Deoxynivalenol-sulfates: identification and quantification of novel conjugated (masked) mycotoxins in wheat

Abstract

We report the identification of deoxynivalenol-3-sulfate and deoxynivalenol-15-sulfate as two novel metabolites of the trichothecene mycotoxin deoxynivalenol in wheat. Wheat ears which were either artificially infected with Fusarium graminearum or directly treated with the major Fusarium toxin deoxynivalenol (DON) were sampled 96 h after treatment. Reference standards, which have been chemically synthesized and confirmed by NMR, were used to establish a liquid chromatography-electrospray ionization (LC-ESI)-MS/MS-based “dilute and shoot” method for the detection, unambiguous identification, and quantification of both sulfate conjugates in wheat extracts. Using this approach, detection limits of 0.003 mg/kg for deoxynivalenol-3-sulfate and 0.002 mg/kg for deoxynivalenol-15-sulfate were achieved. Matrix-matched calibration was used for the quantification of DON-sulfates in the investigated samples. In DON-treated samples, DON-3-sulfate was detected in the range of 0.29–1.4 mg/kg fresh weight while DON-15-sulfate concentrations were significantly lower (range 0.015–0.061 mg/kg fresh weight). In Fusarium-infected wheat samples, DON-3-sulfate was the only detected sulfate conjugate (range 0.022–0.059 mg/kg fresh weight). These results clearly demonstrate the potential of wheat to form sulfate conjugates of DON. In order to test whether sulfation is a detoxification reaction in planta, we determined the ability of the sulfated DON derivatives to inhibit in vitro protein synthesis of wheat ribosomes. The results demonstrate that both DON-sulfates can be regarded as detoxification products. DON-15-sulfate was about 44× less inhibitory than the native toxin, and no toxicity was observed for DON-3-sulfate in the tested range.Graphical abstractᅟElectronic supplementary materialThe online version of this article (doi:10.1007/s00216-014-8340-4) contains supplementary material, which is available to authorized users.

Detoxification of Deoxynivalenol via Glycosylation Represents Novel Insights on Antagonistic Activities of Trichoderma when Confronted with Fusarium graminearum

“…The details about the endogenous self-protection mechanism against DON in Trichoderma strains needs further investigation and interpretation after the detoxification UGT genes from Trichoderma are identified. On the other hand, other detoxification products of DON have been identified in plant detoxification processes, such as DON-sulfates, DON-15-glucoside, and DON-glutathione [25,40,41]. Seeking and identifying other modified mycotoxins generated from Trichoderma and Fusarium are also essential to reveal the mycotoxin detoxification mechanism of Trichoderma .…”

Breeding strategies and advances in line selection for Fusarium head blight resistance in wheat

“…Several conjugated forms of DON such as DON-3-glucoside (Poppenberger et al 2003) and DON sulfates (Warth et al 2015), but also of zearalenone and fumonisins have been identified to date (De Saeger and Van Egmond 2012;Berthiller et al 2013).…”

Nucleophilic Addition of Thiols to Deoxynivalenol

“…Several DON derivatives have been identified as DON-sulfonates, 4,5 DONsulfates, 6 or DON−glutathione conjugates. 3,7 Glutathione (GSH) is a natural tripeptide containing cysteine and possesses a free thiol (−SH) group that behaves both as a nucleophile and as a reducing agent.…”