Blocking a Key COVID-19 Enzyme with Diet

Many chemical compounds found in certain foods, like persimmon and berries, have been known to have antiviral properties. A recent study conducted at North Carolina State University, Raleigh, has identified ones in common items that could potentially help fight the coronavirus disease 2019 (COVID-19).

"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," De-Yu Xie, a lead author on the study said.

The researchers identified five Crude extracts from green tea, cacao, chocolate, and two muscadine grapes, that are abundant in flavan-3-ols and proanthocyanidins (PAs), which showed inhibitory effects on SARS-CoV-2’s main protease (Mpro) activity. Proteases are enzymes that break down peptides and proteins which are vital to a virus’s health. When a main Mpro is inhibited, cells are not able to execute important functions like replication.

The team utilized lab studies and computer simulations to examine how COVID-19’s Mpro reacted when one of the chemical compounds was introduced to it. The simulations provided by the computer, along with in vitro lab experiments, revealed that the compounds being used in the study were able to bind to different portions of the COVID-19’s Mpro. The data also showed that the extracts inhibited the Mpro activity with an IC50 value, 2.84 ± 0.25, 29.54 ± 0.41, 29.93 ± 0.83, 153.3 ± 47.3, and 256.39 ± 66.3 μg/ml. This demonstrates that the structural features of flavan-3-ols are critical in creating the inhibitory impact against the Mpro activity.

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

Since there has not been an effective medication for the treatment of COVID-19 yet, the data found demonstrates that these nutraceutical compounds and extracts of green tea, grape, and cacao could potentially be able to be utilized to aid other therapies to help with pandemic.