INTERACTION BETWEEN MODEL MEMBRANES AND A NEW CLASS OF SURFACTANTS WITH ANTIOXIDANT FUNCTION

The effect of two series of amphiphilic quaternary ammonium salts on s ome properties of phospholipid membranes was studied. The compounds of one series, N-benzyl-N,N-dimethyl-N-alkyl ammonium bromides, exert a destructive effect on membranes and are treated as reference compounds . The compounds of the other series, 5-di-t-butyl-4-hydroxy)benzyl-N,N -dimethyl-N-alkyl ammonium bromides, are derivatives of the former one s, exhibit antioxidant properties, and do only relatively slight damag e to the membranes, The aim of the work was to explain the difference in molecular interaction with membranes between the two kinds of hydro phobic compounds. Thermodynamic methods, a new mixing technique, and m onolayer and quantum calculation methods were used, It has been shown that the antioxidant molecules are less hydrophobic than those of the reference compounds and disturb the membrane organization to a lesser extent. On the basis of monolayer data, we suggest that the studied an tioxidant behaves like a substitutional impurity, whereas the referenc e behaves like an interstitial one.