Discovery of SARS-CoV-2 Papain-like Protease Inhibitors through a Combination of High-Throughput Screening and a FlipGFP-Based Reporter Assay.

The papain-like protease (PL) of SARS-CoV-2 is a validated antiviral drug target. Through a fluorescence resonance energy transfer-based high-throughput screening and subsequent lead optimization, we identified several PL inhibitors including and with improved enzymatic inhibition and antiviral activity compared to , which was reported as a SARS-CoV PL inhibitor. Significantly, we developed a cell-based FlipGFP assay that can be applied to predict the cellular antiviral activity of PL inhibitors in the BSL-2 setting.

Expedited Approach toward the Rational Design of Noncovalent SARS-CoV-2 Main Protease Inhibitors.

The main protease (M) of SARS-CoV-2 is a validated antiviral drug target. Several M inhibitors have been reported with potent enzymatic inhibition and cellular antiviral activity, including , , , and , with each containing a reactive warhead that covalently modifies the catalytic Cys145. Coupling structure-based drug design with the one-pot Ugi four-component reaction, we discovered one of the most potent noncovalent inhibitors, () that is structurally distinct from the canonical M inhibitor .

Discovery of SARS-CoV-2 papain-like protease inhibitors through a combination of high-throughput screening and FlipGFP-based reporter assay.

The papain-like protease (PL ) of SARS-CoV-2 is a validated antiviral drug target. PL is involved in the cleavage of viral polyproteins and antagonizing host innate immune response through its deubiquitinating and deISG15ylating activities, rendering it a high profile antiviral drug target. Through a FRET-based high-throughput screening, several hits were identified as PL inhibitors with IC values at the single-digit micromolar range.