Uncaria tomentosa (cat’s claw): a promising herbalmedicine against SARS-CoV-2/ACE-2 junction andSARS-CoV-2 spike protein based on molecularmodeling

COVID-19 is a novel severe acute respiratory syndrome coronavirus. Currently, there is no effective
treatment and vaccines seem to be the solution in the future. Virtual screening of potential drugs
against the S protein of severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) has provided
small molecular compounds with a high binding affinity. Unfortunately, most of these drugs do not
attach with the binding interface of the receptor-binding domain (RBD)–angiotensin-converting
enzyme-2 (ACE-2) complex in host cells. Molecular modeling was carried out to evaluate the potential
antiviral properties of the components of the medicinal herb Uncaria tomentosa (cat’s claw) focusing
on the binding interface of the RBD–ACE-2 and the viral spike protein. The in silico approach starts
with protein–ligand docking of 26 Cat’s claw key components followed by molecular dynamics simulations
and re-docked calculations. Finally, we carried out drug-likeness calculations for the most qualified
cat’s claw components. The structural bioinformatics approaches led to the identification of
several bioactive compounds of U. tomentosa with potential therapeutic effect by dual strong interaction
with interface of the RBD–ACE-2 and the ACE-2 binding site on SARS-CoV-2 RBD viral spike. In
addition, in silico drug-likeness indices for these components were calculated and showed good predicted
therapeutic profiles of these phytochemicals found in U. tomentosa (cat’s claw). Our findings
suggest the potential effectiveness of cat’s claw as complementary and/or alternative medicine for
COVID-19 treatment.