Determination of antibacterial activities of some salicylaldimine derived-schiff base with their copper complexes on some pathogenic bacteria

The urgent request of potent chemical or natural antibacterial drugs by the nowadays world against antibacterial-resistant bacteria is critical in order to combat the raising microbial-resistance issue toward antibacterial drugs. In our study, we checked the antibacterial action of (8) Salicylaldimine derived Schiff-bases compounds (Ligands and Cupper complexes) and Gentamicin (positive control), by antibacterial MTT-assay against three pathogenic bacterial strains of: Klebsiella pneumonia(K. pneumonia), Proteus mirabilis(P. mirabilis) and Streptococcus pyogenes(S. pyogenes).The compounds have been prepared in different concentration of 1 μM, 10 μM, 100 μM and 1000 μM, then have been cultivated with adjusted standard number of standard bacteria, then after the application of the MTT-stain, and adding dimethyl sulfoxide for crystal dissolving, the optical density (OD) values for each well were recorded by an Microplate reader at 570 nm and MIC50 value of any compound have been calculated. In result, the most effective MIC50 value of Genta was (1.6 μM) for P. mirabilis, followed by (1.8 and 2.4 μM) for both S. pyogenes and K. pneumonia, respectively. And the compounds MIC50 range for S. pyogenes was 1.9-3.9 μM followed by (5.7 to >100 μM) for K. pneumoniae and (3.9 to >100 μM) for P. mirabilis, respectively. In our study, C3 has the best activity on gram negatives and C1 on S. pyogenes (Gram positive), while almost the entire compounds have moderate activity except of C6. In regarding with different bacterial response, the ligands with their Copper complexes had showed better effect on these bacteria, which may be due to their different cellular structure.