Transcriptome and proteomics conjoint analysis reveal anti-alcoholic liver injury effect of Dianhong Black Tea volatile substances.

Dianhong Black Tea, a fermented tea containing various bioactive ingredients, has been found to have a significant role in alleviating alcoholic liver injury (ALI). One of its main unique components, Dianhong Black Tea volatile substances (DBTVS), may have potential anti-ALI effects. However, its effects and underlying molecular mechanisms are still unknown. In this study, we aimed to investigate the potential of DBTVS as an anti-ALI agent using alcohol-fed rats. We assessed the effect of DBTVS on ALI by analyzing serum transaminase and lipid levels, as well as conducting hematoxylin-eosin and oil red O staining. Additionally, GC-MS was used to detect the components of DBTVS, while transcriptome, proteomics analysis, Western blot, and molecular docking were employed to uncover the underlying mechanisms. Our results demonstrated that DBTVS significantly reduced serum ALT and AST levels and improved lipid metabolism disorders. Moreover, we identified 14 components in DBTVS, with five of them exhibiting strong binding affinity with key proteins. These findings suggested that DBTVS could be a promising agent for the prevention and treatment of ALI. Its potential therapeutic effects may be attributed to its ability to regulate lipid metabolism through the PPAR signaling pathway.

Changes in Intestinal Microbiota of Type 2 Diabetes in Mice in Response to Dietary Supplementation With Instant Tea or Matcha.

OBJECTIVE: Gut microbiota plays a key role in metabolism and health in diabetes patients with gastrointestinal microbiota dysbiosis. Thus, regulating the ecological balance of gut microbiota may provide a pathway toward improvement for these patients. Our previous study showed that functional ingredients in tea may inhibit cornstarch digestion in vitro. METHODS: A cornstarch-tea diet was developed, and in this study we investigated the effects of such a diet on blood glucose and gut microbiota in diabetic mice. RESULTS: Diabetes resulted in significant weight loss, hyperphagia and hyperglycemia. 16S rDNA sequencing revealed that in diabetes there is significantly increased Bacteroidaceae, Helicobacteraceae, Ruminococcaceae, Enterobacteriaceae, Rikenellaceae and Saccharibacteria_genera_incertae_sedis, and significantly decreased Lactobacillaceae, Prevotellaceae, Coriobacteriaceae, Verrucomicrobiaceae and Bifidobacteriaceae. The cornstarch‒tea diet resulted in a trend toward reduced blood glucose, with particularly increased levels of Coriobacteriaceae, Lactobacillaceae, Prevotellaceae and Bifidobacteriaceae, and decreased Bacteroidaceae, Ruminococcaceae, Helicobacteraceae and Enterobacteriaceae. CONCLUSIONS: Instant tea and matcha supplementation had beneficial effects on regulation of blood glucose and gut microbiota, reversing the changes in microbiota caused by alloxan injection. The cornstarch‒tea regulation pathway is involved in bacterium group regulation rather than single-species regulation, which suggests that cornstarch combined with tea may be used as a functional food supplement for diabetes patients.

Effect of epigallocatechin gallate on the gelatinisation and retrogradation of wheat starch.

The effects of epigallocatechin gallate (EGCG) on the gelatinisation and retrogradation characteristics of wheat starch (WS) were investigated using rapid viscosity analysis (RVA), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR), and Raman spectroscopy. The addition of EGCG resulted in decreased peak viscosity, trough viscosity, final viscosity and setback value of WS, as shown by RVA tests. After storage at 4 °C, observations by XRD and TGA revealed that the EGCG-WS complex had lower crystallinity and thermal stability than the control, indicating that EGCG retarded the retrogradation of WS. FT-IR and Raman spectroscopy results showed that EGCG formed hydrogen bonds with WS, through which EGCG could interfere with the reassociation of starch chains during storage, thereby delaying retrogradation. EGCG may therefore prove to be a useful additive in wheat products and in nutrition-related applications.

Comparison of the main compounds in Fuding white tea infusions from various tea types.

The purpose of this study was to compare the main components, and particularly catechins, caffeine, theanine, free amino acids, and water extracts, in Bai Hao Yin Zhen, Bai Mu Dan, and Shou Mei Fuding white tea infusions brewed at different temperatures, and their contributions to taste were estimated by dose-over-threshold value. Infusion temperature had a distinct effect on the main components extracted, and 100 °C was found to be optimal for extracting catechins and caffeine. However, the effect of temperature on theanine, free amino acids, and water extracts varied with tea type. Bai Mu Dan and Shou Mei yielded a higher content of the major compounds than did Bai Hao Yin Zhen. Thus, infusion temperature had a large effect on extracting the main compounds, and the differences in content between the three white teas presumably reflected differences in the harvest time, processing method or leaf shape.

Effect of tea products on the in vitro enzymatic digestibility of starch.

The importance of postprandial hyperglycemia in the treatment of diabetes has been recognized recently. Tea products, such as tea polyphenols (TP), epigallocatechin gallate (EGCG), matcha, and instant tea, were chosen as constituents of tea-flour food, aimed at regulating the release of glucose from starchy foods in the postprandial period. Six starches were chosen for internal composition analysis and hydrolysis studies in vitro. Corn starch, wheat starch, and lily root flour appeared to have higher resistant starch content, slower digestion profiles, and lower kinetic constants, implying sustained release of glucose in the gastrointestinal tract. The effect of tea products on starch digestion was determined in order to get a desired formulation of dietary product for patients with hyperglycemia. Compared with macha and instant tea, TP and EGCG exerted greater inhibition of amylase and amyloglucosidase, especially for corn starch with 0.5% TP or 0.5% EGCG.

Nε-(carboxymethyl)lysine and Nε-(carboxyethyl)lysine in tea and the factors affecting their formation.

The levels of Nε-(carboxymethyl)lysine (CML) and Nε-(carboxyethyl)lysine (CEL) in 99 tea samples from 14 geographic regions, including 44 green, 7 oolong, 41 black, and 7 dark teas were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The CML and CEL contents varied from 11.0 to 1701µg/g tea and 4.6 to 133µg/g tea, respectively. Dark tea presented the highest levels of CML and CEL, whereas green and oolong teas presented the lowest levels. Five kinds of catechins in the tea were also analyzed, and spearman's correlation coefficients showed that all the catechins negatively correlated with CML and CEL. The results suggested that withering, fermentation and pile fermentation may facilitate the formation of CML and CEL. Catechins might inhibit the formation of CML and CEL, but their inhibitory effects may be affected by tea processing. The results of this study are useful for the production of healthier tea.

Effect of water quality on the main components in Fuding white tea infusions.

The aim of this study was to investigate the effect of water quality on the main components in Fuding white tea infusions, including catechins, caffeine, theanine and free amino acids. Pure, tap and spring water were tested, and water quality was found to have a distinct effect on the main compounds extracted. Pure water, which was weakly acidic and low in dissolved ions, achieved the highest catechin content, whereas caffeine and theanine, and amino acids, were higher in infusions made with spring and tap water, respectively. Sensory evaluation was performed to evaluate infusion colour, taste and aroma, and sensory quality was similarly influenced by water type, due primarily to differences in dissolved ions. Pure water was more suitable for brewing white tea with superior colour, aroma and taste.

Influence of brewing conditions on taste components in Fuding white tea infusions.

BACKGROUND: White tea has received increasing attention of late as a result of its sweet taste and health benefits. During the brewing of white tea, many factors may affect the nutritional and sensory quality of the resulting infusions. The present study aimed to investigate the effect of various infusion conditions on the taste components of Fuding white tea, including infusion time, ratio of tea and water, number of brewing steps, and temperature. RESULTS: Brewing conditions had a strong effect on the taste compound profile and sensory characteristics. The catechin, caffeine, theanine and free amino acid contents generally increased with increasing infusion time and temperature. Conditions comprising an infusion time of 7 min, a brewing temperature of 100 °C, a tea and water ratio of 1:30 or 1:40, and a second brewing step, respectively, were shown to obtain the highest contents of most compounds. Regarding tea sensory evaluation, conditions comprising an infusion time of 3 min, a brewing temperature of 100 °C, a tea and water ratio of 1:50, and a first brewing step, resulted in the highest sensory score for comprehensive behavior of color, aroma and taste. CONCLUSION: The results of the present study reveal differences in the contents of various taste compounds, including catechins, caffeine, theanine and free amino acids, with respect to different brewing conditions, and sensory scores also varied with brewing conditions. © 2016 Society of Chemical Industry.

Inhibition of wheat starch retrogradation by tea derivatives.

The effect of four industrial tea derivatives (tea polyphenols [TPS], tea water-soluble extracts [TSE], tea polysaccharides [TSS], and green tea powder [GTP]), on the retrogradation of wheat starch was investigated using texture profile analysis (TPA), differential scanning calorimetry (DSC), rapid viscosity analysis (RVA), and the α-amylase-iodine method. The addition of the four tea derivatives resulted in decreased hardness and increased cohesiveness of the starch gel as shown by the TPA test. The DSC data demonstrated an increase in the enthalpy change of starch gelatinization and a decrease in the enthalpy change of starch recrystallite dissociation. The RVA results indicated that the peak viscosity, representing the intermolecular forces of wheat starch, was reduced after addition of TPS, TSE, and TSS, respectively, but was increased by GTP. Furthermore, the half crystallization time in the Avrami equation almost doubled after the separate addition of the tea derivatives.

Effect of FTY720 on some physiological indexes of Non-Obese Diabetic (NOD) Mice.

The studies were performed to investigate the physiological characteristics of non-obese diabetic (NOD) mice treated with FTY720. At the age of 12 weeks, each mouse was fed with FTY720 or physiological saline once a day for 10 weeks running, and their blood glucose, weight, anti-GAD antibody and organ indexes were determined. No mouse in group FTY720 (NOD mice treated with FTY720) showed diabetic symptoms. The average content of serum anti-GAD antibody in group FTY720 decreased 48.75% (P < 0.01). It was concluded that the spleen, kidney and liver of NOD mice treated with FTY720 shriveled significantly in the progression of diabetes (P < 0.01 or P < 0.05). The body weight of group FTY720 mice was slightly lower than that of the model control (MC) group and these two groups both had less body weight than the normal control (NC) group (P < 0.01). The result of tests of anti-GAD antibody suggested that FTY720 treatment could suppress the anti-GAD response.

Determination of theanine and gamma-aminobutyric acid in tea by high performance- liquid chromatography with precolumn derivatization.

A method of precolumn derivatization-high performance liquid chromatography (HPLC) for the determination of theanine and gamma-aminobutyric acid (GABA) in tea was established. o-Phthalaldehyde (OPA) and N-acetyl-L-cysteine (NAC) were chosen as the derivatization reagents. The effects of teapolyphenol (Tp), proline (Pro) and Vitamin C (Vc) on derivatization yields were investigated. The results indicated that Vc not only stabilized the stock solution of OPA, but also enhanced the yield of GABA derivative. However, the yield of theanine derivative was less affected. The HPLC separation system was also optimized. The resolution of the derivatives was improved by adjusting the pH value and phosphate-citric buffer concentration of the mobile phase. The limits of detection (LODs) for GABA and theanine were 3.01 x 10(-5) mmol/L and 7.98 x 10(-5) mmol/L, and the limits of quantification (LOQs) were 9.99 x 10(-5) mmol/L and 2.658 x 10(-4) mmol/L, respectively. The linear ranges of GABA and theanine were 0.01 - 0.4 mmol/L with the correlation coefficient of 0.996 and 0.05 - 0.8 mmol/L with the correlation coefficient of 0.995, respectively. The main recoveries for GABA and theanine in green tea, Oolong tea, and black tea, ranged from 99.29% to 119.60% and from 62.88% to 141.06% respectively. The method with simple procedure and efficient separation was proved to be suitable for the determination of GABA and theanine in tea.

Supercritical carbon dioxide extraction of bioactive compounds from Ampelopsis grossedentata stems: process optimization and antioxidant activity.

Supercritical carbon dioxide (SC-CO(2)) extraction of bioactive compounds including flavonoids and phenolics from Ampelopsis grossedentata stems was carried out. Extraction parameters such as pressure, temperature, dynamic time and modifier, were optimized using an orthogonal array design of L(9) (3(4)), and antioxidant activities of the extracts were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay and ferrous ion chelating (FIC) assay. The best conditions obtained for SC-CO(2) extraction of flavonoids was 250 bar, 40 °C, 50 min, and with a modifier of methanol/ethanol (1:3, v/v), and that for phenolics extraction was 250 bar, 40 °C, 50 min, and with a modifier of methanol/ethanol (1:1, v/v). Meantime, flavonoids and phenolics were found to be mainly responsible for the DPPH scavenging activity of the extracts, but not for the chelating activity on ferrous ion according to Pearson correlation analysis. Furthermore, several unreported flavonoids such as apigenin, vitexin, luteolin, etc., have been detected in the extracts from A. grossedentata stems.