Masitinib analogues with the -methylpiperazine group replaced - A new hope for the development of anti-COVID-19 drugs.

Masitinib is an orally acceptable tyrosine kinase inhibitor that is currently investigated under clinical trials against cancer, asthma, Alzheimer's disease, multiple sclerosis and amyotrophic lateral sclerosis. A recent study confirmed the anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) activity of masitinib through inhibition of the main protease (M) enzyme, an important pharmacological drug target to block the replication of the coronavirus. However, due to the adverse effects and lower potency of the drug, there are opportunities to design better analogues of masitinib. Herein, we substituted the -methylpiperazine group of Masitinib with different chemical moieties and evaluated their drug-likeness and toxicities. The filtered analogues were subjected to molecular docking studies which revealed that the analogues with substituents methylamine in M10 (CID10409602), morpholine in M23 (CID59789397) and 4-methylmorpholine in M32 (CID143003625) have a stronger affinity to the drug receptor compared to masitinib. The molecular dynamics (MD) simulation analysis reveals that the identified analogues alter the mobility, structural compactness, accessibility to solvent molecules, and the number of hydrogen bonds in the native target enzyme. These structural alterations can help explain the inhibitory mechanisms of these analogues against the target enzyme. Thus, our studies provide avenues for the design of new masitinib analogues as the SARS-CoV-2 M inhibitors.