Stellenbosch University researchers find rare sought-after medicinal properties in cannabis leaves
Researchers from Stellenbosch University (SU) found first evidence of rare phenolic compounds in cannabis leaves. These are sought after in the pharmaceutical industry for their antioxidant, anti-inflammatory, and anti-carcinogenic properties.
The SU analytical chemists have provided the first evidence of a rare class of phenolics, called flavoalkaloids, in cannabis leaves. Phenolic compounds, especially flavonoids, are well-known and sought after in the pharmaceutical industry because of their antioxidant, anti-inflammatory and anti-carcinogenic properties.
The researchers identified 79 phenolic compounds in three strains of cannabis grown commercially in South Africa, of which 25 were reported for the first time. Sixteen of these were tentatively identified as flavoalkaloids which, interestingly, were found mainly in the leaves of only one of the strains. The results were published in the Journal of Chromatography A recently.
Highlights medical potential of cannabis
Dr Magriet Muller, an analytical chemist in the LC-MS laboratory of the Central Analytical Facility (CAF) at Stellenbosch University and first author of the paper, said the analysis of plant phenolics is challenging due to their low concentration and extreme structural diversity.
“Most plants contain highly complex mixtures of phenolic compounds,” she explained, “and while flavonoids occur widely in the plant kingdom the flavoalkaloids are very rare in nature.
“We know that cannabis is extremely complex. It contains more than 750 metabolites, but we did not expect such a high variation in phenolic profiles among only three strains, nor to detect so many compounds for the first time in the species. The first evidence of flavoalkaloids in cannabis, especially, was very exciting.”
For her postgraduate studies in SU’s Department of Chemistry and Polymer Science Muller developed powerful analytical methods combining comprehensive two-dimensional liquid chromatography and high-resolution mass spectrometry for the detailed characterisation of phenolic compounds.
“We were looking for a new application for the methods that I developed, after successfully testing them on rooibos tea, grapes and wine. I then decided to apply the methods to cannabis because I knew it was a complex sample, and that cannabis phenolics have not been well characterised.”
Dr Magriet Muller
“We were looking for a new application for the methods that I developed, after successfully testing them on rooibos tea, grapes and wine. I then decided to apply the methods to cannabis because I knew it was a complex sample, and that cannabis phenolics have not been well characterised.” According to Prof André de Villiers, her study leader and main author on the paper, he was blown away by the chromatographic results she had obtained: “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”. He leads the analytical chemistry research group in SU’s Department of Chemistry and Polymer Science.
De Villiers said it is obvious there is still much to gain from studying this controversial plant, as the bulk of research into it to date has been focused on the pharmacological properties of the mood-affecting compound in it, cannabinoids.
“Our analysis again highlights the medicinal potential of cannabis plant material, currently regarded as waste. Cannabis also exhibits a rich and unique (non-cannabinoid) phenolic profile, which could be significant from a biomedical research perspective.”
ALSO READ: CanPlan: Cape farm plan unveiled
