Small-Molecule Thioesters as SARS-CoV-2 Main Protease Inhibitors: Enzyme Inhibition, Structure-Activity...

Area of Science:

• Medicinal Chemistry
• Virology
• Structural Biology

Background:

• The SARS-CoV-2 main protease (M^pro) is vital for viral replication and a key target for antiviral drug development.
• Developing potent and specific inhibitors of M^pro is crucial for combating SARS-CoV-2 and related coronaviruses.

Purpose of the Study:

• To design, synthesize, and characterize novel small-molecule thioesters as inhibitors of SARS-CoV-2 M^pro.
• To evaluate the antiviral activity and structure-activity relationships of these novel compounds.

Main Methods:

• Chemical synthesis of thioester compounds.
• Biochemical assays to determine M^pro inhibition kinetics (k_inac/K_i).
• Cell-based antiviral assays in Calu-3 and Vero76 cells.
• X-ray crystallography for co-crystallization studies with M^pro.

Main Results:

• Compounds 3w and 3x demonstrated potent inhibition of SARS-CoV-2 M^pro with high inactivation rates.
• Several compounds (3h, 3i, 3l, 3r, 3v, 3w, 3x) exhibited nanomolar antiviral activity in cell-based assays.
• X-ray structures confirmed covalent binding of inhibitors to the catalytic Cys145 residue of M^pro.
• Inhibitors showed cross-activity against M^pro from SARS-CoV-1 and MERS-CoV.

Conclusions:

• Novel thioester compounds are effective inhibitors of SARS-CoV-2 M^pro.
• These inhibitors possess broad-spectrum antiviral activity against beta-coronaviruses.
• The findings support the potential of these compounds as therapeutic agents for various coronavirus infections.