The unexpected antiviral effect of St. John's wort
Perhaps St. John's wort not only protects against sadness and depression, but also against infection by the coronavirus. This discovery was made by Saudi biochemists who exposed cells to SARS-CoV-2 in vitro.
Researchers from King Abdulaziz University exposed cells to SARS-C0V-2 in test tubes. At the same time, they exposed the cells to extracts of St. John's wort before or after exposure. The researchers did the same with echinacea extracts, but we will largely ignore that part of their research in this post.
The researchers then determined the effect of the extracts on the reproduction of the virus.
If the researchers exposed the cells to St. John's wort extract before or after infection with SARS-CoV-2, the number of virus particles was reduced. Exposure before the infection occurred seemed particularly effective. This suggests that St. John's wort supplementation may reduce the risk of infection with the coronavirus.
St. John's wort worked better than echinacea.
In another in vitro study, the researchers first exposed the coronaviruses to St. John's wort extract before the viruses could enter the cells. St. John's wort also reduced the replication of the virus in that study.
This means that St. John's wort can theoretically protect against SARS-CoV-2 in 3 different ways. Components of St. John's wort directly inhibit the virus, inhibit the virus from entering cells and, once the virus has penetrated cells, inhibit the virus from replicating.
St. John's wort contains hypericin, hyperforin, hyperoside and quercetin. [Metabolomics. 2014;10:574-88.]
Click on the figure for a larger version.
According to in silico studies, the quercetin analogues - especially quercetin-3-o-xyloside - in St. John's wort inhibit viral RdRp and viral proteases. In previously published in vitro research, hypericin inhibits the formation of the proteins of the virus capsule.
More coming soon.
Sci Rep. 2022 Dec 15;12(1):21723.
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St. Johns Wort