Síntese e avaliação antibacteriana de bases de Schiff

Abstract

Schiff ́s bases are an important class of organic compounds, that have the azomethine group which is responsible for a wide variety of biological applications including antibacterial activity. Like Schiff's bases, heterocycles such as thiazole, pyridine and indole are pharmacophores present in several pharmaceutical products, where antibacterial properties are also reported. Thus, the present work aims at the synthesis of Schiff ́s bases compounds containing the heterocycles: thiazol, indole and pyridine through the condensation of aldehydes with aromatic amines. Six compounds (LQM385-LQM390) were obtained with yields greater than 70%. The structures were characterized by the Nuclear Magnetic Resonance (NMR) method of hydrogen (1H) and carbon (13C). The antibacterial activity was evaluated by the broth microdilution method against two gram-negative bacterial strains (Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853) and two gram-positive strains (Staphylococcus aureus ATCC 25923 and Enterococcus faecalis ATCC 29212), the compounds presented significant to moderate activity with minimal inhibitory concentrations (MIC) of 62.5 μg/mL-500 μg/mL against mo st strains. The evaluation of the antibacterial activity showed that the compounds LQM385, LQM389 and LQM390 exhibited the best MIC against the S. aureus ATCC 25923 strain, being the lowest in the study including also the MIC of the compound LQM 385 against E. faecalis ATCC 29212.