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  • Küçük Resim
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    The effects of radioprotectant and potential antioxidant agent amifostine on the structure and dynamics of DPPC and DPPG liposomes
    (Elsevier Science Bv, 2019) Arslan, Gülgün Çakmak; Severcan, Feride
    Agents capable of scavenging ROS have attracted attention recently because of their potential use as anti oxidative agents. Amifostine, a ROS scavenger, has the potential to be used as an antioxidant in therapeutic applications. In this study, the effect of amifostine on neutral zwitterionic dipalmitoylphosphatidylcholine (DPPC) and anionic dipalmitoylphosphatidylglycerol (DPPG) model membranes' structure and dynamics is aimed to be examined by Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). Our results revealed that amifostine at concentrations used (1-24 mol%) does not induce any important alteration in the shape of phase transition curve and phase transition temperature in the DPPC and DPPG membranes. High concentrations of amifostine slightly increased the acyl chain flexibility of DPPC membranes in the liquid crystalline phase and DPPG membranes in the gel phase. A lessening in the dynamics of DPPC liposomes was observed for all concentrations of amifostine in both phases but slight dual effect was observed only in the gel phase as a decrease in dynamics at low concentrations and an increase at higher concentrations of amifostine in DPPG liposomes. Additionally, strong hydrogen bonding was observed for both C=O and PO2- groups in case of DPPC and for PO2- groups in case of DPPG. Dehydration around the C=O regions occurred in case of DPPG. Accordingly, amifostine is proposed to be interacting strongly with zwitterionic and negatively charged membrane head groups and glycerol backbone in all concentrations and because of this interaction it causes some changes in lipid order and dynamics especially at high concentrations.
  • Küçük Resim Yok
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    The investigation of the molecular changes during lipopolysaccharide-induced systemic inflammation on rat hippocampus by using FTIR spectroscopy
    (Wiley-V C H Verlag Gmbh, 2024) Cakmak-Arslan, Gulgun; Kaya, Yildiray; Mamuk, Soner; Akarsu, Eyup Sabri; Severcan, Feride
    The aim of this study is to reveal the molecular changes accompanying the neuronal hyper-excitability during lipopolysaccharide (LPS)-induced systemic inflammation on rat hippocampus using Fourier transform infrared (FTIR) spectroscopy. For this aim, the body temperature of Wistar albino rats administered LPS or saline was recorded by radiotelemetry. The animals were decapitated when their body temperature began to decrease by 0.5 degrees C after LPS treatment and the hippocampi of them were examined by FTIR spectroscopy. The results indicated that systemic inflammation caused lipid peroxidation, an increase in the amounts of lipids, proteins and nucleic acids, a decrease in membrane order, an increase in membrane dynamics and changes in the secondary structure of proteins. Principal component analysis successfully separated control and LPS-treated groups. In conclusion, significant structural, compositional and functional alterations occur in the hippocampus during systemic inflammation and these changes may have specific characteristics which can lead to neuronal hyper-excitability.
  • Küçük Resim
    Öğe
    Structural and functional damages of whole body ionizing radiation on rat brain homogenate membranes and protective effect of amifostine
    (Taylor & Francis Ltd, 2016) Arslan, Gülgün Çakmak; Severcan, Mete; Zorlu, Faruk; Severcan, Feride
    Purpose: To investigate the effects of whole body ionizing radiation at a sublethal dose on rat brain homogenate membranes and the protective effects of amifostine on these systems at molecular level. Materials and methods: Sprague-Dawley rats, in the absence and presence of amifostine, were whole-body irradiated at a single dose of 8Gy and decapitated after 24 h. The brain homogenate membranes of these rats were analyzed using Fourier Transform Infrared (FTIR) spectroscopy. Results: Ionizing radiation caused a significant increase in the lipid to protein ratio and significant decreases in the ratios of olefinic = CH/lipid, CH2/lipid, carbonyl ester/lipid and CH3/lipid suggesting, respectively, a more excessive decrease in the protein content and the degradation of lipids as a result of lipid peroxidation. In addition, radiation changed the secondary structure of proteins and the status of packing of membrane lipid head groups. Furthermore, it caused a decrease in lipid order and an increase in membrane fluidity. The administration of amifostine before ionizing radiation inhibited all the radiation-induced alterations in brain homogenate membranes. Conclusions: The results revealed that whole body ionizing radiation at a sublethal dose causes significant alterations in the structure, composition and dynamics of brain homogenate membranes and amifostine has a protective effect on these membranes.