Cannabis is best known for its cannabinoids like THC and CBD, but new research shows that the plant hides even more chemical surprises—especially in its leaves, which are often treated as waste.
A team of analytical chemists from Stellenbosch University in South Africa has discovered, for the first time, a rare group of compounds called flavoalkaloids in cannabis leaves.
These molecules are part of a wider family of phenolic compounds, which are already highly valued in the pharmaceutical world for their antioxidant, anti-inflammatory, and even anti-carcinogenic properties.
The study, published recently in the Journal of Chromatography A, analyzed three commercially grown strains of cannabis from South Africa. In total, the researchers identified 79 different phenolic compounds.
Twenty-five of them had never before been reported in cannabis, and 16 were tentatively classified as flavoalkaloids. Surprisingly, these rare compounds were concentrated mainly in the leaves of just one strain.
Dr. Magriet Muller, the study’s first author, explained why this discovery was so exciting.
“Most plants contain highly complex mixtures of phenolic compounds, and while flavonoids are common across the plant kingdom, flavoalkaloids are very rare in nature. To detect them in cannabis for the first time was remarkable,” she said.
Muller carried out much of the work at Stellenbosch University’s Central Analytical Facility, where she used advanced techniques that combine two-dimensional liquid chromatography and high-resolution mass spectrometry.
These methods allow scientists to separate and identify compounds present in very small amounts within a plant’s chemical mix.
She had already tested her approach on rooibos tea, grapes, and wine, but decided to try cannabis because of its extraordinary complexity—it contains more than 750 known metabolites.
The results exceeded expectations. Even among just three strains, the researchers found striking differences in chemical profiles, uncovering far more variation than anticipated. According to Muller’s supervisor, Professor André de Villiers, the strength of the technique was key to the breakthrough.
“The excellent performance of two-dimensional liquid chromatography allowed us to separate the flavoalkaloids from the much more abundant flavonoids, which is why we could detect these rare compounds in cannabis for the first time,” he said.
Until now, most cannabis research has focused on cannabinoids, the compounds responsible for the plant’s psychoactive and medicinal effects.
But this study highlights how much remains to be discovered in the plant’s so-called “waste material.” Cannabis leaves, often overlooked, may actually hold untapped potential for biomedical research.
As De Villiers concluded: “Our analysis shows that cannabis is chemically richer than we imagined. The leaves and other non-cannabinoid parts of the plant could have real medicinal value, and we are only beginning to uncover what they can offer.”
