Allyl rhodanine azo dye derivatives: Potential antimicrobials target d‐alanyl carrier protein ligase and nucleoside diphosphate kinase

Abstract 3‐Allyl‐5‐(4‐arylazo)‐2‐thioxothiazolidine‐4‐one (HL n ) ligands (where n = 1 to 3) were hypothesized to have antimicrobial activities mediated through inhibition of new antimicrobial targets. The ligands (HL n ) were synthesized and characterized by infrared (IR) and 1 H nuclear magnetic resonance ( 1 H NMR) spectra. The ligands (HL n ) were in silico screened to their potential inhibition to models of d ‐alanyl carrier protein ligase (DltA) (from Bacillus cereus , PDB code 3FCE) and nucleoside diphosphate kinase (NDK) (from Staphylococcus aureus ; PDB code 3Q8U). HL 3 ligand has the best energy and mode of binding to both NDK and DltA, even though its binding to DltA was stronger than that to NDK. In antimicrobial activity of HL 3 ligand, morphological and cytological changes in HL 3 ‐treated bacteria agreed with the in silico results. The HL 3 ligand showed significant antimicrobial activity against B. cereus , S. aureus, and Fusarium oxysporium . The HL 3 ‐treated bacterial cells appeared malformed and incompletely separated. Its cell walls appeared electron‐lucent and ruptured. They contained more mesosomes than normal cells. It was found that the HL 3 ligand represented as a bactericide against B. cereus and S. aureus by blocking target DltA, and may target NDK.