Fig. 1.
Hit validation/invalidation of dipyridamole, chloroquine, hydroxychloroquine, montelukast sodium, candesartan, candesartan cilexetil, oxytetracycline, and atazanavir as SARS-CoV-2 Mpro inhibitors. The most active 8 compounds out 16 identified in ref. 1 were evaluated in a FRET-based enzymatic assay in the presence (A) or absence (B) of 4 mM DTT, thermal shift binding assay (C), and native MS binding assay (D–H). The FRET-based enzymatic assay was carried out with 100 nM SARS-CoV-2 Mpro protein with 10 µM FRET substrate Dabcyl-KTSAVLQ/ SGFRKME-Edans (2, 4–6), the thermal shift binding assay was carried out with 3 µM Mpro protein and 40 µM testing compounds (2, 4–6), and the native MS binding assay was carried out with 4 µM Mpro protein and 10 to 30 µM testing compounds (2, 4, 5).