α-Ketoamides as Broad-Spectrum Inhibitors of Coronavirus and Enterovirus Replication: Structure-Based Design,...

Area of Science:

• Virology
• Drug Discovery
• Structural Biology

Background:

• Coronaviruses and enteroviruses possess essential proteases with similar active-site architectures.
• These viral proteases, crucial for polyprotein processing, are key targets for antiviral drug development.
• A unique glutamine requirement at the P1 position of the substrate is characteristic of these proteases.

Purpose of the Study:

• To design and develop near-equipotent, broad-spectrum antiviral agents targeting both coronavirus main proteases and enterovirus 3C proteases.
• To utilize structure-based design principles for creating novel peptidomimetic α-ketoamide inhibitors.
• To achieve broad-spectrum activity against alphacoronaviruses, betacoronaviruses, and enteroviruses.

Main Methods:

• Structure-based design of peptidomimetic α-ketoamides.
• Determination of six crystal structures of protease-inhibitor complexes.
• Synthesis and in vitro testing of compounds against recombinant proteases, viral replicons, and infected cell cultures.

Main Results:

• Optimization of the P2 substituent on α-ketoamides was critical for achieving near-equipotency across virus genera.
• Compounds 11u and 11r demonstrated low-micromolar EC50 values against enteroviruses, alphacoronaviruses, and betacoronaviruses in cell culture.
• In Huh7 cells, inhibitor 11r showed three-digit picomolar activity against Middle East Respiratory Syndrome coronavirus.

Conclusions:

• Peptidomimetic α-ketoamides are effective inhibitors of essential viral proteases from both coronavirus and enterovirus genera.
• Structure-based optimization, particularly of the P2 substituent, led to potent, broad-spectrum antiviral candidates.
• The identified inhibitors represent promising leads for the development of novel antiviral therapies against a range of significant viral infections.