Total flavonoids of Potentilla discolor alleviate type 2 diabetes by regulating gut microbiota and endogenous metabolites.

BACKGROUND AND AIMS: Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease with an high incidence rate worldwide. It has recently shown a trend toward affecting younger populations. Total flavonoids from Potentilla discolor Bunge (PB) are associated with antipyretic and antidiarrheal properties. Several studies have also reported that PB exhibits anti-T2DM effects. However, the interactions between PB, T2DM, and gut microbiota, and the underlying mechanisms responsible for PB-mediated regulation of gut microbiota, have not been fully elucidated. This study performed in vitro fermentation, in vivo fecal microbiota transplantation (FMT), and 16S rRNA high-throughput sequencing to determine the mechanism by which PB ameliorates T2DM, with specific focus on its effects on gut microbiota. METHODS: Ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS) was used to analyze the flavonoid components in PB. The db/db mice were used as the T2DM model to assess the therapeutic effects of PB. The relationships between PB, T2DM, and gut microbiota were analyzed by 16S rRNA sequencing technology, in vivo FMT, and in vitro fermentation experiments. Fecal non-targeted metabolomics was also used to elucidate the potential mechanisms. RESULTS: In PB, we identified 41 compounds, including 8 flavonoids, 9 flavonols, and 2 dihydroflavonoids. PB effectively reduced the blood glucose and glycated hemoglobin (GHb) levels (p < 0.05), increased the levels of insulin and glucagon-like peptide-1 (GLP-1) (p < 0.05), and significantly alleviated T2DM-related damage in the liver, kidney, and pancreas in T2DM model mice (p < 0.05). The 16S rRNA sequencing results showed that Firmicutes and Bacteroidetes were the main phyla and Ligilactobacillus, Limosilactobacillus and Prevotellaceae-UCG were the key bacterial genera in the T2DM mice. Fecal non-targeted metabolomics results identified 15 differential metabolites between control, T2DM, and PB-treated T2DM mice. Metabolites such as isoindoline, ethyl 2-aminobenzoate, L-tyrosine, argininic acid, glutamine, dodecylbenzene, 1-octene, 2,3-pentanedione, benzohydrazide, maslinic acid 3-O-β-D-glucoside and 1-pentanol were significantly upregulated in the T2DM model group, whereas high-dose PB treatment (HPB) effectively reversed these effects and restored their composition to a normal range. CONCLUSION: The present study demonstrates that PB contains several flavonoid components, which ameliorate glucose metabolism and alleviate organ injury in T2DM mice by restoring gut microbiota homeostasis. Furthermore, identification of 15 differential metabolites by fecal metabolomics provides important information for further in-depth mechanistic research.