Figure 6.

In vitro inhibitory activity of the drugs identified through the virtual screen of the FDA-approved drug library along with GRL0617 inhibitor, a known antagonist of SARS-CoV-2 PLpro. (A) Acarbose, (B) Darunavir, (C) FAD hydrate, (D) Oxidized L-Glutathione disulphide, (E) Mefloquine-HCl, (F) Lactitol, (G) Lopinavir, (H) Ritonavir, (I) RutinTrihydrate, and (J) GRL0617 (5-amino-2-methyl-N-[(1R)-1-naphthalen-1-ylethyl]benzamide). The identified nine molecules with GRL0617 molecules were diluted (10-0 mM) and incubated with PLpro at 37°C for 45 min. After incubation, peptide-AMC substrate reaction was added at 37°C for 45 min to initiate the reaction. Finally, release of the AMC was measured by excitation λ: 364 nm; emission λ: 440 nm using a microplate reader. The IC₅₀ values were calculated by the dose-response-inhibition function by GraphPad prism software. The assay experiments were performed in biological duplicatives.