Fig. 5.

Mechanism of action of 2 and 3 against SARS-CoV-2 Delta variant. (a) Inhibition of viral replication in Calu-3 cells, pre-treated with 2 or 3 1 h before infection with 0.1 MOI of SARS-CoV-2 Delta. (b) Inhibition of viral replication in Calu-3 cells, post-treated 1 h after infection as in (a). Viral loads were determined at 24 hpi by RT-qPCR. (c) Inhibition of viral replication in Calu-3 cells, infected with 0.1 MOI of SARS-CoV-2 Delta and treated with 3 (62.3 µM) at 0 and 2 hpi. Viral loads were determined at 8 hpi by RT-qPCR. (d) Virucidal activity assessed in Vero E6 cells with 1E5 PFU and the maximum non-toxic dose of each drugs (20.7 µM for 2 and 31.1 µM for 3) were incubated for 3 h at 37 °C. The mixture of virus plus molecule was then serially diluted, from 1/10 (2 µM and 3.1 µM) to 1/1E6 (0.02 nM and 0.03 nM) and transferred on cells. Mean values and SD were calculated from two independent experiments performed in duplicate. Statistical significance was calculated using Ordinary one-way (2c) and two-way (2a-b) ANOVA analysis: * ** , p ≤ 0.001; * ** *, p ≤ 0.0001. A schematic representation of the procedure created with BioRender.com is shown on top of each panel.