Physico-chemical investigation of asymmetrical peptidolipidyl-cyclodextrins

A new class of amphiphilic peptidolipidyl-cyclodextrins is reported. The derivatives are chiral due to the presence of an L-leucine in the spacer arm that links a saccharide moiety and a grafted, saturated hydrocarbon chain. Self-assembly properties of the peptidolipidyl-cyclodextrins are characterized by quasi-elastic light scattering, turbidity and UV-visible absorption measurements. NMR experiments give insight into the intermolecular dipolar interactions as a function of temperature and concentration. N-dodecyl-N-alpha-(6(I)-amidosuccinyl-6(I)-deoxy-cyclomaltoheptaose)-L-leucine (1) is poorly soluble in aqueous media. N-dodecyl-N-alpha-(6(I)-amidosuccinyl-6(I)-deoxy-2(I),3(I)-di-O-methyl-hexakis-(2(II-VII),3(II-VII),6(II-VII)-tri-O-methyl)-cyclomaltoheptaose)-L-leucine(2) is found to be more soluble and self-assembles into stable supramolecular colloidal aggregates with nanometric dimensions above a critical aggregation concentration (CAC). It has a propensity for solubilization of hydrophobic species revealing a micellar-like behavior, which is compared to that of the non-ionic detergent octyl glucoside. On the contrary, compound I precipitates in a crystalline phase beyond its water solubility limit, and it does not display any solubilizing capacity. The observed behavior corroborates at the molecular level with the NMR results. (c) 2008 Elsevier Inc. All rights reserved.