Antimicrobial and Cytotoxic Properties of Bisquaternary Ammonium Bromides of Different Spacer Length

A group of cationic gemini surfactants (bisquaternary ammonium bromides) with different spacer chain lengths (8-6-8, 8-7-8, 8-8-8, 8-9-8) was investigated, paying special attention to antimicrobial and the cytotoxic properties as well as their antimicrobial activity during long-term storage. It was shown that the compounds investigated exhibit excellent antimicrobial activity against Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Pseudomonas aeruginosa) as well as antifungal properties (Candida albicans). The gemini surfactants tested had the differential level of cytotoxicity against normal lymphocytes. It was shown that the spacer chain length plays an important role in antibacterial activity and influences the cytotoxicity. The gemini surfactants with shorter spacer chain length, that had higher critical micelle concentration, showed generally weaker antibacterial properties, but on the other hand, these exhibited lower level of cytotoxicity. Furthermore, the aqueous solution of gemini surfactants exhibited the same antimicrobial activity even after 3 months.