2-phenylethanol and some of its amphiphilic derivatives as inhibitors of platelet aggregation. Structure-activity...

The relationship between chemical structure and inhibitory activity of some simple water soluble phenylalkyl derivatives has been investigated. The inhibitory effect of the following analogous and homologous derivatives increases in the sequence: phenylacetic acid less than 2-phenylethanol less than 2-phenylethylamine = 4-phenylbutyric acid less than 3-phenylpropanol less than 4-phenylbutylamine, i.e., the inhibitory effect is potentiated. 1. by elongation of the alkyl chain, which is accompanied by an increase of the lipophilic character, and 2. when the polar portion is represented by the positively charged amino-group. The effect of these amphiphilic compounds on platelet aggregation appears to be mediated through polar and apolar interactions with the outer layers of the plasma membrane. The fact that the amino derivatives are the most active inhibitors suggests that negatively charged groups may be involved in the polar binding of these inhibitors. Experiments with neuraminidase-treated platelets revealed that the enzymatically removable sialic acid residues are not those negatively charged binding sites. Phentolamine and propranolol which block adrenergic alpha- and beta-receptors, respectively, do not influence the inhibitory effect of these agents.