Synthesis, Structure-Activity Relationships, and Antiviral Activity of Allosteric Inhibitors of Flavivirus NS2B-NS3 Protease

J Med Chem. 2021 Mar 11;64(5):2777-2800. doi: 10.1021/acs.jmedchem.0c02070. Epub 2021 Feb 17.


Flaviviruses, including Zika, dengue, and West Nile viruses, are important human pathogens. The highly conserved NS2B-NS3 protease of Flavivirus is essential for viral replication and therefore a promising drug target. Through compound screening, followed by medicinal chemistry studies, a novel series of 2,5,6-trisubstituted pyrazine compounds are found to be potent, allosteric inhibitors of Zika virus protease (ZVpro) with IC50 values as low as 130 nM. Their structure-activity relationships are discussed. The ZVpro inhibitors also inhibit homologous proteases of dengue and West Nile viruses, and their inhibitory activities are correlated. The most potent compounds 47 and 103 potently inhibited Zika virus replication in cells with EC68 values of 300-600 nM and in a mouse model of Zika infection. These compounds represent novel pharmacological leads for drug development against Flavivirus infections.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Allosteric Regulation / drug effects
  • Animals
  • Antiviral Agents / chemical synthesis
  • Antiviral Agents / therapeutic use*
  • Cell Line, Tumor
  • Dengue Virus / enzymology
  • Humans
  • Mice
  • Molecular Structure
  • Pyrazines / chemical synthesis
  • Pyrazines / therapeutic use*
  • Serine Endopeptidases / metabolism*
  • Serine Proteinase Inhibitors / chemical synthesis
  • Serine Proteinase Inhibitors / therapeutic use*
  • Structure-Activity Relationship
  • Viral Nonstructural Proteins / antagonists & inhibitors
  • Viral Proteins / metabolism*
  • Virus Replication / drug effects
  • West Nile virus / enzymology
  • Zika Virus / enzymology
  • Zika Virus Infection / drug therapy*


  • Antiviral Agents
  • Pyrazines
  • Serine Proteinase Inhibitors
  • Viral Nonstructural Proteins
  • Viral Proteins
  • nonstructural protein 2B, Dengue virus
  • NS3 protein, zika virus
  • NS3 protease, dengue virus
  • Serine Endopeptidases