Effet du cholestérol sur les propriétés physiques des membranes liposomiales de type dipalmitoylphosphatidylcholine : application aux triterpènes tétra- et pentacycliques

Abstract : Triterpenes are C30 compounds derived from the cyclization of 2,3-epoxysqualene. The industrial use and the therapeutic interest of the triterpenes represent a capital importance in the field of the research of the natural substances. As for cholesterol, it has been widely known in the literature by its modulating role of natural as well as synthetic membranes. In our thesis work, we were interested in studying the effect of triterpenes and cholesterol on the fluidity and permeability of dipalmitoylphosphatidylcholine liposomes. Two approaches are used to carry out these studies via liposomes fillers or preformed liposomes. Permeability studies are carried out by fluorescence spectroscopy through the monitoring of a hydrophilic fluorophore, sulforhodamine B as a function of time. Studies of fluidity are carried out by electronic paramagnetic resonance. These probes make it possible to evaluate the fluidity at the interface of the membrane as well as at the hydrophobic core of the membrane. The data obtained from the release kinetics of sulforhodamine are quantified by mathematical models. These latter will serve as tools to predict the release mechanisms. Our results show that the permeability as well as the fluidity of the membranes are reduced following the addition of cholesterol. The effect of triterpenes on the physical properties of membranes is highly dependent on membrane composition, cholesterol level, the drug structure and incubation time
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Samar Kaddah. Effet du cholestérol sur les propriétés physiques des membranes liposomiales de type dipalmitoylphosphatidylcholine : application aux triterpènes tétra- et pentacycliques. Biotechnologie. Université de Lyon, 2018. Français. ⟨NNT : 2018LYSE1102⟩. ⟨tel-02145211v1⟩

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