You may have heard about the method of cannabis classification called “chemotyping.” Chemotyping classifies based on the ratios of chemical compounds. In cannabis, the major cannabinoids delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) have been used to classify cannabis in three different groups. However, chemotyping does not consider the whole metabolome which includes the total number of metabolites present in a plant.
- Chemotype I: Δ9-THC/CBD greater than 1 (drug-type)
- Chemotype II: Δ9-THC/CBD about equal to 1 (intermediate type)
- Chemotype III: Δ9-THC/CBD less than 1 (fiber-type, hemp)
In the research paper “Cannabinoids vs. whole metabolome: relevance of cannabinomics in analyzing Cannabis varieties,” the authors propose a new approach to chemotyping that considers minor cannabinoids, terpenes, flavonoids, and other cannabis metabolites. They have termed this metabolome-encompassing approach as “cannabinomics.”
To perform this type of analyses, they applied a liquid chromatography–mass spectrometry (LC-MS)-based metabolomics workflow on medium polarity extracts of cannabis leaves and flowers to classify chemotypes as well as map and annotate metabolites of the phytocannabinoids family and other phytochemical classes.
The research team worked with cannabis of all three chemotypes. The material was dried, ground, and extracted. Analysis data was compared with databases to confirm results. They also performed genotyping via polymerase chain reaction, or PCR.
The analyses validated the three-chemotype model that has been previously proposed but divided CBD-dominant varieties of chemotype III from cannabigerol (CBG)-dominant varieties of chemotype III. Their analyses also demonstrated that minor cannabinoids can effectively be used as biomarkers. For example, they found that hemp used for seed production could be distinguished by its content of C3 varin-type phytocannabinoids, and strigolactone derivatives like cannabispirenone A (plant hormones that inhibit shoot branching) were characteristic of drug-type cannabis plants.
While such in-depth classification may not be entirely practical, it could be especially useful when looking for cannabis varieties that have specific metabolites of medical interest. The researchers summarize their work saying, “An overall analysis of the data shows that Cannabis varieties are more efficiently discriminated and characterized by untargeted cannabinomics analysis (metabotyping) rather than quantitation of major phytocannabinoids.” Indeed, minor cannabis compounds play a major role in defining a cannabis variety and shaping its unique effects.
Reference Vásquez-Ocmín PG, Marti G, Bonhomme M, et al. Cannabinoids vs. whole metabolome: Relevance of cannabinomics in analyzing Cannabis varieties. Anal Chim Acta. 2021;1184:339020. doi:10.1016/j.aca.2021.339020. [journal impact factor = 6.558; times cited = 0]
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