Bidirectional interactions between St. John´s wort and gut microbiome: Potential implications on gut-brain-axis.

Area of Science:

• Microbiology
• Pharmacology
• Neuroscience

Background:

• Emerging evidence links gut microbiome alterations to mental health disorders like depression.
• The potential role of the microbiome-gut-brain axis in mediating antidepressant effects is under investigation.

Purpose of the Study:

• To investigate if St. John's wort extract (STW 3-VI) interacts with the gut microbiome.
• To explore the microbiome-gut-brain axis as a potential mechanism for STW 3-VI's antidepressant effects.

Main Methods:

• Simulated in vitro digestion of STW 3-VI followed by ex vivo incubation with human fecal microbiota from ten healthy volunteers.
• Analysis of chemical profile changes in the extract and alterations in gut microbiome composition and function.
• Differential abundance and functional profiling of microbial taxa and metabolic pathways.

Main Results:

• Gut microbiota biotransformed flavonoids and hypericins in STW 3-VI, forming metabolites involved in gut-brain communication.
• Significant changes in microbiome composition were observed, including an increase in the Firmicutes/Bacteroidetes ratio.
• Modulation of microbial pathways related to tyrosine and tryptophan metabolism, crucial for gut-brain communication.

Conclusions:

• St. John's wort extract undergoes significant biotransformation by gut microbiota.
• These interactions suggest the gut microbiome may mediate the pharmacological effects of St. John's wort via the microbiome-gut-brain axis.