Effects of excessive Platycodon grandiflorus root on gut microbiota and host co-metabolism in mice

Abstract

Ethnopharmacological relevance

Platycodon grandiflorus root, is a widely used herb in East Asia for treating respiratory diseases, but research on its oral safety is limited.

Aim of the study

This study examines the potential adverse gastrointestinal reactions resulting from excessive consumption of Platycodon grandiflorus root (PR) and its effects on gut microbiota and host co-metabolism.

Materials and methods

This study evaluated the effects of different doses (1.5, 4.5, and 7.5 g/kg/day) of PR on ICR mice through gavage. Select the 7.5 g/kg/day dosage group and the control group to assess intestinal morphology and conduct histopathological studies. Examine inflammation-related factors and tight junction proteins using WB, qPCR, and ELISA. Additionally, perform 16S rDNA sequencing and metabolomic analyses to evaluate changes in gut microbiota and endogenous metabolites. Finally, the clearance of gut microbiota with antibiotics, the effects of excessive PR on mice were investigated.

Results

Excessive intake of PR can lead to mortality in mice, as well as symptoms such as intestinal flatulence and slowed intestinal transit, suggesting the occurrence of chronic intestinal pseudo-obstruction accompanied by endotoxemia. It altered both α-diversity and β-diversity in the gut microbiota of mice, with increased relative abundances of Pseudomonadota, Verrucomicrobiota, Escherichia-Shigella, Akkermansia, Bacteroides, and Klebsiella, closely linked to intestinal obstruction and bacterial overgrowth. Excessive intake of PR also resulted in metabolic disturbances in mice, particularly in the levels of metabolites such as bate-hydroxybutyrate, 5,6-dihydrouracil, uridine, isoleucine, mannitol, bate-alanine, L-cysteine, L-tyrosine, and orotic acid, which may provide insights into the side effects associated with excessive consumption of PR. Clearing the gut microbiota significantly mitigated adverse effects on the intestines and restored metabolite levels.

Conclusions

This study demonstrates that excessive PR induces gut microbiota and metabolic disruption in normal mice, with the overgrowth of Gram-negative bacteria releasing LPS that impair smooth muscle contraction, leading to adverse effects such as chronic intestinal pseudo-obstruction.