Synthesis and anti-microbial screening of some Schiff bases of 3-amino-6,8-dibromo-2-phenylquinazolin-4(3 H)-ones

In the present study, a series of novel Schiff bases were synthesized by condensation of 3-amino-6,8-dibromo-2-phenylquinazolin-4(3 H)-ones with different aromatic aldehydes via cyclized intermediate 6,8-dibromo-2-phenyl benzoxazin-4-one. The chemical structures were confirmed by means of IR, 1H NMR, 13C NMR, Mass spectral and Elemental analysis. These compounds were screened for anti-bacterial ( Staphylococcus aureus ATCC-9144, Staphylococcus epidermidis ATCC-155, Micrococcus luteus ATCC-4698, Bacillus cereus ATCC-11778, Escherichia coli ATCC-25922, Pseudomonas aeruginosa ATCC-2853, and Klebsiella pneumoniae ATCC-11298) and anti-fungal ( Aspergillus niger ATCC-9029 and Aspergillus fumigatus ATCC-46645) activities by paper disc diffusion technique. The minimum inhibitory concentrations (MICs) of the compounds were also determined by agar streak dilution method. Among the synthesized compounds 3-(3,4,5-trimethoxybenzylideneamino)-6,8-dibromo-2-phenylquinazolin-4(3 H)-one 10 was found to be the most potent anti-microbial activity with MICs of 18.9, 19.1, 18.8, 21.7, 18.2, 19.3, 16.7, 8.6 and 10.1 μg/ml against above mentioned respective strains. Compounds were found to exhibit more anti-fungal than anti-bacterial activity. Synthesis, characterization and anti-microbial studies of novel Schiff bases of 3-amino-6,8-dibromo-2-phenylquinazolin-4(3 H)-ones were described against the standard Gram-positive, Gram-negative and fungi strains and compound 10 was found to be the most effective. [Display omitted]