Investigating theobromine as a potential anti-human coronaviral agent

Area of Science:

• Virology
• Drug Discovery
• Computational Chemistry

Background:

• Coronaviruses (CoVs) pose a significant threat, with existing vaccines lacking cross-species efficacy and the risk of new pandemic strains emerging.
• Developing broad-spectrum antiviral drugs is crucial for pandemic preparedness against diverse CoVs.
• Targeting conserved viral proteins offers a strategy for pan-coronaviral drug development.

Purpose of the Study:

• To identify pan-coronaviral agents by targeting the conserved main protease (Mpro) across different human CoVs.
• To screen for potential drug candidates effective against multiple coronavirus species.

Main Methods:

• Molecular docking was employed to screen drug candidates against the Mpro catalytic dyad of four human CoVs (SARS-CoV-2, NL63, OC43, 229E).
• The leading candidate, theobromine, was evaluated in cell culture models of coronavirus infection.
• Antiviral activity and binding affinity of theobromine were assessed against different CoV strains.

Main Results:

• Theobromine demonstrated strong binding to the Mpro of SARS-CoV-2 and HCoV-NL63, moderate binding to HCoV-OC43 Mpro, and no significant binding to HCoV-229E Mpro.
• Theobromine exhibited dose-dependent inhibition of SARS-CoV-2 in Calu3 cells but not in cells infected with seasonal CoVs.
• The study indicates that theobromine's antiviral potency varies among different CoV species.

Conclusions:

• Theobromine shows potential as an antiviral agent targeting the Mpro of coronaviruses.
• Its efficacy is strain-specific, suggesting limitations for broad-spectrum application without further optimization.
• Further research is needed to develop more potent and broadly effective pan-coronavirus antiviral drugs.