Fig. 4. Anti-SARS-CoV-2 activity of TMPyP4 in cell-based assays.

a–c Vero E6 cells infected with SARS-CoV-2 (10³ TCID₅₀ virus/mL) were pretreated with different concentrations of TMPyP4, TMPyP2, PDP or remdesivir. At 72 h post infection, viral RNA copies in cell lysates (a) and in cell culture supernatants (b) were detected by qRT-PCR. Viral titers (log₁₀TCID₅₀/mL) (c) were quantified by TCID₅₀. Lower limit of detection for viral titers is indicated with a red dotted line. TCID₅₀, median tissue culture infectious dose. d Fitting viral loads (viral RNA copies/mL) and cell viability under increasing concentration of TMPyP4 to determine the EC₅₀ and CC₅₀ of TMPyP4, PDP and remdesivir. The drugs cytotoxicity was detected by SRB assays. EC₅₀, half-maximal effective doses. EC₉₀, 90% maximal effective doses. CC₁₀, 10% cytotoxic concentration. CC₅₀, half-cytotoxic concentration. Data are shown as means ± SEM of three independent experiments, two-tailed Student’s t-test. ^**P < 0.01, ^***P < 0.001, ^****P < 0.0001.