in Cannabis was very exciting."
The breakthrough was made possible by advanced analytical tools that Muller developed as part of her postgraduate research. The method combines two-dimensional liquid chromatography with high-resolution mass spectrometry, enabling scientists to separate and identify compounds with unprecedented precision. Muller had previously refined these techniques while studying rooibos tea, grapes, and wine before applying them to cannabis.
Prof. Andre de Villiers, who oversaw the research, noted that the sophistication of the technology was essential to the discovery. "The excellent performance of two-dimensional liquid chromatography allowed separation of the flavoalkaloids from the much more abundant flavonoids, which is why we were able to detect these rare compounds for the first time in Cannabis."
Most cannabis research has concentrated on cannabinoids, the compounds responsible for the plant's psychoactive effects. This work suggests scientists have overlooked a much broader chemical landscape. De Villiers emphasized that cannabis leaves and other parts currently treated as waste could contain valuable compounds with biomedical applications.
The research was published in the Journal of Chromatography A in 2025. The findings highlight how much remains unexplored about cannabis chemistry and could reshape how the plant is valued as a source of therapeutic compounds.
Author Jessica Williams: "This discovery is a reminder that the most important breakthroughs often come from looking harder at what we thought we already understood."
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