Bioactive Component Screening and Mechanistic Study of the Anti-Diabetic Activity of Lophatherum gracile Brongn Extract.

Type 2 diabetes mellitus (T2DM), a metabolic disorder defined by glucose and lipid metabolism dysregulation, has become a major global health issue. Hence, effective measures to prevent T2DM are urgently required. Lophatherum gracile Brongn (LGB) has been used in managing diabetes-related systemic diseases. However, the hypoglycemic bioactive components in LGB and the mechanisms underlying their hypoglycemic activity remain elusive. The current study sought to characterize the bioactive components of LGB and elucidate its mechanism of action against T2DM. Six common characteristic peaks were identified from six batches of LGB, with 39 characteristic chemical components preliminarily identified. Through component-activity correlation analysis, three functional components-namely isoorientin, orientin, and isovitexin-were selected as key candidates. In T2DM mice, LGB effectively improved glucose and lipid metabolic dysfunction. Untargeted metabolomics analysis revealed that LGB modulated pathways related to lipid and carbon metabolism. 16S rRNA gene sequencing and targeted metabolomics analysis revealed that LGB decreased the ratio of Firmicutes to Bacteroidetes and increased the abundance of bacterial groups such as Lactobacillales and Bacteroides. Additionally, LGB elevated the levels of SCFAs, specifically acetic and butyric acid. Moreover, LGB alleviated intestinal inflammation and upregulated the expression of tight junction proteins by inhibiting the LPS/TLR4/NF-κB signaling pathway. This study demonstrated that LGB treated T2DM, with isoorientin, orientin, and isovitexin identified as the main contributing components. The hypoglycemic mechanism is linked to the "gut microbiota-SCFAs-inflammatory response" signaling axis.