Investigation on Patulin biotransformation in Zebrafish and its toxicological function evaluation

Patulin (PAT) is a mycotoxin that poses a significant health risk to both humans and animals. However, knowledge regarding its in vivo biotransformation and toxicological effects remains limited. In this study, zebrafish were exposed to a lethal dose of PAT for 24 h. Metabolite profiles in the intestine and liver were analyzed using UHPLC-Q-Orbitrap-HRMS, and toxicological effects were evaluated via histopathological examination, oxidative stress assays, RT-qPCR of target genes, and 16 S rRNA sequencing of the gut microbiota. The key results are as follows: (1) In addition to forming PAT-GSH adducts in the liver, zebrafish can metabolize PAT into ascladiol and hydroascladiol in the intestine, with distinct tissue-specific distribution. The gut bacterium Lactobacillus may play a crucial role in this conversion process. (2) Quantitative analysis revealed that the levels of ascladiol and hydroascladiol peaked during the initial exposure stage and then declined sharply, followed by a rapid increase in PAT-GSH adduct accumulation. (3) PAT exposure also induced tissue inflammation, oxidative stress, upregulation of pro-inflammatory factors, and gut microbiota dysbiosis. Importantly, the severity of adverse effects in the intestine and liver was directly correlated with both the distribution of non-toxic metabolites (ascladiol and hydroascladiol) and the accumulation of PAT-GSH adducts. We hypothesize that the intestine acts as an initial defense barrier against PAT, but with prolonged exposure, disruption of the gut microbiota impairs this detoxification process. Consequently, excess unmetabolized PAT enters the liver via enterohepatic circulation, triggering hepatic inflammation and oxidative damage. These findings provide new insights into the in vivo modulation of PAT toxicity.