New breakthrough in research on cannabis leaves
Phenolic compounds are sought after in the pharmaceutical industry for their anti-oxidant, anti-inflammatory and anticarcinogenic properties, and the analysis highlights the medicinal potential of Cannabis plant material.
Analytical chemists from University of Stellenbosch (US) have found the first evidence of a rare class of phenols, called flavo-alkaloids, occurring in cannabis leaves.Phenolic compounds, especially flavonoids, are well known and sought after in the pharmaceutical industry due to their anti-oxidative, anti-inflammatory and anticarcinogenic properties.
The researchers identified 79 phenolic compounds in three cannabis plant lines grown commercially in South Africa, of which 25 were encountered for the first time in cannabis. Sixteen of these compounds were tentatively identified as flavo-alkaloids. Interestingly, the flavo-alkaloids were found mainly in the leaves of only one of the strains. These results were recently published in the Journal of Chromatography A.
Dr Magriet Muller, an analytical chemist in the LC-MS laboratory of the Central Analytical Facility (SAF) at SU and first author of the article, says that the analysis of plant phenolics is challenging due to the low concentrations in which they occur and their extreme structural diversity.
“Most plants contain highly complex mixtures of phenolic compounds, and although flavonoids are widespread in the plant kingdom, the occurrence of flavo-alkaloids in nature is very rare,” she explains.
More than 750 metabolites
“We know that cannabis is extremely complex – it contains more than 750 metabolites – but we did not expect such a large variation in phenolic profiles between just three strains, much less to expose so many compounds for the first time in the species. It was particularly exciting to discover the first evidence of flavo-alkaloids in cannabis.”
For her postgraduate studies in US’s Department of Chemistry and Polymer Science, she developed powerful analytical methods that combine comprehensive two-dimensional liquid chromatography and high-resolution mass spectrometry for the detailed characterisation of phenolic compounds.
“After successfully testing the methods I developed on rooibos tea, grapes and wine, we were looking for a new application of the methods. I decided to apply them to cannabis based on the complexity of the sample, and because cannabis phenols have not yet been well characterised,” she explained.
Medical potential
According to Prof André de Villiers, her supervisor and lead author of the article, he was amazed by the chromatographic results that Muller obtained: “The excellent separation power of two-dimensional liquid chromatography made it possible to separate the flavo-alkaloids from the flavonoids that are much more abundant, and therefore we were able to observe these rare components in cannabis for the first time.”
He heads the analytical chemistry research group in US’s department of chemistry and polymer science.
De Villiers says it is obvious that there is still much to learn from studying cannabis, as most research in this field to date has focused on the pharmacological properties of the cannabinoids that affect mood.
“Our analysis highlights the medicinal potential of cannabis plant material, which is currently considered waste. Cannabis shows a rich and unique non-cannabinoid profile that could be relevant from a biomedical research perspective,” he concluded.