New derivatives of benzimidazole and their antimicrobial activity

Azolium salts and neutral 2-aryl derivatives of benzimidazole, benzothiazole and benzoxazole were synthesized and compounds were identified by 1H and 13C NMR spectroscopy and microanalytical methods. In this work the salts 1 and the neutral compounds 2 were evaluated for their in vitro antimicrobial activity against standard strains: Enterococcus faecalis (ATCC 29212), Staphylococcus aureus (ATCC 29213), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Candida albicans and Candida tropicals. The compounds 1f, 1g, 1l, 1m, 1n, 2a, 2b, 2c, 2e, 2f showed antimicrobial activity against Enterococcus faecalis (ATCC 29212), Staphylococcus aureus (ATCC 29213), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Candida albicans and Candida tropicals, with minimum inhibitory concentrations (MICs) ranging between 50 to 200 mg/mL. Compounds 1f, 1g, 1l, lm, 2b, 2c showed the highest activity. Benzothiazolium and benzoxazolium salts were more active than 1,3-disubstituted benzimidazolium salts and neutral 2-substituted benzimidazole, benzothiazole and benzoxazole derivatives.