Antibacterial activity, structure and CMC relationships of alkanediyl alpha,omega-bis(dimethylammonium bromide) surfactants

Some alpha,omega-alkanediyl bis-dimethylammonium bromide compounds (gemini surfactants) referred as "m-s-m" have been synthesized, purified and characterized by usual spectroscopic methods. These compounds have been screened for antibacterial activity against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. Their activity was compared. The compounds tested showed excellent in vitro antibacterial activity against Staphylococcus aureus ranging from 1.5 to 20 microg/ml and had variable activity against E. coli with minimum minimum inhibitory concentration (MIC) of 50 microg/ml. These compounds are less active against P. aeruginosa. On the other hand, contrary to the antibacterial activity of these products against S. aureus, a relation between the MIC and the critical micellar concentration (CMC) was found and relationship between chain's Length and antibacterial activity was found.