Examining gut microbiota and metabolites to clarify mechanisms of Dimocarpus longan Lour leaf components against type 2 diabetes.

BACKGROUND: Dimocarpus longan Lour leaf components (DLC) contain key active compounds such as quercetin, kaempferol, and quercitrin. They are effective for managing type 2 diabetes mellitus (T2DM), though the exact mechanism by which DLC acts remains unclear. AIM: To investigate the material basis and mechanism underlying the therapeutic effect of DLC in T2DM. METHODS: T2DM was triggered in rats using a high-sugar, high-fat diet alongside 35 mg/kg streptozotocin. The effect of DLC on the intestinal microbiota in T2DM rats was analyzed via 16S rDNA sequencing. Targeted metabolomics was conducted to evaluate the impact of DLC on the levels of nine short-chain fatty acids (SCFAs). Untargeted metabolomics examined DLC-induced alterations in fecal metabolites and associated metabolic pathways. Additionally, Spearman's correlation analysis assessed gut microbiota and fecal metabolite relationships. RESULTS: DLC significantly attenuated pathological weight loss, reduced fasting blood glucose levels, restored blood sugar homeostasis, and ameliorated dyslipidemia in T2DM rats. The 16S rDNA sequencing revealed that DLC enhanced microbial diversity and reversed intestinal dysbiosis. Targeted metabolomics indicated decreased acetic acid and propionic acid levels and increased butyric acid, isobutyric acid, and 2-methylbutyric acid levels after DLC treatment. Untargeted metabolomics revealed 57 metabolites with altered expression associated with amino acid, carbohydrate, purine, and biotin pathways. The Spearman analysis demonstrated significant links between specific gut microbiota taxa and fecal metabolites. CONCLUSION: DLC may exert hypoglycemic effects by modulating intestinal flora genera, SCFA levels, and fecal metabolites.