Hexakis (3,6-anhydro)-tetrakis [2I,II,IV,V-O-(2-ethoxyethyl)] derivatives of (3,6-anhydro)-α-cyclodextrin exhibits novel cation affinities and tensioactive properties on membranes

The synthesis of hexakis (3,6-anhydro)-tetrakis[2I,II,IV,V-O-(2-ethoxyethyl)] cyclomaltohexaose (AEOE) was designed to obtain cation complexing properties. 1H NMR study showed ionic radius dependence of AEOE cation affinity, markedly observed for Cs+ and Rb+. Besides, AEOE was found haemolytic (HC50=9mM) and superficial tension measurements revealed positive tensio active properties. A 31P and 2HNMR study of phospholipid dispersions (dimyristoyl phosphatidyl cholin, DMPC) in the presence of AEOE was performed; it was found that, beside the typical lineshape of phospholipid bilayers, two new NMR lines were detected in the presence of AEOE: a) an isotropic line consistent with a detergent effect b) another isotropic resonance of 1 Hz linewidth over phase transition temperature (298 K), indicating a true solubilization. Coupling constant measurements confirmed that the main conformation at the polar head group level was close to that observed in chloroform/methanol solution. It was finally concluded that AEOE could form true solutions of DMPC, similarly to those induced by diethyl ether interactions with membranes, while giving soluble complexes.