Thermodynamic interactions of a cis and trans benzanilide with Escherichia coli bacterial membranes

The activity of a membrane interactive cis and trans benzanilide against Escherichia coli membrane mimics was investigated using Langmuir monolayers. It was found that in the presence of E. coli lipid mix monolayers, cis-benzanilide induced maximal surface pressure changes of 1 mN m(-1), whereas a reduced interaction was observed with trans-benzanilide. Compression isotherm analysis of these monolayers showed a dagger G (mix) < 0, indicating membrane stabilisation by both compounds. The binding coefficient for trans-benzanilide was circa 890 mu M and for the cis-benzanilide was 820 mu M, suggesting that both benzanilide compounds bound to the E. coli membranes.