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Updated: Jun 2, 2026

Mass Spectrometry and Luminogenic-based Approaches to Characterize Phase I Metabolic Competency of In Vitro Cell Cultures
Published on: March 28, 2017
In vitro phase I metabolism of the depsipeptide enniatin B
Lada Ivanova1, Christiane Kruse Faeste, Silvio Uhlig
1Section for Chemistry and Toxicology, Norwegian Veterinary Institute, Sentrum, Oslo, Norway.
Abstract:
The enniatins are a group of more than 20 cyclic depsipeptides from fungi with numerous biological effects. Enniatin B is commonly one of the principal analogues in species of the genus Fusarium, known to have ionophoric, antibiotic and insecticidal activity. In the present study, enniatin B was incubated with rat, dog and human liver microsomes. The compound was extensively metabolised, and 12 biotransformation products (M1-M12) were detected and their structures tentatively identified using a combination of mass spectrometric techniques and chemical derivatisation. Ion trap mass spectrometry, multiple-stage MS(n) fragmentation and high-resolution mass spectrometry were the instrumental backbone for structural determination, while acetylation, methylation and Jones oxidation were useful derivatisation techniques for the localisation of the site of biotransformation. Comparison of mass spectrometric data of the metabolism products with that of enniatin B suggested that M1-M5 are monohydroxylated species, while M8-M12 are the result of multiple oxidations (oxygenation and dehydrogenation). Metabolites M6 and M7 appeared to be enniatin B homologues and are the result of N-demethylation. Our findings show that oxidation and N-demethylation are the principal metabolic pathways in enniatin B phase I metabolism.
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