The investigation of the interactions of an important agent, in treatment of cancer, curcumin with model membranes with spectroscopic and calorimetric techniques

Curcumin (diferuloylmethane) (CUR) is an important drug which extracted from the rhizome of the plant Curcuma longa (turmeric) and has anticancer effects besides antibiotic, antiviral, antifungal and anti-inflammatory properties. The aim of this thesis is to investigate the interactions between model membranes and Curcumin at molecular level. Because of the complex structure of biological membranes, we have worked with model membranes as an alternative to which we can change component and concentration. Dipalmitoylphosphatidylcholine (DPPC), one of the most common phospholipids and cholesterol (CHOL), another important component in biological membranes were prepared model membranes in the form of multilayer vesicles (MLV). The effects of the presence of Curcumin on lipid bilayers, which were separated into binary (DPPC + CUR) and triple systems (DPPC / CHOL + CUR) were investigated. The amount of cholesterol was kept constant (7:1 for DPPC: CHOL) suitably according to the lipid: cholesterol ratio in the living beings between 0.11 and 0.33. The effect of different concentrations of Curcumin on model membranes was investigated on both systems by Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared (FTIR) spectroscopy techniques. The results obtained from DSC showed that the use of the agent and cholesterol with the agent lead to loss of the pretransition temperature in both the binary and triple systems. The presence of Curcumin at different concentrations in both systems resulted in a decrease in the main phase transition temperature (Tm) and enthalpy (ΔH) values, while an increase in half-height width (ΔT1/2). The results obtained from FTIR showed that the presence of curcumin and cholesterol with it decreased the order of the model membranes in the gel phase in both systems, and increased the liquid crystal phase, besides the increase in fluidity in both phases. By the analyses of C = O streching bands, an increase was seen in wavenumber values in both systems and in both phases. By the analyses of PO2 streching bands, the increase in the wavenumber values for 24 % mole curcumin and the decrease in the wavenumbers for other concentrations occurred in the binary system. In the triple system, an increase in the wavenumber values was observed for all concentrations in both phases. When all calorimetric and spectroscopic results were evaluated, it was observed that curcumin interacted with lipids as a whole. It is hoped that this thesis study will shed light on the clinical studies to investigate the interactions of cancer which is still a deadly disease and curcumin which is an important agent in its treatment at molecular level.