EPR investigation of clomipramine interaction with phosphatidylcholine membranes in presence and absence of cholesterol

Abstract

The effects of tricylic antidepressant clomipramine (CLO) on the membrane properties of saturated dimyristoyl phosphatidylcholine and dipalmitoyl phosphatidylcholine as well as on unsaturated egg yolk phosphatidylcholine liposomes were investigated by the electron paramagnetic resonance spin-labeling technique, in combination with the simulation of the spectra, taking into account that the membrane is heterogeneous and composed of the regions with different fluidity characteristics. Different spin labels, monitoring membrane properties in the upper and inner parts of the membrane, were used. In general, two spectral components, having different motional characteristics, were detected in all liposomes investigated. In liposomes with saturated chains, CLO decreased the phase-transition temperature, disordered the membrane, and increased polarity in the upper part of the membrane. However, less impact was observed in liposomes with unsaturated chains. In dipalmitoyl phosphatidylcholine liposomes, it also induced molecular rearrangements near the pretransition temperature. The presence of 30 mol% cholesterol increased the fluidizing effect of CLO and modified the lateral diffusion of nitroxide in the inner part of the membrane. A unique anomalous increase in diffusion of nitroxide, dependent on CLO concentration, was detected in the temperature region where the phosphatidylcholine membrane without cholesterol experiences the phase transitions. Since the changes in the central part of the membrane were even more pronounced than in the upper part of the membrane, it could be concluded that CLO incorporates into the membrane with its hydrophobic ring parallel to the phospholipid chains.

Interaction of Antidepressant Drug, Clomipramine, with Model and Biological Stratum Corneum Membrane as Studied by Electron Paramagnetic Resonance

“…This suggests structural phase transition in this region similar to the ones observed in previous FTIR studies . As the membrane of SC is complex and composed of several components, the transition is not as sharp as in DMPC liposomes . However, as in DMPC liposomes, a shift of the discontinuity toward lower temperatures was observed after adding 5 and 10 wt % CLO (Fig.…”

“…Besides, bovine CER (Type III), which contain unsaturated lipids contrary to mainly saturated SC lipids, was used in CER/CH liposomes. These liposomes only serve as a model which is more complex and is closer to intact SC than simple DMPC or PC liposomes in presence and absence of CH, which were examined before . Our results showed fluidizing effect of CLO in all measured models as well as in intact SC in shifting the structural transition to lower temperatures.…”

“…CLO was effective throughout the whole thickness of the membrane. The induced changes were more pronounced in the central part of the membrane, suggesting incorporation of CLO into membrane with its hydrophobic ring parallel to the phospholipid chains …”

“…Presence of 30 mol % CH increased the fluidizing effect of CLO. Fewer effects were observed in liposomes with unsaturated chains and no effect was observed in erythrocyte membrane (unpublished results).…”

Interaction of Alkylphospholipid Formulations with Breast Cancer Cells in the Context of Anticancer Drug Development

“…From the kinetics of EPR spectra intensity decrease, information about the transport and/or interaction of spin probe with cells can be obtained. Reduction kinetics of 5P was found to be much slower as for spin probes usually used in EPR investigations of cell membranes MeFASL(10,3) and HFASL(10,3) (Chen et al, 1988;Yonar et al, 2010) indicating that its transport into the cell cytoplasm and organelles is slower as for the other probes. This is not surprising due to the charge at the head group of 5P (Fig.…”