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

Investigating the modulatory effects of Pu-erh tea on the gut microbiota in ameliorating hyperuricemia induced by circadian rhythm disruption

Circadian rhythm disruption (CRD) can induce a variety of metabolic disorders. Our previous laboratory studies have shown that Pu-erh tea could alleviate CRD-induced syndromes, including obesity, intestinal dysfunction, and tryptophan metabolism disorders. However, its potential protective mechanism against CRD-induced hyperuricaemia remains unclear. In this work, we found that polyphenols of Pu-erh tea were significantly released in the stage of intestinal digestion, which might promote their interaction with gut microbes. Through animal experiments, C57BL6/J mice were given water or different doses of Pu-erh tea for 60 days, followed by a 90-day CRD, the lifestyle of modern individuals who frequently stay up late. Our results indicated that CRD mice exhibited high serum uric acid levels and gut microbiota disorders. Pu-erh tea intake significantly reshaped the gut microbiome, especially increasing the abundance of Bifidobacterium, Akkermansia and Faecalibaculum, and increased the production of short-chain fatty acids (SCFAs), especially acetic acid, which restored the function of the intestinal barrier. This improvement further regulated oxidative stress pathways (NRF2/HO-1), reduced systemic inflammatory response (IL-6, IL-1β, and TNF-α), restored hepatic function (SOD, MOD, CAT, and GSH) and modulated the activity of enzymes related to UA metabolism in the liver (XOD and ADA). Finally, Pu-erh tea intake promoted the excretion of UA and reduced the levels of UA and xanthine in the serum. Moreover, the results of antibiotic experiments showed that the UA improvement effect of Pu-erh tea depended on the existence of the gut microbiota. Collectively, Pu-erh tea intake has the potential to prevent CRD-induced hyperuricaemia by reshaping the gut microbiota.

Phytochemicals from fractioned dark tea water extract enhance the digestive enzyme inhibition, antioxidant capacities and glucose-lipid balance

Dark tea has long been recognized for its health-promoting benefits, attributed to its complex phytochemical composition. However, the specific bioactive compounds responsible for these beneficial effects remain inadequately characterized. This study aimed to explore the impact of dark tea water extract (DTE) on digestive enzyme activity, antioxidant capacity, and glucose-lipid balance. DTE was fractioned into four fractions using gel separation, followed by analysis with high-performance liquid chromatography and quasi-targeted metabolomics. The 30 % ethanol elution (EEA) and 50 % ethanol elution (EEB) fractions showed stronger antioxidant and enzyme inhibition effects compared to the whole DTE. The EEA fraction was rich in 5 catechins and 26 additional phytochemicals, while the EEB fraction contained high levels of caffeine, ECG, and 29 other phytochemicals. Notably, significant correlations were observed between quercetin-3,4'-O-di-β-glucopyranoside and 3-(2-Naphthyl)-L-alanine with digestive enzyme inhibition. Cellular studies revealed the ability of EEA and EEB to reduce lipid accumulation, improve glycolipid metabolism, and alleviate oxidative stress by increasing SOD, CAT, and GSH levels while decreasing MDA and ROS in HepG2 cells. Furthermore, 34 flavonoids, 2 alkaloids, 2 terpenes, 2 alcohols and polyols, 2 phenylpropanoids and polyketides, 1 organoheterocyclic compound were directly linked to the antioxidant activity and the modulation of glucose and lipid levels. These findings offer valuable insights into the phytochemical profiles of dark tea and its potential health benefits.

The Preventive Effect of Theabrownin from Ya'an Tibetan Tea Against UVB-Induced Skin Photodamage in BALB/c Mice via the MAPK/NF-κB and Nrf2 Signaling Pathways

Ya'an Tibetan tea, renowned as a mysterious tea, has been used as a traditional remedy for disease prevention among ethnic minorities in the Qinghai-Tibet Plateau region, which experiences the highest levels of UVB radiation in the world, for over 1000 years. Theabrownin (TB) from Ya'an Tibetan tea exhibits various health benefits. In this study, the preventive effects of TB on UVB-induced skin damage were investigated. The results showed that TB pretreatment significantly alleviated visible skin damage, epidermal hyperplasia, and collagen destruction in BALB/c mice. The mechanism of action involved increasing the mRNA and protein levels of Nrf2 and enhancing SOD enzyme activity, thereby reducing MDA content and improving the body's antioxidant capacity. TB also inhibited the protein synthesis of inflammatory factors such as TNF-α, IL-1β, and IL-6, as well as the expression of NF-κB mRNA and protein, thereby reducing skin inflammation. Furthermore, it suppressed the overexpression of p38 MAPK, ERK, and AP-1 mRNA and protein, along with the downstream MMP-1 protein, to prevent collagen destruction in the skin. Additionally, TB pretreatment prevented cell apoptosis by reducing Caspase-3 overexpression. These results suggest that TB can prevent UVB-induced photodamage and exert its preventive effects in a dose-dependent manner by downregulating the MAPK/NF-κB signaling pathway while promoting the Nrf2 signaling pathway in the skin. Consequently, TB holds promising potential for future applications in skin photodamage prevention and skin health promotion.

Metabolic function and quality contribution of tea-derived microbes, and their safety risk in dark tea manufacture

Microbial fermentation, especially the microbes involved, plays a crucial role in the quality formation of dark tea. Over the last decade, numerous microbes have been isolated from dark tea and in turn, applied to dark tea manufacture through pure-strain, mixed-strain, and enhanced fermentation. This article systematically summarizes the specific metabolic function and quality contribution of tea-derived microbes, with special attention paid to their safety risk. Aspergillus niger converts catechins via hydrolysis, addition, oxidative polymerization, and B-ring fission, contributing greatly to the reddish-brown color and mellow taste of dark tea. Aspergillus sydowii and Penicillium simplicissimum are caffeine-degrading microbes, degrading caffeine mainly into theophylline. However, under adverse conditions, Aspergillus, Penicillium, and Fusarium species potentially produce aflatoxins, ochratoxin A, and citrinin, the mycotoxins occurring in dark tea. The in-depth knowledge of tea-derived microbes is important for improving the quality and safety of dark tea, providing a theoretical basis for its industrial modernization.

Characterisation of the phytochemical and bioactivity profiles of raw tea, stale-aroma, and betelnut-aroma type of Liupao tea through GC/LC-MS-based metabolomics

Liupao tea (LPT) is a Chinese dark tea known to possess a unique flavour. Microbial fermentation plays a crucial role in flavour development and enrichment. Currently, the phytochemical profiles and bioactivities of LPT with and without fermentation are not fully known. In this study, we compared the chemical composition of raw tea (SF), stale-aroma (SA), and betelnut-aroma (BA) type LPT through the application of GC/LC-MS-based metabolomics, and experimentally investigated their bioactivities via antioxidant, anti-inflammatory, hypolipidemic, and hypoglycemic assays in vitro. The results indicated that fermentation enhanced the flavour of LPT as evidenced by the sweetness-producing substances, decreased bitterness and astringency-related compounds and enriched abundance of aroma-generating compounds. Two and four volatiles were detected to be major contributors to the aroma in SA and BA, respectively. Fatty acids and phosphatidylcholines were the primary lipids, among which the lysing diacylglycerol trimethyl homoserines were found to be a new class of lipids in LPT. Notably, the fermentation resulted in the degradation of compounds, particularly glycerophospholipids and saccharolipids. SF had the highest level of bioactivity, followed by BA and SA. These findings expand the present understanding regarding the development of flavour, nutrition, and medicinal value of LPT. Moreover, they provide a theoretical basis for the identification of BA and SA and serve as a reference value for consumers in their selection of LPT products.

Mechanism study on the enhancement of bile acid-binding capacity in corn by-product juice via Lactiplantibacillus plantarum HY127 fermentation

Hyperlipidemia is a common endocrine metabolic disease in humans. Long-term medications often have adverse effects, making the search for safer and more effective treatments crucial. This study aimed to explore the impacts and mechanisms of Lactiplantibacillus plantarum HY127 fermentation on enhancing bile acid-binding capacity (BABC). We fermented corn by-product juice (CBJ) by HY127 and investigated the BABC of HY127 bacterial cells and their metabolites. Our results indicated that HY127 cells (95.25 %) played a major role in enhancing BABC, with metabolites (31.50 %-66.41 %) also contributing. Compared to unfermented CBJ, the contents of phenolics, flavonoids, polysaccharides, and organic acids were significantly higher. Non-targeted metabolomics revealed upregulated amino acids, alkaloids, terpenoids, and other bioactive substances associated with BABC in the supernatant. This study confirmed that HY127 fermentation enhances the BABC of CBJ (increased by 32.02 %-78.76 %), providing a research foundation and technical reference for the development of LAB-fermented corn by-product beverages with hypolipidemic activities.

Chemical profile and in-vitro bioactivities of three types of yellow teas processed from different tenderness of young shoots of Huoshanjinjizhong (Camellia sinensis var. sinensis)

In the present study, bud yellow tea (BYT), small-leaf yellow tea (SYT) and large-leaf yellow tea (LYT) were produced from the same local "population" variety Huoshanjinjizhong (Camellia sinensis var. sinensis), and the effects of raw material tenderness on the chemical profile and bioactivities of these teas were investigated. The results showed that 11 crucial compounds were screened by headspace solid-phase microextraction-gas chromatography-mass spectrometry from 64 volatiles in these yellow teas, among which the heterocyclic compounds showed the greatest variations. In addition, 43 key compounds including organic acids, flavan-3-ols, amino acids, saccharides, glycosides and other compounds were screened by liquid chromatography-mass spectrometry from 1781 non-volatile compounds. BYT showed the best α-glucosidase inhibitory activity and antioxidant capacity among the selected yellow teas, which might be contributed by the higher content of galloylated catechins. These findings provided a better understanding of the chemical profile and bioactivities of yellow teas.

Characterization of the influence of extraction factors on instant Pu-erh tea: Focusing on changes in sensory quality and aroma profile

The objective of this study is to explore the influence of extraction factors, including extraction temperatures, extraction time, and tea-water ratios, on the sensory quality and aroma characteristics of instant Pu-erh tea (IPET). Sensory evaluation, quantitative descriptive analysis (QDA) and HS-SPME-GC × GC-TOF/MS were utilized for analysis. The result showed that the optimal process condition of IPET was a tea-to-water ratio 1:8, an extraction temperature 75 °C, and an extraction time 60 min. A total of 235 volatile compounds were identified and 65 key odor-active compounds with ROAV>1 in all samples. Based VIP > 1, 19 key differential odor-active compounds were identified, including linalool oxide I, 1-dodecanol, linalool oxide II, etc. Further Pearson correlation analysis of key differential odor-active compounds and aroma characteristics showed that positive correlations between woody and ethyl nonanoate and 1-dodecanol, and between herbal and 1-methylnaphthalene. This research provides theoretical support for the production of high-quality IPET.

Impact of the long-term storage on flavor quality of Liupao tea using sensory evaluation combined with metabolomics analysis

This study comprehensively investigated the impact of different storage times on the quality and metabolomic profiles of Liupao tea (LPT). The sensory evaluations revealed that both Maosheng (MS) and Tianyu (TY) teas exhibited a browning of tea appearance and brightening of tea infusion during storage. The taste evolved from bitterness and astringency to purity and briskness, while the aroma shifted from stuffy to woody and aged aromas. Notably, MS teas exhibited superior sensory quality after 10 years, while TY teas reached optimal quality in the 8th year of storage. Correlation analysis of metabolites and sensory attributes has underscored the integral influence of metabolites throughout the storage process, which significantly directed the development of tea quality. The non-volatile metabolites exerted significant influence on tea flavor by modulating key biochemical pathways, including the oxidation of catechins, the formation of alkaloids as well as the glycosylation and/or methylation of flavonoids. However, TY teas experienced both glycosylation and methylation, which promoted the transformation of bitterness and astringency, achieving a mellow and brisk taste more quickly than MS teas. The transformation pathways of volatile metabolites potentially involved the hydrolysis of linalool glycosides and phenylethanol glycosides, the synthesis of sesquiterpenes, the methylation of gallic acid and the degradation of carotenoids. However, the divergent trends observed in ketones and aldehydes between the two types of tea could culminate in distinct aromatic profiles, which might be due to different metabolic pathways or differences in the rates of metabolite formation and degradation during storage. Additionally, the antioxidant analysis revealed that both MS and TY teas exhibited a parabolic trend in comprehensive antioxidant capacity during storage, which primarily influenced by the oxidative polymerization of phenolic compounds and the glycosylation of flavonoids. In summary, this study emphasized the multifaceted attributes of tea quality and the importance of metabolites in shaping sensory quality and health properties. It was found that the optimal storage time of 8 to 10 years for LPT was conducive to attaining a desirable balance of flavor and health benefits.

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.

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.

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.