Synthesis, antimicrobial activity and physico-chemical properties of some n-alkyldimethylbenzylammonium halides

• An optimized synthesis of quaternary ammonium salt is presented.
• Products, stable in ambient conditions, were obtained in excellent yields.
• These compounds may be considered as highly potential antibacterial agents.
• The effect of lipophilic properties on antibacterial activity was examined.

Quaternary ammonium salts (chloride, bromide and iodide; QUATs) with n-alkyl chain lengths between C8 and C18 have been synthesized under optimized experimental conditions. These compounds were tested in vitro for antimicrobial activity against representative bacterial strains (Staphylococcus aureus CIP 4.83, Enterococcus hirae CIP 5855, Pseudomonas aeruginosa CIP 82118, Escherichia coli CIP 53126, Mycobacterium smegmatis CIP 7326) and fungal species (Aspergillus niger ATCC 16404, Candida albicans IP 118079, Trichophyton interdigitale IP 146583). While these compounds showed moderate antifungal activity, several of them (particularly C14-I−) may be considered as highly potential antibacterial agents against S. aureus, E. hirae and E. coli with MIC values lower than that of commercial benzalkonium chloride and ciprofloxacin used as standards. The relationship between the lipophilicity and the antibacterial activity of the tested QUATs was quantified by a multiple linear regression method.

Quaternary ammonium salts (chloride, bromide and iodide; QUATs) with n-alkyl chain lengths between C8 and C18 have been synthesized under optimized experimental conditions. These compounds were tested in vitro for antimicrobial activity against representative bacterial strains and fungal species. The relationship between the lipophilicity and the antibacterial activity of the tested QUATs was quantified by a multiple linear regression method.Figure optionsDownload as PowerPoint slide