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    The effect of alpha lipoic acid on hydrogen peroxide-induced lipid peroxidation in rat liver homogenates
    (Turkish Biochem Soc, 2014) Yapar, Suleyman Bedir; Eskiocak, Sevgi
    Objective: It is known that oxidant species play a role in the pathogenesis of certain diseases such as diabetes mellitus, atherosclerosis, cataract and hepatic cirrhosis. Therefore, the use of antioxidant species for therapeutic purposes has risen up in the recent years. The aim of the study was to investigate the different concentrations of alpha lipoic acid on the induced lipid peroxidation and tissue glutathione level in rat liver homogenates. Methods: Hydrogen peroxide (15 mM) has been used for induction of lipid peroxidation at liver homogenates. The experimental setups induced by lipid peroxidation have been divided into four sub-groups. Alpha lipoic acid was added in 0, 2, 4 and 8 mM concentrations into those groups, respectively. The malondialdehyde levels which is the end product of lipid peroxidation and the levels of tissue glutathione have been determined. Results: The level of malondialdehyde in the activation groups has been found to be significantly higher than to the control group. The levels of malondialdehyde in the all alpha lipoic acid groups have been found to be significantly lower than the activation group. The level of glutathione in the activation group has been detected significantly lower when it was compared to the control group. The levels of glutathione in the all alpha lipoic acid groups have been found to be significantly higher from the activation group. When the time-dependent change in the level of glutathione was investigated it was observed that these initially decrease and then started to increase. In the groups of 4 and 8 mM, this level was even over from the starting point. Conclusion: In conclusion, our findings suggest that lipid peroxidation is induced in the experimental setups where hydrogen peroxide are applied. The reason of significantly lower malondialdehyde and higher glutathione levels in alpha lipoic acid group than activation groups may be a result of the antioxidant property of alpha lipoic acid.
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    An interference study of the copper-induced plasma oxidizability test
    (Pergamon-Elsevier Science Ltd, 2009) Eskiocak, Sevgi; Ege, Turan; Yapar, Suleyman Bedir; Kaya, Sabriye; Sayilan, Gulben
    Objectives: The aim of this Study is to investigate the effect of cristaloid cardioplegic fluid (CCF) and its contents on the susceptibility of plasma to copper-catalyzed lipid peroxidation test. Design and methods: The plasma pool was divided into eight groups. Equal volumes of CCF or one of its contents were added to each group of the plasma pool. The accumulation of conjugated diene (CD) by copper-induced oxidation was monitored for a period of 5 h. Thiobarbituric acid-reactive Substances (TBARS) formed during the incubation of plasma with copper was also measured. Results: It was found that, the production of CD and TBARS were inhibited and the lag time had increased, when the plasma was mixed with CCF or its contents. Conclusions: As a result, we conclude that that the susceptibility of plasma to copper-induced lipid peroxidation is interfered by CCF. The chloride ions, which major content of CCF, may play an important role on this effect. (C) 2009 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.