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Antioxidant and prooxidant effects of α-tocopherol in a linoleic acid-copper(II)-ascorbate system   
Yazarlar
Doç. Dr. Temel Kan BAKIR Doç. Dr. Temel Kan BAKIR
Kastamonu Üniversitesi, Türkiye
Beker Bilge Yıldoğan
İnci Sönmezoğlu
Filiz İmer
Mustafa Reşat Apak
İstanbul Üniversitesi, Türkiye
Özet
The peroxidation of linoleic acid (LA) in the absence and presence of either Cu(II) ions alone or Cu(II)-ascorbate combination was investigated in aerated and incubated emulsions at 37°C and pH 7. LA peroxidation induced by either copper(II) or copper(II)-ascorbic acid system followed pseudo-first order kinetics with respect to primary (hydroperoxides) and secondary (aldehydes- and ketones-like) oxidation products, detected by ferric-thiocyanate and TBARS tests, respectively. α-Tocopherol showed both antioxidant and prooxidant effects depending on concentration and also on the simultaneous presence of Cu(II) and ascorbate. Copper(II)-ascorbate combinations generally led to distinct antioxidant behavior at low concentrations of α-tocopherol and slight prooxidant behavior at high concentrations of α-tocopherol, probably associated with the recycling of tocopherol by ascorbate through reaction with tocopheroxyl radical, while the scavenging effect of α-tocopherol on lipid peroxidation was maintained as long as ascorbate was present. On the other hand, in Cu(II) solutions without ascorbate, the antioxidant behavior of tocopherol required higher concentrations of this compound because there was no ascorbate to regenerate it. Practical applications: Linoleic acid (LA) peroxidation induced by either copper(II) or copper(II)-ascorbic acid system followed pseudo-first order kinetics with respect to primary (hydroperoxides) and secondary (e.g., aldehydes and ketones) oxidation products. α-Tocopherol showed both antioxidant and prooxidant effects depending on concentration and also on the simultaneous presence of Cu(II) and ascorbate. The findings of this study are believed to be useful to better understand the actual role of α-tocopherol in the preservation of heterogenous food samples such as lipid emulsions. Since α-tocopherol (vitamin E) is considered to be physiologically the most important lipid-soluble chain-breaking antioxidant of human cell membranes, the results can be extended to in vivo protection of lipid oxidation. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Anahtar Kelimeler
α-Tocopherol | Copper-initiated prooxidant activity | Hydroperoxides | Linoleic acid peroxidation
Makale Türü Diğer (Teknik, not, yorum, vaka takdimi, editöre mektup, özet, kitap krıtiği, araştırma notu, bilirkişi raporu ve benzeri)
Makale Alt Türü SCI, SSCI, AHCI, SCI-Exp dergilerinde yayımlanan teknik not, editöre mektup, tartışma, vaka takdimi ve özet türünden makale
Dergi Adı European Journal of Lipid Science and Technology
Dergi ISSN 1438-7697
Dergi Tarandığı Indeksler SCI
Makale Dili İngilizce
Basım Tarihi 03-2013
Cilt No 115
Sayı 3
Sayfalar 372 / 376
Doi Numarası 10.1002/ejlt.201200124
Makale Linki http://doi.wiley.com/10.1002/ejlt.201200124