Anti-inflammatory activity and molecular mechanism of Oolong tea theasinensin

Differential effects of theasinensins and epigallocatechin-3-O-gallate on phospholipid bilayer structure and liposomal aggregation

(-)-Epigallocatechin-3-O-gallate (EGCg), the major catechin responsible for the health-enhancing and disease-preventive effects of green tea, is susceptible to auto-oxidation at physiological pH levels. However, whether the oxidized EGCg resulting from its oral consumption possesses any bioactive functions remains unclear. This study presents a differential analysis of intact and oxidized EGCg regarding their interactions with phosphatidylcholine liposomes, serving as a simple biomembrane model. In the presence of ascorbic acid, pre-oxidized EGCg induced liposomal aggregation in a dose-dependent manner, whereas intact EGCg did not. Toxicity evaluation using calcein-loaded liposomes revealed that liposomal aggregation is associated with minimal membrane damage. Through fractionation of the oxidized EGCg sample, the fraction containing theasinensins showed high liposomal aggregation activity. Overall, these results suggest that oxidatively condensed EGCg dimers may stimulate various cells by altering the plasma membrane in a manner different from that of EGCg monomers.

Changes in amino acids, catechins and alkaloids during the storage of oolong tea and their relationship with antibacterial effect

The storage process has a significant impact on tea quality. Few is known about effect of storage on quality of oolong tea. This study aimed to assess the effect of different storage times on the key chemical components of oolong tea by measuring changes in catechin, free amino acid, and alkaloid content. Variation in the main substances was determined by principal component analysis and heat map analysis. The results revealed notable effects of the storage process on the levels of theanine, epigallocatechin gallate (EGCG), and glutamine. These findings suggest that these compounds could serve as indicators for monitoring changes in oolong tea quality during storage. Additionally, the study observed an increase in the antibacterial ability of tea over time. Correlation analysis indicated that the antibacterial ability against Micrococcus tetragenus and Escherichia coli was influenced by metabolites such as aspartic acid, threonine, serine, gamma-aminobutyric acid, ornithine, alanine, arginine, and EGCG. Overall, this study presents an approach for identifying key metabolites to monitor tea quality effectively with relatively limited data.

Camellia sinensis Assisted Synthesis of Copper Oxide Nanoparticles (CuONPs) and Assessment of Its Antioxidant Activity and Zebrafish Embryonic Toxicology Evaluation

BACKGROUND

- Camellia sinensis, or oolong tea, is a partially fermented version of tea used in Asian countries. The remarkable reduction activity of the tea extract can potentially be used for synthesizing nanoparticles. Recently, Camellia sinensis has gained popularity for the formulation of some metal nanoparticles. Aim To formulate green synthesis of copper oxide nanoparticles (CuONPs) mediated by Camellia sinensis (oolong tea) and assess its cytotoxicity and antioxidant properties. Materials & Methods Oolong tea extract is prepared and added to CuSO4 solution to synthesize CuO nanoparticles (CuONPs). The centrifugation pellet of CuONPs is collected and subjected to DPPH (2,2 - diphenyl -1- picrylhydrazyl hydrate) and H2O2 assays. The cytotoxicity screening is performed using zebrafish embryos. Results The reducing activity of oolong tea successfully synthesizes the copper nanoparticles. High values are obtained in DPPH (63% inhibition at 10µL concentration, 73% inhibition at 20µL, 80% at 30µL, 85% at 40µL and 90% at 50µL concentrations) and H2O2 (50% inhibition at 10µL concentration, 65% at 20µL, 68% at 30µL, 75% at 40µL and 80% at 50µL concentrations) assays. There are no morphological deformities in the zebrafish and no loss of cell viability or delayed hatching at low concentrations (below 4-8 µL), as shown by the viable embryos with no morphological deformities. Conclusion The study has evidenced high antioxidant activity and minimal cytotoxicity of CuO nanoparticles produced using Camellia sinensis, thus proving it to be a good biomaterial for a wide range of biological applications.

Construction of curcumin-fortified juices using their self-derived extracellular vesicles as natural delivery systems: grape, tomato, and orange juices

Different fruit and vegetable juices were first used to encapsulate curcumin to improve its solubility, stability, and bioaccessibility, which is expected to enable designing of polyphenol-enriched beverages and impact human health and well-being. Briefly, fruit and vegetable-derived extracellular vesicles usually serve as transport and communication tools between different cells, which means they also may be utilized as delivery carriers for other bioactive agents. Curcumin, as a model polyphenol with many physiological activities, typically has low water-solubility, stability, and bioaccessibility. Therefore, extracellular vesicles were applied to load curcumin to overcome these challenges and to facilitate its incorporation into fruit and vegetable juices. Three kinds of curcumin-loaded fruit and vegetable juices, including curcumin-loaded grape (Cur-G), tomato (Cur-T), and orange (Cur-O) juices, exhibited higher encapsulation efficiency (>80%) than others. The patterns of XRD and FTIR confirmed that curcumin moved into extracellular vesicles in the amorphous form and that the hydrogen bonding force was found between them. Three kinds of fruit and vegetable juices can significantly enhance the solubility, stability and bioavailability of curcumin, but the degrees of improvement are different. For instance, Cur-O exhibited the highest encapsulation efficiency, chemical stability, and effective bioaccessibility than Cur-G and Cur-T. In summary, this study shows that natural fruit and vegetable juices can effectively improve the solubility, stability and bioaccessibility of active polyphenols, which is expected to enable successful designing of nutrient-enriched beverages with a simple method according to various needs of people and be directly applied to food processing and home production.

Cellular Uptake of Epigallocatechin Gallate in Comparison to Its Major Oxidation Products and Their Antioxidant Capacity In Vitro

Depletion of reactive oxygen species and reduction of oxidative stress have been identified as key parameters in the prevention of cellular aging. In previous in vitro studies, the tea catechin epigallocatechin gallate (EGCG) was found to have both pro- and antioxidant properties, disregarding the low stability under cell culture conditions. Besides hydrogen peroxide, theasinensin dimers amongst other oxidation products are formed. Exact quantities, cellular uptake and antioxidant capacities of these dimeric oxidation products remain unknown. Via high-performance liquid chromatography (HPLC) coupled with tandem mass spectrometry (MS/MS), formation kinetics and cellular uptake of EGCG and its major oxidation products are quantified. The antioxidant capacity is determined on a cellular level using a modified dichlorofluorescein (DCF) approach. As a first result, oxidation product quantities of up to 21 µM each are measured after incubation of 50 µM EGCG. While EGCG is taken up equimolarly, its major oxidation products are accumulated in hepatocarcinoma HepG2 cells at millimolar concentrations, especially theasinensin A (TSA). Lastly, the oxidation products show higher antioxidant properties than the monomer EGCG. In correlation with cellular uptake, TSA displays the highest capacity of all tested analytes. The findings reveal the strong influence of EGCG oxidation products on its bioactivity in vitro.

Anti-SARS-CoV-2 activity of various PET-bottled Japanese green teas and tea compounds in vitro

The outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a serious threat to global public health. The emergence of SARS-CoV-2 variants is a significant concern regarding the continued effectiveness of vaccines and antiviral therapeutics. Thus, natural products such as foods, drinks, and other compounds should be investigated for their potential to treat COVID-19. Here, we examined the in vitro antiviral activity against SARS-CoV-2 of various polyethylene terephthalate (PET)-bottled green Japanese teas and tea compounds. Six types of PET-bottled green tea were shown to inhibit SARS-CoV-2 at half-maximal inhibitory concentrations (IC₅₀) of 121- to 323-fold dilution. Our study revealed for the first time that a variety of PET-bottled Japanese green tea drinks inhibit SARS-CoV-2 infection in a dilution-dependent manner. The tea compounds epigallocatechin gallate (EGCG) and epicatechin gallate showed virucidal activity against SARS-CoV-2, with IC₅₀ values of 6.5 and 12.5 µM, respectively. The investigated teas and tea compounds inactivated SARS-CoV-2 in a dose-dependent manner, as demonstrated by the viral RNA levels and infectious titers. Furthermore, the green teas and EGCG showed significant inhibition at the entry and post-entry stages of the viral life cycle and inhibited the activity of the SARS-CoV-2 3CL-protease. These findings indicate that green tea drinks and tea compounds are potentially useful in prophylaxis and COVID-19 treatment.

Gut Microbiota as a Novel Tool to Dissect the Complex Structures of Black Tea Polymers

Thearubigins, polymers of tea catechins, account for more than 20% of the black tea polyphenols and have been reported to be the active components in black tea. However, the chemical structures and underlying mechanisms regarding how the thearubigins, being poorly bioavailable, generate in vivo health benefits are still largely unknown. Using germ-free and specific pathogen-free husbandry conditions combined with LC/MS-based nontargeted and targeted metabolomic analyses, we investigated the role of intestinal bacteria in thearubigin metabolism. Theaflavins and theasinensins were identified as the major microbial metabolites of thearubigins, suggesting that these molecules are the building units for the complex thearubigins. To further confirm this, thearubigin depolymerization was done using menthofuran in an acidic condition. Menthofuran-conjugated theaflavins, theasinensins, and catechins as well as their free forms were detected as the major degradation products of thearubigins. This indicated that theaflavins and theasinensins could be further polymerized through B-type proanthocyanidin linkages. Furthermore, four microbial degradation products were able to be detected in urine samples, suggesting that they can be absorbed into the circulatory system. Using the combination of microbial degradation, metabolomics, and chemical degradation, our results demonstrate that thearubigins are the complex polymers of theaflavins, theasinensins, and catechins and can be metabolized by gut microbiota to their corresponding bioactive and bioavailable smaller molecular metabolites.

Anti-Inflammatory Effects of Camellia fascicularis Polyphenols via Attenuation of NF-κB and MAPK Pathways in LPS-Induced THP-1 Macrophages

Purpose

Plant polyphenols possess beneficial functions against various diseases. This study aimed to identify phenolic ingredients in Camellia fascicularis (C. fascicularis) and investigate its possible underlying anti-inflammatory mechanism in lipopolysaccharide (LPS)-induced human monocytes (THP-1) macrophages.

Methods

C. fascicularis polyphenols (CFP) were characterized by ultra-performance liquid chromatography (UPLC) combined with quadrupole-time-of-flight mass/mass spectrometry (Q-TOF-MS/MS). The THP-1 cells were differentiated into macrophages under the stimulation of phorbol 12-myristate 13-acetate (PMA) and then treated with LPS to build a cellular inflammation model. The cell viability was detected by CCK-8 assay. The levels of reactive oxygen species (ROS) were assessed by flow cytometry. The secretion and expression of inflammatory cytokines were tested by enzyme-linked immunosorbent assay (ELISA) and real-time polymerase chain reaction (RT-PCR). In addition, the nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways were analyzed by Western blotting.

Results

Twelve phenolic constituents including (–)-epicatechin, casuariin, agastachoside, etc. in CFP were identified. The CCK-8 assay showed that CFP exhibited no significant cytotoxicity between 100 and 300 μg/mL. After treated with CFP, the release of ROS was significantly suppressed. CFP inhibited inflammation in macrophages by attenuating the polarization of LPS-induced THP-1 macrophages, down-regulating the expression of the pro-inflammatory cytokines IL-6, IL-1β and TNF-α, and up-regulating the expression of the anti-inflammatory cytokine IL-10. Western blotting experiments manifested that CFP could markedly inhibit the phosphorylation of p65, ERK and JNK, thereby suppressing the activation of NF-κB and MAPK signaling pathways.

Conclusion

These findings indicated that CFP exerted anti-inflammatory activity by inhibiting the activation NF-κB and MAPK pathways which may induce the secretion of pro-inflammatory cytokines. This study offers a reference for C. fascicularis as the source of developing natural, safe anti-inflammatory agents in the future.

Assessment of Antioxidant, Immunomodulatory Activity of Oxidised Epigallocatechin-3-Gallate (Green Tea Polyphenol) and Its Action on the Main Protease of SARS-CoV-2—An In Vitro and In Silico Approach

Owing to the instability of Epigallocatechin Gallate (EGCG), it may undergo auto-oxidation and form oxidised products or dimers. In the present study, we aimed to evaluate the therapeutic effects, including antioxidation and immunomodulatory action, of the Oxidised Epigallocatechin Gallate (O-EGCG) as compared to native EGCG and the action of these compounds on main protease (Mpro) docking against SARS-CoV-2. HCT-116 (Human Colon Cancer) cell lines were used to estimate the total antioxidant capacity and lipid peroxidation levels and pro-inflammatory markers (human IL-6, IL-1β, TNF-α). Further, molecular docking analysis was performed by AutoDock and visualised in Discovery studio. Improved antioxidant capacity of O-EGCG was observed, and there was a significant decrease in the inflammatory markers (IL-1β, IL-6, and TNF-α) when O-EGCG was applied as compared to EGCG. The O-EGCG was shown to be strongly associated with the highest docking score and active site residues of IL-1, IL-6, and TNF- α, as well as the Mpro of SARS-CoV-2, according to in silico approach. The in vitro and in silico analyses indicate an improved therapeutic action of the oxidised form of EGCG. The effective inhibitory action of O-EGCG against SARS-CoV-2 suggests further exploration of the compound against COVID-19 and its efficacy. However, in vivo studies and understanding of the mechanism of action of O-EGCG may yield a better opinion on the use of O-EGCG and future human clinical trials.

Sensory and chemical characteristics of Tieguanyin oolong tea after roasting

Roasting, a critical process for oolong tea, has been applied to Tieguanyin tea to improve flavor attributes. To investigate the effects of the roasting on the flavor of Tieguanyin, the global metabolomics analysis on the non-volatile and volatile components were proceeded. The weakening of bitterness and astringency, caused by roasting, may be attributed to the decreasing of flavonoids glycosides and procyanidins, whereas the enhancing of sweet aftertaste to the increasing of gallic acid. Besides, l-theanine flavan-3-ols adducts (N-ehtyl-2-pyrrolidinone substituted flavan-3-ols) increased dramatically at 130 °C compared with 105 °C, with the reduction of l-theanine and flavan-3-ols. Meanwhile, high temperature hampered the volatiles' diversity and intensity, resulting from the lowering of floral volatiles, i.e., β-ionone, jasmine, and nerolidol, yet the nitrogen-containing heterocyclic compounds increased, e.g., pyrroles and pyrazines. The results can help to comprehensively understand the influences of roasting technology on the flavor and chemistry of oolong tea.

New insights into the influences of baking and storage on the nonvolatile compounds in oolong tea: A nontargeted and targeted metabolomics study

A nontargeted and targeted metabolomics method was applied to comprehensively investigate the influences of baking and storage on chemical constituents in fresh-, strong-, and aged-scent types of Foshou oolong teas. The contents of N-ethyl-2-pyrrolidone-substituted flavanols (EPSFs), flavone C-glycosides, gallic acid, and most lipids increased after baking and storage, while the contents of cis-flavanols, alkaloids, flavonol O-glycosides, and most amino acids decreased. Degradation, epimerization, and interaction with theanine were main pathways for the decrease in cis-flavanols. Approximately 20.7%, 12.8%, and 11.6% of epigallocatechin gallate were degraded, epimerized, and interacted with theanine after baking, respectively; 22.5% and 8.71% of epigallocatechin gallate were degraded and interacted with theanine after 10-year storage, respectively. Simulated reactions confirmed that the increases in EPSFs and apigenin C-glycosides were caused by interactions between theanine and flavanols and between apigenin aglycone and glucose, respectively. This study offers novel insights into chemical changes during baking and storage of oolong tea.

Molecular mechanisms underlying health benefits of tea compounds

Tea is one of the three most widely consumed beverages in the world, not only because of its unique flavor but also due to its various health benefits. The bioactive components in tea, such as polyphenols, polysaccharides, polypeptides, pigments, and alkaloids, are the main contributors to its health functions. Based on epidemiological surveys, the consumption of tea and its compounds in daily life has positive effects on cardiovascular diseases, cancers, hepatopathy, obesity, and diabetes mellitus. In experimental studies, the antioxidant, anti-inflammatory, anti-cancer, anti-obesity, cardiovascular protective, liver protective, and hypoglycemic activities of tea and the related mechanisms of action have been widely investigated. The regulation of several classical signaling pathways, such as nuclear factor-κB (NF-κB), AMP activated protein kinase (AMPK), and wingless/integrated (Wnt) signaling, is involved. Clinical trials have also demonstrated the potential of tea products to be applied as dietary supplements and natural medicines. In this paper, we reviewed and discussed the recent literature on the health benefits of tea and its compounds, and specifically explored the molecular mechanisms involved.

Antimelanogenesis Effects of Theasinensin A

Theasinensin A (TSA) is a major group of catechin dimers mainly found in oolong tea and black tea. This compound is also manufactured with epigallocatechin gallate (EGCG) as a substrate and is refined after the enzyme reaction. In previous studies, TSA has been reported to be effective against inflammation. However, the effect of these substances on skin melanin formation remains unknown. In this study, we unraveled the role of TSA in melanogenesis using mouse melanoma B16F10 cells and normal human epidermal melanocytes (NHEMs) through reverse transcription polymerase chain reaction (RT-PCR), Western blotting analysis, luciferase reporter assay, and enzyme-linked immunosorbent assay analysis. TSA inhibited melanin formation and secretion in α-melanocyte stimulating hormone (α-MSH)-induced B16F10 cells and NHEMs. TSA down-regulated the mRNA expression of tyrosinase (Tyr), tyrosinase-related protein 1 (Tyrp1), and Tyrp2, which are all related to melanin formation in these cells. TSA was able to suppress the activities of certain proteins in the melanocortin 1 receptor (MC1R) signaling pathway associated with melanin synthesis in B16F10 cells: cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB), protein kinase A (PKA), tyrosinase, and microphthalmia-associated transcription factor (MITF). We also confirmed α-MSH-mediated CREB activities through a luciferase reporter assay, and that the quantities of cAMP were reduced by TSA in the enzyme linked immunosorbent assay (ELISA) results. Based on these findings, TSA should be considered an effective inhibitor of hyperpigmentation.

Significant Inactivation of SARS-CoV-2 In Vitro by a Green Tea Catechin, a Catechin-Derivative, and Black Tea Galloylated Theaflavins

Potential effects of tea and its constituents on SARS-CoV-2 infection were assessed in vitro. Infectivity of SARS-CoV-2 was decreased to 1/100 to undetectable levels after a treatment with black tea, green tea, roasted green tea, or oolong tea for 1 min. An addition of (-) epigallocatechin gallate (EGCG) significantly inactivated SARS-CoV-2, while the same concentration of theasinensin A (TSA) and galloylated theaflavins including theaflavin 3,3'-di-O-gallate (TFDG) had more remarkable anti-viral activities. EGCG, TSA, and TFDG at 1 mM, 40 µM, and 60 µM, respectively, which are comparable to the concentrations of these compounds in tea beverages, significantly reduced infectivity of the virus, viral RNA replication in cells, and secondary virus production from the cells. EGCG, TSA, and TFDG significantly inhibited interaction between recombinant ACE2 and RBD of S protein. These results suggest potential usefulness of tea in prevention of person-to-person transmission of the novel coronavirus.

Rapid Inactivation In Vitro of SARS-CoV-2 in Saliva by Black Tea and Green Tea

Saliva plays major roles in the human-to-human transmission of SARS-CoV-2. If the virus in saliva in SARS-CoV-2-infected individuals can be rapidly and efficiently inactivated by a beverage, the ingestion of the beverage may attenuate the spread of virus infection within a population. Recently, we reported that SARS-CoV-2 was significantly inactivated by treatment with black tea, green tea, roasted green tea and oolong tea, as well as their constituents, (-) epigallocatechin gallate (EGCG), theasinensin A (TSA), and galloylated theaflavins. However, it remains unclear to what extent tea inactivates the virus present in saliva, because saliva contains various proteins, nitrogenous products, electrolytes, and so on, which could influence the antivirus effect of tea. Here, we assessed whether tea inactivated the SARS-CoV-2 which was added in human saliva. A virus was added in healthy human saliva in vitro, and after treatment with black tea or green tea, the infectivity of the virus was evaluated by TCID₅₀ assays. The virus titer fell below the detectable level or less than 1/100 after treatment with black tea or green tea for 10 s. The black tea-treated virus less remarkably replicated in cells compared with the untreated virus. These findings suggest the possibility that the ingestion of tea may inactivate SARS-CoV-2 in saliva in infected individuals, although clinical studies are required to determine the intensity and duration of the anti-viral effect of tea in saliva in humans.

Bipolaricins A-I, Ophiobolin-Type Tetracyclic Sesterterpenes from a Phytopathogenic Bipolaris sp. Fungus

A preliminary phytochemical investigation on the EtOAc extracts of the fungus Bipolaris sp. TJ403-B1 resulted in the identification of 12 ophiobolin-type phytotoxins (1-12), including nine new ones, termed bipolaricins A-I (1-9). The structures of 1-9 were elucidated via spectroscopic data (including HRESIMS and 1D and 2D NMR) and single-crystal X-ray diffraction (Cu Kα) analyses. All of the isolated compounds were tested in terms of HMG-CoA reductase inhibitory, anti-inflammatory, and cytotoxic activities. Compound 10 showed HMG-CoA reductase inhibitory activity (IC₅₀ = 8.4 ± 0.4 μM), and 2, 3, and 10-12 showed significant inhibitory potency against lipopolysaccharide (LPS)-induced nitric oxide production, with IC₅₀ values in the range of 5.1 ± 0.3 to 20 ± 1 μM. Further experiments showed that 10 could significantly inhibit the production of IL-1β, RANTES, MIP-1β, and TNF-α as well as enhance the release of IL-13 in macrophages through the inhibition of HO-1 induction as well as the NF-κB pathway. These findings provide a scientific rationale for an anti-inflammatory therapeutic and a template for a new HMG-CoA reductase inhibitor to produce a potential anti-hyperlipidemia agent.

Plant Resources, Chemical Constituents, and Bioactivities of Tea Plants from the Genus Camellia Section Thea

Tea, as one of the most popular beverages with various bioactivities, is commonly produced from the fresh leaves of two widely cultivated tea plants, Camellia sinensis and C. sinensis var. assamica. Both plants belong to the genus Camellia section Thea, which was considered to have 12 species and 6 varieties according to Min's taxonomic system. Most species, except the cultivated species, are known as wild tea plants and have been exploited and utilized to produce tea by the local people of its growing areas. Thus far, six species and varieties have been phytochemically studied, leading to the identification of 398 compounds, including hydrolyzable tannins, flavan-3-ols, flavonoids, terpenoids, alkaloids, and other phenolic and related compounds. Various beneficial health effects were reported for tea and its components, involving antioxidant, antitumor, antimutagenic, antidiabetic, hypolipidemic, anti-inflammatory, antimicrobial, antiviral, antifungal, neuroprotective, hepatoprotective, etc. In this review, the geographical distribution of tea plants and the chemical constituents (1-398) reported from the genus Camellia section Thea and some tea products (green, black, oolong, and pu-erh tea) that have ever been studied between 1970 and 2018 have been summarized, taking species as the main hint, and the main biological activities are also discussed.

Chemical characterization and bioactivity of phenolics from Tieguanyin oolong tea

Phenolics are the main bioactive components in tea and greatly contribute to human health. Three phenolic-enriched extracts, the ethyl acetate fraction (TEF), n-butanol fraction (TBF), and water fraction (TWF), were obtained from Tieguanyin oolong tea, which is considered a typical type of semi-fermented tea. The chemicals in the extracts and their antioxidant activity and cytotoxicity against 4T1 breast cancer cells were investigated in the present work. TEF was found to have the highest contents of phenolics, flavonoids, procyanidins, sugars, and catechin monomers. Meanwhile, TEF exhibited the strongest antioxidant capacity, which may be due to its abundant bioactive compounds, as validated by Pearson correlation and hierarchical clustering analysis. Furthermore, TEF showed greater inhibition of the growth of 4T1 murine breast cancer cells than TBF and TWF. PRACTICAL APPLICATIONS: Fermentation during the processing of oolong tea causes many alterations in polyphenols, leading to different bioactivities. In the present work, three phenolic-enriched extracts, the ethyl acetate fraction (TEF), n-butanol fraction (TBF), and water fraction (TWF), were obtained from Tieguanyin oolong tea. Further tests showed that TEF and TBF from Tieguanyin oolong tea possessed remarkable antioxidant activity and inhibitory potential inhibition of the growth of 4T1 murine breast cancer cells in vitro due to their main bioactive compounds, including phenolics and flavonoids. Thus, the phenolic-enriched extracts from Tieguanyin tea are expected to have a potential application in the food and pharmaceutical industries after further study.

Antidiabetic Effects of Tea

Diabetes mellitus (DM) is a chronic endocrine disease resulted from insulin secretory defect or insulin resistance and it is a leading cause of death around the world. The care of DM patients consumes a huge budget due to the high frequency of consultations and long hospitalizations, making DM a serious threat to both human health and global economies. Tea contains abundant polyphenols and caffeine which showed antidiabetic activity, so the development of antidiabetic medications from tea and its extracts is increasingly receiving attention. However, the results claiming an association between tea consumption and reduced DM risk are inconsistent. The advances in the epidemiologic evidence and the underlying antidiabetic mechanisms of tea are reviewed in this paper. The inconsistent results and the possible causes behind them are also discussed.

Protective effects of theasinensin A against carbon tetrachloride-induced liver injury in mice

TSA markedly reduced the CCl₄-induced liver injury in mice.

Trichostatin A potentiates TRAIL-induced antitumor effects via inhibition of ERK/FOXM1 pathway in gastric cancer

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is an ideal apoptosis inducer and believed to have promise in cancer therapy, yet part of cancer cells exhibit resistance to TRAIL-mediated apoptosis. This necessitates the exploration of agents that resensitizes cancer cells to TRAIL. In our study, we found that Trichostatin A (TSA), an histone deacetylase (HDAC) inhibitor, augmented TRAIL-induced apoptosis in gastric cancer cells in a caspase-dependent manner. Besides, upregulation of DR5 and downregulation of anti-apoptotic proteins including XIAP, Mcl-1, Bcl-2 and Survivin also contributed to this synergism. Noticeably, TSA treatment inhibited Forkhead boxM1 (FOXM1), which expression level showed negative correlation with TRAIL sensitivity. Similarly, silencing of FOXM1 by small interfering RNA (siRNA) resensitized cancer cells to TRAIL and strengthened the TRAIL-augmenting effect of TSA. In addition, we demonstrated the depletion of FOXM1 was a consequence of the inactivation of ERK mediated by TSA. Collectively, it was first shown that TSA potentiated TRAIL sensitivity via ERK/FOXM1 pathway in gastric cancer cells. FOXM1 might serve as a biomarker for predicting sensitivity to TRAIL.