EGCG

EGCG may impede SARS-CoV-2 infection by activating Nrf2 which downregulates ACE2 and TMPRSS2. EGCG may suppress SARS-CoV-2 replication via inhibiting SARS-CoV-2 main protease, mitochondrial ROS and ER-resident GRP78. EGCG may protect against ROS burst inflicted by SARS-CoV-2 induced neutrophil extracellular traps. EGCG may decrease SARS-CoV-2 triggered cytokine storm, sepsis, thrombosis and lung fibrosis. EGCG may prevent diabetes comorbidity risk in COVID-19 patients [1].

Another study showed the inhibition effects of EGCG on SARS-CoV-2 occur through its actions on the ACE2 receptor, the main protease (Mpro, a 3C-like protease) and RdRp (RNA-dependent RNA polymerase). Molecular docking experiments revealed that EGCG had a higher atomic contact energy value, binding energy, Ki value, ligand efficiency and surface area than hydroxychloroquine (HCQ) during binding with the spike protein. There were three binding sites on the spike protein. EGCG can bind with all of the three sites, while HCQ binds only with site III, based on the fact that sites I and sites II are in closer contact with open state location and viral–host contact area. These suggest that EGCG has a stronger ability to inhibit the infection of SARS-CoV-2 to the host cells than HCQ [2]. 

Molecular docking test on various plant polyphenol compounds showed that EGCG had the highest binding affinity with SARS-COV-2 spike proteins among the 11 tested plant polyphenols [3].

Conclusion: EGCG is shown to be able to bind strongly with many molecules in viruses, especially protease and protein; therefore, it influences their functional activities. Through attaching with virion surface or the receptors on the host cell membrane, EGCG disturbs the interaction between viral and host cells. EGCG suppresses viral genome replication and viral protein expression, inactivating viral activity and inhibiting pro-inflammatory factor promotion. Besides, EGCG exhibits synergistic effects on several antiviral-specific drugs via reducing toxicity and enhancing the efficacy of drugs, increasing the resistance of cells to drugs [4].

Figure. Schematic diagram of SARS-CoV-2 life cycle and the inhibition effects of EGCG.

The inhibition effects of EGCG on SARS-CoV-2 occur through its actions on the ACE2 receptor, the main protease (Mpro, a 3C-like protease) and RdRp (RNA-dependent RNA polymerase). [4].

1. Potential protective mechanisms of green tea polyphenol EGCG against COVID-19. Trends in Food Science & Technology, Volume 114, August 2021, Pages 11-24 https://doi.org/10.1016/j.tifs.2021.05.023

2. Epigallocatechin gallate and theaflavin gallate interaction in SARS-CoV-2 spike protein central channel with reference to the hydroxychloroquine interaction: Bioinformatics and molecular docking study. Drug Dev. Res. 2020

3. In silico molecular docking analysis targeting SARS-CoV-2 spike protein and selected herbal constituents. J. Pure Appl. Microbiol. 2020, 14, 989–998.

4. Antiviral Effects of Green Tea EGCG and Its Potential Application against COVID-19. Molecules 2021, 26(13), 3962; https://doi.org/10.3390/molecules26133962