A comparative study of the hemolytic effect of polyenic antibiotics and of other cholesterol-binding agents.

Macrocyclic polyenic antibiotics were compared, on the basis of their hemolytic efficiency (expressed as critical occupancy level and as mean intrinsic association constant) with each other and with other cholesterol-specific hemolytic agents, such as digitonin and streptolysin O. In all cases, except for the larger polyenic antibiotics (amphotericin B and nystatin), the experimental results were compatible with the existence in the membrane of a large number of identical binding sites which are independent from each other. Simultaneous addition of two different agents gave either synergistic or antagonistic effects, indicating that digitonin, streptolysin O and filipin have different mechanisms of action from each other and from the mycosamine-containing polyenes.