Hydrolyzed Fumonisin B1

An accurate, reliable, and specific method was developed for the quantitative determination of fumonisins B1, B2, B3, and their hydrolyzed metabolites, HFB1, HFB2, and HFB3, in broiler chicken feed and excreta using ultra-performance liquid chromatography combined with tandem mass spectrometry (UPLC-MS/MS). The samples were extracted and diluted for the determination of parent fumonisins. Another portion of the extracted samples was alkaline-hydrolyzed and cleaned using a strong anionic exchange adsorbent (MAX) for the determination of hydrolyzed fumonisins. Chromatographic separation was performed on a CORTECS C18 column (2.1 mm × 100 mm, 1.6 μm) using 0.2% formic acid aqueous solution and methanol with 0.2% formic acid as the mobile phase under gradient elution. The six fumonisins, FB1, FB2, FB3, HFB1, HFB2, and HFB3, were analyzed by tandem mass spectrometry using multiple-reaction monitoring (MRM) mode. The six fumonisins showed good linearity, with relative coefficients of r > 0.99. The limits of quantitation (LOQs) were 160 μg/kg. At the low, medium, and high spiked levels, the recovery of fumonisins in chicken feed and excreta ranged from 82.6 to 115.8%, with a precision (RSD) of 3.9-18.9%. This method was successfully applied to investigate the migration and transformation of fumonisins in broiler chickens.

Fumonisins are mycotoxins produced by Fusarium fujikuroi species complex that may contaminate food and feed threatening human and animal health. Among the fumonisins group, fumonisin B1 is the most widespread and best characterized in terms of toxicity, while additional toxicological data on its congeners, such as N-acylated and hydrolyzed forms, need to be collected to support the group-based risk assessment. The inhibition of ceramide synthase has been identified as the key molecular mechanism of fumonisins toxicity resulting in modifications of sphingolipids rheostat. However, the existence of ancillary mechanisms and biological targets are likely to occur given the growing number of evidence reporting the multitarget mechanisms of mycotoxins toxicity. Therefore, in the framework of the early warning analysis of multitarget toxicity of fumonisins group, the present study aimed at searching potential targets for future hazard characterization studies of fumonisin B1 and its hydrolyzed and N-acetylated forms. In particular, on the basis of structural analogies with known inhibitors, the molecular interaction between N-acylated and hydrolyzed forms of fumonisin B1 and either ceramide transfer protein or sphingosine kinase I was assessed with a molecular modeling study. Our results pointed out that the molecular features of N-acylated hydrolyzed fumonisin B1 and hydrolyzed fumonisin B1 may allow the interaction with the ceramide transfer protein and with the sphingosine kinase I enzyme, respectively. Overall, our results identified such proteins as relevant targets that might take part in fumonisins group toxicity, adding plausible mechanistic insights to better understand fumonisins toxicity. Moreover, possible divergences in the mechanisms of action of fumonisin B1 and its modified forms were identified pointing out the need to assess their relevance with high priority to enhance the understanding of group toxicity.

A colorimetric method was developed for the determination of the mold toxin fumonisin B1 (FB1). It is based on the aggregation of cysteamine-capped gold nanoparticles (Cys-AuNPs). The assay involves alkaline hydrolysis of FB1 to obtain hydrolyzed fumonisin B1 (HFB1). The latter induces the aggregation of Cys-AuNPs which results in a color change from wine-red to blue-gray, best at a pH value of 9.0. A plot of absorbance ratio at 645/520 nm versus FB1 concentration is linear in the 2-8 μg kg-1 FB1 concentration range, and the detection limit is 0.90 μg kg-1. Inter-day and intra-day precisions are <6.2%, and recoveries from spiked samples ranged from 93 to 99%. The assay was successfully applied to the determination of FB1 in corn samples. It has a high selectivity over other competitive mycotoxins including aflatoxin, zearalenone, citrinin and patulin. The method is more selective than the detection of FB1 directly which may lead to false-positive errors. Graphical abstract Schematic representation of colorimetric assay of fumonisin B1 (FB1). FB1 was alkali-hydrolyzed and its product (hydrolyzed fumonisin B1) induces cysteamine-capped gold nanoparticles (Cys-AuNPs) via hydrogen bondings. The aggregation of Cys-AuNPs causes changes in color from wine-red to blue-gray.