Preparation and characterization of liposomes incorporating cucurbitacin E, a natural cytotoxic triterpene

International audience; Cucurbitacin E (Cuc E), highly oxygenated triterpene from cucurbitaceae ă family, was demonstrated to possess anti-proliferative, ă anti-inflammatory and anti-oxidant activities. Here, we studied the ă effect of Cuc E on the properties of the phospholipid membrane. Large ă unilamellar vesicles, with and without sulforhodamine B (SRB), were ă prepared in the absence and presence of Cuc E. The fluorescence ă increase, resulting from SRB release from vesicles due to inhibition of ă auto-quenching, was used to assess the permeability of liposome at 4 ă degrees and 37 degrees C. At 4 degrees C, blank liposomes and those ă containing Cuc E were stable; while at 37 degrees C Cuc E loaded ă liposomes showed less stability than blank ones. The loading efficiency ă of Cuc E into the vesicles was demonstrated to be 85% by HPLC. Dynamic ă light scattering measurements showed that liposomes embedding Cuc E were ă smaller than those which did not. Multilamellar vesicles were ă manufactured from dipalmitoylphosphatidylcholine in the presence and ă absence of Cuc E (molar ratio 7%). Results obtained by differential ă scanning calorimetry suggest that Cuc E binds mainly at the polar/apolar ă interfacial region of lipid bilayers and may incorporate into the lipid ă bilayer. Cuc E does not produce phase separation and thus might be ă included in liposome formulation. (C) 2013 Elsevier B.V. All rights ă reserved.