Fig. 3: Antiviral activities of the identified natural compounds and drugs against SARS-CoV-2.
From: Fluorogenic reporter enables identification of compounds that inhibit SARS-CoV-2
a, Schematic showing the experimental design (Methods). b–d, Quantitative analysis of viral titre from plaque assays on Vero-E6 cells treated with drugs at 5 μM (b) or natural compounds at 2 or 1 μM (c) or at 0.1 μM (d). b–d, MOI = 0.5. Data presented as mean + s.d. (n = 3). P values, two-sided nonpaired t-test between compound- and DMSO-treated groups. *P < 0.05. **P < 0.01, ***P < 0.001. Exact P values: b, starting from ciclopirox: 0.14, 0.00096, 0.00096, 0.0013, 0.00099, 0.00096, 0.00096; c, starting from oleandrin: 0.00083, 0.0011, 0.00088, 0.0011, 0.00090, 0.0026, 0.00087, 0.00089, 0.0011, 0.00085, 0.0025, 0.00087, 0.00080, 0.00080, 0.00080, 0.00081, 0.00080; d, starting from bruceine D: 0.22, 0.00093, 0.00093, 0.0010, 0.0020. e, Dose–response and cell toxicity curve of each compound against SARS-CoV-2 by plaque assay (MOI = 0.5). Percentage of relative infection was determined by the ratio of infection rate of SARS-CoV-2 treated with each compound divided by that of DMSO control. EC50 and CC50 are presented as mean ± s.d. (n = 3). f,g, Immunofluorescence staining (f) of SARS-CoV-2 N and S protein in Vero-E6 cells and quantification (g) of number of stained cells at 16 h.p.i. (MOI = 0.5), treated with 200 nM anisomycin, bruceine A, gamabufotalin or remdesivir. Scale bars, 100 μm. Data presented as mean ± s.d. (n = 3). P values, two-sided nonpaired t-test between compound- and DMSO-treated groups. ***P < 0.001. Exact P values: starting from gamabufotalin anti-N: 0.00023, 0.00028, 0.00029, 0.82; starting from gamabufotalin anti-S: 0.00016, 0.00019, 0.00021, 0.63. NS, not significant; ND, not detectable.
