Chemical compounds in foods can inhibit key COVID-19 enzyme, study finds

Chemical compounds in foods or beverages like green tea, muscadine grapes, and dark chocolate can bind to and block the function of a particular enzyme or protease, in SARS-CoV-2, the virus that causes the novel coronavirus (COVID-19), according to a new study by researchers at North Carolina State University published in the journal Frontiers in Plant Science.

Proteases are important to the health and viability of cells and viruses, the researchers said. If proteases are inhibited, cells cannot perform many important functions, like replication.

In the study, the NC State researchers performed both computer simulations and lab studies showing how the so-called "main protease" in the SARS-CoV-2 virus reacted when confronted with a number of different plant chemical compounds already known for their potent anti-inflammatory and antioxidant properties.

Computer simulations showed that the studied chemical compounds from green tea, two varieties of muscadine grapes, cacao powder, and dark chocolate were able to bind to different portions of the main protease, according to the study.

In vitro lab experiments showed similar results. The chemical compounds in green tea and muscadine grapes were very successful at inhibiting the main protease's function, while chemical compounds in cacao powder and dark chocolate reduced main protease activity by about half, the researchers said.

"Green tea has five tested chemical compounds that bind to different sites in the pocket on [the main protease], essentially overwhelming it to inhibit its function," said  De-Yu Xie, PhD, corresponding author of the study and a professor of plant and microbial biology, in a statement. "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."

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