UDP-Glucosyltransferases from Rice, Brachypodium, and Barley: Substrate Specificities and Synthesis of Type A and B Trichothecene-3-O-β-d-glucosides

Trichothecene toxins are confirmed or suspected virulence factors of various plant-pathogenic Fusarium species. Plants can detoxify these to a variable extent by glucosylation, a reaction catalyzed by UDP-glucosyltransferases (UGTs). Due to the unavailability of analytical standards for many trichothecene-glucoconjugates, information on such compounds is limited. Here, the previously identified deoxynivalenol-conjugating UGTs HvUGT13248 (barley), OsUGT79 (rice) and Bradi5g03300 (Brachypodium), were expressed in E. coli, affinity purified, and characterized towards their abilities to glucosylate the most relevant type A and B trichothecenes. HvUGT13248, which prefers nivalenol over deoxynivalenol, is also able to conjugate C-4 acetylated trichothecenes (e.g., T-2 toxin) to some degree while OsUGT79 and Bradi5g03300 are completely inactive with C-4 acetylated derivatives. The type A trichothecenes HT-2 toxin and T-2 triol are the kinetically preferred substrates in the case of HvUGT13248 and Bradi5g03300. We glucosylated several trichothecenes with OsUGT79 (HT-2 toxin, T-2 triol) and HvUGT13248 (T-2 toxin, neosolaniol, 4,15-diacetoxyscirpenol, fusarenon X) in the preparative scale. NMR analysis of the purified glucosides showed that exclusively β-D-glucosides were formed regio-selectively at position C-3-OH of the trichothecenes. These synthesized standards can be used to investigate the occurrence and toxicological properties of these modified mycotoxins.© 2018 by the author

Mycotoxins in beverages: Occurrence, regulation, economic impact and cost-effectiveness of preventive and removal methods

Publisher Copyright: © 2020 Elsevier Inc. All rights reserved.The risk of mycotoxins is a global issue and nowadays there is an increasing concern with their potential effects on human health. Mycotoxins are toxic secondary metabolites produced by filamentous fungi, whose occurrence in beverages is global. Worldwide regulations (with significant emphasis in the EU) are paying special attention to this matter and many beverages have been already affected by regulations establishing maximum levels of mycotoxins. Ochratoxin A, patulin, Alternaria toxins, deoxynivalenol, and aflatoxin M1 are the most commonly mycotoxins found in beverages. All of them have been shown to cause health hazards and are related to significant economic losses in the beverage industry. This chapter provides an overview of the prevalence of mycotoxins, related current global legislation, and their economic impact on beverages. Finally, several actual methods to prevent and remove mycotoxins from beverages are reviewed and a brief analysis about the need to conduct further research about the cost effectiveness of these methods is provided.Peer reviewe