COVID-19: Green tea and chocolate compounds help block SARS-CoV-2 functions, researchers find

01 Dec 2020 --- Chemical compounds found in green tea, muscadine grapes and dark chocolate can bind to and block the function of the main protease (Mpro) in SARS-CoV-2 – the virus that causes the disease known as COVID-19.

The biologists behind the study flag that if proteases are inhibited, cells cannot perform many important functions – like replication.

“If we can inhibit or deactivate Mpro, the virus will die,” says De-Yu Xie, the study’s co-author and professor of plant and microbial biology at North Carolina State University. 

The researchers performed both computer simulations and lab studies showing how Mpro in the SARS-CoV-2 virus reacted when confronted with 12 different plant chemical compounds already known for their potent anti-inflammatory and antioxidant properties.

It is possible that these findings could contribute toward some form of supplement or medication. “One of our lab’s focuses is to find nutraceuticals in food or medicinal plants that inhibit either how a virus attaches to human cells or the propagation of a virus in human cells,” explains Xie. 

“Given that there is not an effective medicine for the treatment of COVID-19 and not a vaccine for preventing against the SARS-Cov-2 infection and transmission, these data recommend that these nutraceutical compounds and extracts of green tea, grape and cacao can be utilized to interfere with the devastation of SARS-Cov-2,” the researchers write. 

A simplified diagram showing the essential function of Mpro involved in SARS-Cov-2 replication in infected host cells (Source: Frontiers in Plant Science).Promising results
Computer simulations showed that the plant flavan-3-ols and proanthocyanidins from green tea, two varieties of muscadine grapes, cacao powder and dark chocolate were able to bind to different portions of Mpro. 

Xie explains that Mpro has a portion that is like a ‘pocket’ that was ‘filled’ by the chemical compounds. “When this pocket was filled, the protease lost its important function.”

In vitro lab experiments yielded similar results. The chemical compounds in green tea and muscadine grapes were very successful at inhibiting Mpro’s function. 

Meanwhile, chemical compounds in cacao powder and dark chocolate reduced Mpro activity by about half.

“Green tea has five tested chemical compounds that bind to different sites in the pocket on Mpro, essentially overwhelming it to inhibit its function,” says Xie.

Furthermore, muscadine grapes contain these inhibitory chemicals in their skins and seeds. 

“Plants use these compounds to protect themselves, so it is not surprising that plant leaves and skins contain these beneficial compounds,” Xie continues. 

Earlier this year, investigations found that ashwagandha and propolis ingredients also have the potential to interact with and block the activity of Mpro in SARS-CoV-2.

Opportunities in plant compounds
The cranberry industry has long highlighted the potential for proanthocyanidins, which have a host of other uses. A study in August found that cranberry juice has the potential to be a natural, complementary management strategy for adults infected with H. pylori, which can cause gastritis. 

Additionally, a study recently demonstrated how E. coli clumped together in the presence of cranberry proanthocyanins.

Meanwhile, green tea has been linked to reduced mortality in people with Type 2 diabetes, as well as potentially suppressing food allergies. 

Edited by Katherine Durrell

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