Cannabis: 25 new phenolic compounds and rare flavoalkaloids

On 14 August 2025 Stellenbosch University in South Africa presented a study that identifies 79 phenolic compounds in cannabis, 25 of which had never been reported in the plant before. Of the compounds found, 16 were tentatively identified as flavoalkaloids, a class of substances the researchers describe as very rare in nature. The flavoalkaloids occur mainly in the leaves, a part of the plant that is today largely regarded as waste.

In brief

• 79 phenolic compounds identified in three cultivars grown commercially in South Africa.
• 25 compounds reported for the first time in cannabis.
• 16 likely flavoalkaloids, found mainly in the leaves of just one of the three cultivars.
• The study is published in the Journal of Chromatography A.

How the study was carried out

The first author is Magriet Muller, an analytical chemist at the LC-MS laboratory of the university's Central Analytical Facility; the study was led by André de Villiers, head of the analytical chemistry group in the Department of Chemistry and Polymer Science. The team used comprehensive two-dimensional liquid chromatography combined with high-resolution mass spectrometry. The methods had previously been tested on rooibos tea, grapes and wine.

The technique combines two successive separations, hydrophilic interaction chromatography and reversed-phase chromatography, and made it possible to distinguish the flavoalkaloids from the far more abundant flavonoids, which would otherwise have masked them. Both inflorescences and leaves were analysed; the compounds identified are mostly derivatives of flavones and hydroxycinnamic acids.

What it adds to knowledge of the plant

According to the researchers, cannabis contains more than 750 metabolites, but attention has so far focused mainly on cannabinoids. Phenolic compounds are a different family, and the study shows that the three cultivars analysed have very different phenolic profiles: the flavoalkaloids were concentrated mainly in the leaves of a single cultivar.

The work also has limits, noted in media coverage: the identification of the flavoalkaloids is tentative, because the data were not sufficient to determine the structure of every compound, and only three cultivars were analysed. The study is limited to the chemical identification of the substances. The topic stayed in the news in the following months: on 28 September 2026 the German portal Forschung und Wissen devoted an article to it.

What it means for the Swiss sector

According to the Stellenbosch researchers, leaves are today mostly regarded as a cultivation waste product. The study does not concern Swiss cultivars, but it indicates that this part of the plant also has a rich chemical composition that differs from one cultivar to another.

For those growing hemp for its flowers in Switzerland and Ticino, this points to possible areas of future research, not a practical application that is already available. The result also shows that differences between cultivars involve compounds other than cannabinoids.

Frequently asked questions

What are phenolic compounds?

A large family of plant substances that includes the flavonoids. In the study, derivatives of flavones and hydroxycinnamic acids predominate.

What are flavoalkaloids?

A class of compounds that the researchers describe as very rare in nature. The Stellenbosch study provides the first evidence of them in cannabis, with an identification that is still tentative.

Do the results apply to all cultivars?

No. Three cultivars with very different profiles were analysed, and the flavoalkaloids were found mainly in the leaves of just one of them.

On the best-known aroma compounds in flowers, terpenes, MeO-LaB has published a dedicated guide.

Sources

• Stellenbosch University – Don't throw away those Cannabis leaves – they are packed with rare compounds, 14 August 2025
• Forschung und Wissen – In Cannabisblättern stecken Dutzende nie beschriebene Pflanzenstoffe, 28 September 2026

Updated on 12 October 2026.