Application of Acoustic Ejection MS System to High-Throughput Screening for SARS-CoV-2 3CL Protease Inhibitors

MS is a powerful methodology for chemical screening to directly quantify substrates and products of enzymes, but its low throughput has been an issue. Recently, an acoustic liquid-handling apparatus (Echo (R)) used for rapid nano -dispensing has been coupled to a high-sensitivity mass spectrometer to create the Echo (R) MS system, and we applied this system to screening of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) 3CL protease inhibitors. Primary screening of 32033 chemical samples was completed in 12 h. Among the hits showing selective, dose-dependent 3CL-inhibitory activity, 8 compounds showed antiviral activity in cell-based assay.