Acid In Tea Research Articles

Vitamin E isoforms (d α-tocopherol and δ-tocotrienol) promote healing of secondary skin wounds in diabetic rats

l-theanine, the most abundant free amino acid in tea, has been documented to possess many different bioactive properties through oral or intragastrical delivery. However, little is known about the effect of topical delivery of l-theanine on acute inflammation. In the present study, by using 12-O-tetradecanoylphorbol-13-acetate (TPA, 2.5 μg/ear)-induced ear edema model in mice, we first found that single-dose local pretreatment of l-theanine 30 min before TPA time- and dose-dependently suppressed the increases in both skin thickness and weight. Subsequently l-theanine ameliorated TPA-induced erythema, vascular permeability increase, epidermal and dermal hyperplasia, neutrophil infiltration and activation via downregulating the expression of PECAM-1 (a platelet endothelial adhesion molecule-1) in blood vessels and the production of pro-inflammatory cytokines IL-1β, TNF-α, and mediator cyclooxygenase-2 (COX-2), which is mainly expressed in neutrophils. It highlighted the potential of l-theanine as a locally administrable therapeutic agent for acute cutaneous inflammation.

Reduced Stress and Improved Sleep Quality Caused by Green Tea Are Associated with a Reduced Caffeine Content.

Caffeine, one of the main components in green tea, can interfere with sleep and block the effect of theanine. Since theanine, the main amino acid in tea leaves, has significant anti-stress effects in animals and humans, we examined the effects of green tea with lowered caffeine content, i.e., low-caffeine green tea (LCGT), on stress and quality of sleep of middle–aged individuals (n = 20, mean age 51.3 ± 6.7 years) in a double-blind crossover design. Standard green tea (SGT) was used as the control. These teas (≥300 mL/day), which were eluted with room temperature water, were consumed over a period of seven days after a single washout term. The level of salivary α-amylase activity (sAA), a stress marker, was significantly lower in participants that consumed LCGT (64.7 U/mL) than in those that consumed SGT (73.9 U/mL). Sleep quality was higher in participants that consumed a larger quantity of LCGT. In addition, a self-diagnostic check for accumulated fatigue was significantly lower in those participants that consumed LCGT than SGT. These results indicate that LCGT intake can reduce stress in middle-aged individuals and improve their quality of sleep. The reduction in caffeine is suggested to be a valid reason for enhancing the anti-stress effect of green tea.

Variation of Shikimic Acid and Amino Acids in Tea Leaves as Influenced by Glyphosate Application

Variation of Shikimic Acid and Amino Acids in Tea Leaves as Influenced by Glyphosate Application

AMINO ACID COMPOSITION AS PRECURSOR FLAVORS CHANGES IN TEA LEAVES (CAMELLIA SINENSIS) DURING ORTHODOX BLACK TEA MANUFACTURING

The content of amino acids in tea leaves at different stages of OTD black tea manufacture was measured. Considerable changes of amino acids were observed in all stages but in each stage, total free amino acids was found to be increase both in withering fermentation stages and was dramatically decrease at frying stages. The results showed that the some of free a-amino acid contents which was defined as flavour precursor like phenylalnine, methionine and isoleucine in tea leaves were significantly increase during withering whereas they was found to be an decreasing trend during fermentation but others a-amino acid contents like alanine, methionine and glycine was found to be trend increase in both stage of processing. The zero-order, first-order and quadratic models were used to explain the a-amino acid included alanine, valine, isoleucine, leucine and phenylalanine changes kinetics during processing and it was observed that the linear, growth, compounds and quadratic model could be used for explaning the changes of flavour compounds during OTD black tea manufature.

Proteolysis of chloroplast proteins is responsible for accumulation of free amino acids in dark-treated tea (Camellia sinensis) leaves

Shade management (dark treatment) on tea (Camellia sinensis) plants is a common approach to improve free amino acids in raw materials of tea leaves. However, the reason for amino acid accumulation in dark-treated tea leaves is still unknown. In the present study, dark treatment significantly increased content of free amino acids and reduced content of soluble proteins in tea leaves. Quantitative proteomics analysis showed that most enzymes involved in biosyntheses of amino acids were down-accumulated by dark treatment. Chloroplast numbers reduced in dark-treated leaves and the content of soluble proteins reduced in the chloroplasts isolated from dark-treated leaves compared to control. These suggest that proteolysis of chloroplast proteins contributed to amino acid accumulation in dark-treated leaves. Two chloroplasts proteases, ATP-dependent Clp protease proteolytic subunit 3 and protease Do-like 2, were up-accumulated in dark-treated leaves. This study firstly elucidated the mechanism of accumulation of amino acids in dark-treated tea leaves. Biological significanceEffect of dark on crop growth has been widely studied, while less attention has been paid to effect of dark on quality-related metabolites in crops. Shade management (dark treatment) on tea plants is a common approach to improve free amino acids in tea leaves. However, the reason for accumulation of free amino acids in dark-treated tea leaves is still unknown. In the present study, an iTRAQ-based quantitative proteomic analysis was performed and the results revealed the accumulation of free amino acids in dark-treated tea leaves was not due to activation of biosyntheses of amino acids, but resulted from proteolysis of chloroplast proteins. The information will advance our understanding of formation of quality or function-related metabolites in agricultural crops exposed to dark stress/shade management.

Separation and detection of free d- and l-amino acids in tea by off-line two-dimensional liquid chromatography

An off-line 2D-HPLC method was employed to achieve enantiomeric separation of amino acids in tea samples. 16 free amino acids in longjing, black, oolong, and pu-erh teas were separated and collected after FMOC-Cl derivatization in the first dimension, and the fractions were collected and concentrated and then separated on a chiral column.

Anti-stress Effect of Green Tea with Lowered Caffeine on Humans: A Pilot Study.

Theanine, an amino acid in tea, has significant anti-stress effects on animals and humans. However, the effect of theanine was blocked by caffeine and gallate-type catechins, which are the main components in tea. We examined the anti-stress effect of green tea with lowered caffeine, low-caffeine green tea, on humans. The study design was a single-blind group comparison and participants (n=20) were randomly assigned to low-caffeine or placebo tea groups. These teas (≥500 mL/d), which were eluted with room temperature water, were taken from 1 week prior to pharmacy practice and continued for 10 d in the practice period. The participants ingested theanine (ca. 15 mg/d) in low-caffeine green tea. To assess the anxiety of participants, the state-trait anxiety inventory test was used before pharmacy practice. The subjective stress of students was significantly lower in the low-caffeine-group than in the placebo-group during pharmacy practice. The level of salivary α-amylase activity, a stress marker, increased significantly after daily pharmacy practice in the placebo-group but not in the low-caffeine-group. These results suggested that the ingestion of low-caffeine green tea suppressed the excessive stress response of students. This study was registered at the University Hospital Medical Information Network (ID No. UMIN14942).

Golf ball-assisted electrospray ionization of mass spectrometry for the determination of trace amino acids in complex samples

During the electrospray ionization (ESI) process, ions move through a heated capillary aperture to be detected on arrival at a mass analyzer. However, the ESI process creates an ion plume, which expands into an ion cloud with an area larger than that of the heated capillary aperture, significantly contributing to an ion loss of 50% due to coulombic repulsion. The use of DC and RF fields to focus ions from the ion source into the vacuum chamber has been proposed in the literature, but the improvement of ion transmission efficiency is limited. To improve ion transmission, in this study we propose a novel method using a home-made golf ball positioned between the ion source and the inlet of the mass analyzer to hydrodynamically focus the ions passing through the golf ball. The ion plume produced by the ESI process passes through the golf ball will reduce the size of the ion cloud then be focused and most of them flowed into the mass analyzer. Therefore, the sensitivity will be improved, the aim of this investigation is to study the enhancing of the signal using golf ball-assisted electrospray ionization liquid chromatography tandem mass spectrometry (LC-MS/MS) to determine 20 trace amino acids in complex samples, including tea, urine and serum. The results showed that the analytical performance of the determination of the 20 amino acids in tea, urine and serum samples using the home-made golf ball-assisted ESI source is better than that of a commercial ESI source. The signal intensities of the 20 amino acids were enhanced by factors of 2–2700, 11–2525, and 31–342680 in oolong tea, urine and serum analyses, respectively. The precision of the proposed method ranged from 1–9%, 0.4–9% and 0.4–8% at low, medium and high concentration levels of amino acids, respectively. The home-made golf ball-assisted ESI source effectively increased the signal intensity and enhanced the ion transmission efficiency and is also an easy, convenient and economical device. This technique can be applied to the analysis of trace compounds in complex matrices.

Anti-stress effects of drinking green tea with lowered caffeine and enriched theanine, epigallocatechin and arginine on psychosocial stress induced adrenal hypertrophy in mice

BackgroundTheanine, an amino acid in tea, has significant anti-stress effects on animals and humans. However, the anti-stress effects of drinking green tea have not yet been elucidated. Hypothesis/purposeThe present study aimed to explore anti-stress effects of green tea and roles of tea components in a mouse model of psychosocial stress. Study designWe examined anti-stress effects of three types of green teas, theanine-rich “Gyokuro”, standard “Sencha”, and Sencha with lowered caffeine (low-caffeine green tea). Furthermore, the roles of tea components such as caffeine, catechins, and other amino acids in anti-stress effects were examined. MethodsTo prepare low-caffeine green tea, plucked new tea leaves were treated with a hot-water spray. Mice were psychosocially stressed from a conflict among male mice under confrontational housing. Mice consumed each tea that was eluted with room temperature water ad libitum. As a marker for the stress response, adrenal hypertrophy was compared with mice that ingested water. ResultsCaffeine was significantly lowered by spraying hot-water on tea leaves. While epigallocatechin gallate (EGCG) is the main catechin in tea leaves, epigallocatechin (EGC) was mainly infused into water at room temperature. Adrenal hypertrophy was significantly suppressed in mice that ingested theanine-rich and low-caffeine green tea that were eluted with water at room temperature. Caffeine and EGCG suppressed the anti-stress effects of theanine while EGC and arginine (Arg) retained these effects. ConclusionThese results suggest that drinking green tea exhibits anti-stress effects, where theanine, EGC and Arg cooperatively abolish the counter-effect of caffeine and EGCG on psychosocial stress induced adrenal hypertrophy in mice.

Dual mechanisms regulating glutamate decarboxylases and accumulation of gamma-aminobutyric acid in tea (Camellia sinensis) leaves exposed to multiple stresses.

γ-Aminobutyric acid (GABA) is one of the major inhibitory neurotransmitters in the central nervous system. It has multiple positive effects on mammalian physiology and is an important bioactive component of tea (Camellia sinensis). GABA generally occurs at a very low level in plants but GABA content increases substantially after exposure to a range of stresses, especially oxygen-deficiency. During processing of tea leaves, a combination of anoxic stress and mechanical damage are essential for the high accumulation of GABA. This is believed to be initiated by a change in glutamate decarboxylase activity, but the underlying mechanisms are unclear. In the present study we characterized factors regulating the expression and activity of three tea glutamate decarboxylase genes (CsGAD1, 2, and 3), and their encoded enzymes. The results suggests that, unlike the model plant Arabidopsis thaliana, there are dual mechanisms regulating the accumulation of GABA in tea leaves exposed to multiple stresses, including activation of CsGAD1 enzymatic activity by calmodulin upon the onset of the stress and accumulation of high levels of CsGAD2 mRNA induced by a combination of anoxic stress and mechanical damage.

Investigation of free amino acid, total phenolics, antioxidant activity and purine alkaloids to assess the health properties of non-Camellia tea

To find novel functional beverages from folk teas, 33 species of frequently used non-Camellia tea (plants other than Camellia) were collected and compared with Camellia tea (green tea, pu-erh tea and black tea) for the first time. Data are reported here on the quantities of 20 free amino acids (FAAs) and three purine alkaloids (measured by UHPLC), total polyphenols (measured by Folin-Ciocalteu assay), and antioxidant activity (DPPH). The total amounts of FAAs in non-Camellia tea (0.62–18.99mg/g) are generally less than that of Camellia tea (16.55–24.99mg/g). However, for certain FAAs, the quantities were much higher in some non-Camellia teas, such as γ-aminobutyric acid in teas from Ampelopsis grossedentata, Isodon serra and Hibiscus sabdariffa. Interestingly, theanine was detected in tea from Potentilla fruticosa (1.16±0.81mg/g). Furthermore, the content of polyphenols in teas from A. grossedentata, Acer tataricum subsp. ginnala are significantly higher than those from Camellia tea; teas from I. serra, Pistacia chinensis and A. tataricum subsp. ginnala have remarkable antioxidant activities similar to the activities from green tea (44.23μg/mL). Purine alkaloids (caffeine, theobromine and theophylline) were not detected in non-Camellia teas. The investigation suggest some non-Camellia teas may be great functional natural products with potential for prevention of chronic diseases and aging, by providing with abundant polyphenols, antioxidants and specific FAAs.

Simultaneous determination of free amino acids in Pu-erh tea and their changes during fermentation

Pu-erh ripened tea is produced through a unique microbial fermentation process from the sun-dried leaves of large-leaf tea species (Camellia sinensis (Linn.) var. assamica (Masters) Kitamura) in Yunnan province of China. In this study, the changes of amino acid profiles during fermentation of Pu-erh tea were investigated, based on the improved HPLC–UV method with PITC pre-column derivatization for the simultaneous determination of twenty free amino acids. Results showed that aspartic acid, glutamic acid, arginine, alanine, theanine and tyrosine were the major amino acids in tea samples. Fermentation significantly influenced on the amino acid profiles. The total free amino acid contents significantly decreased during fermentation (p<0.05). Meanwhile, low amount of acrylamide were detected. Its concentration increased after 7-days’ fermentation and then decreased gradually. The results provided the useful information for the manipulation of fermentation process according to the changes of amino acids and acrylamide contents in Pu-erh ripened tea.

L-theanine, unique amino acid of tea, and its metabolism, health effects, and safety

ABSTRACTTea has been a very popular beverage around the world for centuries. The reason that it is delicious, enabling hydration, showing warming and relaxing effect can be mentioned why it is consumed so much in addition to its prominent health effects. Although the catechins and caffeine are the primary bioactive components that are related with the health effects of the tea, the health effects of theanine amino acid, which is a nonproteinic amino acid special to tea, has become prominent in recent years. It has been known that the theanine amino acid in tea has positive effects especially on relaxing, cognitive performance, emotional status, sleep quality, cancer, cardiovascular diseases, obesity, and common cold. The results of acute and chronic toxicity tests conducted on the safety of theanine express that L-theanine is reliable in general even if it is consumed too much with diet. However, it has not revealed a clear evidence-based result yet regarding theanine metabolism, health effects, and its safety. Within this frame, chemical structure of theanine, its biosynthesis, dietary sources, metabolism, health effects, and safety are discussed in present study.

Occurrence, Biosynthesis and Metabolism of Theanine (γ-Glutamyl-L-ethylamide) in Plants: A Comprehensive Review

Theanine (γ-glutamyl-L-ethylamide) is the most abundant non-protein amino acid in tea leaves. In addition to Camellia sinensis, theanine occurs in several plants belonging to the Ericales. Biosynthesis of theanine from glutamic acid and ethylamine by theanine synthetase is present in all organs of tea seedlings, but roots are the major site of theanine biosynthesis in adult tea trees. Theanine is transported from roots to young leaves via the xylem sap. Theanine is hydrolysed to glutamic acid and ethylamine in leaves. Ethylamine produced from theanine is predominantly used for catechin biosynthesis. Concentration of ammonia and light intensity influence the biosynthesis and degradation of theanine, respectively. Biosynthesis, translocation and degradation of theanine and related enzymes and genes are reviewed.

Study on drying methods and their influences on effective components of loquat flower tea

Different drying methods and their influences on effective components contents of loquat flower tea were investigated in this study. The determination of total polyphenols (TP), total flavonoids (TF), free amino acid (AA), caffeine and triterpene acids showed relatively higher contents were found at full-bloom stage and in petal tissue. This stage flower was dried to produce loquat flower tea by methods of freeze drying, microwave drying, vacuum drying and hot-air drying, respectively. The results showed that four water-soluble components contents in tea prepared by freeze drying were the highest. Those by microwave drying increased firstly, then decreased with power, with the maximum at 420 W. In vacuum-dried tea, total polyphenols content (TPC) and total flavonoids content (TFC) reduced with temperature, but for AA, it increased with temperature. In hot-air dried flower tea, TPC and TFC exhibited a similar tendency as those by microwave dry, with the maximum at 80 °C and minimum at 40 °C. For AA, it increased with temperature. The contents of caffeine, triterpene acid in tea prepared by all drying methods showed no significant difference. It was concluded that the methods of freeze drying and microwave drying at 420 W can protect the effective components preferably.

Prevention of senescence and stress by food composition

The high prevalence of dementia in aged individuals suggests that aging is the most important risk factor and that senescence further enhances dementia. We have searched for dietary factors that prevent brain senescence using a mouse model of age-related neurodegeneration (SAMP10). This mouse line is suitable for studying brain senescence because brain atrophy and cognitive dysfunction are observed with aging, similar to humans. The production of reactive oxygen species and oxidative damage are high in the brains of aged SAMP10. We found that green tea catechin and β-cryptoxanthin in Japanese mandarin oranges prevented brain atrophy and cognitive dysfunction. In addition, psychosocially chronically stressed mice exhibited a shortened life span and accelerated cognitive dysfunction. These deficiencies were prevented by the ingestion of theanine, an amino acid in tea, under stressed conditions. While a number of factors affect brain senescence, our results suggest that non-nutritive food components such as catechin, β-cryptoxanthin and theanine may be useful for preventing brain senescence.

Chemical composition, thermal stability and antioxidant properties of tea seed oils obtained by different extraction methods: Supercritical fluid extraction yields the best oil quality

A comparison study has been performed for tea seed oils (TSO) extracted from different methods and sources, which were oil from cold‐pressing of tea seeds [TSO(CP)], oil from supercritical fluid extraction of seeds [TSO(SCF)], and oil from supercritical fluid extraction of tea seed cake [TSCO(SCF)]. The chemical composition, thermal stability, antioxidant properties, and physicochemical properties of the oils were determined. The main ingredient in seed and cake was fat, fiber, total sugar, and considerable amounts of amino, 74.59 and 93.25 g/100 g protein, respectively were found. The results also indicated that oleic acid and linoleic acid were the dominant unsaturated fatty acids in tea seed oils, irrespective of extraction methods and sources. The TSO(SCF) contained the highest levels of squalene, lupeol, and total sterols whereas TSCO(SCF) and TSO(CP) had higher contents of total phenolics and α‐tocopherol. The TG/DTG curves showed TSO(CP) and TSO(SCF) were more thermally stable than TSCO(SCF), and the antioxidant activity assays demonstrated that TSO(CP) and TSCO(SCF) exhibited stronger radical scavenging ability. The overall physicochemical properties of the tested oils indicated that TSO(SCF) had the best oil quality. This work may be useful to food oil industry to produce high quality tea seed oils through utilization of suitable oil extraction methods and raw materials.Practical applications: The growing consumption of green tea promoted the increased production of tea seed, which has totaled as much as 1.6 million tons annually since 2011. As an important source of edible oil, the exploitation rate of tea seed is insufficient (≤1%) in China. This study indicates that oil extracted from tea seed as well as cold‐pressing cake can be exploited for high quality edible oil because of similar fatty acid composition and better bioactive compound composition (e.g., α‐tocopherol, total phytoterols, and lupeol) compared to olive oil. Further, the evaluation of thermal stability provides basis for oil's refining to prepare salad oil, mayonnaise, etc. TSO(SCF) and TSCO(SCF) both had good antioxidant activity, which is applicable in the industry of skincare.A comparison study has been performed for tea seed oils (TSO) extracted from different methods and sources, which were oil from cold‐pressing of tea seeds [TSO(CP)], oil from supercritical fluid extraction of seeds [TSO(SCF)], and oil from supercritical fluid extraction of tea seed cake [TSCO(SCF)]. The chemical composition, thermal stability, antioxidant properties, and physicochemical properties of the oils were determined.

Study of the matrix effects and sample dilution influence on the LC-ESI-MS/MS analysis using four derivatization reagents.

For liquid chromatographic analysis of amino acids involving derivatization and mass-spectrometric detection, it becomes more important to evaluate the presence of matrix effects in complex samples. This is somewhat complicated for amino acid analysis where analyte free sample matrix is often unavailable. In this work, matrix effects were investigated using post-column infusion method for 9-fluorenylmethyl chloroformate (FMOC-Cl) derivatives of β-Ala, Gly and Phe and diethyl ethoxymethylenemalonate (DEEMM) derivative of β-Ala. While for DEEMM derivatives, the main signal suppression was due to the borate buffer, in case of FMOC-Cl, other FMOC-derivatives caused signal suppression. Analysis of amino acids in tea and honey with DEEMM, FMOC-Cl, p-N,N,N-trimethylammonioanilyl N'-hydroxysuccinimidyl carbamate iodide (TAHS) and dansyl chloride (DNS) showed that amino acid concentrations found with different reagents do not agree well. Sample dilution experiments indicated that the sample matrix affected the analysis results obtained with DEEMM the least, but with FMOC-Cl, TAHS and DNS, sample dilution had an influence on the results. When sample dilution and extrapolative dilution approach were applied on the latter results, an agreement of amino acid concentrations measured with different reagents was achieved within relative standard deviation (RSD) of 22% for most cases.

REVIEW AND CALCULATION OF ACTIVITY CO EFFICIENT OF TEA POLYPHENOLS AND ITS SOLUBILITY IN DIFFERENT SOLVENTS

Tea, one of the most popular beverages, has been co nsumed for thousands of years for their flavors and health benefits. Polyphenols are the flavanoid and phenolic acids in tea that co ntribute to health benefits. There are more than 45 polyphenols in tea. In this review, the structure, health benefits and suitable solvent selection for extraction of these polyphen ols is covered. Further the calculation of activity coefficient of tea polyphen ol is also done. This study helps us to understand the suitability of a solvent and its temperature dependency in its extraction process f rom tea leaves.

Anti-stress effect of theanine on students during pharmacy practice: Positive correlation among salivary α-amylase activity, trait anxiety and subjective stress

PurposeTheanine, an amino acid in tea, has significant anti-stress effect on experimental animals under psychosocial stress. Anti-stress effect of theanine on humans was evaluated in 5th-year university students during pharmacy practice. MethodThe study design was a single-blind group comparison and participants (n=20) were randomly assigned to theanine or placebo groups. Theanine or placebo (lactose) tablets (200mg, twice a day, after breakfast and lunch) were taken from 1week prior to the pharmacy practice and continued for 10days in the practice period. To assess the anxiety of the participants, the state–trait anxiety inventory test was carried out before the pharmacy practice. Salivary α-amylase activity (sAA) was measured as a marker of sympathetic nervous system activity. ResultsIn the placebo-group, sAA in the morning (pre-practice sAA) was higher than in theanine-group during the pharmacy practice (p=0.032). Subjective stress was significantly lower in the theanine-group than in the placebo-group (p=0.020). These results suggest that theanine intake had anti-stress effect on students. Furthermore, students with higher pre-practice sAA showed significantly higher trait anxiety in both groups (p=0.015). Similarly, higher pre-practice sAA was correlated to shorter sleeping time in both groups (p=0.41×10−3). ConclusionStressful condition increased the level of sAA that was essentially affected by individual trait anxiety. The low levels of pre-practice sAA and subjective stress in the theanine-group suggest that theanine intake suppressed initial stress response of students assigned for a long-term commitment of pharmacy practice.