Short-Term Intake of Hesperetin-7-O-Glucoside Affects Fecal Microbiota and Host Metabolic Homeostasis in Mice

Long-Term Triclocarban Exposure Induced Enterotoxicity by Triggering Intestinal AhR-Mediated Inflammation and Disrupting Microbial Community in Mice

Exposure to triclocarban (TCC), a commonly used antibacterial agent, has been shown to induce significant intestine injuries and colonic inflammation in mice. However, the detailed mechanisms by which TCC exposure triggered enterotoxicity remain largely unclear. Herein, intestinal toxicity effects of long-term and chronic TCC exposure were investigated using a combination of histopathological assessments, metagenomics, targeted metabolomics, and biological assays. Mechanically, TCC exposure caused induction of intestinal aryl hydrocarbon receptor (AhR) and its transcriptional target cytochrome P4501A1 (Cyp1a1) leading to dysfunction of the gut barrier and disruption of the gut microbial community. A large number of lipopolysaccharides (LPS) are released from the gut lumen into blood circulation owing to the markedly increased permeability and gut leakage. Consequently, toll-like receptor-4 (TLR4) and NF-κB signaling pathways were activated by high levels of LPS. Simultaneously, classic macrophage phenotypes were switched by TCC, shown with marked upregulation of macrophage M1 and downregulation of macrophage M2 that was accompanied by striking upregulation of proinflammatory factors such as Il-1β, Il-6, Il-17, and Tnf-α in the intestinal lamina propria. These findings provide new evidence for the TCC-induced enterotoxicity.

Triclocarban exposure aggravates dextran sulfate sodium-induced colitis by deteriorating the gut barrier function and microbial community in mice

Triclocarban (TCC) is an antibacterial component widely used in personal care products with potential toxicity possessing public health issues. Unfortunately, enterotoxicity mechanisms of TCC exposure remain largely unknown. Using a combination of 16S rRNA gene sequencing, metabolomics, histopathological and biological examinations, this study systematically explored the deteriorating effects of TCC exposure on a dextran sulfate sodium (DSS)-induced colitis mouse model. We found that TCC exposure at different doses significantly aggravated colitis phenotypes including shortened colon length and altered colonic histopathology. Mechanically, TCC exposure further disrupted intestinal barrier function, manifested by significant downregulation of the number of goblet cells, mucus layer thickness and expression of junction proteins (MUC-2, ZO-1, E-cadherin and Occludin). The gut microbiota composition and its metabolites such as short-chain fatty acids (SCFAs) and tryptophan metabolites were also markedly altered in DSS-induced colitis mice. Consequently, TCC exposure markedly exacerbated colonic inflammatory status of DSS-treated mice by activating NF-κB pathway. These findings provided new evidence that TCC could be an environmental hazards for development of IBD or even colon cancer.

Multiomics Analyses Reveal That Long-Term Intake of Hesperetin-7-O-glucoside Modulates the Gut Microbiota and Bile Acid Metabolism in Mice

Hesperetin-7-O-glucoside (Hes-7-G) is a typical flavonoid monoglucoside, which can be generated from hesperidin with the removal of rhamnose by hydrolysis. Untargeted and targeted metabolomics together with 16S rRNA gene sequencing were employed to explore the exact absorption site of Hes-7-G and its beneficial effect in mice. Intestinal ¹H nuclear magnetic resonance (NMR)-based metabolomics screening showed that Hes-7-G is mainly metabolized in the small intestine of mice, especially the ileum segment. Quantification analysis of bile acids (BAs) in the liver, intestinal tract, feces, and serum of mice suggests that Hes-7-G intake accelerates the processes of biosynthesis and excretion of BAs, thus promoting digestion and lowing hepatic cholesterol and triglyceride. 16S rRNA gene sequencing reveals that Hes-7-G significantly elevates the diversity of the gut microbiota in mice, especially those bacteria associated with BA secondary metabolism. These results demonstrated that long-term dietary Hes-7-G plays beneficial roles in health by modulating the gut bacteria and BA metabolism in mice.

Novel Catabolic Pathway of Quercetin-3-O-Rutinose-7-O-α-L-Rhamnoside by Lactobacillus plantarum GDMCC 1.140: The Direct Fission of C-Ring

Lychee pulp phenolics (LPP) is mainly catabolized in the host colon, increasing the abundances of Bacteroides and Lactobacillus. Herein, five selected gut microbial strains (Bacteroides uniformis, B. thetaiotaomicron, Lactobacillus rhamnosus, L. plantarum, and L. acidophilus) were separately incubated with LPP to ascertain the specific strains participating in phenolic metabolism and the corresponding metabolites. The results indicated that B. uniformis, L. rhamnosus, and L. plantarum were involved in LPP utilization, contributing to 52.37, 28.33, and 45.11% of LPP degradation after 48 h fermentation, respectively. Unprecedentedly, the metabolic pathway of the major phenolic compound quercetin-3-O-rutinose-7-O-α-L-rhamnoside by L. plantarum, appeared to be the direct fission of C-ring at C2–O1 and C3–C4 bonds, which was proved from the occurrence of two substances with the deprotonated molecule [M–H]⁻ ion at m/z 299 and 459, respectively. Meanwhile, it was fully confirmed that B. uniformis participated in the catabolism of isorhamnetin glycoside and procyanidin B2. In the B. uniformis culture, kaempferol was synthesized through dehydroxylation of quercetin which could be catabolized into alphitonin by L. rhamnosus. Furthermore, LPP metabolites exerted higher antioxidant activity than their precursors and gave clues to understand the interindividual differences for phenolic metabolism by gut microbiota.

Adding sorbitol improves the thermostability of α-l-rhamnosidase from Aspergillus niger and increases the conversion of hesperidin

In this study, we found the addition of sorbitol could improve the thermostability of α-l-rhamnosidase from Aspergillus niger. When α-l-rhamnosidase with sorbitol was heat-treated at 60°C, 65°C, and 70°C, the half-life t_1/2 increased by 28-, 18-, and 9-fold, respectively. Inactivation thermodynamic analysis showed that both E_a and ΔG^≠ of α-l-rhamnosidase increased. Through the response surface methodology (RSM) analysis, the higher hesperidin conversion (63.26%) by α-l-rhamnosidase was attained with 0.7 M sorbitol at 60°C and pH 4.5 for 10 min. Furthermore, hesperidin could be completely hydrolyzed after 10 hr of reaction. Overall, the results indicated that the addition of sorbitol improved the thermostability of α-l-rhamnosidase and increased the enzymatic conversion of hesperidin to hesperetin-7-O-glucoside (HMG). It also provided a simple and efficient way to increase enzymatic conversion of other valuable flavonoid monomers due to the broad substrate specificities of α-l-rhamnosidase from A. niger. PRACTICAL APPLICATIONS: Hesperetin-7-O-glucoside (HMG), a derhamnosylation product of hesperidin, is considered as a synthetic precursor for novel and efficient sweeteners and is important in food, functional food, and nutraceutical industries. Compared to chemical hydrolysis methods, the enzymatic conversion of hesperidin is milder and has the advantages of high specificity. Adding sorbitol can improve the thermostability of α-l-rhamnosidase and increase the enzyme efficacy against hesperidin. This study gave more evidence that adding sorbitol could improve the thermostability of enzymes and provide a better choice for improving biotransformation potency of enzymes.

In Vitro and In Vivo Studies Reveal that Hesperetin-7-O-glucoside, a Naturally Occurring Monoglucoside, Exhibits Strong Anti-inflammatory Capacity

Hesperetin-7-O-glucoside (Hes-7-G) is a naturally occurring flavonoid monoglucoside in Citri Reticulatae Pericarpium and exhibits relatively high biological activities. To explore the anti-inflammatory capacity of dietary Hes-7-G, lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages and dextran sodium sulfate (DSS)-induced colitis mice were used here as in vitro and in vivo inflammation models. The results showed that Hes-7-G (5 μM) significantly restored cellular metabolic disorders and inflammation in LPS-stimulated RAW264.7 macrophages. In the in vivo study, dietary Hes-7-G (1 mg/kg body weight) markedly alleviated the inflammatory status in DSS-induced colitis mice, manifested by the recovered colon length from 5.91 ± 0.66 to 6.45 ± 0.17 cm, histopathological changes, and mRNA levels of colonic inflammatory factors including Tnf-α and Il-22. Furthermore, dietary Hes-7-G not only profoundly regulated the gut microbiota composition including phyla Bacteroidetes, Cyanobacteria, Desulfobacterota, and Deferribacteres and genus Enterorhabdus, Prevotellaceae, Gastranaerophilales, Enterococcus, Intestinimonas, Ruminococcaceae, and Eubacterium in the cecal contents but also especially adjusted the co-metabolites such as short chain fatty acids and indole metabolites (indole-3-propionic, indole acetic acid), which were markedly altered by DSS treatment in mice. These findings demonstrated that Hes-7-G has strong anti-inflammatory activity in vitro and in vivo and potential preventive or therapeutic effects for chronic inflammation diseases.