In-depth study of zearalenone degradation by Ery 4 laccase-mediator systems: in vitro efficacy, mechanistic insights, and application to contaminated corn

Laccases are promising enzymes for zearalenone (ZEN) degradation, especially when used with redox mediators in Laccase Mediator Systems (LMSs). Ery4 laccase and three mediators, 2,2′-azino-bis (3-ethylbenzothiazoline-6- sulfonic acid) (ABTS), 2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO), and acetosyringone (AS), were tested for ZEN removal in vitro and in naturally contaminated corn. All mediators enabled complete ZEN degradation, with AS 1 mM and 1 U/mL Ery4 in only ten minutes. ZEN was reduced by 55.3 % in corn flour. By High-resolution mass spectrometry and Density Functional Theory (DFT) three major degradation products were identified: an oxidation product (14-hydroxyZENquinone), and for the first time, two AS- ZEN coupling products (AS-ZEN and AS-hydroxyZEN). In silico prediction revealed that 14-hydroxyZENquinone and AS-ZEN may possess lower estrogenic potential, indicating LMS as a safe detoxification strategy in food systems. These findings offer key insights into LMS for ZEN degradation and the underlying degradation pathway, thereby advancing its potential application in food safety strategies.