Synthesis and <i style="">in vitro</i> antibacterial activity of <i style="">N</i>-alkyl and <i style="">N</i>-aryl piperazine derivatives

Abstract

196-200A series of N-alkyl and N-aryl substituted piperazine derivatives have been synthesized in order to evaluate their antibacterial activity against four Gram-positive (Streptococcus mutans MTCC 890, Staphylococcus aureus MTCC 96, Bacillus subtilis MTCC 121, Staphylococcus epidermidis MTCC 435) and one Gram-negative (Escherichia coli MTCC 723) bacteria by disc diffusion and microbroth dilution methods. These compounds have been characterized by their MS, IR, 1H and 13C NMR spectral data. The benzyl piperazine derivatives 2-(4-benzylpiperazin-1-yl)-1-p-tolylethanone  and 2-(4-benzylpiperazin-1-yl)-1-(4-methoxyphenyl) ethanone show remarkable antibacterial activity even at low concentration against S. epidermidis, S. mutans and B. subtilis bacterial strains and are even close to the standard antibiotic, ampicillin. Furthermore, benzyl substitution increases antibacterial activity as compared to methyl and phenyl substituents under identical conditions