Figure 1.

The antiviral activity of Hypericum perforatum (HP1) against the pseudo-typed VSV virus carrying the SARS-CoV-2 S protein. (A,C) Vero cells were seeded overnight, and on the next day, cells and the VSV-pseudo-typed virus were incubated with Hypericum perforatum (HP1) or solvent control (DMSO) for 1 h prior to infection, at 37 °C or room temperature, respectively. After pre-incubation, infection was performed with a MOI of 0.01 for 1 h, and cells were finally washed and incubated without further treatments. After 16–18 h, GFP signal was visualized under fluorescent microscope. (A) GFP-positive cells as % of control are shown (mean and s.d.), and one-way ANOVA with Dunnett’s multiple comparisons was done by comparing each value with the control. (C) Dose–response curve of the normalized GFP-positive cell values as % of control is depicted (mean and s.d.). (B,D) Vero cells were seeded overnight, and on the next day, incubation with HP1 or solvent control was initiated. 24 h after the start of incubation, the MTT assay-based cytotoxicity was measured. (B) Cell viability as % of control is shown (mean and s.d.), and one-way ANOVA with Dunnett’s multiple comparisons was done by comparing each value with the control. (D) Dose–response curve of the normalized cytotoxicity values as % of control is depicted (mean and s.d.). * for p ≤ 0.05, ** for p ≤ 0.01, and **** for p ≤ 0.0001.