Space-filling effects in membrane disruption by cationic amphiphiles.

We studied the hemolytic activity towards bovine erythrocytes of novel synthetic steroid-polyamine conjugates consisting of a rigid hydrophobic steroid unit, and a flexible hydrophilic polyamine unit connected by a linker. The steroid structure, polyamine chain length, and the presence of a hydrophobic substituent on the steroid, all influenced the activity. Analysis of the time dependence of hemolysis suggested that these structurally related cationic amphiphiles have different mechanisms of membrane perturbation.