Assay Drug Dev Technol. 2017 Jul;15(5):198-209. doi: 10.1089/adt.2017.789.

Identification of Antipneumococcal Molecules Effective Against Different Streptococcus pneumoniae Serotypes Using a Resazurin-Based High-Throughput Screen.

Kim HJ1, Kim N2, Shum D2, Huddar S3,4, Park CM3, Jang S1.

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Streptococcus pneumoniae is a major human pathogen, causing around 1.6 million deaths worldwide each year. By optimizing a resazurin-based assay to detect S. pneumoniae growth in 384-well microplates, we developed a new high-throughput screening (HTS) system for the discovery of antipneumococcal molecules, which was unsuccessful using conventional absorbance measurements. Before applying our protocol to a large-scale screen, we validated the system through a pilot screen targeting about 7,800 bioactive molecules using three different S. pneumoniae serotypes. Primary screenings of a further 27,000 synthetic small molecules facilitated the identification of 3-acyl-2-phenylamino-1,4-dihydropquinolin-4-one (APDQ) derivatives that inhibited growth of S. pneumoniae with MIC90 values <1 μM (0.03-0.81 μM). Five selected APDQ derivatives were also active against Staphylococcus aureus but neither Klebsiella pneumoniae nor Pseudomonas aeruginosa, suggesting that APDQ may act specifically against Gram-positive bacteria. Our results both validated and demonstrated the utility of the resazurin-based HTS system for the identification of new antipneumococcal molecules. Moreover, the identified new antipneumococcal molecules in this study may have potential to be further developed as new antibiotics.


Streptococcus pneumoniae; antipneumococcals; high-throughput screening; resazurin

PMID: 28723269 DOI: 10.1089/adt.2017.789