Study of the chemical reduction of the fumonisins toxicity using allyl, benzyl and phenyl isothiocyanate in model solution and in food products

Abstract

Fumonisins (FBs) are bioactive compounds produced by several strains of Fusarium spp. which contain a polyketide structure similar to sphinganine. These mycotoxins contain a free amino group that could work as an electron donor and react with the electrophile carbon present within the isothiocyanate (ITC) group. The objective of this study was to determine the effect of ITCs (allyl, benzyl and phenyl) on the stability of FB(1), FB(2) and FB(3). Firstly, PBS solutions at three pH levels (4, 7 and 9) were prepared and added with pairs of one FB (1 mg/L) plus one ITC (1 mg/L). Then, gaseous ITC was used to fumigate corn kernels and corn flour contaminated with FBs produced by Gibberella moniliformis CECT 2987 in situ. Mycotoxin levels were evaluated using liquid chromatography coupled to mass spectrometry in tandem (LC-MS/MS), while products formed from the reaction of FBs and ITCs were examined by liquid chromatography coupled to mass spectrometry-linear ion trap (LC-MS-LIT). The reduction of FB(1) and FB(2) in solution ranged from 42 to 100% on a time-dependent manner. This variance was greatly influenced by pH. In general, lower pH levels eased the reaction between ITCs and FBs. ITC fumigation treatment (50, 100 and 500 μL/L) was able to reduce 53-96% of FB(1) levels, 29-91% of FB(2) and 29-96% of FB(3). Four reaction products between the bioactive compounds employed in this study were identified, corresponding to FB + ITC conjugates.