In lab tests, tannins stopped an enzyme that the coronavirus uses to replicate
A new study suggests that tannic acids, found in plants and, most notably, in grape skins, may help suppress COVID-19. The findings don’t suggest that a bottle of Barolo is therapeutic, but the study could lead to future treatments.
While scientists have developed vaccines at record pace, others have focused their research on treatments for patients already infected with COVID-19, looking at how to suppress viral activity once a patient tests positive. Remdesivir is currently the only medication approved by the FDA to specifically use against COVID-19. But some studies suggest that the drug may not be as effective for those undergoing long hospitalizations.
New research from China Medical University in Taiwan, led by the institution’s president, Dr. Mien-Chie Hung, has found that tannic acids may be successful in limiting the replication of SARS-CoV-2, the virus that causes COVID-19, in sick patients. Viruses hijack human cells and use them to produce more viruses. Hung and his team studied tannic acids along with five other natural compounds to test their effectiveness against viral activity.
«Among the six compounds tested, only tannic acid showed significant activity of inhibiting up to 90 percent of the enzymatic activity of SARS-CoV-2,» reports the study, published online in the American Journal of Cancer Research.
The team looked at how the natural compounds could be used to inhibit the activity of enzymes that play a key role in replicating viruses. They collected tannic acids and tested them in the lab against virus particles. They discovered that Mpro, a protein used by SARS-CoV-2 to replicate in human cells, was largely blocked by tannic acids.
«It has not been tested against COVID-19 yet. We only know tannic acid can inhibit Mpro, a key protease that is required for SARS-CoV-2 virus replication,» Hung told Wine Spectator. «Tannic acid has a dual function—inhibition of both SARS-CoV-2 virus infection to human cells and virus replication in the cells (if the virus has already entered the human cells)—one stone, two birds.»
Tannic acid, a form of tannin, is found in a variety of fruit skins, woods and leaves. In nature, tannins are found in large amounts in fruit and deter animals from eating it before it fully ripens. Tannins are best known as a component in wine; they contribute greatly to its structure, and can also be responsible for astringent or drying sensations.
The findings don’t mean that drinking wine can cure COVID-19 patients. But the study suggests that the wine ingredient could lead to new treatments. «The compound might have potential to be developed into therapeutics for COVID-19,» said Hung. «However, additional investigation is required to test its activity on a cellular and animal level. Then human clinical trials are required to test efficacy and potential side effects. «
