Formation of fumonisin B(1)-glucose reaction product, in vitro cytotoxicity, and lipid peroxidation on kidney cells.

Fumonisin B(1) (FB(1)) content in corn products decreases during the heating process in foods containing reducing sugars, mainly because of the formation of N-(carboxymethyl)fumonisin B(1). In this study, a rapid method has been developed for the determination of both compounds in corn products using a high-speed blender, Ultra-Turrax, for solvent extraction and liquid chromatography-tandem mass spectrometry. The kinetics of FB(1) degradation and the formation of the Maillard adduct were studied in a model system constituted by corn bread spiked with FB(1) and heated at 160, 180, and 200 degrees C for 3, 6, 10, 15, and 20 min. FB(1) decreased from 0.96 to 0.3 mg/kg and N-(carboxymethyl)fumonisin B(1) increased to 0.1 mg/kg. Cytotoxicity and lipid peroxidation were studied in monkey kidney cells (Vero cells). After 24 h exposure, FB(1) revealed an IC(50) (median inhibitory concentration) of 55 +/- 7 microM with neutral red uptake, but no IC(50) was obtained after N-(carboxymethyl)fumonisin B(1) exposure at the studied concentrations. Lipid peroxidation was assessed using the thiobarbituric acid reactive substance (TBARS) method for 90 min and 24 and 48 h. FB(1) significantly increased the production of malondialdehyde in Vero cells exposed to 1 microM FB(1) after 24 h, while malondialdehyde increased after 5 microM N-(carboxymethyl)fumonisin B(1) exposure. These findings showed that the transformation products exhibit lower cytotoxicity than fumonisin B(1) and lipid peroxidation may be involved in the cytotoxicity induced by both toxins.