Action of surface-active substances on biological membranes. II. Hemolytic activity of nonionic surfactants.

The hemolytic action of commercially available nonionic surfactants and synthesized polyoxyethylene fatty acids and mercaptans on human erythrocytes was measured. It is shown that the hemolytic power of the detergents depends on the mutual effect of the hydrophobic and hydrophylic fragments of the agent molecule and does not depend on the hydrophile-lipophile balance of the compounds. A graphical image of the structure-activity relationship obtained in the study is similar to the one found in the literature when studying the analgesic effect of imidazoline derivatives on rats in vivo. This fact is discussed on the basis of assumption that the mechanism of both processes in vivo and in vitro is related to influence of the agents on cellular membranes. It is suggested that the role of the polyoxyethylene chain is its effect on the dipole moment and the relative lipophilicity of the compound or in the participation of the fragment in the interaction with the surface components when the agent is sorbed on the membrane. It is concluded that when the correlation between the hydrophile-lipophile balance values and a membrane effect the capacity of the surfactants this indicates that the effect is caused not by destruction of the membrane but by some rearrangement of the membrane structure accompanying the surfactant adsorption.