Biotransformation of the mycotoxin enniatin B1 in pigs: A comparative in vitro and in vivo approach

- Tentative identification of ENNB1 biotransformation products from metabolism in liver microsomes of different pig strains.
- Characterisation of putative ENNB1 metabolites using high-resolution and ion trap mass spectrometry.
- The structural determination was supported by chemical derivatisations.
- Kinetics of ENNB1 metabolites in in vitro biotransformation experiments.
- Determination of metabolites in plasma of pigs after single oral or intravenous application of ENNB1.
- Formation and elimination kinetics of ENNB1 metabolites in vivo in pigs.

Enniatins (ENNs) are hexadepsipeptidic mycotoxins produced by Fusarium species. They occur in mg/kg levels in grain from Northern climate areas. Major ENNs such as ENN B and B1 have shown considerable cytotoxicity in different in vitro test systems. To adequately assess exposure and in vivo toxicity the toxicokinetic properties need to be investigated. The present study describes the metabolism of ENN B1 both in vitro and in vivo in pigs, comparing metabolites found in vitro in experiments with liver microsomes from different pig strains to those found in the plasma of pigs after single oral or intravenous application of ENN B1. Metabolites of hepatic biotransformation were tentatively identified and characterised by high performance liquid chromatography coupled to ion trap and high-resolution mass spectrometry, as well as chemical derivatisations. Kinetic parameters of metabolite formation and elimination were determined. Metabolite formation was higher when ENN B1 was absorbed from the gut compared to intravenous administration indicating pre-systemic metabolism of ENN B1 after oral uptake. The in vitro approach resulted in the detection of ten ENN B1 metabolites, while six were detected in in vivo samples. The putative ENN B1 metabolites were products of hydroxylation, carbonylation, carboxylation and oxidative demethylation reactions.

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