Design, synthesis and evaluation of antibacterial and antifungal quinazolinone derivatives bearing Thiazole Schiff Base Moiety

Abstract

Various quinazolinone derivatives with thiazole substituent was synthesised in good yields starting from 4-chloroanthranilic acid and ethyl-2-aminothiazole acetate in condensation reactions. The synthesized compounds were characterised using proton and carbon-13 nuclear magnetic resonance (¹H NMR, ¹³C NMR), Fourier Transform Infrared (FT-IR), and mass spectrometry (GCMS) analyses. The antibacterial activity of the compounds against a number of micro-organisms was tested by the Micro broth dilution method. It was found that the synthesised compounds exhibited variable antimicrobial activity against Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) as well as the fungus (Candida pseudotropicalis). It was also found that compounds 6c and 6d among others were the most effective on both Gram-negative and Gram-positive bacteria. The two compounds were also found to be the most effective against the fungus, Candida pseudotropicalis. The results of the antimicrobial activity suggest that compounds 6c and 6d are potent antimicrobial agents.