Inhibition of TMPRSS2 and 3CL Proteases by natural polyphenols to prevent SARS-CoV-2 infectivity and replication

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In this research, we propose to prove that polyphenols (PLs) can inhibit the harmful effects of the SARS-CoV-2 virus by inhibiting two key proteases for virus infection and replication. To infect a cell, the SARS-CoV-2 virus must enter a host cell and bind to its membrane receptor ACE-2. The main host protease involved in the activation of protein -S on primary target cells and initial viral entry is the transmembrane serine protease 2 (TMPRSS2). Once in the cell, a fragment of SARS-CoV-2 is cleaved by the 3-chymotrypsin-like cysteine protease (3CL), which controls the replication of the coronavirus, essential for its life cycle. Our hypothesis is that certain PLs could attenuate the effects of the virus by acting on two levels, e.g.: 1) preventing TMPRSS2 from activating the protein -S, and 2) inhibiting the 3CL necessary for the replication and maturation of coronavirus. To do this, we propose 3 objectives: 1- Use a multidisciplinary approach, theoretical (molecular modeling and molecular docking) and experimental (DLS, SPR, particle tracking), to better understand the physicochemical interactions between phenolic ligands and TMPRSS2 and 3CL; 2- In vitro evaluation of protease inhibition by PLs by measuring the cleavage of peptide sequences by TMPRSS2 and 3CL in the presence, or absence, of increasing concentrations of PLs; 3-To assess the effects of PLs on the internalization of viruses mediated by the interaction between the protein -S viral and ACE-2, facilitated by the TMPRSS2, as well as the interactions on cellular models in culture (pulmonary, vascular endothelial cells of the blood-brain-barrier). In addition, as the evidence accumulates on the invasion of SARS-CoV-2 in the nervous system and thus it effects on the brain, we propose to study the effects of PLs on the dorsal root ganglia cell line, on neuronal and microglial cells involved in neuroinflammation because once in the brain, SARS-CoV-2, like SARS-CoV, can induce neuroinflammation. The results of this study will demonstrate the protective potential of PLs against SARS-CoV-2, hence, open up multiple perspectives in the development of treatments for SARS-CoV-2 and in the neuroinvasive mechanisms.