Phenolic Analysis of Cannabis Reveals Rare Flavoalkaloids in Leaves

Flavoalkaloids have been detected in cannabis leaves for the first time, a new study explains (1), noting that phenolic compounds are associated with health benefits. Flavoalkaloids are a group of secondary metabolites that are present in plants but are less common that flavonoids, it explains. The study, “Comprehensive two-dimensional liquid chromatographic analysis of Cannabis phenolics and first evidence of flavoalkaloids in Cannabis,” was published in the Journal of Chromatography A in May 2025.

The researchers from Department of Chemistry and Polymer Science at Stellenbosch University (SU) in South Africa used three commercial strains (named Cape Cookie, CBG, and Blue Sky) of cannabis inflorescence and leaf samples. For the separation and analysis of the flavonoids, a hydrophilic interaction chromatography (HILIC) × reversed-phase liquid chromatography (RP-LC) method, an in-house developed program, was used. Two-dimensional liquid chromatography (LC × LC) was used to analyze the phenolic mixtures.

Highlighted results of the study include:

• 79 compounds were tentatively identified and were mostly comprised of flavone and (hydroxy)cinnamic acid derivatives
• 25 phenolic compounds were reported for the first time in cannabis
• In one strain, flavoalkaloids were detected in the leaf extracts, though there was not enough data to assign the alkaloid moieties

“Most plants contain highly complex mixtures of phenolic compounds, and while flavonoids occur widely in the plant kingdom, the flavoalkaloids are very rare in nature," stated study author Magriet Muller, PhD, in an August 14 news article from Stellenbosch University (2). “We know that Cannabis is extremely complex – it contains more than 750 metabolites – but 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. Especially the first evidence of flavoalkaloids in Cannabis was very exciting."

Dr. Muller also explained that she had initially tested the new analytical method on rooibos tea, grapes, and wine before applying it to cannabis.

The results support the use of HILIC and RP-LC-HR-MS for studying the phenolics of cannabis, the researchers stated. More research is needed for revealing the structures and prevalence of the compounds.

“Our analysis again highlights the medicinal potential of Cannabis plant material, currently regarded as waste,” explained André de Villiers, study author and professor at SU. “Cannabis exhibits a rich and unique non-cannabinoid phenolic profile, which could be relevant from a biomedical research perspective.” de Villiers also explained how the two-dimensional LC was crucial in the separation of the flavoalkaloids and flavonoids.

References

1. Muller, M.; de Villiers, A. Comprehensive two-dimensional liquid chromatographic analysis of Cannabis phenolics and first evidence of flavoalkaloids in Cannabis, Journal of Chromatography A, 2025, 1754, DOI: 10.1016/j.chroma.2025.466023.
2. Fourie-Basson, W. Don’t throw away those Cannabis leaves – they are packed with rare compounds https://www.sun.ac.za/english/Lists/news/DispForm.aspx?ID=11490 (accessed Aug 26, 2025).