Hydrolytic fate of deoxynivalenol-3-glucoside during digestion.

Deoxynivalenol-3-β-D-glucoside (D3G), a plant phase II metabolite of the Fusarium mycotoxin deoxynivalenol (DON), occurs in naturally contaminated wheat, maize, oat, barley and products thereof. Although considered as a detoxification product in plants, the toxicity of this substance in mammals is currently unknown. A major concern is the possible hydrolysis of the D3G conjugate back to its toxic precursor mycotoxin DON during mammalian digestion. We used in vitro model systems to investigate the stability of D3G to acidic conditions, hydrolytic enzymes and intestinal bacteria, mimicking different stages of digestion. D3G was found resistant to 0.2 M hydrochloric acid for at least 24 h at 37 °C, suggesting that it will not be hydrolyzed in the stomach of mammals. While human cytosolic β-glucosidase also had no effect, fungal cellulase and cellobiase preparations could cleave a significant portion of D3G. Most importantly, several lactic acid bacteria such as Enterococcus durans, Enterococcus mundtii or Lactobacillus plantarum showed a high capability to hydrolyze D3G. Taken together these data indicate that D3G is of toxicological relevance and should be regarded as a masked mycotoxin.
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