Onset of p53/NF-κB signaling crosstalk in human melanoma cells in response to anti-cancer theabrownin.

As a major tea component, theabrownin represents a promising anti-cancer candidate. However, its effect on the melanoma is unknown. To evaluate the in vitro and in vivo anti-melanoma efficacy of TB, we conducted cell viability, immunostaining, comet, and TUNEL assays on human A375 melanoma cells, and employed a zebrafish xenograft model of A375 cells. Real-time PCR (qPCR) and western blot were conducted to explore the molecular mechanisms of TB. In vitro, TB significantly inhibited the proliferation of A375 cells, and A375 cells showed the highest inhibitory rate among the other melanoma cell line (A875) and human dermal fibroblasts. TB triggered DNA damage and induced apoptosis of A375 cells and significantly inhibited the growth of A375 xenograft tumors in zebrafishes. Several key molecular events were activated by TB, including DNA damage-associated p53 and NF-κB pathways, through up-regulation of GADD45α, γ-H2A.X, phospho-ATM(p-ATM), phospho-ATR (p-ATR), phospho-p53 (p-p53), phospho-IKKα/ß (p-IKKα/ß), phospho-p65 (p-p65), etc. However, the TB-activated molecular events were counteracted by either knockdown of p53 or p65, and only dual knockdown of both p53 and p65 completed counteracted the anti-melanoma efficacy of TB. In conclusion, TB triggered DNA damage and thereby inhibited proliferation and induced cellular senescence and apoptosis of melanoma cells through mechanisms mediated by p53/NF-κB signaling crosstalk. This is the first report on the efficacy and mechanisms of TB on melanoma cells, making TB a promising candidate for anti-melanoma agent development.

Theabrownin of raw and ripened pu-erh tea varies in the alleviation of HFD-induced obesity via the regulation of gut microbiota.

PURPOSE: Pu-erh tea can be classified into raw pu-erh tea and ripened pu-erh tea. Theabrownin (TB) is one of the major components of pu-erh tea. The difference of the anti-obesity activity between raw pu-erh tea TB (R-TB) and ripened pu-erh tea TB (F-TB) has not been comprehensively investigated yet. Therefore, this article aimed to systemically study the anti-obesity activity and the underlying mechanism of R-TB and F-TB. METHOD: High-fat diet (HFD)-induced C57BL/6J mice with obesity were gavaged with R-TB or F-TB to assess the effect of R-TB and F-TB on the amelioration of obesity, the expression of lipid metabolism-related genes, and the regulation of gut flora imbalance. RESULTS: Administration of both R-TB and F-TB could suppress body weight gain, improve insulin sensitivity and glucose homeostasis, regulate the lipid level and reduce the chronic inflammation in obese mice. The underlying anti-obesity mechanism of R-TB and F-TB might involve the regulation of lipogenesis and lipolysis, amelioration of the gut microbiota disorder and promotion of microbial metabolism. Interestingly, R-TB was more efficient in the regulation of blood glucose, reduction of inflammation and suppression of partial adipogenesis-related genes and protein, while F-TB was more effective in the inhibition of lipolysis-related genes and protein. In addition, F-TB might be more effective in adjusting the dysbacteria caused by HFD back to normal by promoting the proliferation of the beneficial microbiota, such as Lactobacillus and Lachnospiraceae_NK4A136_group. CONCLUSION: Taken together, both R-TB and F-TB had the potential to be developed as beneficial dietary supplements or functional foods for ameliorating obesity and obesity-related metabolic disorders, but their effects and the ability to regulate the intestinal flora varied.

Green tea-derived theabrownin induces cellular senescence and apoptosis of hepatocellular carcinoma through p53 signaling activation and bypassed JNK signaling suppression.

BACKGROUND: Theabrownin (TB) is a bioactive component of tea and has been reported to exert effects against many human cancers, but its efficacy and mechanism on hepatocellular carcinoma (HCC) with different p53 genotypes remains unclarified. METHODS: MTT assay, DAPI staining, flow cytometry and SA-ß-gal staining were applied to evaluate the effects of TB on HCC cells. Quantitative real time PCR (qPCR) and Western blot (WB) were conducted to explore the molecular mechanism of TB. A xenograft model of zebrafish was established to evaluate the anti-tumor effect of TB. RESULTS: MTT assays showed that TB significantly inhibited the proliferation of SK-Hep-1, HepG2, and Huh7 cells in a dose-dependent manner, of which SK-Hep-1 was the most sensitive one with the lowest IC50 values. The animal data showed that TB remarkably suppressed SK-Hep-1 tumor growth in xenograft model of zebrafish. The cellular data showed TB's pro-apoptotic and pro-senescent effect on SK-Hep-1 cells. The molecular results revealed the mechanism of TB that p53 signaling pathway (p-ATM, p-ATR, γ-H2AX, p-Chk2, and p-p53) was activated with up-regulation of downstream senescent genes (P16, P21, IL-6 and IL-8) as well as apoptotic genes (Bim, Bax and PUMA) and proteins (Bax, c-Casp9 and c-PARP). The p53-mediated mechanism was verified by using p53-siRNA. Moreover, by using JNK-siRNA, we found JNK as a bypass regulator in TB's mechanism. CONCLUSIONS: To sum up, TB exerted tumor-inhibitory, pro-senescent and pro-apoptotic effects on SK-Hep-1 cells through ATM-Chk2-p53 signaling axis in accompany with JNK bypass regulation. This is the first report on the pro-senescent effect and multi-target (p53 and JNK) mechanism of TB on HCC cells, providing new insights into the underlying mechanisms of TB's anti-HCC efficacy.

Theabrownin from Pu-erh tea together with swinging exercise synergistically ameliorates obesity and insulin resistance in rats.

PURPOSE: Theabrownin (TB)-containing Pu-erh tea has been shown to be hypolipidemic in rats fed a high-fat diet. Physical exercise such as swinging is also known to reduce obesity. We hypothesized that TB in combination with swinging can synergistically ameliorate obesity and insulin resistance in rats with metabolic syndrome. METHODS: TB, rosiglitazone, or lovastatin (controls) was administered by gavage to rats fed a diet high in fat, sugar, and salt. A subgroup of the rats was subjected to a 30-min daily swinging exercise regimen, whereas the other rats did not exercise. RESULTS: Theabrownin in combination with swinging was found to significantly improve serum lipid status and prevent development of obesity and insulin resistance in rats. Liver transcriptomics data suggested that theabrownin activated circadian rhythm, protein kinase A, the adenosine monophosphate-activated protein kinase, and insulin signaling pathways by enhancing cyclic adenosine monophosphate levels and, hence, accelerating nutrient metabolism and the consumption of sugar and fat. The serum dopamine levels in rats increased significantly after exercise. In parallel work, intraperitoneal dopamine injections were shown to significantly reduce weight gain and prevent the elevation in triglyceride levels that would otherwise be induced by the high fat-sugar-salt diet. Theabrownin prevented obesity and insulin resistance mainly by affecting the circadian rhythm, while swinging exercise stimulated the overproduction of dopamine to accelerate metabolism of glucose and lipid. CONCLUSIONS: Theabrownin and exercise synergistically ameliorated metabolic syndrome in rats and effectively prevented obesity.

Theabrownin triggers DNA damage to suppress human osteosarcoma U2OS cells by activating p53 signalling pathway.

Osteosarcoma becomes the second leading cause of cancer death in the younger population. Current outcomes of chemotherapy on osteosarcoma were unsatisfactory to date, demanding development of effective therapies. Tea is a commonly used beverage beneficial to human health. As a major component of tea, theabrownin has been reported to possess anti-cancer activity. To evaluate its anti-osteosarcoma effect, we established a xenograft model of zebrafish and employed U2OS cells for in vivo and in vitro assays. The animal data showed that TB significantly inhibited the tumour growth with stronger effect than that of chemotherapy. The cellular data confirmed that TB-triggered DNA damage and induced apoptosis of U2OS cells by regulation of Mki67, PARP, caspase 3 and H2AX, and Western blot assay showed an activation of p53 signalling pathway. When P53 was knocked down by siRNA, the subsequent downstream signalling was blocked, indicating a p53-dependent mechanism of TB on U2OS cells (p53 wt). Using osteosarcoma cell lines with p53 mutations (HOS, SAOS-2 and MG63), we found that TB exerted stronger inhibitory effect on U2OS cells than that on p53-mut cell lines, but it also exerted obvious effect on SAOS-2 cells (p53 null), suggesting an activation of p53-independent pathway in the p53-null cells. Interestingly, theabrownin was found to have no toxicity on normal tissue in vivo and could even increase the viability of p53-wt normal cells. In sum, theabrownin could trigger DNA damage and induce apoptosis on U2OS cells via a p53-dependent mechanism, being a promising candidate for osteosarcoma therapy.

Serum metabolomics analysis of rat after intragastric infusion of Pu-erh theabrownin.

BACKGROUND: The aim was to study the effects of Pu-erh theabrownin (TB) (Mw > 50 kDa) on the metabolism of rat serum by nuclear magnetic resonance (NMR)-based metabolomics and identify candidate marker metabolites associated with Pu-erh TB, and thus provide fundamental information for a better understanding of the metabolism of Pu-erh tea in animals. RESULTS: TB infusion induced different changes in endogenous serum metabolites depending on the type of diet. Compared with the control group, the TB infusion group showed significantly reduced serum glycine and choline levels, as well as significantly increased taurine, carnitine and high-density lipoprotein (all P < 0.05). Compared with the high-lipid group, the high-lipid TB infusion group exhibited significantly reduced low-density lipoprotein and acetate levels, as well as significantly increased inositol, carnitine and glycine levels (all P < 0.05). CONCLUSION: Examination of the variations of these differential expressed metabolites and their individual functions revealed that the TB extract accelerated lipid catabolism in rats and might affect glucose metabolism. Of these, carnitine level significantly increased after intragastric infusion of TB regardless of the type of diet, and activities of carnitine palmitoyltransferases I and II changed significantly, suggesting carnitine may be a candidate serum marker for tracking the metabolism of TB in rats. © 2015 Society of Chemical Industry.

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.

Dynamics changes in metabolites and pancreatic lipase inhibitory ability of instant dark tea during liquid-state fermentation by Aspergillus niger.

Instant dark tea (IDT), prepared by liquid-state fermentation using Aspergillus niger, is known for its high theabrownins content and lipid-lowering effect. To explore the impact of fungal fermentation on IDT compositions and its pancreatic lipase inhibitory ability (PLIA), untargeted and targeted metabolomic analysis were applied to track the changes of metabolites over a 9-day fermentation period, and correlation analysis was then conducted between metabolites and PLIA of IDT. There were 54 differential metabolites exhibited significant changes from day 3 to day 5 of fermentation. The concentrations of theabrownins and caffeine increased during fermentation, while phenols and free amino acids decreased. The PLIA of IDT samples significantly increased from day 5 to day 9 of fermentation. Theabrownins not only positively correlated with the PLIA but also exhibited a high inhibition rate. These findings provide a theoretical basis to optimize the production of IDT as functional food ingredient.

Theabrownin as a Potential Prebiotic Compound Regulates Lipid Metabolism via the Gut Microbiota, Microbiota-Derived Metabolites, and Hepatic FoxO/PPAR Signaling Pathways.

The dysregulation of lipid metabolism poses a significant health threat, necessitating immediate dietary intervention. Our previous research unveiled the prebiotic-like properties of theabrownin. This study aimed to further investigate the theabrownin-gut microbiota interactions and their downstream effects on lipid metabolism using integrated physiological, genomic, metabolomic, and transcriptomic approaches. The results demonstrated that theabrownin significantly ameliorated dyslipidemia, hepatic steatosis, and systemic inflammation induced by a high-fat/high-cholesterol diet (HFD). Moreover, theabrownin significantly improved HFD-induced gut microbiota dysbiosis and induced significant alterations in microbiota-derived metabolites. Additionally, the detailed interplay between theabrownin and gut microbiota was revealed. Analysis of hepatic transcriptome indicated that FoxO and PPAR signaling pathways played pivotal roles in response to theabrownin-gut microbiota interactions, primarily through upregulating hepatic Foxo1, Prkaa1, Pck1, Cdkn1a, Bcl6, Klf2, Ppara, and Pparg, while downregulating Ccnb1, Ccnb2, Fabp3, and Plin1. These findings underscored the critical role of gut-liver axis in theabrownin-mediated improvements in lipid metabolism disorders and supported the potential of theabrownin as an effective prebiotic compound for targeted regulation of metabolic diseases.

Theabrownin from Qingzhuan tea prevents high-fat diet-induced MASLD via regulating intestinal microbiota.

The aim of this study was to investigate whether the therapeutic effect of theabrownin extracted from Qingzhuan tea (QTB) on metabolic dysfunction-associated steatosis liver disease (MASLD) is related to the regulation of intestinal microbiota and its metabolite short-chain fatty acids (SCFAs). Mice were divided into four groups and received normal diet (ND), high-fat diet (HFD) and HFD+QTB (180, 360 mg/kg) for 8 weeks. The results showed that QTB significantly reduced the body weight of HFD mice, ameliorated liver lipid and dyslipidemia, and increased the level of intestinal SCFAs in HFD mice. The results of 16 S rRNA showed that the relative abundance of Bacteroides, Blautia and Lachnoclostridium and their main metabolites acetate and propionate were significantly increased after QTB intervention. The relative abundance of Colidextribacter, Faecalibaculum and Lactobacillus was significantly reduced. QTB can also significantly up-regulate the expression of ATGL, PPARα, FFAR2 and FFAR3, and inhibit the expression of LXRα, SREBP-1c, FAS and HMGCR genes. This makes it possible to act as a prebiotic to prevent MASLD.

Pu-erh tea theabrownin improves the ovarian function and gut microbiota in laying hens.

Studies have reported that theabrownin can moderate the lipid metabolism and intestinal microbiota, thereby affecting the health of humans and model animals, however the research on laying hens is scarce. The present study aimed to investigate the effects of dietary theabrownin supplementation on lipid metabolism, microbial composition and ovarian function in laying hens. A total of 80 laying hens (25 wk of age) were fed with normal diet (CON) and normal diet +100 mg/kg theabrownin (PT group) for 12 wk. The results showed that the addition of theabrownin enhanced villus height of duodenum and decreased crypt depth of jejunum (P < 0.05). At the same time, compared with CON, the concentration of IL-6 and the mRNA expression of IL-1ß and IL-6 were decreased significantly in PT group (P < 0.05). Dietary theabrownin reduced the concentration of total cholesterol and glycerol, while decreased lipid droplet optical density in liver (P < 0.05). Compared with CON group, the mRNA expression of PPARγ, HMG-CoAS, ACC were down-regulated and the mRNA expression of CYP8B1 was up-regulated in PT group (P < 0.05). The ACE, Chao1 and Observed_species indexes in cecum microbiota were increased by PT group intervention (P < 0.05). Dietary PT supplementation enhanced the relative abundance of Firmicutes (phylum), Lactobacillus (genus) and the Firmicutes to Bacteroidetes ratio, and reduced the relative abundance of Bacteroidetes (phylum) in cecum (P < 0.05). The organic acids and its derivatives were up-regulated by theabrownin intervention in serum metabolites (P < 0.05). Dietary theabrownin supplementation resulted in higher mRNA expression of Bcl-2 and SIRT1 in ovary and increased the concentration of estradiol in serum (P < 0.05). These discovering indicated that dietary theabrownin supplementation enhanced the intestinal function and influenced serum metabolism by improving intestinal morphology, microbiota community structure and reducing the concentration and expression of inflammatory cytokines in intestine. Dietary theabrownin reduced hepatic lipid deposition and it also decreased the cell apoptosis rate to improve ovarian function and egg weight which were associated with the SIRT1 pathway.

Phytochemical composition of Tibetan tea fermented by Eurotium cristatum and its effects on type 1 diabetes mice and gut microbiota.

"Golden-flower" Tibetan tea (GTT) is an innovative dark tea fermented via fungus Eurotium cristatum. To study GTT effects on alleviating the symptoms of type 1 diabetes mellitus (T1DM), GTT's extract (GTTE) was prepared. GTTE chemical compositions were analyzed via HPLC, pyrolysis-gas chromatography-mass (Py-GC-MS) spectrometry analysis, and chemistry analyses. GTTE effects on T1DM were explored on T1DM mice model induced by streptozotocin (STZ). GTTE was composed mainly of tea pigment theabrownin (TB) (49.18%), with high percentages of polysaccharide (16.93%), protein (10.15%), polyphenols (13.90%), amino acids (5.89%), caffeine (1.83%), and flavonoids (0.67%). Py-GC-MS results exhibited that GTTE constituted of phenols, lipids, sugars, and proteins. GTTE attenuated T1DM conditions of mice, relieved their liver and pancreatic injury, restored damaged islet cells, decreased oxidative stress by increasing superoxide dismutase (SOD) and catalase (CAT) levels, modulated cytokine expression leading to the decreasing pro-inflammatory cytokines TNF-α and IL-6, increased anti-inflammatory cytokines IL-4 to improve inflammatory responses, and optimized gut microbiota composition and structure based on high-throughput 16S rDNA sequencing, suggesting multi-channel anti-diabetes mechanisms.

Qingzhuan dark tea Theabrownin alleviates hippocampal injury in HFD-induced obese mice through the MARK4/NLRP3 pathway.

Background: Feeding on a high-fat diet (HFD) results in obesity and chronic inflammation, which may have long-term effects on neuroinflammation and hippocampal injury. Theabrownin, a biologically active compound derived from the microbial fermentation of Qingzhuan dark tea, exhibits anti-inflammatory properties and lipid-lowering effects. Nevertheless, its potential in neuroprotection has yet to be investigated. Consequently, this study aims to investigate the neuroprotective effects of Theabrownin extracted from Qingzhuan dark tea, as well as its potential therapeutic mechanisms. Methods: Male C57 mice were subjected to an 8-week HFD to induce obesity, followed by oral administration of Theabrownin from Qingzhuan dark tea. Lipid levels were detected by Elisa kit, hippocampal morphological damage was evaluated by HE and Nissl staining, and the expression levels of GFAP, IBA1, NLRP3, MARK4, and BAX in the hippocampus were detected by immunofluorescence (IF), and protein expression levels of NLRP3, MARK4, PSD95, SYN1, SYP, and Bcl-2 were detected by Western Blot (WB). Results: Theabrownin treatment from Qingzhuan dark tea prevents alterations in body weight and lipid levels in HFD-fed mice. Furthermore, Theabrownin decreased hippocampal morphological damage and reduced the activation of astrocytes and microglia in HFD-fed mice. Moreover, Theabrownin decreased the expression of MARK4 and NLRP3 in HFD-fed mice. Besides, Theabrownin elevated the expression of PSD95, SYN1, and SYP in HFD-fed obese mice. Finally, Theabrownin prevented neuronal apoptosis, reduced the expression of BAX, and increased the expression of Bcl-2 in HFD-fed obese mice. Conclusions: In summary, our current study presents the first demonstration of the effective protective effect of Theabrownin from Qingzhuan dark tea against HFD-induced hippocampal damage in obese mice. This protection may result from the regulation of the MARK4/NLRP3 signaling pathway, subsequently inhibiting neuroinflammation, synaptic plasticity, and neuronal apoptosis.

Theabrownin ameliorates liver inflammation, oxidative stress, and fibrosis in MCD diet-fed C57BL/6J mice.

Introduction: Nonalcoholic steatohepatitis (NASH), also known as metabolic steatohepatitis, is a clinical syndrome with pathological changes like alcoholic hepatitis but without a history of excessive alcohol consumption. NASH is closely related to metabolic disorders such as obesity, insulin resistance, type 2 diabetes mellitus, and hyperlipidemia. Its main characteristics are hepatocyte steatosis with hepatocyte injury and inflammation. In severe cases, it can develop into liver cirrhosis. At present, there is no special treatment for NASH. Theabrownin (TB) is the main pigment substance in fermented tea. Theabrownin has beneficial effects on lipid metabolism and intestinal flora. However, the effect of theabrownin on NASH has not been studied. Methods: This study was aimed at exploring the effects of theabrownin from Fuzhuan brick tea on NASH. 8-week-old mice were randomly assigned to three groups and fed with chow diet (CD), methionine and choline sufficient (MCS) diet (MCS Ctrl), which is a Methionine/choline deficient (MCD) control diet, and MCD diet. After 5 weeks of feeding, the MCD group mice were randomly divided into two groups and were gavaged with double distilled water (MCD Ctrl) or theabrownin (MCD TB) (200mg/kg body weight, dissolved in double distilled water) every day for another 4 weeks respectively, while continuing MCD diet feeding. Results: We found that theabrownin treatment could not improve liver mass loss and steatosis. However, theabrownin ameliorated liver injury and decreased liver inflammatory response. Theabrownin also alleviated liver oxidative stress and fibrosis. Furthermore, our results showed that theabrownin increased hepatic level of fibroblast growth factor 21 (FGF21) and reduced the phosphorylation of mitogen-activated protein kinase p38 in MCD diet-fed mice.

Theabrownin from Fu Brick Tea Improves Ulcerative Colitis by Shaping the Gut Microbiota and Modulating the Tryptophan Metabolism.

Fu brick tea theabrownin (FBTB) is a kind of biomacromolecule produced by oxidative polymerization of tea polyphenols. Although a variety of diseases can be alleviated by TB, its ability to treat ulcerative colitis (UC) is still worth exploring. A dextran sulfate sodium (DSS)-induced chronic UC mouse model was designed to first explore the alleviatory effect of FBTB on UC and its underlying mechanism by the sequencing of fecal 16S rRNA genes, metabolomics, and fecal microbiota transplantation (FMT). Administration of FBTB at 400 mg/kg bw in DSS-damaged mice could effectively reduce colonic damage and inflammation and improve colonic antioxidant capacity to relieve the UC-caused symptoms. FBTB could correct the disrupted gut microbiota caused by UC and contribute to the proliferation of Lactobacillus and Parasutterella. FMT in combination with antibiotic treatment showed that FBTB could elevate the levels of microbial tryptophan metabolites, including indole-3-acetaldehyde (IAld) and indole-3-acetic acid (IAA), by selectively promoting the growth of Lactobacillus. Importantly, FBTB-elevated IAld and IAA could activate aromatic hydrocarbon receptors (AhRs) and enhance interleukin-22 production to repair the intestinal barrier. These findings demonstrated that FBTB alleviated UC mainly by targeting the gut microbiota involved in the AhR pathway for prophylactic and therapeutic treatment of UC.

Effects of Key Components on the Antioxidant Activity of Black Tea.

Many components (such as tea polyphenols, catechins, theaflavins, theasinensins, thearubigins, flavonoids, gallic acid, etc.) in black tea have antioxidant activities. However, it is not clear which components have a greater influence on the antioxidant activity of black tea. In this study, the antioxidant activity and contents of tea polyphenols, catechins, theaflavins, thearubigins, theabrownins, TSA, total flavonoids, amino acids, caffeine, and total soluble sugar were analyzed in 51 black teas. Principal component analysis (PCA), orthogonal partial least-squares discrimination analysis (OPLS-DA), and the correlation analysis method were used for data analysis. The results showed that catechins in tea polyphenols were the most important components that determine the antioxidant activity of black tea. Among them, epicatechin gallate (ECG), epi-gallocatechin gallate (EGCG), epicatechin (EC), and epi-gallocatechin (EGC) were significantly positively correlated with the antioxidant activity of black tea, and theabrownin was negatively correlated with the antioxidant activity of black tea. Furthermore, this study analyzed the correlation between the changes in catechin and its oxidized polymers with antioxidant activity during black tea fermentation; it verified that catechins were significantly positively correlated with the antioxidant activity of black tea, and theabrownin showed a negative correlation. And the antioxidant activity of catechins and their oxidation products in vitro and their correlation in black tea processing were used as validation. This study provides a comparison method for comparing the antioxidant activity of black tea.

Theabrownin from Wuniuzao Dark Tea Regulates Hepatic Lipid Metabolism and Gut Microbiota in Mice Fed High-Fat Diet.

The search for functional foods with no side effects that can alleviate obesity has been a common trend. Wuniuzao dark tea could be a safe choice. This study aimed to explore whether theabrownin from Wuniuzao dark tea could regulate hepatic lipid metabolism and gut microbiota in mice fed a high-fat diet. In total, fifty 8-week-old male C57BL/6 mice were randomly divided into five treatment groups, including a normal control group, high-fat diet group, positive control group, low-dose theabrownin group, and high-dose theabrownin group. After a 9-week intervention, these mice were selected from each treatment group for sampling. The results showed that the body weight and epididymis fat weight of obese mice fed with theabrownin were decreased. Serum total triglycerides, total cholesterol, and low-density lipoprotein cholesterol, and activities of aspartate aminotransferase and alanine aminotransferase were also decreased. Protein and mRNA expression of fatty acid synthesis and lipid production-related genes of mice fed with theabrownin were downregulated. The gut microbiota composition in the theabrownin group was improved. The study indicated that theabrownin from Wuniuzao dark tea could achieve the liver protection and anti-obesity effects by regulating the Srebp lipid metabolism pathway and bile acid metabolism process, and improving the gut microbiota composition of mice.

Theabrownin inhibits obesity and non-alcoholic fatty liver disease in mice via serotonin-related signaling pathways and gut-liver axis.

INTRODUCTION: Non-alcoholic fatty liver disease (NAFLD) with obesity seriously threats public health. Our previous studies showed that dark tea had more potential on regulating lipid metabolism than other teas, and theabrownin (TB) was considered to be a main contributor to the bioactivity of dark tea. OBJECTIVES: This in vivo study aims to reveal the effects and molecular mechanisms of TB on NAFLD and obesity, and the role of the gut-liver axis is explored. METHODS: The histopathological examinations, biochemical tests, and nuclear magnetic resonance were applied to evaluate the effects of TB on NAFLD and obesity. The untargeted metabolomics was used to find the key molecule for further exploration of molecular mechanisms. The 16S rRNA gene sequencing was used to assess the changes in gut microbiota. The antibiotic cocktail and fecal microbiota transplant were used to clarify the role of gut microbiota. RESULTS: TB markedly reduced body weight gain (67.01%), body fat rate (62.81%), and hepatic TG level (51.35%) in the preventive experiment. Especially, TB decreased body weight (32.16%), body fat rate (42.56%), and hepatic TG level (42.86%) in the therapeutic experiment. The mechanisms of action could be the improvement of fatty acid oxidation, lipolysis, and oxidative stress via the regulation of serotonin-related signaling pathways. Also, TB increased the abundance of serotonin-related gut microbiota, such as Akkermansia, Bacteroides and Parabacteroides. Antibiotics-induced gut bacterial dysbiosis disrupted the regulation of TB on serotonin-related signaling pathways in liver, whereas the beneficial regulation of TB on target proteins was regained with the restoration of gut microbiota. CONCLUSION: We find that TB has markedly preventive and therapeutic effects on NAFLD and obesity by regulating serotonin level and related signaling pathways through gut microbiota. Furthermore, gut microbiota and TB co-contribute to alleviating NAFLD and obesity. TB could be a promising medicine for NAFLD and obesity.

Insight into structural characteristics of theabrownin from Pingwu Fuzhuan brick tea and its hypolipidemic activity based on the in vivo zebrafish and in vitro lipid digestion and absorption models.

Fuzhuan brick tea (FBT) is a post-fermented dark tea preferred by consumers for its excellent hypolipidemic activity, and theabrownin (TB) is the main bioactive composition in FBT. This work explored the structural and hypolipidemic properties of TB derived from Pingwu FBT, and investigated whether it exerted hypolipidemic activity by inhibiting intestinal lipid absorption. Structural characterization revealed that TB was an amorphous polymerized phenolic compound rich in hydroxyl and carboxyl groups with good thermostability. In vivo, TB and its fractions with different molecular weights (TB-LT3k, TB-3-10k, TB-10-30k, TB-30-100k, TB-GT100k) significantly reduced the lipid levels of hyperlipidemia zebrafish (P < 0.05). Moreover, TB attenuated hyperlipidemia by inhibiting intestinal lipid absorption, as TB effectively bound to bile acids, inhibited enzymatic activity of pancreatic lipase and cholesterol esterase, influenced micelle formation, and decreased micellar cholesterol solubility. Results facilitated research on TB and offered support for its feasibility as a natural alternative to prevent hyperlipidemia.

Theabrownin from Dark Tea Ameliorates Insulin Resistance via Attenuating Oxidative Stress and Modulating IRS-1/PI3K/Akt Pathway in HepG2 Cells.

Dark tea has great potential in regulating glycolipid metabolism, and theabrownin (TB) is considered to be the characteristic and bioactive constituent of dark tea. This study evaluated the ability of TB1 (fermented for 7 days) and TB2 (fermented for 14 days) isolated from dark tea to reverse insulin resistance (IR) in HepG2 cells. The results indicated that TB significantly ameliorated oxidative stress by improving mitochondrial function. In addition, TB improved glycogen synthesis and glucose consumption, and inhibited gluconeogenesis and fatty acid synthesis, by regulating GSK3ß (Glycogen synthase kinase 3ß), G6Pase (Glucose-6-phosphatase), GCK (Glucokinase), PEPCK1 (Phosphoenolpyruvate carboxy kinase 1), SREBP-1C (sterol regulatory element-binding protein 1C), FASN (fatty acid synthase), and ACC (Acetyl-CoA carboxylase). Additionally, the results of Western blot and real-time PCR experiments demonstrated that TB modulated glucolipid metabolism through the IRS-1 (Insulin receptor substrate 1)/PI3K (phosphatidylinositol-3 kinase)/Akt (protein kinase B) signaling pathway. Treatment with the PI3K inhibitor demonstrated a favorable correlation between PI3K activation and TB action on glycolipid metabolism. Notably, we observed that TB2 had a greater effect on improving insulin resistance compared with TB1, which, due to its prolonged fermentation time, increased the degree of oxidative polymerization of TB.