Screening of FDA-Approved Drugs Against SARS-CoV-2

Fluorogenic peptide substrate Dabcyl-KTSAVLQSGFRKME-Edans of 3CL^pro was synthesized by Yuan Yu Ltd. (Taiwan). The fluorogenic substrate peptide (Z-Arg-Leu-Arg-Gly-Gly-AMC) for PL^pro was purchased from Bachem (Bubendorf, Switzerland). The collections of 1,068 and 2,701 FDA-approved drugs were purchased from Target Molecule Corp. (Boston, MA, USA) and Selleck Chemicals (Houston, TX, USA), respectively. After screening, the active compounds in bulk size (e.g., 25 mg) were purchased from the companies for IC₅₀, EC₅₀, and CC₅₀ measurements. The plasmid miniprep kit, DNA gel extraction kit, and Ni-NTA resin were purchased from Qiagen (Hilden, Germany). FXa and the protein expression kit, including pET32a and pET16b vectors as well as competent Escherichia coli JM109 and BL21(DE3) cells were obtained from Novagen (Merck KGaA, Darmstadt, Germany). The SARS-CoV-2 virus used in this study was SARS-CoV-2/NTU13/TWN/human/2020 (accession identifier [ID] EPI_ISL_422415) as previously described (50 (link)). All commercial buffers and reagents were of the highest grade.