Synthesis and structure-activity relationship of 1-[(E)-3-phenyl-2-propenyl] piperazine derivatives as suitable antibacterial agents with mild hemolysis

A new series of 1-[(E)-3-phenyl-2-propenyl]piperazine derivatives (5a-m) as antibacterial agents was designed and synthesized. The synthetic strategy was initiated by coupling different anilines (1a-m) with bromoacetyl bromide (2) in aqueous basic medium to acquire different electrophiles, 3a-m, with good yields. These electrophiles were further reacted with 1-[(E)-3-phenyl-2-propenyl]piperazine (4) to yield the desired compounds, N-(substituted)-2-{4-[(E)-3-phenyl-2-propenyl]-1-perazinyl}acetamides (5a-m). The structures of these compounds were established from their IR, 1H-NMR, 13C-NMR, EI-MS and CHN analysis data. The bacterial biofilm inhibitory potential of these piperazine derivatives was tested against two pathogenic strains, Bacillus subtilus and Escherichia coli. Two compounds, 5d and 5h were identified as suitable antibacterial agents. The cytotoxicity of these molecules was profiled through hemolytic assay and it was inferred that all the compounds were nearly harmless for membrane of red blood cells.