VanX is an induced zinc metallo d-Ala-d-Ala dipeptidase involved in the viable remodeling of bacterial cell wall that is essential for the development of VREF. Here we report two cyclic thiohydroxamic acid-based peptide analogs that were designed, synthesized and investigated as vancomycin re-sensitizing agents. These compounds exhibit low micromolar inhibitory activity against vanX, with low cytotoxicity and were shown to increase vancomycin sensitivity against VREF. The improved pharmacological properties of these novel inhibitors over previous transition state mimics should provide an enhanced platform for designing potent vanX inhibitors for overcoming vancomycin resistance.