Synthesis and antimicrobial activity of some benzazole derivatives

A series of 2-(1H-benzimidazol/1,3-benzoxazol/1,3-benzothiazol-2-ylmercapto)-N-(1,5-dimethyl-2-phenyl-3-oxo-2,3-dihydro-1H-pyrazol-4-yl)acylamines 5a-h and 2-(1H-benzimidazol-2-ylmercapto)-N-(5-substituted-2-oxo-1,2-dihydro-3H-indol-3-ylidene)acetohydrazides 8a-e have been synthesized. Their structures are determined by the elemental analyses and spectral data (IR, 1 H-NMR, EIMS). These new derivatives are evaluated for in vitro antimicrobial activity against Staphylococcus aureus ATCC 6538, Staphylococcus epidermidis ATCC 12228, Escherichia coli ATCC 8739, Klebsiella pneumoniae ATCC 4352, Pseudomonas aeruginosa ATCC 1539, Salmonella typhi, Shigella flexneri, Proteus mirabilis ATCC 14153 and Candida albicans ATCC 10231. 8a, 8c and 8e demonstrating activity against Staphylococcus epidermidis ATCC 12228 in the primary screen are re-tested at lower concentrations to determine the actual minimum inhibitory concentration (MIC).