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The whole plant of Plantago depressa is commonly used as traditional Chinese medicine and functional food ingredient. Total phenolic content and total flavonoid content evaluation indicated that its ethyl acetate and n-butanol fractions were rich in polyphenols. However, to date, the polyphenolic profile is limited because of the complex matrix. Here, polyphenols in ethyl acetate and n-butanol fractions of P. depressa were first separated and enriched by High-Speed Countercurrent Chromatography (HSCCC). Then, their structures were characterized or tentatively identified by High-Performance Liquid Chromatography (HPLC)-Diode Array Detector (DAD)-Quadrupole Time-of-Flight Tandem Mass Spectrometry (QTOF-MS/MS) (HSCCC × HPLC-DAD-QTOF-MS/MS). Because of the orthogonality of HSCCC and HPLC, 37 polyphenols were identified. Notably, 29 polyphenols were discovered from P. depressa for the first time. Finally, contents of two potential new compounds, 2-ethoxy plantamajoside isomers (17 and 29), were determined as 0.27 ± 0.03 and 0.04 ± 0.01 mg/g, respectively. Results indicated that P. depressa could be used as a promising source of polyphenols for health promotion, and the developed method (HSCCC × HPLC) was efficient to explore polyphenolic profile for complex natural products.

High-fat diet (HFD) is closely related to the formation of metabolic diseases. Studies have confirmed that neohesperidin dihydrochalcone (NHDC) possesses the biological activity of preventing glycolipid metabolism disorder. To explore the mechanism of its preventive activity against glucolipid metabolism disorder, HFD-treated rats were orally administered with NHDC for 12 weeks continuously. The results showed that, compared with the HFD group, the intervention of 40−80 mg/kg body weight of NHDC effectively downregulated the level of fasting blood glucose. Western blot analysis revealed that the treatment of NHDC alleviated the inhibitory effect of HFD on the expression of hepatic GLUT-4 and IRS-1. Further studies confirmed that NHDC reduced the degree of HFD-stimulated inflammation of ileum through the TLR4/MyD88/NF-κB signaling pathway. Moreover, ileum intestinal flora analysis showed that intragastric administration of NHDC reversed the change of Proteobacteria abundance and the Firmicutes/Bacteroidetes (F/B) ratio caused by HFD. At the generic level, NHDC promoted the relative abundance of Coprococcus, Bif idobacterium, Clostridium, Oscillospira, and [Eubacterium], while reducing the relative abundance of Defluviitalea and Prevotella. Taken together, these findings suggest that NHDC possesses the biological activity of improving HFDinduced glycolipid metabolism disorder.