The current COVID-19 pandemic caused by a novel coronavirus
SARS-CoV-2 urgently calls for a working therapeutic. Here, we
report a computation-based workflow for efficiently selecting a
subset of FDA-approved drugs that can potentially bind to the
SARS-CoV-2 main protease M
PRO
. The workflow started
with docking (using Autodock Vina) each of 1615 FDA-approved
drugs to the M
PRO
active site. This step selected 62
candidates with docking energies lower than −8.5
kcal/mol. Then, the 62 docked protein–drug complexes were
subjected to 100 ns of molecular dynamics (MD) simulations in a
molecular mechanics (MM) force field (CHARMM36). This step
reduced the candidate pool to 26, based on the
root-mean-square-deviations (RMSDs) of the drug molecules in the
trajectories. Finally, we modeled the 26 drug molecules by a
pseudoquantum mechanical (ANI) force field and ran 5 ns hybrid
ANI/MM MD simulations of the 26 protein–drug complexes.
ANI was trained by neural network models on quantum mechanical
density functional theory (wB97X/6-31G(d)) data points. An RMSD
cutoff winnowed down the pool to 12, and free energy analysis
(MM/PBSA) produced the final selection of 9 drugs:
dihydroergotamine, midostaurin, ziprasidone, etoposide,
apixaban, fluorescein, tadalafil, rolapitant, and palbociclib.
Of these, three are found to be active in literature reports of
experimental studies. To provide physical insight into their
mechanism of action, the interactions of the drug molecules with
the protein are presented as 2D-interaction maps. These findings
and mappings of drug–protein interactions may be
potentially used to guide rational drug discovery against
COVID-19.