Synthesis and Biological Evaluation of Benzo[<i>b</i>]thiophene Acylhydrazones as Antimicrobial Agents against Multidrug-Resistant <i>Staphylococcus aureus</i>

Abstract

The benzo[b]thiophene nucleus and the acylhydrazone functional group were combined to prepare three new series of compounds for screening against Staphylococcus aureus. The reaction of substituted benzo[b]thiophene-2-carboxylic hydrazide and various aromatic or heteroaromatic aldehydes led to a collection of 26 final products with extensive structural diversification on the aromatic ring and on position 6 of the benzo[b]thiophene nucleus. The screening lead to the identification of eight hits, including (E)-6-chloro-N’-(pyridin-2-ylmethylene)benzo[b]thiophene-2-carbohydrazide (II.b), a non-cytotoxic derivative showing a minimal inhibitory concentration of 4 µg/mL on three S. aureus strains, among which were a reference classical strain and two clinically isolated strains resistant to methicillin and daptomycin, respectively.

Keywords

• benzothiophene
• acylhydrazone
• <i>Staphylococcus aureus</i>
• antibacterial
• MRSA