A Comparative Study on the Antibacterial Effects of Some Newly Synthesized Thiazole, Imidazolidine and Tetrahydropyrimidine Derivatives Against Bacillus cereus and Salmonella typhimurium

Background: Bacillus cereus and Salmonella typhimurium are important human pathogenic bacteria. The spread of strains of drug-resistant these pathogens has encouraged researchers to identify and use novel antibacterial compounds. In this research project, we studied antibacterial effects of some newly synthesized thiazole, imidazolidine and tetrahydropyrimidine derivatives against B. cereus and S. typhimurium. Methods: 2-(E)-Cyano(thiazolidin-2-ylidene)thiazoles 1-4 and (imidazolidin or tetrahydropyrimidin-2-ylidene)malononitriles 5-11 were synthesized. Then, the disk diffusion and broth microdilution methods were applied to evaluate antibacterial effects. Results were recorded as the minimum inhibitory concentrations (MICs) and the growth inhibition zone diameters. Results: The in vitro assessment of antibacterial effects showed that only thiazole derivative 4 had considerable inhibitory effects against B. cereus and S. Typhimurium, whereas the others didn't have so. The inhibitory effects of thiazole derivative 4 against B. cereus and S. typhimurium were proven according to the MICs 125 and 500 µg/mL and the growth inhibition zone diameters 19.2±0.1 and 8.4±0.2 mm, respectively. Conclusion: The antibacterial effects of thiazole, imidazolidine and tetrahydropyrimidine derivatives were different, these effects were observed only in thiazole derivative 4. It could be due to the presence of 4-thiazolone ring in derivative 4, witch could reinforce these effects. After confirming that compound 4 is bactericidal against B. cereus and S. typhimurium, further studies can be accomplished on the determination of the cytotoxic and therapeutic effects of this compound in laboratory animals.