M. Maral Sünnetçioğlu

Detection of Irradiated Wheat Using the Electron Paramagnetic Resonance Spin Probe Technique

ABSTRACT In this study, the electron paramagnetic resonance (EPR) spin probe technique is applied as a detection method in the differentiation of irradiated and unirradiated wheat seeds. Two wheat cultivars, Kunduru and Bezostaya, were used. Aqueous solutions of 4-hydroxy-TEMPO (TANOL) spin probe prepared with a line-broadening agent, potassium ferricyanide, were used in all experiments. The EPR spectra of the samples were recorded against time. A decrease in the signal intensity and a change in the shape of the intensity-time curve (rehydration curve) were observed, depending on the applied level of irradiation. The ratio of the lipid and aqueous regions at the high field (mI = -1) line changes, depending on the dose of irradiation.

An EPR study of wheat seeds by the use of nitroxide spin probes

Summary The viability of a variety of wheat seeds was investigated by use of the EPR technique. Three different types of spin probes (4-Hydroxy-TEMPO (TANOL), 3-Carbamoyl-2,2,5,5-tetramethyl-3-pyrrolin-l-yloxy, 3-Carbamoyl-PROXYL) were utilized in examining the viability of embryo cells. The penetration of the spin probe across the membrane was observed via the change in signal intensity against time for dry embryos of the variety of wheat seeds soaked in aqueous solutions of spin probe and line broadening agent. From the analysis of the signal intensity-time curves (i.e. rehydration curves) it was observed that the two kinds having different genetic roots (Bezostaya, Kunduru) exhibit similar saturation behaviour whereas Gerek saturates much more easily. The rehydration curves for naturally aged seeds indicates that aging causes rapid saturation and an important decrease in the signal intensity. In order to get better insight on the effect of the signals from polar and nonpolar regions on the experimental spectra, these spectra were simulated by the use of the theoretical models developed.

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

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.

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

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.

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

The interactions of tricyclic antidepressant drug, clomipramine (CLO), with pig ear stratum corneum (SC) and model membranes were investigated by electron paramagnetic resonance (EPR) spin labeling to get some insight into the possible application of this drug in transdermal delivery. The changes in membrane characteristics caused by CLO in the regions that are close to the water-lipid interfaces and the central parts of the membranes were searched. The experimental results were supported by computer simulation of EPR spectra, which showed heterogeneity of the membranes composed of regions with different fluidity characteristics. CLO was effective in both parts of the layers, indicating intercalation of the drug into model membranes as well as into the pig ear SC. Introduction of various molar ratios of CLO caused a decrease in the order parameter and an increase in the rotational diffusion of nitroxide moiety in different membrane regions as well as an increase in the polarity of spin probe environment. It also changed the number of resolved spectral components, which reflects the heterogeneity of the membrane. The fluidizing effect of CLO on pig ear SC throughout the whole membrane layers indicates that CLO penetrates into the SC, which is important for its transdermal delivery.

Effect of cis-(Z)-flupentixol on DPPC membranes in the presence and absence of cholesterol.

Cis-(Z)-flupentixol dihydrochloride (FLU), a thioxanthene drug, is used in therapy of schizophrenia as well as in anxiolytic and depressive disorders. Since the action mechanism of FLU is not completely understood, the main objective of present study is to provide a detailed evaluation of flupentixol-phospholipid membrane interactions at molecular level. FLU-dipalmitoylphosphatidylcholine (DPPC) interactions in presence and absence of cholesterol (CHO) were investigated as a function of temperature. The changes in upper part of membrane were more pronounced than those in central part of membrane, as indicated by EPR and FTIR. FLU was proposed to incorporate into phospholipid membranes with its triple ring parallel to head group and its chain toward alkyl chain of phospholipids. According to DSC results, the incorporation of 10 mol% FLU into DPPC caused a shoulder in transition peak, suggesting the occurence of a phase separation, and formation of this new phase is still observable in presence of CHO. It is well known that, structure and dynamics of lipids have significant influence on the function of membrane bound proteins, and consecutively their actions. Based upon these, it was proposed that FLU may modify membrane associated receptors and transport proteins, which would form the basis of its clinical efficiency.

The use of simulation in the EPR spin probe technique for detection of irradiated seeds.

An electron paramagnetic resonance (EPR) spin probe study of irradiated wheat seeds was performed depending on irradiation dose. The structural changes in the membrane integrity were followed using aqueous solutions of 4-hydroxy-TEMPO (TANOL) spin probe and a line broadening material. In the studies dry seed embryos were kept in these solutions for 150 min. The spectra were recorded at various times of air drying process. The simulation of these spectra indicated a decrease in the water content of the embryos depending on the increasing irradiation dose. This indicates the increase in the permeability of the membranes as a result of the radiation damage. From the decay curves it is possible to determine about irradiation dose, however, this approach is not very successful at close irradiation doses.

Correction to: Temperature-Dependent Electron Paramagnetic Resonance Studies of Docosahexaenoic Acid and Gamma Linolenic Acid Effects on Phospholipid Membranes With and Without Cholesterol

In the metadata of the article on SpringerLink the second author’s name is incorrect. The name should read N. Horasan.