Gut Microbiota, a Potential Mediated Target for Reducing Geniposide Hepatotoxicity by Interacting with Isoflavones

• Clarifying the interplay of gut microbiota, enzyme and geniposide metabolism. • Unearthing the role of Lactobacillus spp. in alleviating drug-induced liver injury. • Clinical study on the regulatory role of isoflavone-rich diets on Lactobacillus. Geniposide, the principal active iridoid glucoside ingredient in Fructus gardeniae used in numerous traditional Chinese clinical prescriptions, has been shown to cause herbal hepatotoxicity because of its glycone metabolite genipin. This study explored the role of gut microbiota in alleviating geniposide hepatotoxicity with isoflavones in soy products. Metabolic profiling using ultra high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q/TOF-MS) revealed two metabolic pathways and six main forms of geniposides in vivo . Enzyme inhibitor experiments have shown that isoflavones alter geniposide metabolism by mediating specific enzymes, including β-glucosidase (β-GC) and sulfotransferase (SULT), in an established pseudo-sterile rat model. Isoflavones pretreatment by gavage for three weeks optimized the structure of the gut microbiota was linked to the regulation of key metabolic enzymes. Furthermore, experiments involving fecal microbiota transplantation (FMT) established the direct contribution of the gut microbiota to the regulation of enzyme activities and geniposide metabolism. This study demonstrated that isoflavones in soy products regulated the metabolic enzymes of geniposode dependent on gut microbiota, especially Lactobacillus spp., which was further verified in our clinical trials analyzed using 16S ribosomal RNA (rRNA) and metagenomic sequencing, thus regulating geniposide metabolism. Furthermore, as dominant beneficial bacterium, Lactobacillus spp. were discovered to be promising microbial targets for the better management of geniposide hepatotoxicity. These findings provide valuable insights for the prevention and intervention of drug-induced liver injury.