Theabrownin-targeted regulation of intestinal microorganisms to improve glucose and lipid metabolism in Goto-Kakizaki rats

Roles of Gut Microbiota Metabolites and Circadian Genes in the Improvement of Glucose and Lipid Metabolism in KKAy Mice by Theabrownin

Theabrownin (TB), a prominent pigment in fermented dark tea, exhibits beneficial effects on adiposity reduction. Our study revealed that TB derived from Fu brick tea significantly lowered fasting blood glucose levels and insulin resistance in obese/diabetic KKAy mice. Furthermore, TB demonstrated potent anti-inflammatory effects in the liver, adipose tissue, and intestines, as well as enhancing intestinal integrity. Additionally, TB was found to inhibit hepatic gluconeogenesis and promote fatty acid oxidation. Notably, TB altered gut metabolites, particularly l-palmitoylcarnitine, which showed an elevation in serum, liver, and adipose tissue following TB intervention. l-Palmitoylcarnitine reduced gluconeogenesis in primary hepatocytes and decreased lipid deposition in both primary hepatocytes and 3T3-L1 adipocytes in vitro. However, these effects were abolished when the circadian gene Period 3 (Per3) was knocked down. Our findings suggest that l-palmitoylcarnitine may play a crucial role in improving TB-mediated glucose homeostasis and lipid metabolism by regulating Per3.

Theabrownin remodels the circadian rhythm disorder of intestinal microbiota induced by a high-fat diet to alleviate obesity in mice

The intestinal microbiota undergoes diurnal compositional and functional oscillations within a day, which affect the metabolic homeostasis of the host and exacerbate the occurrence of obesity. TB has the effect of reducing body weight and lipid accumulation, but the mechanism of improving obesity caused by a high-fat diet based on the circadian rhythm of intestinal microorganisms has not been clarified. In this study, we used multi-omics and imaging approaches to investigate the mechanism of TB in alleviating obesity in mice based on the circadian rhythm of gut microbiota. The results showed that TB could significantly regulate the levels and rhythmic expression of serum lipid indicators (TG, TC, LDL) and serum hormones (MT, FT3, LEP, CORT). The number of intestinal microbiota colonizing the colonic epithelium underwent daily fluctuations. TB remodeled the rhythmic oscillation of gut microbes (i.e., Lachnospiraceae_NK4A136_group, Alistipes, etc.), including the number, composition, abundance and rhythmic expression of the biogeographic localization of microbes. TB notably reduced the levels of 16 bile acids (TCA, THDCA, TCDA, GHDCA, T-α-MCA, etc.) and restored the balance of bile acid metabolism. It was found that TB may mitigate high-fat diet-induced obesity in mice by reshaping the circadian rhythm of the gut microbiome and regulating bile acid metabolism.

The association of objective daytime sleepiness with impaired glucose metabolism in patients with obstructive sleep apnea: a multi-omics study

STUDY OBJECTIVES

To examine the joint effect of obstructive sleep apnea (OSA) and objective excessive daytime sleepiness (EDS) on glucose metabolism and the underlying mechanisms.

METHODS

We included 127 patients with OSA. The multiple sleep latency test (MSLT) and Epworth sleepiness scale (ESS) were used to assess objective and subjective EDS, respectively. Disordered glucose metabolism was defined as either a physician diagnosis or having fasting blood glucose levels ≥5.6 mmol/L. Values of fasting insulin and homeostasis model assessment of insulin resistance (HOMA-IR) higher than the median values of our sample were defined as high fasting insulin and insulin resistance. Serum metabolomics and fecal microbiota were used to explore underlying mechanisms.

RESULTS

Lower MSLT values were associated with higher levels of fasting blood glucose, fasting insulin, and HOMA-IR. Furthermore, objective EDS was associated with increased odds of disordered glucose metabolism, elevated fasting insulin, and insulin resistance. Dysregulation of serum valine degradation and dysbiosis of fecal Bacteroides thetaiotaomicron were associated with impaired glucose metabolism in OSA with objective EDS. No association between subjective EDS and impaired glucose metabolism was observed.

CONCLUSIONS

OSA with objective, but not subjective, EDS is associated with an increased risk of disordered glucose metabolism and insulin resistance. Dysregulation of valine degradation and dysbiosis of B. thetaiotaomicron appear to link objective EDS and disordered glucose metabolism in OSA.

Effect of Eurotium cristatum fermentation on chemical composition and hypoglycemic and sedative activities of Anji Baicha (Camellia sinensis)

Anji Baicha (Camellia sinensis), one of the top 10 teas in China, possesses old leaves rich in bioactive ingredients yet is frequently discarded due to inferior taste. This study evaluated the effects of fermentation with Eurotium cristatum, a probiotic known to enhance bioactivity, on the primary nutrients and on the hypoglycemic and sedative properties of old leaves of Anji Baicha. Results indicated a considerable reduction in free amino acids and tea polyphenols post-fermentation. Conversely, the concentrations of flavonoids and theabrownins increased significantly, showing a positive correlation with the in vitro hypoglycemic effect. The contents of L-theanine and γ-aminobutyric acid (γ-GABA), known for their sedative effects, increased after fermentation, while caffeine and glutamate, renowned for their neural stimulation effect, decreased. Molecular docking revealed that L-theanine and γ-GABA may act as a sedative and sleep aid by competing for receptors with caffeine and glutamate, specifically NMDAR2A. This study not only introduces a novel approach for utilizing old leaves of Anji Baicha but also establishes a foundation for further investigating the hypoglycemic, sedative, and sleep-aiding effects of tea fermented with Eurotium cristatum. PRACTICAL APPLICATION: This research offers a sustainable solution for repurposing the underutilized old leaves of Anji Baicha, enhancing their market value and contributing to the circular economy within the tea industry. The fermented tea could be integrated into health-conscious food and beverage products, targeting consumers seeking natural hypoglycemic and sleep-aiding alternatives. Additionally, the findings open avenues for the development of functional teas that cater to specific health needs, such as diabetes management and sleep improvement.

Theabrownin: a dietary nutraceutical with diverse anticancer mechanisms

Cancer, a highly deadly disease, necessitates safe, cost-effective, and readily accessible treatments to mitigate its impact. Theabrownin (THBR), a polyphenolic pigment found in Pu-erh tea, has garnered attention for its potential benefits in memory, liver health, and inflammation control. By observing different biological activities of THBR, recently researchers have unveiled THBR's promising anticancer properties across various human cancer types. By examining existing studies, it is evident that THBR demonstrates substantial potential in inhibiting cell proliferation and reducing tumour size with minimal harm to normal cells. These effects are achieved through the modulation of key molecular markers such as Bcl-2, Bax, various Caspases, Poly (ADP-ribose) polymerase cleavage (Cl-PARP), and zinc finger E box binding homeobox 1 (ZEB 1). This review aims to provide in-depth insights into THBR's role in cancer research. This review also elucidates the underlying anticancer mechanisms of THBR, offering promise as a novel anticancer drug to alleviate the global cancer burden.

Theabrownin from Pu-erh tea attenuated high-fat diet-induced metabolic syndrome in rat by regulating microRNA and affecting gut microbiota

Theabrownin (TB), the primary pigment in Pu-erh tea, has shown potential in alleviating metabolic syndrome (MS), though its precise mechanisms remain unclear. This study investigated the effects of Pu-erh tea water extract (WE) and TB on high-fat diet (HFD)-induced MS in rats, focusing on miRNA regulation and gut microbiota composition. Both WE and TB significantly improved markers of MS, including dyslipidemia, insulin resistance, and inflammation. These improvements were linked to the normalization of specific miRNAs (miR-125b-5p, miR-223-3p_R + 2, miR-148b-3p, and miR-1247-5p), which activated the PI3K/AKT/FOXO signaling pathway, subsequently modulating key genes involved in glucolipid metabolism (SREBP-1C, PEPCK, PGC-1α, and G6pc). Additionally, WE and TB restored gut microbiota balance by decreasing the Firmicutes/Bacteroidetes ratio and increasing beneficial bacteria such as Bacteroides, Lactobacillus, and Bifidobacterium, while reducing harmful bacteria like Pseudomonas. These findings underscore the potential of theabrownin as a functional food component for MS prevention, offering new insights into its miRNA-mediated and microbiota-related mechanisms.

Global hotspots and trends in tea anti-obesity research: a bibliometric analysis from 2004 to 2024

Background

The prevalence of obesity and its related ailments is on the rise, posing a substantial challenge to public health. Tea, widely enjoyed for its flavors, has shown notable potential in mitigating obesity. Yet, there remains a lack of exhaustive bibliometric studies in this domain.

Methods

We retrieved and analyzed multidimensional data concerning tea and obesity studies from January 2004 to June 2024, using the Web of Science Core Collection database. This bibliometric investigation utilized tools such as Bibliometrix, CiteSpace, and VOSviewer to gather and analyze data concerning geographical distribution, leading institutions, prolific authors, impactful journals, citation patterns, and prevalent keywords.

Results

There has been a significant surge in publications relevant to this field within the last two decades. Notably, China, Hunan Agricultural University, and the journal Food and Function have emerged as leading contributors in terms of country, institution, and publication medium, respectively. Zhonghua Liu of Hunan Agricultural University has the distinction of most publications, whereas Joshua D. Lambert of The State University of New Jersey is the most cited author. Analyses of co-citations and frequently used keywords have identified critical focus areas within tea anti-obesity research. Current studies are primarily aimed at understanding the roles of tea components in regulating gut microbiota, boosting fat oxidation, and increasing metabolic rate. The research trajectory has progressed from preliminary mechanism studies and clinical trials to more sophisticated investigations into the mechanisms, particularly focusing on tea's regulatory effects on gut microbiota.

Conclusion

This study offers an intricate overview of the prevailing conditions, principal focus areas, and developmental trends in the research of tea's role against obesity. It delivers a comprehensive summary and discourse on the recent progress in this field, emphasizing the study's core findings and pivotal insights. Highlighting tea's efficacy in obesity prevention and treatment, this study also points out the critical need for continued research in this area.

State-of-the-art review of theabrownins: from preparation, structural characterization to health-promoting benefits

As far as health benefit is concerned, dark tea is one of the best beverages in the world. Theabrownins are the major ingredient contributing to the health benefits of dark tea and known as "the soft gold in dark tea." A growing body of evidence indicated that theabrownins are macromolecular pigments with reddish-brown color and mellow taste, and mainly derived from the oxidative polymerization of tea polyphenols. Theabrownins are the main active ingredients in dark tea which brings multiple health-promoting effects in modulating lipid metabolism, reducing body weight gain, attenuating diabetes, mitigating NAFLD, scavenging ROS, and preventing tumors. More importantly, it's their substantial generation in microbial fermentation that endows dark tea with much stronger hypolipidemic effect compared with other types of tea. This review firstly summarizes the most recent findings on the preparation, structural characteristics, and health-promoting effects of theabrownins, emphasizing the underlying molecular mechanism, especially the different mechanisms behind the effect of theabrownins-mediated gut microbiota on the host's multiple health-promoting benefits. Furthermore, this review points out the main limitations of current research and potential future research directions, hoping to provide updated scientific evidence for their better theoretical research and industrial utilization.

Theabrownin from Pu-erh Tea Improves DSS-Induced Colitis via Restoring Gut Homeostasis and Inhibiting TLR2&4 Signaling Pathway

BACKGROUND

Theabrownin (TB) is a dark brown pigment from Pu-erh tea or other dark teas. It is formed by further oxidization of theaflavins and thearubigins, in combination with proteins, polysaccharides, and caffeine etc. TB is a characteristic ingredient and bioactive substance of Pu-erh tea. However, the effects of TB on ulcerative colitis (UC) remains unclear.

PURPOSE

This study aims to elucidate the mechanism of TB on UC in terms of recovery of intestinal homeostasis and regulation of toll-like receptor (TLR) 2&4 signaling pathway.

METHODS

The colitis models were established by administering 5% dextran sulfate sodium (DSS) to C57BL/6 mice for 5 days to evaluate the therapeutic and preventive effects of TB on UC. Mesalazine was used as a positive control. H&E staining, complete blood count, enzyme-linked immunosorbent assay, immunohistochemistry, flow cytometry, and 16S rRNA sequencing were employed to assess histological changes, blood cells analysis, content of cytokines, expression and distribution of mucin (MUC)2 and TLR2&4, differentiation of CD4+T cells in lamina propria, and changes in intestinal microbiota, respectively. Western blot was utilized to study the relative expression of tight junction proteins and the key proteins in TLR2&4-mediated MyD88-dependent MAPK, NF-κB, and AKT signaling pathways.

RESULTS

TB outstanding alleviated colitis, inhibited the release of pro-inflammatory cytokines, reduced white blood cells while increasing red blood cells, hemoglobin, and platelets. TB increased the expression of occludin, claudin-1 and MUC2, effectively restored intestinal barrier function. TB also suppressed differentiation of Th1 and Th17 cells in the colon's lamina propria, increased the fraction of Treg cells, and promoted the balance of Treg/Th17 to tilt towards Tregs. Moreover, TB increased the Firmicutes to Bacteroides (F/B) ratio, as well as the abundance of Akkermansia, Muribaculaceae, and Eubacterium_coprostanoligenes_group at the genus level. In addition, TB inhibited the activation of TLR2&4-mediated MAPK, NF-κB, and AKT signaling pathways in intestinal epithelial cells of DSS-induced mice.

CONCLUSION

TB acts in restoring intestinal homeostasis and anti-inflammatory in DSS-induced UC, and exhibiting a preventive effect after long-term use. In a word, TB is a promising beverage, health product and food additive for UC.

Formation, physicochemical properties, and biological activities of theabrownins

Theabrownins (TBs) are heterogeneous mixtures of water-soluble brown tea pigments, and important constituents to evaluate the quality of dark tea. TBs have numerous hydroxyl and carboxyl groups and are formed by the oxidative polymerization of tea polyphenols. Many biological activities attributed to TBs, including antioxidant, anti-obesity, and lipid-regulating, have been demonstrated. This review summarizes the research progress made on the formation mechanism and physicochemical properties of TBs. It also discusses their protective effects against various diseases and associated potential molecular mechanisms. Additionally, it examines the signaling pathways mediating the bioactivities of TBs and highlights the difficulties and challenges of TBs research as well as their research prospects and applications.

Distribution and roles of Ligilactobacillus murinus in hosts

Ligilactobacillus murinus, a member of the Ligilactobacillus genus, holds significant potential as a probiotic. While research on Ligilactobacillus murinus has been relatively limited compared to well-studied probiotic lactic acid bacteria such as Limosilactobacillus reuteri and Lactobacillus gasseri, a mounting body of evidence highlights its extensive involvement in host intestinal metabolism and immune activities. Moreover, its abundance exhibits a close correlation with intestinal health. Notably, beyond the intestinal context, Ligilactobacillus murinus is gaining recognition for its contributions to metabolism and regulation in the oral cavity, lungs, and vagina. As such, Ligilactobacillus murinus emerges as a potential probiotic candidate with a pivotal role in supporting host well-being. This review delves into studies elucidating the multifaceted roles of Ligilactobacillus murinus. It also examines its medicinal potential and associated challenges, underscoring the imperative to delve deeper into unraveling the mechanisms of its actions and exploring its health applications.

Theabrownin from Fu Brick tea ameliorates high-fat induced insulin resistance, hepatic steatosis, and inflammation in mice by altering the composition and metabolites of gut microbiota

Fu Brick tea belongs to fermented dark tea, which is one of the six categories of tea. Fu Brick tea has been reported to reduce adiposity and has beneficial effects in the treatment of hypercholesterolemia and cardiovascular disease. Theabrownin (TB) is one of the pigments with the most abundant content in Fu Brick tea. TB has also been reported to have lipid-lowering effects, but its mechanism remains unclear. We found that TB could effectively reduce the insulin resistance and fat deposition induced by a high fat diet (HFD), decrease inflammation in the liver, improve intestinal integrity, and reduce endotoxins in circulation. Further studies showed that TB increased the abundance of Verrucomicrobiota and reduced the abundance of Firmicutes and Desulfobacterota in the intestinal tract of obese mice. The alteration of gut microbiota is closely linked to the metabolic phenotype after TB treatment through correlation analysis. Moreover, TB changed the gut microbial metabolites including L-ornithine, α-ketoglutarate, and glutamine, which have also been found to be upregulated in the liver after TB intervention. In vitro, L-ornithine, α-ketoglutarate, or glutamine significantly reduced lipopolysaccharide (LPS)-induced inflammation in macrophages. Therefore, our results suggest that TB can reduce adiposity, systemic insulin resistance, and liver inflammation induced by a HFD through altering gut microbiota and improving the intestinal tight junction integrity. The metabolites of gut microbiota might also play a role in ameliorating the HFD-induced phenotype by TB.

Astragalus membranaceus and Salvia miltiorrhiza ameliorate diabetic kidney disease via the "gut-kidney axis"

BACKGROUND

The combination of Astragalus membranaceus and Salvia miltiorrhiza (AS) is an effective prescription for treating diabetic kidney disease (DKD) in traditional Chinese medicine. Its efficacy in treating DKD has been confirmed, but the potential regulatory mechanism has not yet been fully clarified.

PURPOSE

To explore the mechanism by which AS regulates the "gut-metabolism-transcription" coexpression network under the action of the "gut-kidney axis" to ameliorate DKD.

METHODS

SD rats were used to establish the DKD model by injecting STZ. After AS intervention, the structure and function of the kidney and colon were observed. We sequenced the gut microbiota utilizing 16S rDNA, identified serum differential metabolites using LC‒MS/MS, and observed renal mRNA expression by RNA seq. The "gut-metabolism-transcription" coexpression network was further constructed, and the target bacteria, target metabolites, and target genes of AS were ultimately screened and validated.

RESULTS

AS improved renal pathology and functional damage and increased the abundance of Akkermansia, Akkermansia_muciniphila, Lactobacillus and Lactobacillus_murinus. Fourteen target metabolites of AS were identified, which were mainly concentrated in 19 KEGG pathways, including sphingolipid metabolism and glycerophospholipid metabolism. Sixty-three target mRNAs of AS were identified. The top 20 pathways were closely related to glycolipid metabolism, and 14 differential mRNAs were expressed in these pathways. Correlation analysis showed that Akkermansia, Akkermansia muciniphila, Lactobacillus and Lactobacillus murinus were closely associated with sphingolipid metabolism, glycerophospholipid metabolism, arachidonic acid metabolism, ascorbate and aldarate metabolism and galactose metabolism. Moreover, the target metabolites and target mRNAs of AS were also enriched in five identical pathways of sphingolipid metabolism, glycerophospholipid metabolism, arachidonic acid metabolism, ascorbate and aldarate metabolism and galactose metabolism, including 8 different metabolites, such as sphingosine, and 5 different genes, such as Kng1. The 8 metabolites had high AUC prediction values, and the validation of the 5 genes was consistent with the sequencing results.

CONCLUSION

Our research showed that AS can improve DKD via the "gut-kidney axis". Akkermansia muciniphila and Lactobacillus murinus were the main driving bacteria, and five pathways related to glycolipid metabolism, especially sphingolipid metabolism and glycerophospholipid metabolism, may be important follow-up reactions and regulatory mechanisms.

Possible Mechanisms of Dark Tea in Cancer Prevention and Management: A Comprehensive Review

Tea is one of the most popular drinks in the world. Dark tea is a kind of post-fermented tea with unique sensory characteristics that is produced by the special fermentation of microorganisms. It contains many bioactive substances, such as tea polyphenols, theabrownin, tea polysaccharides, etc., which have been reported to be beneficial to human health. This paper reviewed the latest research on dark tea's potential in preventing and managing cancer, and the mechanisms mainly involved anti-oxidation, anti-inflammation, inhibiting cancer cell proliferation, inducing cancer cell apoptosis, inhibiting tumor metastasis, and regulating intestinal flora. The purpose of this review is to accumulate evidence on the anti-cancer effects of dark tea, the corresponding mechanisms and limitations of dark tea for cancer prevention and management, the future prospects, and demanding questions about dark tea's possible contributions as an anti-cancer adjuvant.

Yi-Shen-Hua-Shi granule ameliorates diabetic kidney disease by the "gut-kidney axis"

ETHNOPHARMACOLOGICAL RELEVANCE

Yi-Shen-Hua-Shi (YSHS) granule is an effective prescription widely used in traditional Chinese medicine to treat diabetic kidney disease (DKD), its exact efficacy in treating DKD has been confirmed but the underlying regulatory mechanism has not been fully elucidated.

AIM OF THE STUDY

To explore the mechanism by which YSHS granule regulates intestinal flora and serum metabolites and then regulates renal mRNA expression through the "gut-kidney axis", so as to improve DKD.

MATERIALS AND METHODS

40 rats were divided into five groups: Normal group (N) (normal saline), model group (M) (STZ + normal saline), YSHS granule low-dose group (YL) (STZ + 2.27 g kg^-1 d^-1), YSHS granule high-dose group (YH) (STZ + 5.54g kg^-1 d^-1) and valsartan group (V) (STZ + 7.38mg kg^-1 d^-1). After 6 weeks, changes in blood glucose, blood lipids, and renal function related indexes were observed, as well as pathological changes in the kidney and colon. Intestinal microbiota was sequenced by 16S rDNA, serum differential metabolites were identified by LC-MS/MS, and renal differences in mRNA expression were observed by RNA-seq. Further, through the association analysis of intestinal differential microbiota, serum differential metabolites and kidney differential mRNAs, the target flora, target metabolites and target genes of YSHS granule were screened and verified, and the "gut-metabolism-transcription" co-expression network was constructed.

RESULTS

In group M, blood glucose, blood lipid and proteinuria were increased, inflammation, oxidative stress and renal function were aggravated, with the proliferation of mesangial matrix, vacuolar degeneration of renal tubules, accumulation of collagen and lipid, and increased intestinal permeability, and YSHS granule and valsartan improved these disorders to varying degrees. High dose of YSHS granule improved the diversity and abundance of flora, decreased the F/B value, greatly increased the abundance of Lactobacillus and Lactobacillus_murinus, and decreased the abundance of Prevoella UCG_001. 14 target metabolites of YSHS granule were identified, which were mainly enriched in 20 KEGG pathways, such as Glycerophospholipid metabolism, Sphingolipid metabolism and Phenylalanine, tyrosine and tryptophan biosynthesis. 96 target mRNAs of YSHS granule were also identified. The enriched top 20 pathways were closely related to glucose and lipid metabolism, of which a total of 21 differential mRNAs were expressed. Further correlation analysis revealed that Lactobacillus, Lactobacillus_murinus and Prevotella UCG_001 were highly correlated with Glycerophospholipid metabolism, Sphingolipid metabolism and Phenylalanine, tyrosine and tryptophan biosynthesis pathways. At the same time, 6 pathways including Glycerophospholipid metabolism, Arachidonic acid metabolism, Purine metabolism, Primary bile acid biosynthesis, Ascorbate and aldarate metabolism and Galactose metabolism were co-enriched by the target metabolites and the target mRNAs of YSHS granule, including 7 differential metabolites such as phosphatidylethanolamine and 7 differential genes such as Adcy3. The 7 differential metabolites had high predictive value of AUC, and the validation of 7 differential genes were highly consistent with the sequencing results.

CONCLUSION

YSHS granule could improve DKD through the "gut-kidney axis". Lactobacillus and Lactobacillus_murinus were the main driving forces. 6 pathways related to glucose and lipid metabolism, especially Glycerophospholipid metabolism, may be an important follow-up response and regulatory mechanism.

Theabrownin Isolated from Pu-Erh Tea Enhances the Innate Immune and Anti-Inflammatory Effects of RAW264.7 Macrophages via the TLR2/4-Mediated Signaling Pathway

Theabrownin (TB) is a tea pigment extracted from Pu-erh Tea. The effects of TB on innate immunity and inflammation are not well understood. Herein, the effects of TB on innate immunity are investigated using RAW264.7 macrophages. We found that TB promoted the proliferation of RAW264.7 macrophages, altered their morphology, enhanced their pinocytic and phagocytic ability, and significantly increased their secretion of nitric oxide (NO) and cytokines, all of which enhanced the immune response. Additionally, TB inhibited the release of inflammatory signals in RAW264.7 macrophages primed with lipopolysaccharide (LPS), implying that TB modulates the excessive inflammation induced by bacterial infection. A Western blot showed that TB could activate the toll-like receptor (TLR)2/4-mediated myeloid differentiation factor 88 (MyD88)-dependent mitogen activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) signaling pathway and the TLR2-mediated phosphoinositide 3-kinase (PI3K)-AKT signaling pathway, enhancing the immune functions of RAW264.7 macrophages. TB also inhibited the phosphorylation of core proteins in the MAPK/NF-κB/PI3K-AKT signaling pathway induced by LPS. In addition, we analyzed the transcriptomes of RAW264.7 macrophages, and a Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis revealed that TB modulated thetoll-like receptor signal pathway. A gene ontology (GO) enrichment analysis indicated that TB treatment strongly modulated the immune response and inflammation. As a result, TB-enhanced innate immunity and modulated inflammation via the TLR2/4 signaling pathway.

Characterization of gut microbial and metabolite alterations in faeces of Goto Kakizaki rats using metagenomic and untargeted metabolomic approach

BACKGROUND

In recent years, the incidence of type 2 diabetes (T2DM) has shown a rapid growth trend. Goto Kakizaki (GK) rats are a valuable model for the study of T2DM and share common glucose metabolism features with human T2DM patients. A series of studies have indicated that T2DM is associated with the gut microbiota composition and gut metabolites. We aimed to systematically characterize the faecal gut microbes and metabolites of GK rats and analyse the relationship between glucose and insulin resistance.

AIM

To evaluate the gut microbial and metabolite alterations in GK rat faeces based on metagenomics and untargeted metabolomics.

METHODS

Ten GK rats (model group) and Wistar rats (control group) were observed for 10 wk, and various glucose-related indexes, mainly including weight, fasting blood glucose (FBG) and insulin levels, homeostasis model assessment of insulin resistance (HOMA-IR) and homeostasis model assessment of β cell (HOMA-β) were assessed. The faecal gut microbiota was sequenced by metagenomics, and faecal metabolites were analysed by untargeted metabolomics. Multiple metabolic pathways were evaluated based on the differential metabolites identified, and the correlations between blood glucose and the gut microbiota and metabolites were analysed.

RESULTS

The model group displayed significant differences in weight, FBG and insulin levels, HOMA-IR and HOMA-β indexes (P < 0.05, P < 0.01) and a shift in the gut microbiota structure compared with the control group. The results demonstrated significantly decreased abundances of Prevotella sp. CAG:604 and Lactobacillus murinus (P < 0.05) and a significantly increased abundance of Allobaculum stercoricanis (P < 0.01) in the model group. A correlation analysis indicated that FBG and HOMA-IR were positively correlated with Allobaculum stercoricanis and negatively correlated with Lactobacillus murinus. An orthogonal partial least squares discriminant analysis suggested that the faecal metabolic profiles differed between the model and control groups. Fourteen potential metabolic biomarkers, including glycochenodeoxycholic acid, uric acid, 13(S)-hydroxyoctadecadienoic acid (HODE), N-acetylaspartate, β-sitostenone, sphinganine, 4-pyridoxic acid, and linoleic acid, were identified. Moreover, FBG and HOMA-IR were found to be positively correlated with glutathione, 13(S)-HODE, uric acid, 4-pyridoxic acid and allantoic acid and ne-gatively correlated with 3-α, 7-α, chenodeoxycholic acid glycine conjugate and 26-trihydroxy-5-β-cholestane (P < 0.05, P < 0.01). Allobaculum stercoricanis was positively correlated with linoleic acid and sphinganine (P < 0.01), and 2-methyl-3-hydroxy-5-formylpyridine-4-carboxylate was negatively associated with Prevotella sp. CAG:604 (P < 0.01). The metabolic pathways showing the largest differences were arginine biosynthesis; primary bile acid biosynthesis; purine metabolism; linoleic acid metabolism; alanine, aspartate and glutamate metabolism; and nitrogen metabolism.

CONCLUSION

Metagenomics and untargeted metabolomics indicated that disordered compositions of gut microbes and metabolites may be common defects in GK rats.

Anti-Obesity Effect of Theabrownin from Dark Tea in C57BL/6J Mice Fed a High-Fat Diet by Metabolic Profiles through Gut Microbiota Using Untargeted Metabolomics

The epidemic of obesity is a serious public health problem. In this study, the effect of theabrownin from dark tea on obesity was evaluated by biochemical tests and nuclear magnetic resonance in C57BL/6J mice fed a high-fat diet. A mixture of antibiotics was used to deplete gut microbiota and then fecal microbiota transplant was used to restore gut microbiota. Untargeted metabolomics was used to reveal the effects of theabrownin on metabolic profiles through gut microbiota. The results showed that theabrownin significantly reduced body weight gain (83.0%) and body fat accumulation (30.29%) without affecting appetite. Also, theabrownin promoted lipid clearance with a hepatoprotective effect. The extra antibiotics disrupted the regulation of theabrownin on weight control while fecal microbiota transplant restored the beneficial regulation. That is, gut microbiota was important for theabrownin to reduce body weight gain. The untargeted metabolomics indicated that 18 metabolites were related to the anti-obesity effect of theabrownin mediated by gut microbiota. Furthermore, phenylalanine metabolism, histidine metabolism, as well as protein digestion and absorption pathway played a role in the anti-obesity of theabrownin. Our findings suggested that theabrownin significantly alleviated obesity via gut microbiota-related metabolic pathways, and theabrownin could be used for the prevention and treatment of obesity.

Theabrownin Alleviates Colorectal Tumorigenesis in Murine AOM/DSS Model via PI3K/Akt/mTOR Pathway Suppression and Gut Microbiota Modulation

Colorectal cancer (CRC) is one of the most common and fatal cancers worldwide, yet therapeutic options for CRC often exhibit strong side effects which cause patients’ well-being to deteriorate. Theabrownin (TB), an antioxidant from Pu-erh tea, has previously been reported to have antitumor effects on non-small-cell lung cancer, osteosarcoma, hepatocellular carcinoma, gliomas, and melanoma. However, the potential antitumor effect of TB on CRC has not previously been investigated in vivo. The present study therefore aimed to investigate the antitumor effect of TB on CRC and the underlying mechanisms. Azoxymethane (AOM)/dextran sodium sulphate (DSS) was used to establish CRC tumorigenesis in a wild type mice model. TB was found to significantly reduce the total tumor count and improve crypt length and fibrosis of the colon when compared to the AOM/DSS group. Immunohistochemistry staining shows that the expression of the proliferation marker, Ki67 was reduced, while cleaved caspase 3 was increased in the TB group. Furthermore, TB significantly reduced phosphorylation of phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt), and the downstream mechanistic target of rapamycin (mTOR)and cyclin D1 protein expression, which might contribute to cell proliferation suppression and apoptosis enhancement. The 16s rRNA sequencing revealed that TB significantly modulated the gut microbiota composition in AOM/DSS mice. TB increased the abundance of short chain fatty acid as well as SCFA-producing Prevotellaceae and Alloprevotella, and it decreased CRC-related Bacteroidceae and Bacteroides. Taken together, our results suggest that TB could inhibit tumor formation and potentially be a promising candidate for CRC treatment.

Preclinical Studies of Natural Products Targeting the Gut Microbiota: Beneficial Effects on Diabetes

Diabetes mellitus (DM) is a serious metabolic disease characterized by persistent hyperglycemia, with a continuously increasing morbidity and mortality. Although traditional treatments including insulin and oral hypoglycemic drugs maintain blood glucose levels within the normal range to a certain extent, there is an urgent need to develop new drugs that can effectively improve glucose metabolism and diabetes-related complications. Notably, accumulated evidence implicates that the gut microbiota is unbalanced in DM individuals and is involved in the physiological and pathological processes of this metabolic disease. In this review, we introduce the molecular mechanisms by which the gut microbiota contributes to the development of DM. Furthermore, we summarize the preclinical studies of bioactive natural products that exert antidiabetic effects by modulating the gut microbiota, aiming to expand the novel therapeutic strategies for DM prevention and management.

Effects of natural dihydrochalcones in sweet tea (Lithocarpus polystachyus) on diabetes: a systematical review and meta-analysis of animal studies

Sweet tea (Lithocarpus polystachyus Rehd.), a natural functional food highly rich in dihydrochalcones including trilobatin, phlorizin and phloretin, is reported to possess numerous biological activities especially for treating diabetes. Here, the aim of this systematical review and meta-analysis is to assess the effect of dihydrochalcones in sweet tea (DST) on diabetes and summarize their possible mechanisms. We searched in eight databases including Embase, PubMed, Cochrane, Web of Science, WanFang database, VIP database, China National Knowledge Infrastructure and China Biology Medicine from Jan 2000 to Nov 2021 and ultimately included 21 animal studies in this review. A total of 10 outcome measurements including blood lipid indexes, blood glucose, insulin resistance indicators and oxidative stress biomarkers were extracted for meta-analysis using RevMan 5.4 software. DST significantly decreased the levels of triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), blood glucose (BG), homeostasis model assessment of insulin resistance (HOMA-IR) and malondialdehyde (MDA), and increased high-density lipoprotein cholesterol (HDL-c), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity in diabetic animal models. In summary, DST could treat diabetes by regulation of blood glucose/lipid metabolism, oxidative/carbonyl stress, inflammatory response etc.

Integrating Network Pharmacology and Metabolomics to Elucidate the Mechanism of Action of Huang Qin Decoction for Treament of Diabetic Liver Injury

Huang Qin Decoction (HQD), is used for the treatment of diabetic liver injury (DLI) and in this study, its mechanisms were evaluated by metabonomics and system pharmacology. To study the anti-DLI effects of HQD. The 48 male db/db mice were fed adaptively for one week, and a random blood glucose test was performed twice. The db/db mice with a blood glucose level of more than 11.1mol/l were separated into four groups: the model group, the active control group, the high-dose HQD group the low-dose HQD group, the control group consisted of db/m mice. Using the UHPLC/Q-TOF-MS metabolomics approach, 18 metabolites were found to be profoundly altered in the model group, and the levels of these biomarkers were significantly recovered after treatment with HQD. 8 signaling pathways related to HQD, including the Sphingolipid metabolism, Taurine and hypotaurine metabolism, Phenylalanine metabolism, Glutathione metabolism and Glycerophospholipid metabolism, etc. were explored. In addition, the system pharmacology paradigm revealed that HQD contains 141 active ingredients and is related to 265 genes, and 1404 disease genes are related to DLI. The construction of the HQD composition-target-DLI network identified a total of 161 intersection genes. We identified 10 key genes, which is partially compatible with the results of metabolomics. The integrated approach metabolomics and network pharmacology revealed that additional detailed investigation focused on five major targets, including CAT, PTGS2, MAPK3, AKT1, and MAPK8, and their essential metabolites (sphinganine, sphingosine, Glutahione, Oxidized gutahione, Dihydrolipoamide) and pathway (glycerol phospholipid metabolism and tryptophan metabolism). The significant affinity of the primary target for the HQD was confirmed by molecular docking. The results demonstrate that the combination of metabolomics and network pharmacology could be used to reflect the effects of HQD on the biological network and metabolic state of DLI and to evaluate the drug efficacy of HQD and its related mechanisms.