Tea polyphenols (TPP) as a promising wound healing agent: TPP exerts multiple and distinct mechanisms at different phases of wound healing in a mouse model.

Polyphenols have been widely used to treat various chronic skin diseases because they are beneficial in wound healing and show anti-inflammatory effects, however, the mechanism of action remains ambiguous. Previously, we reported the wound healing capability of tea polyphenols (TPP), the major functional component of tea, in vivo. The current study aimed to address the mechanisms of TPP in wound healing during different phases (inflammation, proliferation and remodeling). During the inflammation phase, TPP reduced the production of proinflammatory cytokines (IL-1ß, IL-6 and TNF-α) and inhibited infiltration of neutrophils; during the proliferation phase, TPP promoted the expression of growth factor VEGF-A, which can promote vascular endothelial cell division and induce angiogenesis; TPP improved the morphology of the wound and restored the ratio of type III/I collagens during the remodeling phase, as determined by Masson-trichrome staining and Sirius red staining assays. By tracking the changes in the wound area, TPP and recombinant human epidermal growth factor (rhEGF), rather than povidone-iodine (PVP-I), were able to promote wound healing. These results suggest that TPP plays a pivotal role in all the key stages of wound healing and displays distinct mechanisms from rhEGF, suggesting clinical significance for the future application of TPP as a natural wound healing agent.

L-Theanine and Immunity: A Review.

L-theanine (N-ethyl-γ-glutamine) is the main amino acid in tea leaves. It not only contributes to tea flavor but also possesses several health benefits. Compared with its sedative and calming activities, the immunomodulatory effects of L-theanine have received less attention. Clinical and epidemiological studies have shown that L-theanine reduces immunosuppression caused by strenuous exercise and prevents colds and influenza by improving immunity. Numerous cell and animal studies have proven that theanine plays an immunoregulatory role in inflammation, nerve damage, the intestinal tract, and tumors by regulating γδT lymphocyte function, glutathione (GSH) synthesis, and the secretion of cytokines and neurotransmitters. In addition, theanine can be used as an immunomodulator in animal production. This article reviews the research progress of L-theanine on immunoregulation and related mechanisms, as well as its application in poultry and animal husbandry. It is hoped that this work will be beneficial to future related research.

Tieguanyin extracts ameliorated DSS-induced mouse colitis by suppressing inflammation and regulating intestinal microbiota.

Previous studies have shown that a typical kind of oolong tea, Tieguanyin, has multiple health benefits, while there is no research investigating its effects on inflammatory bowel disease (IBD). In this study, we aimed to explore the alleviation effects of Tieguanyin water (TWE) and ethanol (TES) extracts on IBD. Physiological activity status, colitis severity (disease activity index (DAI), colon and spleen weight), inflammatory cytokines (interleukin (IL)-4, interferon-γ (IFN-γ), IL-17, transforming growth factor-ß (TGF-ß), and IL-10) and microbiota composition were measured in experimental colitis mice induced by dextran sulfate sodium (DSS). TWE and TES exerted remarkable protective effects against experimental colitis, showing decreased colitis severity and improved colon morphology. TES also suppressed colonic inflammation via downregulation of pro-inflammatory cytokines (IL-4, IFN-γ, IL-17, and TGF-ß) and upregulation of the anti-inflammatory cytokine IL-10. In addition, TWE and TES treatment caused significant alterations in the gut microbiota. Oolong tea extract treatment reduced the community abundance of pernicious bacteria Escherichia-Shigella from 21.6% (DSS) to 0.9% (TES) and 1.2% (TWE), and elevated that of probiotics Lachnospiraceae_NK4A136_group from 2.2% to 15.2% (TES) and 11.9% (TWE). Therefore, TWE and TES both remarkably ameliorated DSS-induced colitis, which suggested oolong extracts could be a candidate for IBD treatment.

Role of Nutrition Information in Acceptance and Willingness to Pay for Biofortified Cereal Food: Implications for Better Health and Sustainable Diet.

A range of nutritional needs are met through the use of fortified farm-based foods. Wheat biorfortification with zinc is such an example where biorfortification is carried out for a crucial element like Zinc. Zinc-biofortified wheat (Zn-wheat) has been officially launched in Pakistan since 2016 but its wide-scale dissemination, adoption and consumption have not taken place till to date. On the other hand, essential nutrients deficiencies have wide-ranging implications for public health especially for children and lactating mothers. This study is undertaken to know the reasons for the slow progression of scaling up of biofortified wheat varieties in Pakistan, people's awareness about biofortified wheat and to recognize the role of information in acceptance and willingness to pay for this wheat. For this purpose, randomly selected 474 households were interviewed from four districts of Punjab province. They were categorized into four groups based on their exposure to information in real and hypothetical cheap talk (game theory context). Study findings reveal that respondents were ready to pay for fortified wheat if they are aware about nutrient aspects and Zn deficiency. Using Discrete Choice Experiment, the preferences for and factors affecting the willingness to pay for fortified wheat are evaluated. Main factors having positive impact include household head's education and income, having pregnant women and children <5 years age. It was also found that people having valid information about nutrients of a food would be willing to pay more. The study highlights need for policy focus on educating people about nutritional aspects as well as making available biofortified foods to promote healthy living.

Saponins from Camellia sinensis Seeds Stimulate GIP Secretion in Mice and STC-1 Cells via SGLT1 and TGR5.

Glucose-dependent insulinotropic polypeptide (GIP) is one of the important incretins and possesses lots of physiological activities such as stimulating insulin secretion and maintaining glucose homeostasis. The pentacyclic triterpenoid saponins are the major active ingredients in tea (Camellia sinensis) seeds. This study aimed to investigate the effect of tea seed saponins on the GIP secretion and related mechanisms. Our data showed that the total tea seed saponins (TSS, 65 mg/kg BW) and theasaponin E1 (TSE1, 2-4 µM) could increase the GIP mRNA and protein levels in mice and STC-1 cells. Phlorizin, the inhibitor of Sodium/glucose cotransporter 1 (SGLT1), reversed the TSE1-induced increase in Ca2+ and GIP mRNA level. In addition, TSE1 upregulated the protein expression of Takeda G protein-coupled receptor 5 (TGR5), and TGR5 siRNA significantly decreased GIP expression in TSE1-treated STC-1 cells. Network pharmacology analysis revealed that six proteins and five signaling pathways were associated with SGLT1, TGR5 and GIP regulated by TSE1. Taken together, tea seed saponins could stimulate GIP expression via SGLT1 and TGR5, and were promising natural active ingredients for improving metabolism and related diseases.

Transcriptome analysis provides insight into the anti-diabetic mechanism of theaflavins in high-fat diet and streptozotocin-induced mice.

Black tea exhibits potential to improve hyperglycemia and insulin resistance, where theaflavins (TFs) are its characteristic components. The aim of this study was to explore the anti-diabetic mechanism of TFs. High-fat diet and streptozotocin-induced type 2 diabetes (T2D) mice were administered with TFs by gavage daily for 5 weeks. The biochemical analysis suggested that TFs possess potential anti-diabetic activity, which is comparable to that of metformin. RNA-sequencing analysis showed that TFs had a significant influence on the hepatic transcriptional profile of the T2D mice. The nine significantly enriched KEGG pathways were mainly associated with pancreatic secretion, digestion and metabolism of fat, protein and glycerolipid, and tight junctions. Quantitative real-time PCR and immunohistochemistry analysis verified that TFs improved pancreas function and intestine tight junction, with an increase in the expression of carboxyl ester lipase (Cel), chymotrypsinogen B (Ctrb1), pancreatic triglyceride lipase (Pnlip) and chymotrypsin-like elastase 3B (Cela3b) in the pancreas and cingulin and claudin-1 in the intestine. TFs improved mitochondrial biogenesis with the downregulation of peroxisome proliferator-activated receptor coactivator (PGC) 1α and 1ß in the liver, but had less effect on the muscle. This work revealed the comprehensive mechanism of TFs against T2D, suggesting that TFs are a potential natural agent for improving type 2 diabetes.

Tea Polyphenols Attenuates Inflammation via Reducing Lipopolysaccharides Level and Inhibiting TLR4/NF-κB Pathway in Obese Mice.

Obesity is a worldwide epidemic and increases the risk of metabolic syndrome through chronic inflammation. Tea polyphenols (TP), the major functional component of tea, has shown preventive effects on obesity and obesity-related disease, but the underlying mechanism is complicated and remains obscure. The present study was aimed to elucidate the anti-inflammation effect of TP in high-fat-diet (HFD)-induced obese mice. Results showed that TP reduced obesity-induced inflammation and systemic lipopolysaccharides (LPS) level. The decrease of LPS level in circulation was followed by the downregulation of LPS specific receptor, toll-like receptor 4 (TLR4), and its co-receptor cluster of differentiation 14 (CD14) and adaptor protein differentiation factor 88 (MyD88) in hepatic and adipose tissues. That further inhibited the activation of nuclear factor κB (NF-κB). The serum levels of tumor necrosis factor-alpha (TNF-α), interleukin-1-beta (IL-1ß) and interleukin-6 (IL-6) were significantly decreased by TP in HFD-fed mice. TP also maintained the intestinal barrier integrity by increasing intestinal tight junction proteins and reversed gut dysbiosis in obese mice. These results suggested that TP attenuated obesity-induced inflammation by reducing systemic LPS level and inhibiting LPS-activated TLR4/NF-κB pathway.

Characterization of a new (Z)-3:(E)-2-hexenal isomerase from tea (Camellia sinensis) involved in the conversion of (Z)-3-hexenal to (E)-2-hexenal.

Two major green leaf volatiles (GLVs) in tea that contribute greatly to tea aroma, particularly the green odor, are (E)-2-hexenal and (Z)-3-hexenal. Until now, their formation and related mechanisms during tea manufacture have remained unclear. Our data showed that the contents of (E)-2-hexenal and (Z)-3-hexenal increased more than 1000-fold after live tea leaves were torn. Subsequently, a new (Z)-3:(E)-2-hexenal isomerase (CsHI) was identified in Camellia sinensis. CsHI irreversibly catalyzed the conversion of (Z)-3-hexenal to (E)-2-hexenal. Abiotic stresses including low temperature, dehydration, and mechanical wounding, did not influence the (E)-2-hexenal content in intact tea leaves during withering, but regulated the proportions of (Z)-3-hexenal and (E)-2-hexenal in torn leaves by modulating CsHI at the transcript level. For the first time, this work reveals the formation of (E)-2-hexenal during tea processing and suggests that CsHI may play a pivotal role in tea flavor development as well as in plant defense against abiotic stresses.

Simultaneous Tests of Theaflavin-3,3'-digallate as an Anti-Diabetic Drug in Human Hepatoma G2 Cells and Zebrafish (Danio rerio).

Theaflavin-3,3'-digallate (TF3) is the most important theaflavin monomer in black tea. TF3 was proved to reduce blood glucose level in mice and rats. However, the elaborate anti-diabetic mechanism was not well elucidated. In this work, human hepatoma G2 (HepG2) cells and zebrafish (Danio rerio) were used simultaneously to reveal anti-diabetic effect of TF3. The results showed that TF3 could effectively rise glucose absorption capacity in insulin-resistant HepG2 cells and regulate glucose level in diabetic zebrafish. The hypoglycemic effect was mediated through down-regulating phosphoenolpyruvate carboxykinase and up-regulating glucokinase. More importantly, TF3 could significantly improve ß cells regeneration in diabetic zebrafish at low concentrations (5 µg/mL and 10 µg/mL), which meant TF3 had a strong anti-diabetic effect. Obviously, this work provided the potential benefit of TF3 on hypoglycemic effect, regulating glucose metabolism enzymes, and protecting ß cells. TF3 might be a promising agent for combating diabetes.

Discrimination of white teas produced from fresh leaves with different maturity by near-infrared spectroscopy.

White tea is a special tea product with increasing market demand. The assessment of white tea quality is mainly based on panel sensory by sensory evaluation experts, which is time costly and is limited by many uncertainties. This study established a rapid and accurate method for classification of white teas produced from buds and young leaves and that produced from mature leaves and shoots using near-infrared spectroscopy (NIR). Back propagation neural network modelling and support vector machine (SVM) modelling were compared with six pre-processing methods. The best performance was provided by SVM with particle swarm optimization combined with Savitzky-Golay filter pre-processing method, achieving the accuracy of 98.92% in test samples. The NIR-related chemical compounds of two categories of white teas produced from fresh leaves with different maturity were analyzed, including catechins, alkaloids, amino acids and flavonol glycosides. Compared with chemical component concentration, NIR absorbance had a distinct advantage in quick classification of white teas based on the principal components analysis. In addition, the sensory characteristics of two categories white teas produced from fresh leaves with different maturity were also assessed by panelist. The result showed that characteristics of "umami-like" and "smooth" were more likely present in white teas produced from buds and young leaves, while "woody" and "coarse" characteristics were usually present in white teas produced from mature leaves and shoots. Thus, NIR technique is a rapid and reliable method for discrimination of white teas produced from fresh leaves with different maturity, and is a potential method to discriminate sensory characteristics of white teas.

Simultaneous Determination and Quantification of Triterpene Saponins from Camellia sinensis Seeds Using UPLC-PDA-QTOF-MS/MS.

Saponins in the Camellia sinensis seeds have a broad spectrum of biological properties and application potentials. However, up to now, no chromatographic methods have been developed to provide full fingerprinting and quality assurance for these saponins. This research aimed to develop a novel method to tentatively identify and quantify saponins in C. sinensis seeds by ultra-high-performance liquid chromatography coupled with photo-diode array detector and quadrupole time-of-flight mass spectrometry (UPLC-PDA-QTOF-MS/MS), and compare it with the classic vanillin-sulfuric acid assay. Fifty-one triterpene saponins, including six potentially new compounds, were simultaneously detected by UPLC-PDA-MS/MS, and their chemical structures were speculated according to the retention behavior and fragmentation pattern. The total saponin content in the crude extract and the purified saponin fraction of C. sinensis seeds were quantified to be 19.57 ± 0.05% (wt %) and 41.68 ± 0.09% (wt %) respectively by UPLC-PDA at 210 nm, while the corresponding values were determined to be 43.11 ± 3.17% (wt %) and 56.60 ± 5.79% (wt %) respectively by the vanillin-sulfuric acid assay. The developed UPLC-PDA -MS/MS method could determine specified saponins, and is more reliable for quantifying the C. sinensis seed saponins than the classic spectrophotometric method. It is of great significance for the future investigations and applications of these saponins.

Rapid and non-destructive discrimination of special-grade flat green tea using Near-infrared spectroscopy.

Special-grade green tea is a premium tea product with the best rank and high value. Special-grade green tea is normally classified by panel sensory evaluation which is time and sample costly. Near-infrared spectroscopy is considered as a promising rapid and non-destructive analytical technique for food quality evaluation and grading. This study established a discrimination method of special-grade flat green tea using Near-infrared spectroscopy. Full spectrum was used for partial least squares (PLS) modelling to predict the sensory scores of green tea, while specific spectral regions were used for synergy interval-partial least squares (siPLS) modelling. The best performance was achieved by the siPLS model of MSC + Mean Centering pretreatments and subintervals from 15 intervals. The optimal model was used to discriminate special-grade flat green tea with the prediction accuracy of 97% and 93% in the cross-validation and external validation respectively. The chemical compositions of green tea samples were also analyzed, including polyphenols (total polyphenols, catechins and flavonol glycosides), alkaloids and amino acids. Principal components analysis result showed that there is potential correlation between specific spectral regions and the presence of polyphenols and alkaloids. Thus, NIR technique is a practical method for rapid and non-destructive discrimination of special-grade flat green tea with chemical support.

Study on the antioxidant activity of tea flowers (Camellia sinensis).

Major chemical compounds in different extracts from tea flowers (Camellia sinensis) were analyzed. Distilled water or 70% ethanol extracts were then fractionated with chloroform, ethyl acetate and n-butanol, respectively. Each extract fraction was tested its scavenging activities on 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl free radicals. The results showed that ethyl acetate fraction of ethanol-extract of tea flower (EEA) exhibited the highest quenching activity to hydroxyl radicals (SC50 11.6 mug/ml), followed by ethanol-extract (EE) of tea flower (SC50 19.7 microg/ml). Same tea flower extract showed big different scavenging activities on different free radicals. EEA quenched 80% of hydroxyl radicals generated by Fenton's reaction, however, only 40% of DPPH radical was scavenged in the Fe (II)-H2O2 -luminol system. The contents of flavones, polyphenols and catechins in EE and EEA fractions were higher than those in other fractions. We suggest that the stronger scavenging abilities to free radicals might be due to polyphenols, EGCG, ECG and flavones. However, the water extracts of tea flower and their fractions showed lower antioxidant activity for their inhibitory effect on hydroxyl radicals and DPPH radicals.

Free radical scavenging effect of Pu-erh tea extracts and their protective effect on oxidative damage in human fibroblast cells.

In the present study, we successively extracted the Pu-erh tea with acetone, water, chloroform, ethyl acetate, and n-butanol, and the extracts were then isolated by column chromatography. Our study demonstrates that the Pu-erh tea ethyl acetate extract, n-butanol extract, and their fractions had superoxide anion and hydroxyl radical scavenging activity: fractions 2 and 8 from the ethyl acetate extract and fractions 2, 4, and 5 from the n-butanol extract showed protective effects against hydrogen peroxide-induced damage in human fibroblast HPF-1 cells and increased the cells' viability under normal cell culture conditions. In addition, it is found that these fractions, except fraction 5 from the n-butanol extract, decreased the accumulation of intracellular reactive oxygen species in hydrogen peroxide-induced HPF-1 cells. Interestingly, the antioxidant effect of fraction 8 from the ethyl acetate extract on the above four systems was much stronger than that of the typical green tea catechin (-)-epigallocatechin-3-gallate, but there were almost no monomeric polyphenols, theaflavins, and gallic acid in fraction 8.