Antimicrobial, Genotoxic and Acute Toxic Effects of Newly Synthesized N-Pyridine Schiff Base Derivatives

Nine N-pyridine Schiff bases (1-9) that were synthesized by reacting different ortho-, meta- and ortho-meta-substituted salicylaldehyde and 3,5-substituted aminopyridine were evaluated for their antimicrobial activity. The acute in vivo toxicity and genotoxic activity of these compounds were also tested. All of the compounds exhibited antimicrobial activity against Gram-positive (Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus and S. epidermidis) and Gram-negative bacteria (Citrobacter freundii, Enterobacter aerogenes, Escherichia coli, Proteus vulgaris and Salmonella typhimurium) and against yeasts (Candida albicans, C. glabrata, C. utilis, Pichia membranafaciens and Rhodotorula rubra). The minimum inhibitory concentrations (MICs) of the compounds ranged from 0.95 to 1000 µg/ml. For the yeasts tested, the MICs ranged from 0.97 to 250 µg/ml. Compounds 1-6, which were substituted with CH3, NO2, Br and Cl, showed especially significant inhibitory activity against C. albicans, and the MICs of these compounds ranged from 0.97 to 7.81 µg/ml. An in vivo brine shrimp (Artemia salina) acute toxicity assay was used to determine the LD50 values of the test compounds. The LD50 (24 h) values of these compounds ranged from 31.64 to 94.9 µg/ml. Additionally, according to umu-test results, none of the tested compounds showed a genotoxic effect over a range from 10 to 5000 µg/ml.