New 5-benzylidenethiazolidin-4-one inhibitors of bacterial MurD ligase: Design, synthesis, crystal structures, and biological evaluation

► 16 new MurD inhibitors of 4 structural series were prepared and evaluated against MurD from E. coli. ► Several compounds exhibited promising inhibitory activities with IC50 values up to 28 μM. ► The most potent compound 26 had an IC50 of 28 μM on MurD from E. coli. ► Crystal structures of MurD in complex with two new inhibitors (compounds 23 and 51) were obtained. ► Inhibitor 37 displays a weak antibacterial activity against S. aureus and E. faecalis.