Allyl rhodanine azo dye derivatives: potential antimicrobials target D-alanyl carrier protein ligase and nucleoside diphosphate kinase

3-Allyl-5-(4-arylazo)-2-thioxothiazolidine-4-one (HL_n) ligands (where n = 1-3)was hypothesized to have antimicrobial activities mediated through inhibition of new antimicrobial targets. The ligands (HL_n) were synthesized and characterized by IR and ¹H NMR spectra. The ligands (HL_n) were insilico 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). HL₃ ligand has the best energy and mode of binding to both NDK and DltA, even if its binding to DltA was stronger than that to NDK. The antimicrobial activity of HL₃ ligand, morphological and cytological changes in HL₃-treated bacteria agreed with the insilico results. HL₃ ligand showed significant antimicrobial activity against Bacillus cereus, Staphylococcus aureus and Fusarium oxysporium. HL₃-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 HL₃ ligand represents a bactericide against B. cereus and S. aureus, targets DltA, and may target NDK.