Antibacterial effects of chlorine bromine and methyl bearing Schif base derivatives on P. mirabilis, S. pyogenes and K. pneumoniae

Schiff bases are crucial class of ligands in the field of co-ordination chemistry. Schiff bases have been employed in treating a wide range of diseases because of their biological activity. We employed artificial chlorine bromine methyl bearing Schiff bases to study their effects on three strains of pathogenic microorganisms Proteus mirabilis, Streptococcus pyogenes and Klebsiella pneumoniae resistant to most antibiotic. After dissolving the compounds in ethanol, they were added in triple order 1 µM, 10 µM, 100 µM, and 1000 µM to 96-well culture plates. The same concentrations of gentamicin served as positive controls. Following adjustment to the 0.5 McFarland standards for the nutrient broth, 100 µL of bacteria suspension was added to each well and incubated at 37 °C. Once the incubation period had lasted for four hours, each culture well received a dose of 10 µL of MTT solution at a 250 µM concentration. The formazan produced by live bacteria was then dissolved by adding DMSO. The MIC50 for gentamicin against K. pneumoniae was 2.6 µM, while for P. mirabilis and S. pyogenes was 2.59 and 2.26 respectively. We measured the optical density (OD) of each well of culture plates by using an ELIZA micro-plate reader at 570 nm. MIC50 values for each compound were determined through the application of nonlinear regression analyses as a result, the MIC50 values against Streptococcus pyogenes varied from 6.27 to 38.00 µM. While the effectiveness of SB compounds against Proteus mirabilis ranged from 7.59 to 32.60, µM. However, the MIC50 for Klebsiella pneumoniae was between 19.80 and 80.90 µM. Based on their different cellular structure the compound ligands had effects differently on these bacteria.