EFFECTS OF FUMONISIN B-1 ON LIPID-PEROXIDATION IN MEMBRANES

Electron spin resonance (ESR)(1) spill-label oximetry and spin trappin g techniques have been used to study the effect of fumonisin B-1 (FB1) , an amphipathic mycotoxin on lipid peroxidation in egg yolk phosphati dylcholine (EYPC) bilayers. In the study of the interaction between FB 1 and lipid bilayers our results show that fumonisin disturbs the orde ring of membranes, enhances oxygen transport in membranes, and also in creases membrane permeability. In our model system, lipid peroxidation s were initiated by extended incubation of the liposomes, or by induci ng Fr2+ ions, UV illumination of H2O2 or ultrasound irradiation. As an indication of the rates of lipid oxidation in EYPC, the consumption o f molecular oxygen was studied by monitoring the oxygen concentration in the aqueous phases of the liposomes. Lipid-derived free radicals ge nerated during the oxidation process were measured by a spin trapping method. The incorporation of FB1 in the test samples made the membrane s highly susceptible to oxidation. Our results provide the first evide nce that the fumonisins appear to increase the rate of oxidation, prom ote the free radical intermediate production and accelerate the chain reactions associated with lipid peroxidation. The disruption of membra ne structure, the enlargement of the relative oxygen diffusion-concent ration products, as well as the enhancement effects on membrane permea bility, thus provide additional insights into potential mechanisms by which the fumonisins could enhance oxidative stress and cell damage. ( C) 1998 Elsevier Science B.V.