Identification and structure-activity relationships for a series of N, N-disubstituted 2-aminobenzothiazoles as potent inhibitors of S. aureus.

An internal collection of commercial and synthetically derived small molecule compounds was screened against several drug-resistant bacterial pathogens. Compound 1, a known N, N-disubstituted 2-aminobenzothiazole, was found to be a potent inhibitor of Staphylococcus aureus and several associated clinically relevant strains of methicillin-resistant S. aureus suggesting a possible novel mechanism of inhibition. It failed to show activity in any of the Gram-negative pathogens it was tested in. Evaluation in Escherichia coli BW25113 and Pseudomonas aeruginosa PAO1, as well as in their respective hyperporinated and efflux pump-deletion mutants revealed that activity in Gram-negative bacteria is diminished because this benzothiazole scaffold is a substrate for bacterial efflux pumps. Several analogs of 1 were synthesized to generate basic structure-activity relationships for the scaffold which highlighted that the N-propyl imidazole moiety was critical for the observed antibacterial activity.