Determining antimicrobial activities of tri- and tetra-fluorine bearing Schiff base ligands against infectious bacteria

Treatment of infectious diseases is becoming increasingly complex for medical professionals. One of the main reasons is the increase in drug-resistant bacterial species. For this purpose, there is a great need for the discovery of new antibacterial drugs. Schiff bases are organic compounds with proven potential against bacteria, fungi, and viruses, especially cancer. Adding fluorine atoms to Schiff bases to increase their antimicrobial properties is one of the latest approaches. Our research is based on testing the antibacterial effect of six fluorinated Schiff base derivatives (C1-6) in comparison with gentamicin against three infectious bacterial species: Streptococcus pyogenes, Klebsiella pneumoniae, and Proteus mirabilis. The MIC50 values of each compound on the tested bacteria were determined using the colorimetric MTT method. MIC50 values of each compound were calculated using OD data. In general, Schiff base compounds were found to be more effective against S. pyogenes, with MIC50 values ranging from 4.03 to 8.17 μM, with C6 (4.03 μM) showing the strongest antibacterial activity. The MIC50 values of the compounds against K. pneumoniae varied widely, from 13.29 to 23.59 μM, and the MIC50 values for P. mirabilis ranged from 8.77 to 88.13 μM. It is concluded that fluorinated Schiff base derivatives should be examined in more detail with further analyses and in vivo studies, especially in terms of S. pyogenes.