Artemisia annua yields potent inhibitor against Alpha SARS-CoV-2 variant
Plant compound arteannuin B shows strong anti–COVID-19 activity in lab tests
A natural compound from the medicinal plant Artemisia annua has shown a strong ability to block the Alpha variant of SARS-CoV-2 (the virus that causes COVID-19) in laboratory experiments.
An international team from Bosnia and Herzegovina, Serbia, and the United States studied two well-known plant molecules: artemisinin (the antimalarial drug) and arteannuin B (a related compound). In their tests on virus-infected cells, arteannuin B clearly reduced viral replication, while artemisinin showed little or no antiviral effect under the same conditions.
Why look at Artemisia annua?
COVID-19 has highlighted the need for new antiviral drugs that are effective, safe, and able to keep up with emerging variants. Existing antivirals like remdesivir, molnupiravir, and nirmatrelvir-ritonavir help many patients but have drawbacks, including side effects, interactions with other medicines, and reduced power against some variants.
Artemisia annua L. has a long history in traditional medicine and is best known as the source of artemisinin. Earlier lab studies suggested that extracts of A. annua could inhibit multiple SARS-CoV-2 variants, but it was not clear which compound was responsible.
What the researchers did
The team extracted compounds from A. annua leaves using:
ethanol (alcohol) with ultrasound
supercritical carbon dioxide (SC-CO₂), an environmentally friendly method
They then used high-speed countercurrent chromatography to separate artemisinin and arteannuin B and to create:
a fraction enriched in arteannuin B
an "artemisinin knockout" fraction with no artemisinin but other related plant compounds
All samples were tested in Vero E6 cells infected with an Alpha SARS-CoV-2 strain carrying known mutations linked to higher transmissibility.
Key results
Among all samples tested, the arteannuin B–rich fraction was the most potent:
- It inhibited viral replication at the lowest concentrations.
- At higher test doses, it reduced viral genetic markers by up to 100%.
- Whole plant extracts also showed antiviral activity but were less potent.
- Pure artemisinin was not significantly active at the same levels.
Cell-health tests showed that, at antiviral concentrations, more than 85% of cells remained alive. No major toxic effects were seen below 200 micrograms per milliliter for any sample, suggesting arteannuin B works at non-toxic levels in this lab system.
What it means—and what it doesn't
Previous research suggests that arteannuin B may block the virus's main protease, an enzyme essential for its replication. The new study supports this idea by showing that arteannuin B–rich fractions can sharply reduce viral growth in cells.
The findings also support the view that artemisinin is not the main antiviral compound in Artemisia annua against SARS-CoV-2.
However, the work is still at an early stage:
- All data come from cell culture experiments, not animals or humans.
- We do not yet know how arteannuin B behaves in the body or whether it would be safe and effective as a medicine.
The authors stress that these results do not justify using Artemisia annua teas, extracts, or supplements to treat or prevent COVID-19. Those products are very different from the controlled, purified samples used in the lab.
Next steps will include animal studies, detailed safety testing, and checking whether arteannuin B is active against newer variants such as Omicron sub-variants.
More information:
Irma Gušić et al, Profiling of sesquiterpenoid fractions from Artemisia annua L. and testing their in vitro anti-SARS-CoV-2 activity. Biomol Biomed [Internet]. 2025 Apr. 25 [cited 2025 Nov. 24];25(10):2345–2363.
Available from: https://doi.org/10.17305/bb.2025.12052
Journal information: Biomolecules and Biomedicine
Provided by: Association of Basic Medical Sciences of FBIH
Provided by Association of Basic Medical Sciences of FBIH
