Browsing by Author "Huyut, Zubeyr"

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Radical Scavenging and Antioxidant Activity of Tannic Acid
(Elsevier Science Bv, 2010) Gulcin, Ilhami; Huyut, Zubeyr; Elmastas, Mahfuz; Aboul-Enein, Hassan Y.
Tannic acid, a naturally occurring plant polyphenol, is composed of a central glucose molecule derivatized at its hydroxyl groups with one or more galloyl residues. In the present paper, we examines the in vitro radical scavenging and antioxidant capacity of tannic acid by using different in vitro analytical methodologies such as 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH center dot) scavenging, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, total antioxidant activity determination by ferric thiocyanate, total reducing ability determination using by Fe3+-Fe2+ transformation method, superoxide anion radical scavenging by riboflavin-methionine-illuminate system, hydrogen peroxide scavenging and ferrous ions (Fe2+) chelating activities. Also, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), alpha-tocopherol and trolox, a water-soluble analogue of tocopherol, were used as the reference antioxidant radical scavenger compounds. Tannic acid inhibited 97.7% lipid peroxidation of linoleic acid emulsion at 15 mu g/mL concentration. On the other hand, the above mentioned standard antioxidants indicated an inhibition of 92.2%, 99.6%, 84.6% and 95.6% on peroxidation of linoleic acid emulsion at 45 mu g/mL concentration, respectively. In addition, tannic acid had an effective DPPH? scavenging, ABTS(center dot+) radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, Fe3+ reducing power and metal chelating on ferrous ions activities. Also, those various antioxidant activities were compared to BHA, BHT, alpha-tocopherol and trolox as references antioxidant compounds. The present study shows that tannic acid is the effective natural antioxidant component that can be used as food preservative agents or nutraceuticals. (C) 2009 King Saud University. All rights reserved.
The Susceptibility of Erythrocytes To Oxidation During Storage of Blood: Effects of Melatonin and Propofol
(Pergamon-elsevier Science Ltd, 2012) Sekeroglu, Mehmet Ramazan; Huyut, Zubeyr; Him, Aydin
Objectives: We investigated the effects of melatonin and propofol in lipid peroxidation and antioxidant capacity of erythrocytes in stored bloods. Design and methods: Donated blood was taken into three citrate-phosphate-dextrose containing blood bags. One bag was used as control, the others were added either melatonin or propofol. Erythrocyte lipid peroxidation and antioxidant capacity and their sensitivity to in vitro oxidation were measured on days 0, 7, 14, 21 and 28. Results: In control group, erythrocyte malondialdehyde levels and sensitivity to in vitro oxidation were increased whereas glutathione, glutathione peroxidase and superoxide dismutase levels were decreased. Melatonin prevented malondialdehyde accumulation and preserved glutathione, glutathione peroxidase and superoxide dismutase levels. Propofol preserved glutathione and glutathione peroxidase levels but did not affect catalase and superoxide dismutase activities. Conclusions: We showed that melatonin in stored blood could prevent lipid peroxidation and increase the resistance of erythrocytes to in vitro oxidation while propofol did not show such effects. (C) 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.