Synthesis, antibacterial and QSAR evaluation of 5-oxo and 5-thio derivatives of 1,4-disubstituted tetrazoles.

A series of 1,4-disubstituted tetrazol-5-ones 3a, 5, 7, 12, 13 and 1,4-disubstituted tetrazol-5-thiones 3b, 9, 10 was synthesized and fully characterized by IR, MS, (1)H NMR and (13)C NMR. The series was evaluated for in vitro antibacterial activity against four Gram negative (Escherichia coli, Proteus mirabilis, Klebsiella pneumonia, and Pseudomonas aeruginosa) and three Gram positive (Staphylococcus aureus, Enterococcus faecalis, and Bacillus subtilis) bacteria. The zone of inhibition was measured using the well-diffusion assay, and in vitro minimum inhibitory concentration (MIC) was determined by microbroth dilution assay. MIC values indicate that compounds exhibited a varied range (0.2-37 μg/mL) of antibacterial activity against the tested bacterial strains. Statistically significant QSAR models were developed by the simple linear regression analysis for the correlation of MIC with computed descriptors. The concluded cross validated regression factors are 0.953 and 0.986 for E. coli, and S. aureus, respectively.