The antimicrobial activities of a series of bis-quaternary ammonium compounds

A series of bis-quaternary ammonium compounds (bis-QACs) N, N′-hexamethylenebis(1-alkyl-4-carbamoyl pyridinium bromide) (4BCAP-6, n) (alkyl chain length, n = 8, 10, 12, 14, 16 and 18) were synthesized and characterized. Their surface tensions, critical micelle concentrations (CMC), and antimicrobial activities were evaluated. 4BCAP-6, 10 exhibited the strongest antimicrobial activities except for that against Proteus vulgari. The activities of 4BCAP-6, n against Escherichia coli zk126 were not significantly influenced by temperature, pH and initial bacteria concentration. These results indicate that bis-QACs exhibit high antimicrobial activity regardless of the environmental conditions.