Space-filling effects in membrane disruption by cationic amphiphiles

We studied the hemolytic activity towards bovine erythrocytes of novel synt hetic steroid-polyamine conjugates consisting of a rigid hydrophobic steroi d unit, and a flexible hydrophilic polyamine unit connected by a linker. Th e steroid structure, polyamine chain length, and the presence of a hydropho bic substituent on the steroid, all influenced the activity. Analysis of th e time dependence of hemolysis suggested that these structurally related ca tionic amphiphiles have different mechanisms of membrane perturbation. (C) 2001 Elsevier Science Ltd. All rights reserved.