Synthesis, characterization and biological applications of novel Schiff bases of 2-(trifluoromethoxy) aniline

A series of five new Schiff bases (1-5) were synthesized by reacting 2-(trifluoromethoxy) aniline with different aromatic aldehydes. The Schiff base compounds were characterized by spectroscopic and analytical methods. Crystal structure of one new compound was also reported. The pharmacological properties, including antibacterial (14 bacterial species), antifungal (7 strains), antimalarial, anti-trypanosomal and anti-HIV activities of the compounds, were investigated. Cytotoxicity of the tested compounds was evaluated against human cervix adernocarcinoma cells (HeLa). Bacterial minimum inhibitory concentration (MIC) results by broth microdilution method showed that Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, Proteus vulgaris, Klebsiella oxytoc and Klebsiella pneumonia were more sensitive in the presence of tested compounds with an MIC value of 15.6 μg/mL. All the tested compounds showed good to moderate activity against fungi. The sensitivity of Aspergillus fumigatus was higher than other strains with a minimum cell death concentration (MFC) of 15.6 μg/mL. Compound 1 showed greater antimalarial and anti-trypanosomal properties with very low to no cytotoxic effects against HeLa cells as compared with compound 5, while other compounds exhibited poor activity. Compounds 1-5 demonstrated good activity against HIV type-1. These Schiff base compounds could be used as good antimicrobial agents.