Fig. 1
From: A cell-based large-scale screening of natural compounds for inhibitors of SARS-CoV-2

High throughput screening and identification of a natural compound library for inhibitors of SARS-CoV-2. a Flow chart of the cell-based HTS assay. Vero-E6 cells were seeded in 96-well plates one day prior to infection and infected with SARS-CoV-2 (MOI = 0.01) in the presence of tested compounds, and CPE induced by the virus was quantified by CCK-8 assay at 48 hpi. b Evaluation of anti- SARS-CoV-2 activity and cytotoxicity of the 17 newly discovered compounds and three previously reported CoVs inhibitors (bufalin, digoxin, and cryptotanshinone). At 24 hpi, the viral RNA levels in supernatants were measured by qRT-PCR assay. The cytotoxicity of the compounds at different concentrations was measured by a CCK-8 assay. The EC50 and CC50 were calculated by nonlinear regression analysis using GraphPad Prism 8.0 software. The selective indexes (SI) were calculated as the ratio of CC50 to EC50. c Addition of sodium and potassium assay. Vero-E6 cells seeded in 24-well plates were treated with DMSO or bufalin in the medium supplemented with NaCl (at a concentration of 0, 6.25, 12.5, 25, 50, or 100 mM) and KCl (at a concentration of 0, 1.5625, 3.125, 6.25, 12.5, or 25 mM) for 1 h, respectively, and then incubated with SARS-CoV-2 at an MOI of 0.01 for 24 h. The viral RNA levels in supernatants were determined by qRT-PCR assay. Inhibition rates were calculated as the percentage of infected cells normalized to DMSO-treated cells