Development of GS-441524 Derivatives as Potent SARS-CoV-2 Mac1 Inhibitors via a Direct-to-Biology Approach

Area of Science:

• Virology
• Medicinal Chemistry
• Structural Biology

Background:

• Viral macrodomains (Mac) are crucial targets for antiviral drug development, particularly in light of the COVID-19 pandemic.
• Existing inhibitors for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Mac1 show moderate potency.
• Middle East respiratory syndrome coronavirus (MERS-CoV) also presents a significant public health threat, necessitating broad-spectrum antiviral strategies.

Purpose of the Study:

• To develop novel, potent inhibitors targeting viral Mac1 domains.
• To explore an efficient iterative direct-to-biology approach for accelerated drug discovery.
• To elucidate the binding mode of novel inhibitors through structural analysis.

Main Methods:

• Iterative direct-to-biology approach utilizing amide-coupling reactions.
• High-throughput screening via mix-and-read fluorescence polarization (FP) assays without purification.
• Cocrystallization of a SARS-CoV-2 Mac1 derivative to determine its binding mode.

Main Results:

• Conversion of GS-441524 to KP-S54 (18c), a potent inhibitor of SARS-CoV-2 Mac1 (IC50: 44 nM) and MERS-CoV Mac1 (IC50: 91 nM).
• Demonstration of an efficient drug discovery workflow leveraging direct screening of reaction mixtures.
• Obtained cocrystal structure of a derivative (12p) bound to SARS-CoV-2 Mac1, revealing key interactions.

Conclusions:

• The developed iterative direct-to-biology approach significantly enhances the potency of viral Mac1 inhibitors.
• KP-S54 represents a promising lead compound for developing new antiviral therapies against coronaviruses.
• Structural insights from cocrystallography will guide the rational design of next-generation macrodomain inhibitors.