Fig. 2.
Anti-coronavirus activity of hit compounds. SARS-CoV-2 Mpro activity in vitro in the presence of (A) 100 μM or (B) different doses of selected hits. Graphs represent mean ± SD of n ≥ 3 experiments in duplicate. Data were normalized to the control (Mpro samples containing the same % of DMSO [vol/vol]). (C) Dose-dependent inhibition of the replication of SARS-CoV-2 in infected Vero E6 cells by selected hits. Graphs represent the mean ± SD of n ≥ 3 experiments in duplicate. (D) Antiviral activity of selected hit compounds in human Calu-3 cells infected with SARS-CoV-2 and treated with different concentrations of test compounds or 50 μM boceprevir (BOC) and 10 μM remdesivir (RMV) as controls. At 36 h p.i., supernatants were collected and titrated onto fresh Vero E6 cell monolayers. Graph represents the mean ± SD of n = 3 experiments in duplicate. Data were analyzed by a one-way ANOVA followed by Dunnet's multiple comparison test. ****p < 0.0001 compared to control (infected, DMSO-treated samples). (E) Time-of-addition studies with selected hit compounds. Test compounds at nontoxic concentrations (i.e., 50 μM for hit compounds and 25 μM for BOC) were added to Vero E6 cells prior to (−2 h), at the time of (0 h), or after (+2 h, +4 h) infection with SARS-CoV-2 at MOI of 1 PFU/cell. At 9 h p.i., supernatants were collected and titrated onto fresh Vero E6 cell monolayers. Graph represents the mean ± SD of n = 3 experiments in duplicate. (F) Dose-dependent inhibition of HCoV-OC43 and (G) HCoV-229E replication in MRC-5 cells by selected hit compounds. Graphs represent the mean ± SD of n ≥ 3 experiments in duplicate.