Hypolipidaemic and antioxidant effects of various Chinese dark tea extracts obtained from the same raw material and their main chemical components

The utilization of a data fusion approach to investigate fingerprint profiles of dark tea from China's different altitudes

Dark tea refers to a kind of post-fermented product, and its quality and price vary owing to the distinct altitudes at which it grows. In this study, a novel method based on high performance liquid chromatography with a diode-array detector (HPLC-DAD) and an evaporative light scattering detector (HPLC-ELSD) was proposed for the classification of dark teas from distinct altitudes in China. Through implementing a strategy fusing feature-level data to construct a combined dataset, the classification performance of dark teas from distinct altitudes in China was evaluated after preprocessing. The results suggested that, through the feature fusion strategy, the identification accuracy rate increased from <70% of a single detector to 76.923%. After the implementation of preprocessing, the identification accuracy rate was further improved. Typically, the model identification accuracy rate after short-time Fourier Transform (STFT) treatment reached 92.85%, and the AUROC value was higher than 0.84, exhibiting a favorable generalization ability. This study provides a new thinking for the identification technology of dark teas from different altitudes in China.

Combining bioinformatics and multiomics strategies to investigate the key microbiota and active components of Liupao tea ameliorating hyperlipidemia

ETHNOPHARMACOLOGICAL RELEVANCE

Hyperlipidemia as a major health issue has attracted much public attention. As a geographical indication product of China, Liupao tea (LPT) is a typical representative of traditional Chinese dark tea that has shown good potential in regulating glucose and lipid metabolism. LPT has important medicinal value in hyperlipidemia prevention. However, the active ingredients and metabolic mechanisms by which LPT alleviates hyperlipidemia remain unclear.

AIM OF THE STUDY

This study aimed to systematically investigate the metabolic mechanisms and active ingredients of LPT extract in alleviating hyperlipidemia.

MATERIALS AND METHODS

Firstly, we developed a mouse model of hyperlipidemia to study the pharmacodynamics of LPT. Subsequently, network pharmacology and molecular docking were performed to predict the potential key active ingredients and core targets of LPT against hyperlipidemia. LC-MS/MS was used to validate the identity of key active ingredients in LPT with chemical standards. Finally, the effect and metabolic mechanisms of LPT extract in alleviating hyperlipidemia were investigated by integrating metabolomic, lipidomic, and gut microbiome analyses.

RESULTS

Results showed that LPT extract effectively improved hyperlipidemia by suppressing weight gain, remedying dysregulation of glucose and lipid metabolism, and reducing hepatic damage. Network pharmacology analysis and molecular docking suggested that four potential active ingredients and seven potential core targets were closely associated with roles for hyperlipidemia treatment. Ellagic acid, catechin, and naringenin were considered to be the key active ingredients of LPT alleviating hyperlipidemia. Additionally, LPT extract modulated the mRNA expression levels of Fxr, Cyp7a1, Cyp8b1, and Cyp27a1 associated with bile acid (BA) metabolism, mitigated the disturbances of BA and glycerophospholipid (GP) metabolism in hyperlipidemia mice. Combining fecal microbiota transplantation and correlation analysis, LPT extract effectively improved species diversity and abundance of gut microbiota, particularly the BA and GP metabolism-related gut microbiota, in the hyperlipidemia mice.

CONCLUSIONS

LPT extract ameliorated hyperlipidemia by modulating GP and BA metabolism by regulating Lactobacillus and Dubosiella, thereby alleviating hyperlipidemia. Three active ingredients of LPT served as the key factors in exerting an improvement on hyperlipidemia. These findings provide new insights into the active ingredients and metabolic mechanisms of LPT in improving hyperlipidemia, suggesting that LPT can be used to prevent and therapeutic hyperlipidemia.

Hypolipidemic and Antithrombotic Effect of 6'-O-Caffeoylarbutin from Vaccinium dunalianum Based on Zebrafish Model, Network Pharmacology, and Molecular Docking

Vaccinium dunalianum leaf buds make one of the most commonly used herbal teas of the Yi people in China, which is used to treat articular rheumatism, relax tendons, and stimulates blood circulation in the body. In addition, 6'-O-caffeoylarbutin (CA) is a standardized extract of V. dunalianum, which has been found in dried leaf buds, reaching levels of up to 31.76%. Because of the uncommon phenomenon, it is suggested that CA may have a potential therapeutic role in hyperlipidemia and thrombosis. This study was designed to study the efficacy of CA on treating hyperlipidemia and thrombosis and the possible mechanisms behind these effects. Hyperlipidemia and thrombosis zebrafish models were treated with CA to observe variations of the integrated optical density within the vessels and the intensity of erythrocyte staining within the hearts. The possible mechanisms were explored using network pharmacology and molecular docking. The results demonstrate that CA exhibits an excellent hypolipidemic effect on zebrafish at concentrations ranging from 3.0 to 30.0 μg/mL and shows thrombosis inhibitory activity in zebrafish at a concentration of 30.0 μg/mL, with an inhibition rate of 44%. Moreover, network pharmacological research shows that MMP9, RELA, MMP2, PRKCA, HSP90AA1, and APP are major targets of CA for therapy of hyperlipidemia and thrombosis, and may relate to pathways in cancer, chemical carcinogenesis-receptor activation, estrogen signaling pathway, and the AGE-RAGE signaling pathway in diabetic complications.

Exploration of the hypoglycemic mechanism of Fuzhuan brick tea based on integrating global metabolomics and network pharmacology analysis

Introduction: Fuzhuan brick tea (FBT) is a worldwide popular beverage which has the appreciable potential in regulating glycometabolism. However, the reports on the hypoglycemic mechanism of FBT remain limited. Methods: In this study, the hypoglycemic effect of FBT was evaluated in a pharmacological experiment based on Kunming mice. Global metabolomics and network pharmacology were combined to discover the potential target metabolites and genes. In addition, the real-time quantitative polymerase chain reaction (RT-qPCR) analysis was performed for verification. Results: Seven potential target metabolites and six potential target genes were screened using the integrated approach. After RT-qPCR analysis, it was found that the mRNA expression of VEGFA, KDR, MAPK14, and PPARA showed significant differences between normal and diabetes mellitus mice, with a retracement after FBT treatment. Conclusion: These results indicated that the hypoglycemic effect of FBT was associated with its anti-inflammatory activities and regulation of lipid metabolism disorders. The exploration of the hypoglycemic mechanism of FBT would be meaningful for its further application and development.

A systemic review on Liubao tea: A time-honored dark tea with distinctive raw materials, process techniques, chemical profiles, and biological activities

Liubao tea (LBT) is a unique microbial-fermented tea that boasts a long consumption history spanning 1500 years. Through a specific post-fermentation process, LBT crafted from local tea cultivars in Liubao town Guangxi acquires four distinct traits, namely, vibrant redness, thickness, aging aroma, and purity. The intricate transformations that occur during post-fermentation involve oxidation, degradation, methylation, glycosylation, and so forth, laying the substance foundation for the distinctive sensory traits. Additionally, LBT contains multitudinous bioactive compounds, such as ellagic acid, catechins, polysaccharides, and theabrownins, which contributes to the diverse modulation abilities on oxidative stress, metabolic syndromes, organic damage, and microbiota flora. However, research on LBT is currently scattered, and there is an urgent need for a systematical recapitulation of the manufacturing process, the dominant microorganisms during fermentation, the dynamic chemical alterations, the sensory traits, and the underlying health benefits. In this review, current research progresses on the peculiar tea varieties, the traditional and modern process technologies, the substance basis of sensory traits, and the latent bioactivities of LBT were comprehensively summarized. Furthermore, the present challenges and deficiencies that hinder the development of LBT, and the possible orientations and future perspectives were thoroughly discussed. By far, the productivity and quality of LBT remain restricted due to the reliance on labor and experience, as well as the incomplete understanding of the intricate interactions and underlying mechanisms involved in processing, organoleptic quality, and bioactivities. Consequently, further research is urgently warranted to address these gaps.

Simultaneous Determination of Pesticide Residues and Mycotoxins in Storage Pu-erh Tea Using Ultra-High-Performance Liquid Chromatography Coupled with Tandem Mass Spectrometry

Mycotoxins and pesticides are the most concerning chemical contaminants that can affect the quality of Pu-erh tea during its production and storage. This study presents a method that can simultaneously determine 31 pesticide residues and six mycotoxins in Pu-erh tea within 11 min using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) after QuEChERS extraction. The lower limit of quantification (LOQ) for all analytes ranged between 0.06 and 50 ppb. Recoveries for each pesticide and mycotoxin ranged between 62.0 and 130.3%, with intra- and inter-day precisions lower than 15%. Good linear relationships were obtained, with correlation coefficients of r2 > 0.991 for all analytes. The established method was applied to 31 Pu-erh tea samples, including raw and ripened Pu-erh tea with different storage times. As a result, pesticide residues were not detected in any of the collected samples, and the mycotoxins detected in the samples were well below the official maximum residue limits (MRLs). Notably, the levels of aflatoxin B1 (AFB1), aflatoxin G1 (AFG1) and aflatoxin G2 (AFG2) were lower than 1 ppb in the samples stored for more than 30 years.

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.

Characterization of volatile metabolites in Pu-erh teas with different storage years by combining GC-E-Nose, GC-MS, and GC-IMS

Storage time is one of the important factors affecting the aroma quality of Pu-erh tea. In this study, the dynamic changes of volatile profiles of Pu-erh teas stored for different years were investigated by combining gas chromatography electronic nose (GC-E-Nose), gas chromatography-mass spectrometry (GC-MS), and gas chromatography-ion mobility spectrometry (GC-IMS). GC-E-Nose combined with partial least squares-discriminant analysis (PLS-DA) realized the rapid discrimination of Pu-erh tea with different storage time (R²Y = 0.992, Q² = 0.968). There were 43 and 91 volatile compounds identified by GC-MS and GC-IMS, respectively. A satisfactory discrimination (R²Y = 0.991, and Q² = 0.966) was achieved by using PLS-DA based on the volatile fingerprints of GC-IMS. Moreover, according to the multivariate analysis of VIP > 1.2 and univariate analysis of p < 0.05, 9 volatile components such as linalool and (E)-2-hexenal were selected as key variables to distinguish Pu-erh teas with different storage years. The results provide theoretical support for the quality control of Pu-erh tea.

Protective effects and molecular mechanisms of tea polyphenols on cardiovascular diseases

Aging is the most important factor contributing to cardiovascular diseases (CVDs), and the incidence and severity of cardiovascular events tend to increase with age. Currently, CVD is the leading cause of death in the global population. In-depth analysis of the mechanisms and interventions of cardiovascular aging and related diseases is an important basis for achieving healthy aging. Tea polyphenols (TPs) are the general term for the polyhydroxy compounds contained in tea leaves, whose main components are catechins, flavonoids, flavonols, anthocyanins, phenolic acids, condensed phenolic acids and polymeric phenols. Among them, catechins are the main components of TPs. In this article, we provide a detailed review of the classification and composition of teas, as well as an overview of the causes of aging-related CVDs. Then, we focus on ten aspects of the effects of TPs, including anti-hypertension, lipid-lowering effects, anti-oxidation, anti-inflammation, anti-proliferation, anti-angiogenesis, anti-atherosclerosis, recovery of endothelial function, anti-thrombosis, myocardial protective effect, to improve CVDs and the detailed molecular mechanisms.

Preparation, Identification and Preliminary Application of the Fenvalerate Monoclonal Antibody in Six Kinds of Dark Tea

Fenvalerate has the advantages of a broad insecticidal spectrum, high efficiency, low toxicity and low cost, and it is widely used in agriculture, especially in tea, resulting in the accumulation of fenvalerate residues in tea and the environment, posing a serious threat to human health. Therefore, the timely monitoring of fenvalerate residue dynamics is vital for ensuring the health of humans and the ecological environment, and it is necessary for establishing a fast, reliable, accurate and on-site method for detecting fenvalerate residues. Based on the methods of immunology, biochemistry and molecular biology, mammalian spleen cells, myeloma cells and mice were used as experimental materials to establish a rapid detection method of an enzyme-linked immunosorbent assay to detect the residues of fenvalerate in dark tea. Three cell lines-1B6, 2A11 and 5G2-that can stably secrete fenvalerate antibodies were obtained by McAb technology, and their sensitivities (IC₅₀) were 36.6 ng/mL, 24.3 ng/mL and 21.7 ng/mL, respectively. The cross-reaction rates of the pyrethroid structural analogs were all below 0.6%. Six dark teas were used to detect the practical application of fenvalerate monoclonal antibodies. The sensitivity IC₅₀ of the anti-fenvalerate McAb in PBS with 30% methanol is 29.12 ng/mL. Furthermore, a latex microsphere immunochromatographic test strip with an LOD of 10.0 ng/mL and an LDR of 18.9-357 ng/mL was preliminarily developed. A specific and sensitive monoclonal antibody for fenvalerate was successfully prepared and applied to detect fenvalerate in dark teas (Pu'er tea, Liupao tea, Fu Brick tea, Qingzhuan tea, Enshi dark tea and selenium-enriched Enshi dark tea). A latex microsphere immunochromatographic test strip was developed for the preparation of rapid detection test strips of fenvalerate.

Compound dark tea ameliorates obesity and hepatic steatosis and modulates the gut microbiota in mice

Dark tea is a fermented tea that plays a role in regulating the homeostasis of intestinal microorganisms. Previous studies have found that dark tea can improve obesity and has a lipid-lowering effect. In this study, green tea, Ilex latifolia Thunb (kuding tea) and Momordica grosvenori (Luo Han Guo) were added to a new compound dark tea (CDT), to improve the taste and health of this beverage. High-fat diet-fed C57BL/6J mice were treated with low- (6 mg/mL) or high- (12 mg/mL) concentrations of CDT for 18 weeks to assess their effect on lipid metabolism. Our results suggest that low- and high-concentrations of CDT could reduce body weight by 15 and 16% and by 44 and 38% of body fat, respectively, by attenuating body weight gain and fat accumulation, improving glucose tolerance, alleviating metabolic endotoxemia, and regulating the mRNA expression levels of lipid metabolism-related genes. In addition, low concentrations of CDT were able to reduce the abundance of Desulfovibrio, which is positively associated with obesity, and increase the abundance of Ruminococcus, which are negatively associated with obesity. This study demonstrates the effect of CDT on ameliorating lipid metabolism and provides new insights into the research and development of functional tea beverages.

Green extraction, chemical composition, and in vitro antioxidant activity of theabrownins from Kangzhuan dark tea

Theabrownins (TBs) in dark tea have received increasing attention for their multiple health benefits. In this study, ultrasound assisted extraction with deep eutectic solvent (UAE-DES) was developed for the extraction of TBs from Kangzhuan dark tea (KZDT). The highest yield (12.59%) of TBs was obtained using UAE-choline (ChCl)/malic acid (MA) with a liquid to solid ratio of 20:1 (v/w), ultrasonic power of 577 W, ultrasonic time of 25 min, and water content of 30%. TBs were further eluded by silica gel to obtain six theabrownine fractions (TBFs), namely, TBFs1, TBFs2, TBFs3, TBFs4, TBFs5, and TBFs6. LC-MS/MS revealed that flavonoids, terpenes, phenolic acids, alkaloids, lipids, and amino acids are the leading components of TBFs. The TBFs4, with the DPPH, ABTS, and FRAP values of 45.08 ± 0.42 μM Ascorbic acid/g DW, 178.52 ± 0.29 μM Trolox/g DW, and 370.85 ± 6.00 μM Fe(II)/g DW, respectively, showed the highest antioxidant activity among all the TBFs. Overall, this study first provided the evidence that UAE-ChCl/MA combining with silica gel was effective to extract TBs from KZDT, and the 6,7-dihydroxycoumarin-6-glucoside and neohesperidin were found as the leading compounds in the TBFs, providing a guidance for the chemical research and further utilization of dark tea and its TBs.

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Yield of TBs of 12.59% from KZDT was achieved by UAE-ChCl/MA.

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Silica gel powder with methanol (100%–0%) as a mobile phase was used for TBs separation.

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The chemical component of TBFs was revealed.

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Flavonoids are among the leading compounds in the TBFs.

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TBFs4 displayed the highest in vitro antioxidant activity.

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.