Structural Requirements for the Membrane Damaging Effect of Non Homologous Series of Nonionic Tenzides. Structural Requirements for the Biological Activity of Tenzides

The lipophilicity and the membrane damaging effect responsible for microbicidal activity of 26 nonionic tenzides belonging to various homologous series have been determined by reversed‐phase thin‐layer chromatography and by permeability measurements on dipalmitoyl‐phosphatidyl‐choline liposomes respectively. The lipophilicity correlated significantly to the membrane damaging effect, however it explained only about 35% of the total variance. Stepwise regression analysis showed that the requirements for the membrane disorganization are the presence of a bulky hydrophobic part to be built in to the hydrophobic alkyl chains of fatty acids and the optimum number (6–13) of ethylene‐oxide groups per molecule. Tenzides with too short ethylene‐oxide chains are buried in the lipid bilayer, the long ethylene‐oxide chains do not modify the membrane permeability.