Free radical-mediated lipid peroxidation induced by T-2 toxin in yeast ( Kluyveromyces marxianus)

Abstract

Lipid peroxidation may be one of the main manifestations of cellular damage in the toxicity of several mycotoxins. A species of yeast, Kluyveromyces marxianus, was used in this study to determine the oxidative damage induced by T-2 toxin (T-2). Malondialdehyde (MDA), produced from the decomposition of lipid peroxides, was monitored using the thiobarbituric acid reaction. The yeast showed a high sensitivity to T-2 because the addition of 25 ng T-2/mL medium greatly reduced the multiplication rate of yeast. In addition, the MDA content increased when the concentration of T-2 was increased in the growth medium. Preincubation of the yeast with linoleic and linolenic acids in the medium enhanced the effects of T-2. The addition of the antioxidant dl-α-tocopherol acetate completely quenched the effects of T-2 whereas ascorbic acid and reduced glutathione (GSH) acted as prooxidants in this system. Electron paramagnetic resonance (EPR) spin trapping technique using lipid soluble N- tert-butyl-α-phenylnitrone (PBN) or more water soluble α-(4-pyridyl-1-oxide)-N- tert-butylnitrone (4-POBN) as free radical spin traps showed that free radical production was promoted by T-2. Vitamin E effectively quenched the EPR signals of the spin adducts. The observed spin adduct hyperfine splitting constants were consistent with those of α-hydroxyethyl radicals. The spin trapping data strongly suggest that initially generated hydroxyl radicals react with ethanol that is present in the samples, and the α-hydroxyethyl radicals formed in this process are then trapped. These data demonstrate that T-2 stimulates lipid peroxidation in a biological system due to an increased generation of hydroxyl radicals.