Medical Biophysics Division, Physics Department, Faculty of Science, Helwan University, Cairo, Egypt
The biophysical interactions of bisoprolol or enalapril with distearoyl phosphotidylcholine (DSPC) multilamellar liposomes were investigated by using two non-invasive techniques of Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). DSC showed that the mixtures of DSPC and bisoprolol or enalapril show a single peak, which indicates that they are miscible. The incorporated bisoprolol or enalapril is probably associated and interacted to large extent with the lipid bilayers that perturbed them which results in the strong broadening and shift to lower temperature 69 °C and 61 °C, respectively of the major characteristic endothermic peak of pure DSPC that exists at 102 °C. The pretransition of liposomes was eliminated for all samples containing bisoprolol or enalapril. Analysis of C=O stretching bond in FTIR spectroscopy showed that bisoprolol or enalapril does not make any hydrogen bonds with the interfacial region of DSPC liposomes, instead it induces free carbonyl groups in the system. These results revealed that enalapril or bisoprolol was located in the interfacial region of the membrane. The studies with model membranes could provide a rational approach for drug discovery and development as well as for developing efficient drug delivery systems.
Key words: DSPC liposomes, bisoprolol, enalapril, DSC, FTIR.
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