The Effect of Gut Microbiome Perturbation on the Bioavailability of Glycyrrhizic Acid in Rats

<b>Background</b>: Oral administration remains the most common route for drug absorption. Emerging evidence highlights the important role of gut microbiome in the pharmacokinetics of oral medications. Glycyrrhizic acid (GL), a widely used hepatoprotective drug, is orally administrated and subsequently biotransformed by the gut microbiota into its active metabolite, glycyrrhetinic acid (GA), which exerts a therapeutic effect. However, it remains unclear whether the disturbance of the gut microbiome directly impacts the metabolism of GL. <b>Methods</b>: Antibiotic cocktail and probiotic <i>Lacticaseibacillus rhamnosus</i> R0011 were applied as two interventions targeting the gut microbiome. Pharmacokinetic parameters were evaluated by LC-MS, and 16S rRNA sequencing was applied to analyze the gut microbiome composition. The transcriptome analysis of Caco-2 cells was used to elucidate the regulation mechanism of polar metabolites resulting from gut microbiome perturbation. <b>Results</b>: R0011 supplementation could significantly increase the Area Under Curve (AUC) value of GA, which was positively correlated with the change in gut microbiome composition. In contrast, the plasma levels of GA were nearly undetectable following antibiotic intervention. Furthermore, the relative expressions of transporter multidrug resistance gene 1 (MDR1) in the ileum were site specifically downregulated under the probiotic intervention. The polar gut microbial metabolites may play a crucial role in differentiated regulating MDR1 expression, likely through the modulation of transcription factors FoxO1 and TP53. <b>Conclusions</b>: Our research provides new insights into the regulatory mechanism by which the gut microbiome affects the bioabsorption of orally administrated drugs, potentially offering strategies to optimize drug bioavailability and improve clinical efficacy.