A study published last week Natural Products Magazine sparked a wave of headlines proclaiming that cannabis can prevent or cure COVID, like this breathless ditty from Yahoo! Finance: “So that cannabis is associated COVID Prevention, how can you invest in the windfall?” project CBD asked scientist Matt Elmes, whose PhD and postdoctoral research focused on the biochemistry of cannabinoids, to evaluate the importance of this new research, which did not involve human subjects or laboratory animals.
Project CBD: What do you think of the new study by researchers at Oregon State University and Oregon Health and Science University that showed cannabidiolic acid (CBDAthe botanical progenitor of CBD) and other acidic cannabis compounds (CBGA and THCA) can prevent the coronavirus from infecting human cells?
Elmes: I’ve seen a lot of excitement in the media and on social media surrounding this news CBDA Publication. I think it really needs to be muted. The data in this paper comes exclusively from test tubes and petri dishes of cultured cells. We must always be careful not to draw clinical conclusions from pre-clinical experiments like these, because almost every time one tries to translate them into a real setting, there are major caveats.
Project CBD: Aside from the limitations of the in vitro research, what is the substance of these results?
Elmes: To be honest, the data doesn’t even seem particularly exciting to me. They show that acidic cannabinoids can bind to viral spike protein with micromolar affinities. These are extremely high concentrations to achieve in a human! Getting beyond the nanomolar range in most tissues is challenging, which further makes me doubt that this will have real clinical applications. However, it remains an interesting “test tube” result that warrants further study to see if cannabinoids can be helpful COVID beyond their immunomodulatory effects.
Project CBD: Explain what you mean when you say that high levels of acidic cannabinoids are difficult to achieve in humans.
Elmes: The most important finding from this research publication is that CBDA can attach (to have affinity) COVID Spike protein, along with some proof-of-concept experiments showing that sticking this cannabinoid to the virus particles can interfere with its ability to infect new cells. The weaker the strength of what scientists call “ligand-receptor interaction,” the more of that ligand you need to have an effect. In this case, CBDA is the ligand and the COVID Spike protein is the receptor. For this reason, scientists quantify and describe the strength of ligand-receptor interactions in terms of concentration. We describe the concentration of ligand required to achieve significant interaction with the receptor.
Project CBD: What are “micromolar affinities”?
“Micromolar” (or “molarity”) is simply a term of concentration representing the number of molecules of a given compound per liter. The group behind this research found this out experimentally CBDA had to be present in micromolar concentrations to induce an appreciable amount of binding to the viral spike protein. When we consume cannabis, the cannabinoids are distributed in the blood and adipose tissue of our body. Similarly, we describe the concentration of cannabinoids that end up in a tissue as molarity. The data in this new paper shows that we would need to collect enough molecules CBDA per volume of tissue that it falls within the “micromolar concentration range” before we should expect it to have an effect. Most human tissues will not exceed the nanomolar concentration range (which is 1000 times smaller than a micromolar) even when large doses of cannabinoids are regularly ingested! So I think it’s likely that the interaction this group found between acidic cannabinoids and COVID will prove too weak to show much, if any, clinical relevance.