Screening of α-Glucosidase Inhibitors in Cichorium glandulosum Boiss. et Huet Extracts and Study of Interaction Mechanisms.

Cichorium glandulosum Boiss. et Huet (CGB) extract has an α-glucosidase inhibitory effect (IC50 = 59.34 ± 0.07 µg/mL, positive control drug acarbose IC50 = 126.1 ± 0.02 µg/mL), but the precise enzyme inhibitors implicated in this process are not known. The screening of α-glucosidase inhibitors in CGB extracts was conducted by bioaffinity ultrafiltration, and six potential inhibitors (quercetin, lactucin, 3-O-methylquercetin, hyperoside, lactucopicrin, and isochlorogenic acid B) were screened as the precise inhibitors. The binding rate calculations and evaluation of enzyme inhibitory effects showed that lactucin and lactucopicrin exhibited the greatest inhibitory activities. Next, the inhibiting effects of the active components of CGB, lactucin and lactucopicrin, on α-glucosidase and their mechanisms were investigated through α-glucosidase activity assay, enzyme kinetics, multispectral analysis, and molecular docking simulation. The findings demonstrated that lactucin (IC50 = 52.76 ± 0.21 µM) and lactucopicrin (IC50 = 17.71 ± 0.64 µM) exhibited more inhibitory effects on α-glucosidase in comparison to acarbose (positive drug, IC50 = 195.2 ± 0.30 µM). Enzyme kinetic research revealed that lactucin inhibits α-glucosidase through a noncompetitive inhibition mechanism, while lactucopicrin inhibits it through a competitive inhibition mechanism. The fluorescence results suggested that lactucin and lactucopicrin effectively reduce the fluorescence of α-glucosidase by creating lactucin-α-glucosidase and lactucopicrin-α-glucosidase complexes through static quenching. Furthermore, the circular dichroism (CD) and Fourier transform infrared spectroscopy (FT-IR) analyses revealed that the interaction between lactucin or lactucopicrin and α-glucosidase resulted in a modification of the α-glucosidase's conformation. The findings from molecular docking and molecular dynamics simulations offer further confirmation that lactucopicrin has a robust binding affinity for certain residues located within the active cavity of α-glucosidase. Furthermore, it has a greater affinity for α-glucosidase compared to lactucin. The results validate the suppressive impact of lactucin and lactucopicrin on α-glucosidase and elucidate their underlying processes. Additionally, they serve as a foundation for the structural alteration of sesquiterpene derived from CGB, with the intention of using it for the management of diabetic mellitus.

Differences in the flavonoid composition of the leaves, fruits, and branches of mulberry are distinguished based on a plant metabolomics approach.

Mulberry is a common crop rich in flavonoids, and its leaves (ML), fruits (M), and branches (Ramulus Mori, RM) have medicinal value. In the present study, a total of 118 flavonoid metabolites (47 flavone, 23 flavonol, 16 flavonoid, 8 anthocyanins, 8 isoflavone, 14 flavanone, and 2 proanthocyanidins) and 12 polyphenols were identified by ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry. The most abundant in ML were 8-C-hexosyl-hesperetin O-hexoside and astragalin, the most abundant in M were 8-C-hexosyl-hesperetin O-hexoside and naringenin, and the most abundant in RM were cyanidin 3-O-galactoside and gallocatechin-gallocatechin. The total flavonoid compositions of ML and RM were essentially the same, but the contents of flavonoid metabolite in more than half of them were higher than those in M. Compared with ML, the contents of flavone and flavonoid in RM and M were generally down-regulated. Each tissue part had a unique flavonoid, which could be used as a marker to distinguish different tissue parts. In this study, the differences between flavonoid metabolite among RM, ML, and M were studied, which provided a theoretical basis for making full use of mulberry resources.

Cichorium glandulosum Ameliorates HFD-Induced Obesity in Mice by Modulating Gut Microbiota and Bile Acids.

Obesity is an ongoing global health problem, and Cichorium glandulosum (CG, chicory) is traditionally used as a hepatoprotective and lipid-lowering drug. However, there is still a lack of research on the role of CG in the treatment of obesity. In the present study, we found that CG significantly delayed weight gain and positively affected glucolipid metabolism disorders, serum metabolism levels, and the degree of liver and kidney oxidative stress in high-fat diet (HFD) mice. Further examination of the effects of CG on intestinal microenvironmental dysregulation and its metabolites in HFD mice revealed that the CG ethanol extract high-dose group (CGH) did not have a significant regulatory effect on short-chain fatty acids. Still, CGH significantly decreased the levels of 12α-OH/non-12α-OH bile acids and also found significant upregulation of proteobacteria and downregulation of cyanobacteria at the phylum level. CG may have ameliorated obesity and metabolic abnormalities in mice by repairing gut microbiota dysbiosis and modulating bile acid biosynthesis.

Glycoursodeoxycholic acid regulates bile acids level and alters gut microbiota and glycolipid metabolism to attenuate diabetes.

Accumulating evidence suggests that the bile acid regulates type 2 diabetes mellitus (T2DM) through gut microbiota-host interactions. However, the mechanisms underlying such interactions have been unclear. Here, we found that glycoursodeoxycholic acid (GUDCA) positively regulates gut microbiota by altering bile acid metabolism. GUDCA in mice resulted in higher taurolithocholic acid (TLCA) level and Bacteroides vulgatus abundance. Together, these changes resulted in the activation of the adipose G-protein-coupled bile acid receptor, GPBAR1 (TGR5) and upregulated expression of uncoupling protein UCP-1, resulting in elevation of white adipose tissue thermogenesis. The anti-T2DM effects of GUDCA are linked with the regulation of the bile acid and gut microbiota composition. This study suggests that altering bile acid metabolism, modifying the gut microbiota may be of value for the treatment of T2DM.

Effect of Cichorium glandulosum on intestinal microbiota and bile acid metabolism in db/db mice.

This study aims to investigate the effects of Chorum glandulosum Boiss. et Huet (CG) on the intestinal microbiota and serum bile acid (BA) in db/db mice. A total of 12 db/db mice were randomly divided into model (MOD), high-dose CG (CGH), and control (CON) groups. The CON and MOD groups received distilled water by gavage for 8 weeks. Whereas, the CGH group received an alcohol extract of CG at a dose of 200 mg/kg/day. Results showed that CG can reduce blood lipid levels. It change the composition of the intestinal microbiota, and increase the relative abundances of Muribaculaceae, Prevotellaceae, Bifidobacterium_pseudolongum, Bacteroidaceae in db/db mice as well. LC-MS metabolomics results showed that CG adjusted the serum BA levels. The results reduced the levels of primary BAs, such as cholic acid (CA) and chenodeoxycholic acid (CDCA). The results decreased the primary BA/secondary BA (PSA/SBA) ratio in db/db mice. Correlation analysis showed that the abundances of Bifidobacterium_pseudolongum and Bacteroidaceae were positively correlated with acetic acid level and negatively correlated with ursocholic acid (UCA), α-muricholic acid (αMCA), triglyceride (TG), and total cholesterol levels (TC), indicating an interaction between the intestinal microbiota and serum BAs. CG may play a positive role in the interaction between the intestinal microbiota and BAs in lipid metabolism.