Discovery of novel benzoquinazolinones and thiazoloimidazoles, inhibitors of influenza H5N1 and H1N1 viruses, from a cell-based high-throughput screen

J Biomol Screen. 2011 Jan;16(1):73-81. doi: 10.1177/1087057110384613. Epub 2010 Nov 8.


A highly reproducible and robust cell-based high-throughput screening (HTS) assay was adapted for screening of small molecules for antiviral activity against influenza virus strain A/Vietnam/1203/2004 (H5N1). The NIH Molecular Libraries Small Molecule Repository (MLSMR) Molecular Libraries Screening Centers Network (MLSCN) 100,000-compound library was screened at 50 µM. The "hit" rate (>25% inhibition of the viral cytopathic effect) from the single-dose screen was 0.32%. The hits were evaluated for their antiviral activity, cell toxicity, and selectivity in dose-response experiments. The screen yielded 5 active compounds (SI value >3). One compound showed an SI(50) value of greater than 3, 3 compounds had SI values ranging from greater than 14 to 34, and the most active compound displayed an SI value of 94. The active compounds represent 2 different classes of molecules, benzoquinazolinones and thiazoloimidazoles, which have not been previously identified as having antiviral/anti-influenza activity. These molecules were also effective against influenza A/California/04/2009 virus (H1N1) and other H1N1 and H5N1 virus strains in vitro but not H3N2 strains. Real-time qRT-PCR results reveal that these chemotypes significantly reduced M1 RNA levels as compared to the no-drug influenza-infected Madin Darby canine kidney cells.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Antiviral Agents / pharmacology*
  • Birds
  • Cell Line
  • Cytopathogenic Effect, Viral / drug effects
  • Dogs
  • High-Throughput Screening Assays / methods*
  • Humans
  • Imidazoles / pharmacology
  • Influenza A Virus, H1N1 Subtype / drug effects
  • Influenza A Virus, H3N2 Subtype / drug effects
  • Influenza A Virus, H5N1 Subtype / drug effects
  • Influenza in Birds
  • Influenza, Human
  • Inhibitory Concentration 50
  • Quinazolinones / pharmacology
  • RNA / metabolism
  • Small Molecule Libraries / pharmacology*
  • Thiazoles / pharmacology
  • Virus Replication / drug effects*


  • Antiviral Agents
  • Imidazoles
  • Quinazolinones
  • Small Molecule Libraries
  • Thiazoles
  • RNA