FREE RADICAL-MEDIATED LIPID-PEROXIDATION INDUCED BY T-2 TOXIN IN YEAST (KLUYVEROMYCES-MARXIANUS)

Lipid peroxidation may be one of the main manifestations of cellular d amage in the toxicity of several mycotoxins. A species of yeast, Kluyv eromyces marxianus, was used in this study to determine the oxidative damage induced by T-2 toxin (T-2), Malondialdehyde (MDA), produced fro m the decomposition of lipid peroxides, was monitored using the thioba rbituric acid reaction. The yeast show a high sensitivity to T-2 becau se the addition of 25 ng T-2/mL medium greatly reduced the multiplicat ion rate of yeast. In addition, the MDA content increased when the con centration of T-2 was increased in the growth medium. Preincubation of the yeast with linoleic and linolenic acids in the medium enhanced th e effects of T-2. The addition of the antioxidant dl-alpha-tocopheral acetate completely quenched the effects of T-2 whereas ascorbic acid a nd reduced glutathione (GSH) acted as prooxidants in this system. Elec tron paramagnetic resonance (EPR) spin trapping technique using lipid soluble N-tert-butyl-alpha-phenylnitrone (PBN) or more water soluble a lpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN) as free radical spin traps showed that free radical production was promoted by T-2. Vi tamin E effectively quenched the EPR signals of the spin adducts. The observed spin adduct hyperfine splitting constants were consistent wit h those of alpha-hydroxyethyl radicals. The spin trapping data strongl y suggest that initially generated hydroxyl radicals react with ethano l that is present in the samples, and the alpha-hydroxyethyl radical f ormed in this process are then trapped These data demonstrate that T-2 stimulates lipid peroxidation in a biological system due to an increa sed generation of hydroxyl radicals. (J. Nutr. Biochem. 9:370-379, 199 8) (C) Elsevier Science Inc, 1998.