Abstract
In December 2019, a new coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) led to the outbreak of a pulmonary disease called COVID-19, which killed thousands of people worldwide. Therefore, the necessity to find out the potential therapeutic pharmaceuticals is imperious. This study investigates the inhibitory effect of SARS-CoV-2 3-chymotrypsin-like protease (3CL
pro
) using caffeine and caffeine-containing pharmaceuticals (3CPs) based on molecular dynamics simulations and free energy calculations by means of molecular mechanics-Poisson–Boltzmann surface area (MMPBSA) and molecular mechanics-generalized-Born surface area (MMGBSA). Of these 3CPs, seven drugs approved by the US-Food and Drug Administration have shown a good binding affinity to the catalytic residues of 3CL
pro
of His
41
and Cys
145
: caffeine, theophylline, dyphylline, pentoxifylline, linagliptin, bromotheophylline and istradefylline. Their binding affinity score ranged from –4.9 to –8.6 kcal/mol. The molecular dynamic simulation in an aqueous solution of docked complexes demonstrated that the 3CPs conformations bound to the active sites of 3CL
pro
during 200 ns molecular dynamics simulations. The free energy of binding also confirms the stability of the 3CPs–3CL
pro
complexes. To our knowledge, this
in silico
study shows for the first time very inexpensive drugs available in large quantities that can be potential inhibitors against 3CL
pro
. In particular, the repurposing of linagliptin, and caffeine are recommended for COVID-19 treatment after
in vitro, in vivo
and clinical trial validation.
Communicated by Ramaswamy H. Sarma