NUCLEAR-MAGNETIC-RESONANCE STUDY OF A POLAR HEADGROUP DETERMINED ALPHA-CYCLODEXTRIN-PHOSPHOLIPID ASSOCIATION

In order to investigate the hemolytic activity of alpha cyclodextrin, the interactions of this cyclic oligosaccharide with selected membrane phospholipids were studied by H-1-NMR and P-31-NMR. Two natural phospholipids differing by their polar headgroup - phosphatidylcholine and phosphatidylinosito - were tested. H-1-NMR experiments showed a strong interaction with phosphatidylinositol while no significant one was identified with phosphatidylcholine. Indeed, a second population appeared for each resonance of phosphatidylinositol when cyclodextrin was added, without any evidence of an inclusion complex formation. This new population was demonstrated by P-31-NMR to be in dynamic exchange with the original system. These results suggest that interactions of alpha cyclodextrin with phospholipids are at least modulated by the nature of the polar headgroup in a first step. The acyl chains could be implicated in a second step.