Fig. 4

Cell viability test for inhibition of SARS-CoV and CoV-2 E protein by ivermectin (Ivm) and derivatives. A Cytotoxicity test on control cells (mock-transfected). Abs₅₉₅ indicates cell viability, statistical significances relative to control (no inhibitor) values (on-way ANOVA) are indicated. Ivermectin derivatives were cytotoxic in concentrations ≥ 5 µM, except milbemycin, where the onset of toxicity started at ~10 µM. B Cell viability assays after recobinant 1-E (grey colums) and 2-E (black columns) expression in HEK293 cells. Inhibitors were applyed after transfection. Ivermectin (Ivm) and milbemycin (Mil) were tested in a range of 0.2 to 2 µM while ivermectin agylcon (IAP and nemadectin (Nem) were tested at 0.5 to 5 µM. Control was pRK mock-transfected cells. Cell viability of viroporin-transfected cells was normalized to the viability of control (mock-transfected) cells exposed to the same concentration of inhibitor. Statistical significance (one-way ANOVA) relative to the viability values of 1-E or 2-E without inhibitor is indicated, ns: non significant, *: p < 0.05, **: p < 0.01