Aim and Objective:
Antibiotic resistance is a serious constraint to the development of new
effective antibacterials. Therefore, the discovery of the new antibacterials remains one of the main
challenges in modern medicinal chemistry. This study was undertaken to identify novel molecules with
antibacterial activity.
Materials and Methods:
Using our unique double-reporter system, in-house large-scale HTS campaign
was conducted for the identification of antibacterial potency of small-molecule compounds. The
construction allows us to visually assess the underlying mechanism of action. After the initial HTS and
rescreen procedure, luciferase assay, C14-test, determination of MIC value and PrestoBlue test were
carried out.
Results:
HTS rounds and rescreen campaign have revealed the antibacterial activity of a series of Nsubstituted
triazolo-azetidines and their isosteric derivatives that has not been reported previously. Primary
hit-molecule demonstrated a MIC value of 12.5 µg/mL against E. coli Δ tolC with signs of translation
blockage and no SOS-response. Translation inhibition (26%, luciferase assay) was achieved at high
concentrations up to 160 µg/mL, while no activity was found using C14-test. The compound did not
demonstrate cytotoxicity in the PrestoBlue assay against a panel of eukaryotic cells. Within a series of
direct structural analogues bearing the same or bioisosteric scaffold, compound 2 was found to have an
improved antibacterial potency (MIC=6.25 µg/mL) close to Erythromycin (MIC=2.5-5 µg/mL) against the
same strain. In contrast to the parent hit, this compound was more active and selective, and provided a
robust IP position.
Conclusion:
N-substituted triazolo-azetidine scaffold may be used as a versatile starting point for the
development of novel active and selective antibacterial compounds.
Construction of a reporter system for Bifidobacteria using chloramphenicol acetyltransferase and its application for evaluation of promoters and terminators
