Spectroscopic and calorimetric studies on trazodone hydrochloride–phosphatidylcholine liposome interactions in the presence and absence of cholesterol

Abstract

The interaction of antidepressant drug trazodone hydrochloride (TRZ) with dipalmitoyl phosphatidylcholine (DPPC) multilamellar liposomes (MLVs) in the presence and absence of cholesterol (CHO) was investigated as a function of temperature by using Electron Paramagnetic Resonance (EPR) spin labeling, Fourier Transform Infrared (FTIR) Spectroscopy and Differential Scanning Calorimetry (DSC) techniques. These interactions were also examined for dimyristoyl phosphatidylcholine (DMPC) multilamellar liposomes by using Electron Paramagnetic Resonance (EPR) spin labeling technique. In the EPR spin labeling studies, 5- and 16-doxyl stearic acid (5-DS and 16-DS) spin labels were used to monitor the head group and alkyl chain region of phospholipids respectively. The results indicated that TRZ incorporation causes changes in the physical properties of PC liposomes by decreasing the main phase transition temperature, abolishing the pre-transition, broadening the phase transition profile, and disordering the system around the head group region. The interaction of TRZ with unilamellar (LUV) DPPC liposomes was also examined. The most pronounced effect of TRZ on DPPC LUVs was observed as the further decrease of main phase transition temperature in comparison with DPPC MLVs. The mentioned changes in lipid structure and dynamics caused by TRZ may modulate the biophysical activity of membrane associated receptors and in turn the pharmacological action of TRZ.

Reorganization of Hydration Water of DPPC Multilamellar Vesicles Induced by l-Cysteine Interaction

“…This may cause the formation of different regions in terms of interactions. As a result of these different regions, lipids do not melt at the same temperature and the transition zone broadens. − …”

Eudragit S100 Entrapped Liposome for Curcumin Delivery: Anti-Oxidative Effect in Caco-2 Cells

“…The thermogram obtained by heating empty liposomes (Figure 3 When liposomes are loaded with curcumin (Figure 3, red curve) the melting transition broadens and shifts to a lower temperature: Tm = 32.1 • C with a ∆T 1/2 delta of 14.2 • C. The changes of these thermotropic sentitive indicators of physical phenomena that occur in the system, suggest that curcumin induces structural changes in liposomes. In particular, the broadened calorimetric profile indicates a decrease of the cooperativity of the transition which is inversely proportional to the width at the half of the maximum height of the peak [33]. The shift of the melting temperature toward lower temperature means that the presence of curcumin facilitates the trans-gauce conformation transition of lipid hydrocarbon chains increasing the phospholipid rotational freedom [34].…”

“…This modifies the overall balance of the interactions between the head groups and the phospholipid acyl chains that assure the packing of the pure lipid matrix and causes a partial disruption of its packing [36]. In addition, the uploading of curcumin in liposomes gives rise to the formation of regions that differ from each other in terms of interactions and consequently do not melt at the same temperature [33]. DSC profile of Eu-Curc-liposome (Figure 3, blue curve) does not show any thermal transition in the investigated temperature range, confirming the already observed interaction between the polymer and liposomes [24].…”

Fragment-based labeling using condensation reactions of six potential 5-HT7R PET tracers

“…2 Overview of previous work on the fragment-based labeling with reductive animations (Red. Amin) and the extension to condensation reaction within this work moiety is commonly used in medicinal chemistry [27][28][29] and as such, the feasibility of these building blocks to be used in fragment-based PET tracer development is of interest.…”