Structural elucidation and analysis of thermal degradation products of theFusarium mycotoxin nivalenol

Abstract

The major class of mycotoxins produced by Fusarium moulds are trichothecenes, a large group of sesquiterpenes sharing the same basic chemical structure, a 12,13-epoxytrichothec-9-ene ring system. Their toxic effects range from causing diarrhoea, vomiting and gastro-intestinal inflammation to noncompetitive inhibition of the biosynthesis of proteins in eukaryotic cells. Trichothecenes in general are relatively stable compounds, their degradation is observed only at high temperatures and prolonged heating time. In order to investigate the stability of the trichothecene nivalenol (NIV) under food processing conditions such as cooking or baking, we performed model heating experiments and screened the residue for degradation products using gas chromatography-mass spectrometry (GC-MS). Heating of nivalenol, especially under mild alkaline conditions, gave a mixture of four compounds (norNIV A, norNIV B, norNIV C, and NIV lactone), which where isolated and identified by nuclear magnetic resonance (NMR) and MS experiments. Although their formation was also demonstrated in heating experiments with spiked flour samples, only norNIV B was detectable in a screening of several commercially available samples, possibly due to the very low contamination with nivalenol. Furthermore, cell culture experiments using immortalized human kidney epithelial (IHKE) cells showed that the four compounds are less cytotoxic (formazan dye cytotoxicity assay) compared to nivalenol. Whereas nivalenol revealed an EC50 at 0.9 micromol, all other compounds did not show any significant effect up to 100 micromol.

Influence of the heat treatment on the degradation of the minor Fusarium mycotoxin beauvericin

“…The authors evidenced at the end of the heat treatments used, a mean OTA degradation of 69%, with a range of variation variable from 50 to 96%. Bretz, Knecht, Geockler, and Humpf (2005) investigated the stability of the trichothecene nivalenol (NIV) under food-processing conditions such as cooking or baking, using the technique of the gas chromatographyemass spectrometry (GCeMS).…”

“…The degradation of the Fusarium toxin nivalenol (NIV) during the baking and cooking process was studied by Bretz, Knecht, Geockler, and Humpf (2005). The authors observed under all the conditions employed a degradation of NIV, accelerated with the increase of the temperatures used during the heat treatments.…”

Technological properties of durum wheat semolina treated by heating and UV irradiation for reduction of mycotoxin content

“…The application of UVC irradiation for 15 min was sufficient to completely degrade AFB 1 , OTA, and FB 2 , while for NIV, reductions in It is worth noting that, as for ENB, current European legislation does not place limits on NIV contamination in foodstuffs, despite the reporting of toxic effects (Minervini, Fornelli, & Flynn, 2004), and that the issue of NIV contamination has been understood for some time (Bretz, Knecht, Göckler, & Humpf, 2005). Moreover, the combined effect of mycotoxins may result in a greater toxicity than that found for individual compounds (Tammer, Lehmann, Nieber, & Altenburger, 2007).…”

Cytotoxic and antimitotic effects of N‐containing Monascus metabolites studied using immortalized human kidney epithelial cells

“…Photometrical determination of the cytotoxicity was determined using the CCK8 assay (Dojindo Laboratories, Tokyo, Japan) as described in [14]. Results are presented as mean values from three replicate experiments with different passages enclosing ten wells each.…”