The structuring effects of XXXX on pure and @entity12364 - or @entity165 -containing @entity4747 bilayers: a differential scanning calorimetry study.

@entity1 @entity12364 @entity137 @entity2379 @entity4748 @entity364 @entity165 @entity3150 @entity4747 @entity5068 @entity11015
@entity2379 ( @entity11015 ) is the most widely used polyene antibiotic to treat @entity364 which affect an increasing number of immunocompromised @entity1 . It is generally thought that @entity11015 forms pores within the fungi membranes by interacting with @entity12364 , the main @entity5068 of fungi. However, it also interacts with the @entity165 contained in @entity1 cells, hence its @entity137 . In order to have a better understanding of the interactions prevailing between @entity11015 and @entity3150 , differential scanning calorimetry was used to study various mixtures incorporating from 6.5 to 25 mol% of @entity11015 in pure @entity4747 ( @entity4748 ) vesicles and in @entity12364 - or @entity165 -containing @entity4748 vesicles. The @entity5068 concentration was kept constant at 12.5 mol% with respect to the phospholipid. Our results show that three phases co-exist when @entity11015 is dispersed in the pure phospholipid. One corresponds to the phospholipid phase alone. The two others are characterised by a broad transition at temperatures higher than the main transition temperature of the pure phospholipid, corresponding to the drug in interaction with the aliphatic chains of the lipid. The fact that the transition temperatures of these additional components are higher than that of the pure phospholipid suggests that @entity11015 interacts strongly with the aliphatic chains of the lipid, consistent with the idea prevailing in the literature that @entity11015 by itself may form pores in a lipid matrix. When @entity11015 interacts with @entity165 -containing bilayers the thermograms also present three components. Upon increasing the concentration of @entity11015 , though, an important broadening of these components is observed which is explained in terms of destabilisation of the organisation of the aliphatic chains. The situation is strikingly different if @entity12364 is present in the lipid matrix. The thermograms remain unmodified as the concentration of @entity11015 is increased and a broad transition, now involving only two components when the thermograms are decomposed, is observed. An analysis of the results shows that various interacting units, e.g. @entity11015 + @entity4748 and ( @entity11015 + @entity12364 )+ @entity4748 , are present within the membrane. These units involve the phospholipid and hence contribute to its structurisation. The important differences between the thermograms obtained with the @entity12364 - as compared to the @entity165 -containing bilayers, in spite of the structural similarity of these two @entity3150 , provides strong evidence for the selectivity of interaction of @entity11015 with @entity12364 as compared to @entity165 . It is thus clear that the action of @entity11015 on @entity165 - as compared to @entity12364 -containing membranes results from different mechanisms. Finally, UV-visible spectra of @entity11015 in pure as well as @entity5068 -containing @entity4748 vesicles show the presence of absorption bands that give support to the interpretation derived from the calorimetric data.
