Betulinic acid from Inonotus obliquus ameliorates T2DM by modulating short-chain fatty acids producing bacteria and amino acids metabolism in db/db mice.

ETHNOPHARMACOLOGICAL RELEVANCE

Inonotus obliquus has also been used as a traditional folk medicine in Europe and Northeastern China to treat metabolic diseases. Betulinic acid (BA) is a major ingredient with anti-diabetic property derived from I. obliquus, however, its bioavailability is limited. Whether the beneficial effects of BA on type 2 diabetic mellitus (T2DM) referring to modulation of gut microbiota and associated metabolites remain unclear.

AIM OF THE STUDY

This work aims to investigate the alleviating effect of BA on T2DM in db/db mice and elucidate the mechanism from perspective of network pharmacology, gut microbiome and fecal metabolome.

MATERIALS AND METHODS

BA was orally administered to db/db mice for 45 days, and the related biochemical parameters were evaluated. The associated mechanism was explored using network pharmacology analysis, 16S rRNA sequencing and UHPLC-MS metabolomics comprehensively. Additionally, Spearman analysis was performed to assess the correlation between gut microbes, metabolites, and T2DM-related biochemical parameters.

RESULTS

BA ameliorated T2DM symptoms by reducing body weight gain, regulating serum glucose and lipid levels, and mitigating T2DM-associated liver injury in db/db mice. Network pharmacology analysis indicated the ameliorative effect was via targeting at PPAR activity. BA intervention increased the relative abundance of short-chain fatty acids (SCFAs) producing bacteria including Lactobacillus and Eubacterium_xylanophilum group, and enhanced the production of SCFAs. Moreover, BA primarily regulates arginine and proline metabolism, D-glutamine and D-glutamate metabolism, and alanine, aspartate and glutamate metabolism. Spearman analysis indicated a negative correlation between SCFAs-producing bacteria and amino acids, as well as serum glucose and lipid levels.

CONCLUSION

Apart from PPAR signaling pathway, BA modulated gut microbiota composition and associated metabolites in db/db mice. This study provided novel insights into the therapeutic potential of BA for alleviating T2DM symptoms.