Hepatotoxicity Induced by Methyl Eugenol: Insights from Toxicokinetics, Metabolomics, and Gut Microbiota

Due to continuous application as a flavoring agent in the pesticide, pharmaceutical, and food industries, methyl eugenol (ME) persists in the environment and causes deleterious impacts including cytotoxicity, genotoxicity, and liver damage. This study utilized a comprehensive approach, integrating toxicokinetics, metabolomics, and gut microbiota analysis, to explore the mechanisms behind ME-induced hepatotoxicity in mice. The study observed significant rises in ALT and AST levels, along with significant weight loss, indicating severe liver damage. Toxicokinetic data showed delayed Tmax and plasma accumulation after 28 days of repeated ME exposure at doses of 20 mg/kg, 40 mg/kg, and 60 mg/kg. The metabolomic analysis pinpointed four critical pathways-TCA cycle; alanine, aspartate, and glutamate metabolism; arginine biosynthesis; and tyrosine metabolism-linked to 20 potential biomarkers. Gut microbiota analysis revealed that extended ME exposure led to microbial imbalance, particularly altering the populations of Akkermansia, Prevotella, and Ruminococcus, which are key to amino acid metabolism and the TCA cycle, thus contributing to hepatotoxicity. However, the causal relationship between changes in gut microbiota and liver metabolite levels still requires further in-depth research. This study underscores the significant role of liver metabolites and gut microbiota in ME-induced liver damage.