Phosphorylation of Zearalenone retains its toxicity

Microbial biotransformation of Zearalenone (ZEN) is a promising deactivation approach. The residual toxicity and stability of Zearalenone-14-phosphate (ZEN-14-P) and Zearalenone-16-phosphate (ZEN-16-P), two novel microbial phosphorylation products of ZEN, remain unknown. We investigated the cytotoxicity, oxidative stress, pro-inflammatory, and estrogenic activity of phosphorylated ZENs using porcine intestinal cells and uterine explants, and human endometrial cells, and traced their metabolic fate by LC-MS/MS analysis. The phosphorylated ZENs significantly decreased the viability of IPEC-J2 and Ishikawa cells. Similar to ZEN, phosphorylation products induced significant oxidative stress, activated the expression of pro-inflammatory cytokines, and demonstrated estrogenic activity through upregulation of estrogen- responsive genes, activation of alkaline phosphatase and proliferation of endometrial glands. LC-MS/MS analysis pointed that although phosphorylated ZENs are partially hydrolyzed to ZEN, their respective metabolic pathways differ. We conclude that phosphorylation might not be sufficient to detoxify ZEN, leaving its cytotoxic, pro-inflammatory and estrogenic properties intact.