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BACKGROUND: Large yellow croaker (Larimichthys crocea) is an economical marine fish consumed in China. Theaflavins have antibacterial and antioxidant properties. However, there is a lack of research into their application in large yellow croakers during refrigerated storage. This study investigated the effect of theaflavins on the quality of large yellow croaker (Larimichthys crocea) during 12 days of storage at 4 °C. RESULTS: The results showed that theaflavin treatment was able to inhibit microbial growth and reduce the production of total volatile basic nitrogen (TVB‐N). Meanwhile, theaflavins were beneficial in reducing the unfolding of myofibrillar proteins, decreasing the degree of protein aggregation, and improving the stability of protein structure. The degree of protein oxidation was lower in a theaflavin‐treated group compared with an untreated group. Theaflavin treatment effectively inhibited increases in acid value (AV), peroxide value (PV), and malonaldehyde (MDA) content. The effect of theaflavin was positively correlated with an increase in concentration under refrigeration conditions. This study therefore suggests that the use of theaflavins is a viable method for extending the period for which refrigerated large yellow croaker can be preserved. CONCLUSIONS: Adding theaflavins to large yellow croaker can be an effective method for preserving quality during refrigerated storage. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The mandate of the current investigation was to elucidate the therapeutic and antioxidant perspective of black tea. Purposely, black tea compositional analysis followed by polyphenol extraction and antioxidant characterization was done. Moreover, the theaflavin from black tea extract was also isolated through the solvent partition method. Lastly, the neuroprotective effect of isolated theaflavin was assessed through a bio‐efficacy trial. The outcomes delineated that black tea showed promising nutritional composition with special reference to protein and fiber. Among the extraction solvent, ethanol performed better as compared to methanol and water likewise, higher extraction was noticed at 60 min followed by 90 and 30 min. All the extracts indicated antioxidant activity reflected through significant DPPH, TPC, FRAP, and beta carotene as‐69.13 ± 3.00, 1148.92 ± 14.01, 752.44 ± 10.30, and 65.74 ± 3.28, respectively. However, isolated theaflavin exhibited higher antioxidant capacity as‐737.74 ± 12.55, 82.60 ± 2.33, and 853.77 ± 9.55, for TPC, DPPH, and FRAP, respectively, as compared to extracts. In 15 days' efficacy was physically induced with sciatic nerve injury h sciatic nerve injury physically and treated with isolated theaflavin. A total of 12 healthy albino mice were randomly assigned to either the control (n = 6) or theaflavin (5.0 mg/kg (n = 6)) groups. In these groups, behavioral tests were used to assess and compare enhanced functional recovery as well as skeletal muscle mass measurement. Serum samples included oxidative stress markers. In theaflavin leaves, behavioral tests revealed a statistically significant (p <.001) improvement in sensorimotor function restoration, muscle mass restoration, a substantial decrease in TOS, a significant increase in TAC, and enhanced antioxidative enzyme activity. Considering the above‐mentioned therapeutic perspectives of theaflavin, the current research was planned to optimize the isolation of theaflavin from black tea and probed for their neuroprotective effect in mice models. [ABSTRACT FROM AUTHOR]

Summary: Polyphenol oxidase (PPO) plays an important role in tea production, and there are many studies on the enzymatic synthesis of theaflavins using PPO; however, using a purified PPO isozyme (PPOI) instead of a crude PPO enzyme to obtain monomeric theaflavin in vitro is a novel approach that has rarely been previously reported. In the present study, a tea PPOI was purified and used for the enzymatic synthesis of theaflavin monomers. Tea leaf PPOI was purified 12.90‐fold, with recovery yield of 1.30% via the sequential use of precipitation with 30%−80% saturated (NH4)2SO4, Q‐Sepharose Fast Flow anion exchange chromatography and Sephadex G‐75 gel filtration chromatography. Subsequently, PPOI was used in the enzymatic synthesis of theaflavins: under various pH, temperatures, reaction times and catechin substrate composition and concentration, only the amount of theaflavin components produced was changed, and no other theaflavin component apart from the theaflavin monomer was produced. These results highlight the importance of monomeric theaflavin synthesis using purified PPOI isozyme and provide insight into PPO in the context of tea production. [ABSTRACT FROM AUTHOR]

Tyrosinase is a key metalloenzyme for the biosynthesis of melanin that plays a critical role in the prevention of skin damage caused by ultraviolet (UV) radiation. However, the overproduction of melanin may cause a variety of skin diseases. Due to the toxicity and inefficiency of existing tyrosinase inhibitors, it is urgent to identify safe and potent alternatives from natural sources. Theaflavin, a single‐component extracted from black tea, has been found to possess a variety of pharmacological activities. Herein, the inhibition kinetics of theaflavin on tyrosinase and inhibitory mechanism were determined using spectroscopy, molecular docking, and zebrafish model. The results showed that theaflavin inhibited the diphenolase activity of tyrosinase in a reversible mixed type manner with IC50 of 229.75 μmol/L and hindered the synthesis of melanin in zebrafish. This may be due to the formation of eight hydrogen bonds and hydrophobic effects between theaflavin and tyrosinase according to the results of molecular docking. To study the possible effects on the prevention of free radical‐mediated skin cancer and photoaging caused by UV radiation, the antioxidation and UV filter properties of theaflavin were further verified. This study demonstrates that theaflavin is a potential multifunctional compound that can be used in cosmetic and medicinal products. [ABSTRACT FROM AUTHOR]

BACKGROUND The phenol oxidative pathway during fermentation remains unclear. To elucidate the effect of fermentation on phenol conversion, we investigated the effects of fermentation temperature and duration on the conversion of catechins and the formation of theasinensins (TSs), theaflavins (TFs), thearubigins (TRs), and theabrownins (TBs). RESULTS: During fermentation, TSs formation increased initially and then decreased. Long fermentation durations were unfavorable for liquor brightness (LB) and resulted in the production of large amounts of TRs and TBs. Low fermentation temperatures (20 °C and 25 °C) favored the maintenance of polyphenol oxidase activity and the continuous formation of TFs, TSs, and TRSI (a TRs fraction), resulting in better LB and liquor color. Higher temperatures (30 °C, 35 °C, and 40 °C) resulted in higher peroxidase activity, higher oxidative depletion rates of catechins, and excessive production of TRSII (a TRs fraction) and TBs. Analysis of the conversion pathway of polyphenolic compounds during fermentation showed that, during early fermentation, large amounts of catechins were oxidized and converted to TFs and theasinensin B. As fermentation progressed, considerable amounts of theaflavin‐3′‐gallate, theasinensin A, theaflavin‐3‐gallate, theaflavin‐3,3′‐digallate, and theasinensin C were produced and then converted to TRSI; in the final stage, TRSII and TBs were converted continuously. CONCLUSION: Different fermentation temperature and duration combinations directly affected the type and composition of phenolic compounds. The key conditions for controlling phenolic compound conversion and fermentation direction were 60 or 90 min and 25 or 30 °C. Our study provides insights into the regulation of phenolic compound conversion during black tea fermentation. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Tea, and particularly bottled tea, is widely consumed worldwide and is often encountered at crime scenes in poisoning cases or used in place of urine in drug abuse monitoring. Tea is a rich source of polyphenols, such as catechins and theaflavins, and these compounds are useful for identification of trace quantities of tea samples. However, information on the contents of catechins and theaflavins in bottled tea is limited. In this study, a method was developed for simultaneous analysis of eight catechins and four theaflavins in tea using liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). The concentrations of these polyphenols were determined in bottled black, oolong, and green teas after a simple pretreatment process by the standard addition method. The developed LC‐MS/MS method was rapid and all tested polyphenol compounds were separated within ~14 min. All tea types contained all the catechins, at varying concentrations, but not all the theaflavins were present in all the tea types. This indicates that the theaflavin composition reflects the degree of the fermentation and could be used for discrimination among different types of tea. All the green tea samples contained all eight catechins; however, the concentrations of these compounds varied among the tea samples. Principal component analysis and hierarchical cluster analysis were useful for discrimination of samples. It has been unclear whether the variations of chemical components are useful for forensic discrimination. Our results demonstrate that, in addition to identification of tea varieties, catechins and theaflavins can be used for the discrimination of bottled tea samples. [ABSTRACT FROM AUTHOR]

An outbreak of coronavirus disease 2019 (COVID‐19) occurred in Wuhan and it has rapidly spread to almost all parts of the world. For coronaviruses, RNA‐dependent RNA polymerase (RdRp) is an important protease that catalyzes the replication of RNA from RNA template and is an attractive therapeutic target. In this study, we screened these chemical structures from traditional Chinese medicinal compounds proven to show antiviral activity in severe acute respiratory syndrome coronavirus (SARS‐CoV) and the similar chemical structures through a molecular docking study to target RdRp of SARS‐CoV‐2, SARS‐CoV, and Middle East respiratory syndrome coronavirus (MERS‐CoV). We found that theaflavin has a lower idock score in the catalytic pocket of RdRp in SARS‐CoV‐2 (−9.11 kcal/mol), SARS‐CoV (−8.03 kcal/mol), and MERS‐CoV (−8.26 kcal/mol) from idock. To confirm the result, we discovered that theaflavin has lower binding energy of −8.8 kcal/mol when it docks in the catalytic pocket of SARS‐CoV‐2 RdRp by using the Blind Docking server. Regarding contact modes, hydrophobic interactions contribute significantly in binding and additional hydrogen bonds were found between theaflavin and RdRp. Moreover, one π‐cation interaction was formed between theaflavin and Arg553 from the Blind Docking server. Our results suggest that theaflavin could be a potential SARS‐CoV‐2 RdRp inhibitor for further study. Highlights: Theaflavin has a lower idock score in the catalytic pocket of RdRp in SARS‐CoV‐2, SARS‐CoV and MERS‐CoV from idock.Theaflavin has a lowest binding energy when it docks in the catalytic pocket of SARS‐CoV‐2 RdRp.Theaflavin could be potential SARS‐CoV‐2 RdRp inhibitor. [ABSTRACT FROM AUTHOR]

BACKGROUND In this work, we investigated the antioxidant and copper chelating abilities of theaflavin, a polyphenol responsible for astringency, color, and sensation in black tea. Using voltammetric techniques, the analyses were conducted with disposable electrochemical printed carbon chips in conjunction with a portable hand‐held potentiostat. RESULTS: Voltammograms of theaflavin showed five separate oxidation peaks, corresponding to the oxidation of five individual functional groups. Electroanalytical data indicated that, after interaction with copper, theaflavin had higher antioxidant potential and was a better copper chelator than epigallocatechin gallate, a major polyphenol present in green tea and a well‐known antioxidant. This could be attributed to the extra fused ring and larger number of OH groups in theaflavin. CONCLUSIONS: Our findings introduce another natural compound as a potential nutraceutical in oxidation‐ and copper‐modulated illnesses. This simple and fast approach would also be highly pertinent to the inspection of the health benefits of natural food products. To the best of our knowledge, this is the first report of the electrochemical analysis of Cu (II) chelation with theaflavin. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Theaflavins (TFs) are derived from black tea, an important source of dietary polyphenols. Although the potential interactions between dietary polyphenols and drugs have been demonstrated through in vitro and in vivo studies, little information is available concerning the influence of TFs on drug disposition. Organic anion transporting polypeptide 2B1 (OATP2B1) is expressed in human enterocytes and plays a role in the intestinal absorption of numerous drugs. The current study evaluated the effects of black tea extracts on the pharmacokinetics of rosuvastatin in rats, and investigated the effect of four major TFs (theaflavin, theaflavin‐3‐gallate, theaflavin‐3′‐gallate and theaflavin‐3,3′‐digallate) on the transport activity of OATP2B1. Black tea extracts significantly decreased the maximum plasma concentration (Cmax) and area under the plasma concentration–time curve (AUC0–8) of rosuvastatin by 48% and 37%, respectively (p < 0.001 and p < 0.01, respectively). Moreover, OATP2B1‐mediated rosuvastatin and estrone‐3‐sulfate uptake was significantly reduced in the presence of TFs. A kinetic study revealed that the uptake efficiency (in terms of Vmax/Km) of rosuvastatin was decreased following treatment with TFs. Black tea extracts also reduced OATP2B1‐mediated rosuvastatin uptake. These results suggest that black tea reduces the plasma concentrations of rosuvastatin by inhibiting the intestinal OATP2B1‐mediated transport of rosuvastatin. [ABSTRACT FROM AUTHOR]

BACKGROUND Orthodox tea is known for its distinct aroma and superior quality. However, the oxidation step that is most crucial for developing these attributes needs precise control and is also time consuming. In the present study, a super‐atmospheric oxidation chamber (SOC) was designed to address this issue. Oxidation of hand‐rolled tea leaves was performed at an elevated oxygen concentration inside the SOC. Both pressure and processing time were varied over the ranges 101–303 kPa and 0–150 min, respectively. Theaflavin (TF), thearubigin (TR) and total color (TC) were determined experimentally and then predicted through artificial neuron network (ANN) modeling. RESULTS: An increasing oxygen concentration and attainment of 100% relative humidity in the compressed air was recognized at elevated air pressure. The observed rate of formation or depletion in TF, TR and TC values was faster with compression of the ambient air. The experimental data points were predicted based on an ANN network containing 18, 10 and 16 neurons in the hidden layer since lowest mean square error and mean absolute error values were observed for the given experimental TF, TR and TC values respectively. CONCLUSION: Considering the significant decrease in oxidation duration and minimal mechanized complexity of the design, the set‐up developed in the present study can be upscaled for industrial application in orthodox tea processing. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Background and Objective: Theaflavins (TFs), the major polyphenol in black tea, have the ability to reduce inflammation and bone resorption. The aim of this study was to evaluate the effects of TFs on experimental periodontitis in rats. Material and Methods: Thirty rats were divided into five groups: Control (glycerol application without ligation), Ligature (glycerol application with ligation), TF1 (1 mg/mL TF application with ligation), TF10 (10 mg/mL TF application with ligation), and TF100 (100 mg/mL TF application with ligation). To induce experimental periodontitis, ligatures were placed around maxillary first molars bilaterally. After ligature placement, 100 μL glycerol or TFs were topically applied to the rats daily, and rats were euthanized 7 days after ligature placement. Micro‐computed tomography was used to measure bone resorption in the left side of the maxilla, and quantitative polymerase chain reaction was used to measure the expression of interleukin (IL)‐6, growth‐regulated gene product/cytokine‐induced neutrophil chemoattractant (Gro/Cinc‐1, rat equivalent of IL‐8), matrix metalloproteinase‐9 (Mmp‐9), receptor activator of nuclear factor‐kappa Β ligand (Rankl), osteoprotegerin (Opg), and the Rankl/Opg ratio in gingival tissue. With tissue from the right side of the maxilla, hematoxylin and eosin staining was used for histological analysis, immunohistochemical staining for leukocyte common antigen (CD45) was used to assess inflammation, and tartrate‐resistant acid phosphatase (TRAP) staining was used to observe the number of osteoclasts. Results: The TF10 and TF100 groups, but not the TF1 group, had significant inhibition of alveolar bone loss, reduction in inflammatory cell infiltration in the periodontium, and significantly reduced numbers of CD45‐positive cells and TRAP‐positive osteoclasts compared with the Ligature group. Correspondingly, the TF10 and TF100 groups had significantly downregulated gene expression of IL‐6, Gro/Cinc‐1(IL‐8), Mmp‐9, and Rankl, but not of Opg. Consequently, Rankl/Opg expression was significantly increased in the Ligation group but was attenuated in the TF10 and TF100 groups. Conclusion: The results of this study suggest that topical application of TFs may reduce inflammation and bone resorption in experimental periodontitis. Therefore, TFs have therapeutic potential in the treatment of periodontal disease. [ABSTRACT FROM AUTHOR]

Herbal drinks have been considered among the known groups of functional drinks. The aim of this study was to encapsulate green tea and orange peel extracts using double emulsion followed by complex coacervation to be used in the preparation of a functional drink. All of the microcapsule formulations were spherically prepared without cracks in the walls and their sizes increased by decreasing the ratio of the core to the wall. Microcapsules under the best conditions of this study were used to coat the paper of a bag containing black tea. The results showed that theaflavin and its ratio to thearubigin as the quality indices for black tea have increased in comparison with the sample without encapsulation. This study resulted in the production of encapsulated mixed extracts of green tea and orange peel that can be used later for the preparation of a functional drink. [ABSTRACT FROM AUTHOR]

Background and Objective Over the last 10 years, bioactive plant food compounds have received considerable attention in regard to their beneficial effects against periodontal disease. In this study, we investigated the effects of black tea theaflavins ( TFs) on the virulence properties of Porphyromonas gingivalis and gingival keratinocyte tight junction integrity. In addition, the effects of black tea TFs on the nuclear factor-κB ( NF-κB) signaling pathway and proinflammatory cytokine/matrix metalloproteinase ( MMP) secretion by monocytes/macrophages were assessed. Material and Methods Virulence factor gene expression in P. gingivalis was investigated by quantitative real-time PCR. A fluorescence assay was used to determine P. gingivalis adherence to, and invasion of, a gingival keratinocyte monolayer. Tight junction integrity of gingival keratinocytes was assessed by determination of transepithelial electrical resistance. Proinflammatory cytokine and MMP secretion by P. gingivalis-stimulated macrophages was quantified by ELISA. The U937-3xκB- LUC monocyte cell line transfected with a luciferase reporter gene was used to monitor NF-κB activation. Gelatin degradation was monitored using a fluorogenic assay. Results Black tea TFs dose-dependently inhibited the expression of genes encoding the major virulence factors of P. gingivalis and attenuated its adherence to gingival keratinocytes. A treatment of gingival keratinocytes with black tea TFs significantly enhanced tight junction integrity and prevented P. gingivalis-mediated tight junction damage as well as bacterial invasion. Black tea TFs reduced the secretion of interleukin ( IL)-1β, tumor necrosis factor-α, IL-6, chemokine (C-X-C) ligand 8, MMP-3, MMP-8 and MMP-9 by P. gingivalis-stimulated macrophages and attenuated the P. gingivalis-mediated activation of the NF-κB signaling pathway. Lastly, black tea TFs inhibited gelatin degradation by MMP-9. Conclusion This study provides clear evidence that black tea TFs represent promising multifunctional therapeutic agents for prevention and treatment of periodontal disease. [ABSTRACT FROM AUTHOR]

In vertebrates and invertebrates, relationships between diet and health are controlled by a conserved signalling pathway responsive to insulin-like ligands. In invertebrate models for example, forkhead transcription factor family O (FOXO) transcription factors in this pathway regulate the rate of aging in response to dietary cues, and in vertebrates, obesity and age-induced deficits in the same pathway are thought to contribute to dysregulation of hepatic gluconeogenesis through genes such as phosphoenolpyruvate carboxykinase (PEPCK). Recently, we have begun to screen for dietary constituents capable of regulating this pathway in our cell culture model. Here, we identify three black tea theaflavins, theaflavin 3- O-gallate, theaflavin 3′- O-gallate, theaflavin 3,3′di- O-gallate and thearubigins as novel mimics of insulin/IGF-1 action on mammalian FOXO1a, PEPCK and moreover we provide evidence that the effects on this pathway of the green tea constituent (-)-epigallocatechin gallate depend on its ability to be converted into these larger structures. With the exception of water, tea is the most popular drink globally, but despite this, little is known about the biological availability of black tea polyphenols in vivo or the molecular target(s) mediating the effects presented here. Further investigation in these two areas might provide insight into how age-related metabolic disease may be deferred. [ABSTRACT FROM AUTHOR]