Decarboxylated extracts from nine cannabis genotypes showed antiviral activity against SARS-CoV-2 (all IC50 below 10 micromolar), but phenolic compounds in the extracts sometimes antagonized the antiviral effects of CBD and THC.
Pharmacologists, phytochemists, and researchers interested in cannabinoid-drug interactions and the entourage effect.
What the researchers found
Only the neutral (decarboxylated) extracts containing CBD or THC as predominant cannabinoids showed antiviral activity against SARS-CoV-2, with all IC50 values below 10.0 micromolar. However, certain phenolic acids (salicylic acid, chlorogenic acid, ferulic acid) and flavonoids (abietin, luteolin) antagonized the antiviral activity in some genotypes.
Why it matters
While cannabis as a COVID treatment is not clinically viable, understanding which plant compounds enhance or block antiviral activity informs broader pharmaceutical efforts. The finding that other plant compounds can antagonize cannabinoid effects has implications for whole-plant versus isolate product design.
The numbers in context
Nine genotypes tested (7 high-CBD, 2 high-THC). All neutral extract IC50 values below 10.0 micromolar. Acidic (non-decarboxylated) extracts showed no antiviral activity. Antagonistic phenolics identified: salicylic acid, chlorogenic acid, ferulic acid, abietin, luteolin. Potentially synergistic: orientin.
How the study worked
Ethanolic extracts from seven high-CBD and two high-THC Cannabis sativa genotypes were prepared in both acidic (non-decarboxylated) and neutral (decarboxylated) forms. Phytochemical profiling used LC-UV, GC-MS, and LC-MS/MS. Dose-response antiviral assays against SARS-CoV-2 were performed, with correlation analyses between constituent levels and activity.
What this study cannot tell us
In vitro antiviral activity does not predict clinical efficacy. SARS-CoV-2 assay conditions may not reflect physiological cannabinoid concentrations. Correlation-based identification of antagonistic compounds needs direct validation. Only ethanolic extracts tested; other preparation methods may differ.
How to read the evidence
Comprehensive phytochemical characterization with antiviral testing across multiple genotypes, but in vitro only and clinical translation is unlikely.
When this study was published
Published 2025.
The bigger picture
The entourage effect (the idea that whole-plant cannabis works better than isolated compounds) is often assumed to be universally positive. This study provides a concrete example where other plant compounds actually reduced the primary cannabinoid's activity, challenging the assumption that more compounds always means better outcomes.
Questions still open
- Whether formulations that remove antagonistic phenolics could enhance cannabinoid antiviral potency
- Whether these antagonistic interactions apply to other therapeutic applications beyond antiviral activity
Common questions
Can cannabis treat COVID-19?
What does it mean that other plant compounds antagonized the antiviral effect?
Read the original research
Secondary metabolite profiles and anti-SARS-CoV-2 activity of ethanolic extracts from nine genotypes of Cannabis sativa L.
Archiv der Pharmazie, 358(1), e2400607
Citation
Schadich, Ermin; Kaczorová, Dominika; Béres, Tibor; Džubák, Petr; Hajdúch, Marián; Tarkowski, Petr; Ćavar Zeljković, Sanja. (2025). Secondary metabolite profiles and anti-SARS-CoV-2 activity of ethanolic extracts from nine genotypes of Cannabis sativa L.. Archiv der Pharmazie, 358(1), e2400607. https://doi.org/10.1002/ardp.202400607
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