Small molecules with antimicrobial activity against E. coli and P. aeruginosa identified by high‐throughput screening

Abstract

Background and purpose: New antimicrobials are needed because of the emergence of organisms that are resistant to available antimicrobials. The purpose of this study was to evaluate a high-throughput screening approach to identify antibacterials against two common disease-causing bacteria, and to determine the frequency, novelty, and potency of compounds with antibacterial activity. Experimental approach: A high-throughput, turbidometric assay of bacterial growth in a 96-well plate format was used to screen a diverse collection of 150,000 small molecules for antibacterial activity against E. coli and P. aeruginosa. The statistical Z 0 -factor for the assay was X0.7. Key results: Screening for inhibition of E. coli growth gave a 'hit' rate (460% inhibition at 12.5 mM) of 0.025%, which was more than 5-fold reduced for P. aeruginosa. The most potent antibacterials (EC 50 o0.5 mM) were of the nitrofuran class followed by naphthalimide, salicylanilide, bipyridinium and quinoazolinediamine chemical classes. Screening of 4250 analogs of the most potent antibacterial classes established structure-activity data sets. Conclusions and Implications:Our results validate and demonstrate the utility of a growth-based phenotype screen for rapid identification of small-molecule antibacterials. The favourable efficacy and structure-activity data for several of the antibacterial classes suggests their potential development for clinical use.

Challenges of Antibacterial Discovery

“…A recent report of an empirical screen of a library of 150,000 compounds for inhibitors of E. coli or P. aeruginosa growth identified several classes of compounds with reasonable potency: a large nitrofuran class, followed by naphthalimide, salicylanilide, bipyridinium, and quinoazolinediamine chemical classes (90). There was some SAR within the classes, but no mechanisms have yet been determined.…”

HALO384: A Halo-Based Potency Prediction Algorithm for High-Throughput Detection of Antimicrobial Agents

“…5 The second-most bioactive (4408-0539) has been identified as having antimicrobial activity against Escherichia coli and Pseudomonas aeruginosa. 6 in addition, 4408-0539 was identified in a cell-based assay as an inhibitor of the tyrosine kinase dyrk1a, a protein encoded on the critical region of chromosome 21 thought to be involved in learning and memory deficits associated with down syndrome. 7 The least potent compound in the series (5940-0056) is reported to be toxic to mycobacteria.…”

Characterization of Ribosomal Binding and Antibacterial Activities Using Two Orthogonal High-Throughput Screens

“…A single concentration screen for bacterial inhibition studies was adapted from previous work to determine a compounds ability to inhibit bacterial growth in a rapid high-throughput format. De la Fuente et al established this screen using P. aeruginosa and E. coli to identify classes of smallmolecule antimicrobials (31). The single concentration of 5 M used to estimate the inhibition of a compound was chosen by analyzing the effective concentration of neomycin (control) to inhibit the growth of the susceptible strains (S. aureus, S. epidermidis, E. coli, S. marcescens, and E. cloacae) by Ͼ95%.…”

“…The antibacterial activity of the compound library was assessed by using the eight bacterial strains described above. The screening of the compound library performed here is an adaptation of a turbidometric assay described by De La Fuente et al (31). Adaptations include the reduction of drug concentration to 5 M, the use of Mueller-Hinton II cation-adjusted broth, and individual screening of drugs.…”

“…The neomycin dimer library was screened for antibacterial activity using a single concentration high throughput assay developed by De La Fuente et al This method has been previously used as an initial antibacterial screening technique in order to identify promising classes of compounds in a small-molecule library (31). We have adapted this screen to be used with our compound library to provide a high-throughput method for identifying compounds with antibacterial activity.…”