| hplc method for measurement of human salivary α-amylase inhibition by aqueous plant extracts. | control of hyperglycemia is an important treatment in metabolic disorders such as type ii diabetes and obesity. α-amylase, as the first enzyme of glucose release from dietary polysaccharides, is a potential target to identify new sources of novel anti-obesity and anti-diabetic drugs. in this work, different herbal extracts as α-amylase inhibitors were studied by measuring the rate of the cleavage of a maltooligomer substrate 2-chloro-4-nitrophenyl-β-d-maltoheptoside. measurement of chromophore c ... | 2017 | 28605974 |
| physiologically based pharmacokinetic modeling of tea catechin mixture in rats and humans. | although green tea (camellia sinensis) (gt) contains a large number of polyphenolic compounds with anti-oxidative and anti-proliferative activities, little is known of the pharmacokinetics and tissue dose of tea catechins (tcs) as a chemical mixture in humans. the objectives of this study were to develop and validate a physiologically based pharmacokinetic (pbpk) model of tea catechin mixture (tcm) in rats and humans, and to predict an integrated or total concentration of tcm in the plasma of hu ... | 2017 | 28603626 |
| antipyretic potential of herbal coded formulation (pyrexol). | the antipyretic effect of the aqueous extract of herbal coded formulation containing equal amount of salix alba, emblica officinalis, glycyrrhiza glabra, adhatoda vasica, viola odorata, thea sinensis, veleriana officinalis, foeniculum vulgare, sisymbrium irrio and achillea millefolium was investigated using the yeast induced pyrexia model in rabbits. paracetamol was used as a control group. rectal temperatures of all rabbits were recorded immediately before the administration of the extract or p ... | 2017 | 28603131 |
| important medicinal herbs in parkinson's disease pharmacotherapy. | parkinson's disease (pd) is the most common progressive neurodegenerative movement disorder affecting more than 10 million people worldwide. the characteristic hallmark of pd involves progressive loss of dopaminergic (da-ergic) neuron in substantia nigra pars compacta (snpc) region of the brain, however, aetiology of the disease still remains unclear. mitochondrial dysfunction and oxidative insult are considered to be the key culprit. the current therapy available for pd primarily relies on levo ... | 2017 | 28599249 |
| effects of adjacent land-use types on the distribution of soil organic carbon stocks in the montane area of central taiwan. | soil organic carbon (soc) stocks can be altered through reforestation and cropping. we estimated the effects of land use on soc stocks after natural deciduous forests replaced by crops and coniferous plantations by examining the vertical distribution of soc stocks at different depth intervals in an adjacent oolong tea (camellia sinensis l.) plantation, moso bamboo (phyllostachys pubescens) forest, japanese cedar (cryptomeria japonica) forest, and taiwania (taiwania cryptomerioides) forest in cen ... | 2016 | 28597442 |
| accumulation of catechins and expression of catechin synthetic genes in camellia sinensis at different developmental stages. | catechins are the main polyphenol compounds in tea (camellia sinensis). to understand the relationship between gene expression and product accumulation, the levels of catechins and relative expressions of key genes in tea leaves of different developmental stages were analyzed. | 2016 | 28597441 |
| molecular link between leaf coloration and gene expression of flavonoid and carotenoid biosynthesis in camellia sinensis cultivar 'huangjinya'. | 'huangjinya' is an excellent albino tea germplasm cultivated in china because of its bright color and high amino acid content. it is light sensitive, with yellow leaves under intense light while green leaves under weak light. as well, the flavonoid and carotenoid levels increased after moderate shading treatment. however, the mechanism underlying this interesting phenomenon remains unclear. in this study, the transcriptome of 'huangjinya' plants exposed to sunlight and shade were analyzed by hig ... | 2017 | 28596773 |
| bioavailability of black tea theaflavins: absorption, metabolism, and colonic catabolism. | data obtained with in vitro fecal incubations and a feeding study indicate black tea theaflavin and its galloyl derivatives are not absorbed in detectable amounts in either the upper or lower gastrointestinal tract. the theaflavin skeleton is comparatively resistant to degradation by colonic bacteria with a 67% recovery being obtained after a 24 h incubation, which yielded 21 phenolic and aromatic catabolites. the theaflavin galloyl moiety was removed by the microbiota, and the released gallic a ... | 2017 | 28595385 |
| camellia sinensis prevents perinatal nicotine-induced neurobehavioral alterations, tissue injury, and oxidative stress in male and female mice newborns. | nicotine exposure during pregnancy induces oxidative stress and leads to behavioral alterations in early childhood and young adulthood. the current study aimed to investigate the possible protective effects of green tea (camellia sinensis) against perinatal nicotine-induced behavioral alterations and oxidative stress in mice newborns. pregnant mice received 50 mg/kg c. sinensis on gestational day 1 (pd1) to postnatal day 15 (d15) and were subcutaneously injected with 0.25 mg/kg nicotine from pd1 ... | 2017 | 28588748 |
| protective effects of green tea on olanzapine-induced-metabolic syndrome in rats. | atypical antipsychotics particularly olanzapine are associated with obesity and serious metabolic disturbances. as green tea (camellia sinensis) is generally associated with beneficial effects on obesity and other metabolic disturbances, this study was undertaken to evaluate the effect of green tea aqueous extract (gtae) on olanzapine induced weight gain and metabolic abnormalities in rats. male wistar rats were divided into eight groups: control, olanzapine (5mg/kg/day, ip.), gtae (25, 50 and 1 ... | 2017 | 28586744 |
| a randomized, double-blind, placebo-controlled clinical trial examining the effects of green tea extract on systemic lupus erythematosus disease activity and quality of life. | antiinflammatory and immunomodulatory benefit of green tea (camellia sinensis) in autoimmune disease has been proven in recent studies. the objective of this study was to assess the effects of green tea on disease activity and quality of life in systemic lupus erythematosus patients. a randomized controlled trial on subjects with lupus was conducted, and 68 patients in the age range of 39.1 ± 10.3 years and body mass index of 25.7 ± 5.21 kg/m2 completed the 12-week study. patients were randomly ... | 2017 | 28585735 |
| the synergistic potential of various teas, herbs and therapeutic drugs in health improvement: a review. | tea is one of the most widely consumed non-alcoholic beverages in the world next to water. it is classified as camellia sinensis and non-camellia sinensis (herbal teas). the common bioactive compounds found mainly in green teas are flavan-3-ols (catechins) (also called flavanols), proanthocyanidins (tannins) and flavonols. black tea contains theaflavins and thearubigins and white tea contains l-theanine and gamma-aminobutyric acid (gaba), while herbal teas contain diverse polyphenols. phytochemi ... | 2017 | 28585285 |
| a case of green tea (camellia sinensis) imbibement causing possible anaphylaxis. | | 2017 | 28583266 |
| transfer of ochratoxin a from raw black tea to tea infusions prepared according to the turkish tradition. | ochratoxin a (ota) is a natural contaminant of food including tea with multiple toxic effects, which poses a threat to human health. in terms of lifestyle, the turkish population is a frequent visitor of tearooms, and the traditional turkish tea preparation is one of the most popular ways of preparing tea infusion. | 2018 | 28580652 |
| olivibacter flavus sp. nov., a novel endophytic bacterium isolated from the root of camellia sinensis. | a novel gram-negative rod, endophytic bacterium, designated strain tmcc 8258t, was isolated from the root of camellia sinensis collected from puer, south-west china. comparative 16s rrna gene sequence analysis showed that the strain belongs to the family sphingobacteriaceae and a neighbour-joining phylogenetic tree suggested that strain tmcc 8258t formed a cluster with the type strain of olivibacter ginsengisoli (showed the highest 16s rrna gene sequence similarity of 95.8%). chemotaxonomic data ... | 2017 | 28577180 |
| paradigm shift of contamination risk of six heavy metals in tea (camellia sinensis l.) growing soil: a new approach influenced by inorganic and organic amendments. | the present study provides several contamination and ecological risk indices for selected metals (cd, cr, cu, mn, ni and zn) in tea (camellia sinensis l.; cv. s.3a/3) growing soil influenced by lower to higher doses of inorganic and organic amendments. while ecological risk indices were applied, it was observed that same treatment showed different risk levels but contamination risk status did not vary significantly. all the indices showed significant correlation with heavy metals' concentration ... | 2017 | 28575803 |
| c-geranylated flavanones from yingde black tea and their antioxidant and α-glucosidase inhibition activities. | yingde black tea is produced from crude tea prepared from leaves of camellia sinensis var. assamica. in this work, we isolated and identified five novel flavanones, namely, amelliaone a-e (1-5), along with seven known compounds 6-12 from the ethanol extract of yingde black tea. the structures of these five novel phenolic compounds were determined using extensive 1d and 2d nuclear magnetic resonance spectroscopy experiments. the compounds were further evaluated for antioxidant, α-glucosidase inhi ... | 2017 | 28554631 |
| quality improvement of a rice-substituted fried noodle by utilizing the protein-polyphenol interaction between a pea protein isolate and green tea (camellia sinensis) extract. | the quality of rice-substituted fried noodles was improved by applying interaction between pea protein isolate (ppi) and green tea extract (gte). radical-scavenging activities of gte were stably maintained when exposed to acidic ph, uv light, and fluorescent light, but decreased by approximately 65% when exposed to 80°c for 168h. the rva profiles of noodle dough showed that peak viscosity and breakdown increased significantly but that setback and final viscosity remained unchanged with 20% rice ... | 2017 | 28554624 |
| research on pyrolysis behavior of camellia sinensis branches via the discrete distributed activation energy model. | this study aims at investigating the pyrolysis behavior of camellia sinensis branches by the discrete distributed activation energy model (daem) and thermogravimetric experiments. then the discrete daem method is used to describe pyrolysis process of camellia sinensis branches dominated by 12 characterized reactions. the decomposition mechanism of camellia sinensis branches and interaction with components are observed. and the reaction at 350.77°c is a significant boundary of the first and secon ... | 2017 | 28551431 |
| what is in your cup of tea? dna verity test to characterize black and green commercial teas. | in this study, we used several molecular techniques to develop a fast and reliable protocol (dna verity test, dvt) for the characterization and confirmation of the species or taxa present in herbal infusions. as a model plant for this protocol, camellia sinensis, a traditional tea plant, was selected due to the following reasons: its historical popularity as a (healthy) beverage, its high selling value, the importation of barely recognizable raw product (i.e., crushed), and the scarcity of studi ... | 2017 | 28542606 |
| flavanols from the camellia sinensis var. assamica and their hypoglycemic and hypolipidemic activities. | α-glucosidase and lipase inhibitors play important roles in the treatment of hyperglycaemia and dyslipidemia. to identify novel naturally occurring inhibitors, a bioactivity-guided phytochemical research was performed on the pu-erh tea. one new flavanol, named (-)-epicatechin-3-o-(z)-coumarate (1), and 16 known analogs (2-17) were isolated from the aqueous extract of the pu-erh tea. their structures were determined by spectroscopic and chemical methods. furthermore, the water extract of pu-erh t ... | 2017 | 28540171 |
| 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 it ... | 2017 | 28531120 |
| metabolic phenotyping of various tea (camellia sinensis l.) cultivars and understanding of their intrinsic metabolism. | recently, we selected three tea (camellia sinensis) cultivars that are rich in taste, epigallocatechin-3-o-gallate (egcg) and epigallocatechin-3-o-(3-o-methyl)-gallate (egcg3″me) and then cultivated them through asexual propagation by cutting in the same region. in the present study, proton nuclear magnetic resonance (1h nmr)-based metabolomics was applied to characterize the metabotype and to understand the metabolic mechanism of these tea cultivars including wild type tea. of the tea leaf meta ... | 2017 | 28530581 |
| characterization of white tea metabolome: comparison against green and black tea by a nontargeted metabolomics approach. | white tea is considered the least processed form of tea and is reported to have a series of potent bioactivities, such as antioxidant, anti-inflammatory, anti-mutagenic, and anti-cancer activities. however, the chemical composition of white tea and the dynamic changes of the metabolites during the manufacturing process are far from clear. in this study, we applied a nontargeted metabolomics approach based on ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass ... | 2017 | 28528106 |
| functional characterizations of β-glucosidases involved in aroma compound formation in tea (camellia sinensis). | tea (camellia sinensis) aroma is an important factor affecting tea quality. many tea aroma compounds are present as glycosidically conjugated forms in tea leaves, and can be hydrolyzed by β-glucosidase (β-glu) and β-primeverosidase to release free tea aromas. β-primeverosidase has been identified and functionally characterized, while β-glu has not been identified in tea leaves. in the present study, we established a yeast expression system to recombine csgh1bg1, csgh3bg1, and csgh5bg1, which bel ... | 2017 | 28528101 |
| proteomic analysis of tea plants (camellia sinensis) with purple young shoots during leaf development. | tea products made from purple leaves are highly preferred by consumers due to the health benefits. this study developed a proteome reference map related to color changes during leaf growth in tea (camellia sinensis) plant with purple young shoots using two-dimensional electrophoresis (2-de). forty-six differentially expressed proteins were detected in the gel and successfully identified by using maldi-tof/tof-ms. the pronounced changes in the proteomic profile between tender purple leaves (tpl) ... | 2017 | 28520776 |
| expression of key structural genes of the phenylpropanoid pathway associated with catechin epimerization in tea cultivars. | catechin epimerization is an important factor affecting tea catechin compositions and thereby tea quality. however, a lack of tea germplasms with high non-epicatechins limits relative research. here, a tea cultivar y510 with high non-epicatechins was firstly reported and used for catechin and rna sequencing (rna-seq) analysis. results showed that the (-)-gallocatechin gallate and (+)-catechin (c) contents in y510 were at least 136 and 6 times higher than those in fudingdabaicha and 0306i, but th ... | 2017 | 28515736 |
| characterization of l-theanine excitatory actions on hippocampal neurons: toward the generation of novel n-methyl-d-aspartate receptor modulators based on its backbone. | l-theanine (or l-γ-n-ethyl-glutamine) is the major amino acid found in camellia sinensis. it has received much attention because of its pleiotropic physiological and pharmacological activities leading to health benefits in humans, especially. we describe here a new, easy, efficient, and environmentally friendly chemical synthesis of l-theanine and l-γ-n-propyl-gln and their corresponding d-isomers. l-theanine, and its derivatives obtained so far, exhibited partial coagonistic action at n-methyl- ... | 2017 | 28511005 |
| short-term effects of green tea chronotherapy on the metabolic homeostasis of mice on different diets. | biological rhythms can be defined as changes in physiological or behavioral variables that repeat at certain time intervals. rhythms that last approximately 24 h are referred to as circadian rhythms. modern lifestyles have drastically affected human habits, as well as the population's eating habits. these changes have generated an epidemic of metabolic syndromes, such as obesity and diabetes. in an attempt to combat obesity, populations have attempted to use many different herbal remedies and pl ... | 2017 | 28510251 |
| camellia sinensis increased apoptosis on u2os osteosarcoma cells and wound healing potential on nih3t3 fibroblast cells. | camellia sinensis (cs) is a plant which is rich in polyphenols and has antioxidant, antiinflammatory, antimutagenic, anticarcinogenic and antibacterial activities. in this study, two different methanol extracts (cs-i and cs-ii) were prepared from the leaf of c. sinensis in order to investigate the wound healing and anticancer activities. total phenolic content and antioxidant activity of the extracts were determined. wound healing effects of cs extracts were evaluated by using masson's trichrome ... | 2017 | 28509991 |
| quantitative succinyl-proteome profiling of camellia sinensis cv. 'anji baicha' during periodic albinism. | lysine succinylation is a novel dynamic and evolutionarily conserved post-translational modification (ptm) that regulates various biological processes. 'anji baicha' is an albino tea variety that exhibits temperature-based variability of leaf colour and amino acid concentrations. however, the mechanism underlying albinism in 'anji baicha' has not been investigated at the level of succinylation. here, we identify 3530 lysine succinylation sites mapped to 2132 proteins in 'anji baicha', representi ... | 2017 | 28500349 |
| nickel nanoparticle synthesis using camellia sinensis as reducing and capping agent: growth mechanism and photo-catalytic activity evaluation. | recently, the biosynthesis of nanoparticle attracted the attention of scientific community due to its simplicity, ease and eco-friendly nature. in the present study, camellia sinensis (c. sinensis) leaves extract was employed for the synthesis of nickel nanoparticles (ninps). the fabricated ninps were characterized by scanning electron microscopy (sem) and energy-dispersive x-ray (edx) and x-ray diffraction techniques. the photocatalytic activity (pca) was evaluated by degrading crystal violet ( ... | 2017 | 28495625 |
| artemisinin-luminol chemiluminescence for forensic bloodstain detection using a smart phone as a detector. | forensic luminol chemiluminescence test is one of the most sensitive and popular methods for the determination of latent bloodstains. it mainly uses hydrogen peroxide or sodium perborate as coreactants. the easy decomposition of hydrogen peroxide and sodium perborate in the presence of many ions significantly affects the selectivity. artemisinin is a natural peroxide that is quite stable in the presence of common ions. in the present study, artemisinin has been exploited for the forensic bloodst ... | 2017 | 28492080 |
| transcriptome and metabolite analysis identifies nitrogen utilization genes in tea plant (camellia sinensis). | applied nitrogen (n) fertilizer significantly increases the leaf yield. however, most n is not utilized by the plant, negatively impacting the environment. to date, little is known regarding n utilization genes and mechanisms in the leaf production. to understand this, we investigated transcriptomes using rna-seq and amino acid levels with n treatment in tea (camellia sinensis), the most popular beverage crop. we identified 196 and 29 common differentially expressed genes in roots and leaves, re ... | 2017 | 28490757 |
| effects of dietary green tea (camellia sinensis l.) supplementation on growth performance, lipid metabolism, and antioxidant status in a sturgeon hybrid of sterlet (huso huso ♂ × acipenser ruthenus ♀) fed oxidized fish oil. | lipid content of diet is very susceptible to oxidation, especially when stored for a long time, so for evaluating protective effects of green tea in fish received oxidized oil, this study was done. lipid content of diet was replaced by oxidized fish oil (ofo) in 0, 50, and 100%. green tea extract (gte) was added to diet in three levels, 0, 5, and 100 mg/kg giving a total of nine experimental diets. two hundred and seventy sturgeon hybrid of sterlet (huso huso ♀ × acipenser ruthenus ♂) with initi ... | 2017 | 28488192 |
| nitric oxide mediates brassinosteroid-induced flavonoid biosynthesis in camellia sinensis l. | flavonoids are one of the key secondary metabolites determining the quality of tea. although exogenous brassinosteroid (br), a steroidal plant hormone, can stimulate polyphenol biosynthesis in tea plants (camellia sinensis l.), the relevance of endogenous br in flavonoid accumulation and the underlying mechanisms remain largely unknown. here we show that br enhances flavonoid concentration in tea leaves by inducing an increase in the endogenous concentration of nitric oxide (no). notably, exogen ... | 2017 | 28482335 |
| probable benefits of green tea with genetic implications. | tea is produced from the camellia sinensis plant and can generally be divided into categories based on how they are processed. in general, green tea that is unfermented c. sinensis has been considered superior to black tea in health benefits. it contains a unique set of catechins that possess biological activity as antioxidant, anti-inflammatory and antiproliferative, which is potentially significant to the prevention and treatment of various forms of diseases. oral cavity oxidative stress and i ... | 2017 | 28479696 |
| oak kombucha protects against oxidative stress and inflammatory processes. | black tea infusion is the common substrate for preparing kombucha; however other sources such as oak leaves infusions can be used for the same purpose. almost any white oak species have been used for medicinal applications by some ethnic groups in mexico and could be also suitable for preparing kombucha analogues from oak (kao). the objective of this research was to investigate the antioxidant activity and anti-inflammatory effects of kao by examining its modulation ability on macrophage-derived ... | 2017 | 28476604 |
| the tea tree genome provides insights into tea flavor and independent evolution of caffeine biosynthesis. | tea is the world's oldest and most popular caffeine-containing beverage with immense economic, medicinal, and cultural importance. here, we present the first high-quality nucleotide sequence of the repeat-rich (80.9%), 3.02-gb genome of the cultivated tea tree camellia sinensis. we show that an extraordinarily large genome size of tea tree is resulted from the slow, steady, and long-term amplification of a few ltr retrotransposon families. in addition to a recent whole-genome duplication event, ... | 2017 | 28473262 |
| breast cancer chemopreventive and chemotherapeutic effects of camellia sinensis (green tea): an updated review. | camellia sinensis belongs to the plant family of theaceae, native to east asia, the indian subcontinent and southeast asia, but naturalized in many parts of the world. the aim of this study was to overview its anti-breast cancer chemopreventive and chemotherapeutic effects. this review article is aimed to overview breast cancer chemopreventive and chemotherapeutic effects of camellia sinensis (green tea). | 2017 | 28465816 |
| supplementation with different teas from camellia sinensis prevents memory deficits and hippocampus oxidative stress in ischemia-reperfusion. | memory and cognition impairments resultant of ischemic stroke could be minimized or avoided by antioxidant supplementation. in this regard, the neuroprotective potential of green tea from camellia sinensis has been investigated. however, there is a lack of information regarding the neuroprotective potential of others teas processed from the camellia sinensis. here we investigate the neuroprotective role of green, red, white and black tea on memory deficits and brain oxidative stress in a model o ... | 2017 | 28465087 |
| comprehensive transcriptome analyses reveal differential gene expression profiles of camellia sinensis axillary buds at para-, endo-, ecodormancy, and bud flush stages. | winter dormancy is an important biological feature for tea plant to survive cold winters, and it also affects the economic output of tea plant, one of the few woody plants in the world whose leaves are harvested and one of the few non-conifer evergreen species with characterized dormancies. to discover the bud dormancy regulation mechanism of tea plant in winter, we analyzed the global gene expression profiles of axillary buds at the paradormancy, endodormancy, ecodormancy, and bud flush stages ... | 2017 | 28458678 |
| corneal staining and hot black tea compresses. | warm compresses are widely touted as an effective treatment for ocular surface disorders. black tea compresses are a common household remedy, although there is no evidence in the medical literature proving their effect and their use may lead to harmful side effects. | 2017 | 28457091 |
| heterologous expression of three camellia sinensis small heat shock protein genes confers temperature stress tolerance in yeast and arabidopsis thaliana. | cshsp17.7, cshsp18.1, and cshsp21.8 expressions are induced by heat and cold stresses, and cshsp overexpression confers tolerance to heat and cold stresses in transgenic pichia pastoris and arabidopsis thaliana. small heat shock proteins (shsps) are crucial for protecting plants against biotic and abiotic stresses, especially heat stress. however, knowledge concerning the functions of camellia sinensis shsp in heat and cold stresses remains poorly understood. in this study, three c. sinensis shs ... | 2017 | 28455764 |
| reliable reference genes for normalization of gene expression data in tea plants (camellia sinensis) exposed to metal stresses. | tea plants [camellia sinensis (l.) o. kuntze] are an important leaf-type crop that are widely used for the production of non-alcoholic beverages in the world. exposure to excessive amounts of heavy metals adversely affects the quality and yield of tea leaves. to analyze the molecular responses of tea plants to heavy metals, a reliable quantification of gene expression is important and of major importance herein is the normalization of the measured expression levels for the target genes. ideally, ... | 2017 | 28453515 |
| comparison of metabolomics approaches for evaluating the variability of complex botanical preparations: green tea (camellia sinensis) as a case study. | a challenge that must be addressed when conducting studies with complex natural products is how to evaluate their complexity and variability. traditional methods of quantifying a single or a small range of metabolites may not capture the full chemical complexity of multiple samples. different metabolomics approaches were evaluated to discern how they facilitated comparison of the chemical composition of commercial green tea [camellia sinensis (l.) kuntze] products, with the goal of capturing the ... | 2017 | 28453261 |
| formation of (e)-nerolidol in tea (camellia sinensis) leaves exposed to multiple stresses during tea manufacturing. | (e)-nerolidol is a volatile sesquiterpene that contributes to the floral aroma of teas (camellia sinensis). the unique manufacturing process for oolong tea involves multiple stresses, resulting in a high content of (e)-nerolidol, which is not known to form in tea leaves. this study aimed to determine the formation mechanism of (e)-nerolidol in tea exposed to multiple stresses during tea manufacture. c. sinensis (e)-nerolidol synthase (csnes) recombinant protein, found in the cytosol, was found t ... | 2017 | 28450026 |
| l-theanine content and related gene expression: novel insights into theanine biosynthesis and hydrolysis among different tea plant (camellia sinensis l.) tissues and cultivars. | l-theanine content has tissues and cultivars specificity in tea plant (camellia sinensis l.), the correlations of theanine metabolic related genes expression profiles with theanine contents were explored in this study. l-theanine contents in the bud and 1st leaf, 2nd leaf, 3rd leaf, old leaf, stem, and lateral root were determined by hplc from three c. sinensis cultivars, namely 'huangjinya', 'anjibaicha', and 'yingshuang', respectively. the theanine contents in leaves and root of 'huangjinya' w ... | 2017 | 28439281 |
| targeted intracellular heat transfer in cancer therapy: assessment of asparagine-laminated gold nanoparticles in cell model of t cell leukemia. | high temperatures have destructive effects on cancer cells by damaging proteins and structures within cells. gold nanoparticles (aunps) can act as drug delivery vehicles, especially for cancer therapy. due to the selective intake of asparagine molecules into malignant cells, aunps were coated with asparagine; and ccrf-cem human t-cell leukemia cells were treated with the new combination, asn-aunps, at 39 °c. | 2017 | 28435822 |
| effect of black tea consumption on radial blood pulse spectrum and cognitive health. | black tea consumption has been proven to improve endothelial function and to lower the risk of stroke and cognitive impairment. several effects of black tea on cardiovascular system had been surveyed. however, the black tea effect on pressure pulse spectrum remains unknown. the study was aimed to investigate the influence of black tea on radial blood pressure and pulse spectrum. fourteen healthy subjects received water and single doses of black tea (0.05g/kg) in separate weeks. the radial blood ... | 2017 | 28434461 |
| theanine: the unique amino acid in the tea plant as an oral hepatoprotective agent. | for thousands of years, humans have consumed tea made from leaves of camellia sinensis, first as a medicinal herb and then as a widely popular beverage. in the past 10 years, theanine, a tea-derived, unique, nonproteinic amino acid, has been extensively studied for its health benefits. recently, multiple lines of evidence have proven its beneficial effects on hepatic and immune functions. one possible mechanism for its biological activity involves the downregulation of the inflammatory response ... | 2017 | 28429900 |
| regulation of anthocyanin biosynthesis in purple leaves of zijuan tea (camellia sinensis var. kitamura). | plant anthocyanin biosynthesis is well understood, but the regulatory mechanism in purple foliage tea remains unclear. using isobaric tag for relative and absolute quantification (itraq), 815 differential proteins were identified in the leaves of zijuan tea, among which 20 were associated with the regulation of anthocyanin metabolism. we found that the abundances of anthocyanin synthesis-related enzymes such as chalcone synthase, chalcone isomerase, dihydroflavonol 4-reductase and anthocyanin sy ... | 2017 | 28422049 |
| quality, antioxidant activity and composition of indian black teas. | a comparative study was undertaken to determine the difference in quality, antioxidant activity, and mineral content of northern and southern indian tea varieties. the results showed that the antioxidant activity, theaflavin and thearubigin content, color particle size and total soluble solids influence the tea leaf and tea dust. assam leaf showed higher values for all the physico-chemical properties followed by darjeeling leaf. in addition, the mineral composition of the tea infusion was also i ... | 2017 | 28416877 |
| impact of light irradiation on black tea quality during withering. | black tea manufacture usually involves the processes of withering, cutting, fermentation and drying. the aim of present study was to evaluate the effect of the relationship between the quality and withering with different light sources (ultraviolet, yellow, blue, purple, orange, red, cyan, green and white) an quality attribute of tea. the results indicated that the yellow, orange and red light withering significantly improved the aroma and taste, imparting the tea a sweet flavor and a fresh and ... | 2017 | 28416872 |
| spontaneously assembled nano-aggregates in clear green tea infusions from camellia ptilophylla and camellia sinensis. | tea nano-aggregates spontaneously assembled in clear tea infusions are considered as the precursors of tea cream, although their molecular basis remains obscure. here, we characterized nano-aggregates in green tea infusions from camellia ptilophylla, a peculiar tea variety with 6.0% of theobromine, and camellia sinensis as the control for comparative purpose. numerous negatively charged spherical colloidal particles of 50-100 nm in diameter were primarily found in both green tea infusions. catec ... | 2017 | 28412808 |
| pestalotiopsis and allied genera from camellia, with description of 11 new species from china. | a total of 124 pestalotiopsis-like isolates associated with symptomatic and asymptomatic tissues of camellia sinensis and other camellia spp. from eight provinces in china were investigated. based on single- and multi-locus (its, tef, tub2) phylogenies, as well as morphological characters, host associations and geographical distributions, they were classified into at least 19 species in three genera, i.e. neopestalotiopsis, pestalotiopsis and pseudopestalotiopsis. eight novel species in pestalot ... | 2017 | 28408743 |
| bionic multi-tentacled ionic liquid-modified silica gel for adsorption and separation of polyphenols from green tea (camellia sinensis) leaves. | for the first time, a new kind of bionic multi-tentacled ionic liquid-modified silica gel was synthesized and used as selective adsorbent in the preparative separation of tea polyphenols (tp) from green tea leaves. it was found that silica particles with polyvinyl alcohol chains modified by n-methyl imidazole proline salt (pva·im+·pro-@sio2) had the excellent performance in selective adsorption as well as fine separation for target compounds. the new adsorbent exhibited high adsorption capacity ... | 2017 | 28407961 |
| a new cineol derivative, polyphenols and norterpenoids from saharan myrtle tea (myrtus nivellei): isolation, structure determination, quantitative determination and antioxidant activity. | the phytochemical profile of decoction and infusion, obtained from the dried leaves of m. nivellei, consumed as tea in saharan region, was characterized by uhplc-pda-hrms. fourteen compounds were characterized and, to confirm the proposed structures a preparative procedure followed by nmr spectroscopy was applied. compound 3 (2-hydroxy-1,8-cineole disaccharide) was a never reported whereas a bicyclic monoterpenoid glucoside (2), two ionol glucosides (1 and 12), a tri-galloylquinic acid (4), two ... | 2017 | 28363507 |
| [influence of luxury foodstuffs on glaucoma]. | the term "luxury foodstuffs" refers to foods which are not consumed because of their nutritional value. classic modern luxury foodstuffs are alcohol, caffeine-containing drinks, cocoa, sugar and tobacco. the following review article examines some of these modern luxury foodstuffs in detail, as well as their influence on glaucoma. thus, small quantities of alcohol lower high intraocular pressure and have a positive influence on the blood circulation of the optic nerve. in addition, red wine polyp ... | 2017 | 28142165 |
| extraction efficiency of different solvents and lc-uv determination of biogenic amines in tea leaves and infusions. | biogenic amines (bas), that is, spermine, spermidine, putrescine, histamine, tyramine, β-phenylethylamine, cadaverine, and serotonin, have been determined in several samples of tea leaves, tea infusions, and tea drinks by lc-uv method after derivatization with dansyl chloride. different extraction solvents have been tested and tca 5% showed better analytical performances in terms of linearity, recovery percentages, lod, loq, and repeatability than hcl 0.1 m and hclo4 0.1 m and was finally exploi ... | 2016 | 27555979 |
| safety and anti-hyperglycemic efficacy of various tea types in mice. | tea, a beverage consumed worldwide, has proven anti-hyperglycemic effects in animal models. better efficacies of tea beverages are frequently associated with high-dose levels, whose safety attracts considerable attention. based on the inherent nature of tea catechin oxidation, fresh tea leaves are manufactured into diverse tea types by modulating the oxidation degree of catechins. the present study aimed to assess various tea types for their safety properties and anti-hyperglycemic effects. mice ... | 2016 | 27531374 |
| targeting microrna in cancer using plant-based proanthocyanidins. | proanthocyanidins are oligomeric flavonoids found in plant sources, most notably in apples, cinnamon, grape skin and cocoa beans. they have been also found in substantial amounts in cranberry, black currant, green tea, black tea and peanut skins. these compounds have been recently investigated for their health benefits. proanthocyanidins have been demonstrated to have positive effects on various metabolic disorders such as inflammation, obesity, diabetes and insulin resistance. another upcoming ... | 2016 | 28933401 |
| potential of food and natural products to promote endothelial and vascular health. | endothelial dysfunction is now well established as a pivotal early event in the development of major cardiovascular diseases including hypertension, atherosclerosis, and diabetes. the alteration of the endothelial function is often triggered by an imbalance between the endothelial formation of vasoprotective factors including nitric oxide (no) and endothelium-dependent hyperpolarization, and an increased level of oxidative stress involving several prooxidant enzymes such as nadph oxidase and, of ... | 2016 | 26974893 |
| inhibitory effect of camellia sinensis, ilex paraguariensis and ardisia compressa tea extracts on the proliferation of human head and neck squamous carcinoma cells. | in vitro cell proliferation, cell cycle arrest and induction of apoptosis were investigated, using three human head and neck squamous cell carcinoma (hnscc) cell lines (oscc-3, scc-61, and sq-20b). aqueous extracts of camellia sinensis, ilex paraguariensis, and ardisia compressa were tested and (-) epigallocatechin-3-gallate (egcg) was used for comparison. for egcg the ic50 values were between 80 and 166 μm and for the extracts among 75 and 505 μm eq. (+) catechin, with c. sinensis demonstrating ... | 2016 | 28959547 |
| isolation of eugenyl β-primeveroside from camellia sasanqua and its anticancer activity in pc3 prostate cancer cells. | most studies of tea trees have focused on their ornamental properties, there are fewer published studies on their medical values. the purpose of this study was to compare the chemical constituents and the biological potential of the water extract of leaves in eight species of camellia including camellia sinensis. among eight camellia species, camellia sasanqua showed potent anticancer activities in prostate cancer pc3 cells. in addition to catechins, the major component, eugenyl β-primeveroside ... | 2016 | 28911392 |
| effects of blending wheatgrass juice on enhancing phenolic compounds and antioxidant activities of traditional kombucha beverage. | traditional kombucha is a fermented black tea extract and sugar. sweetened black tea (10% w/v) and wheatgrass juice (wgj) were mixed in various ratios and used as fermentation substrate for enhancing phenolic compounds and antioxidant activity. starter, comprising of yeast (dekkera bruxellensis) and acetic acid bacteria (gluconacetobacter rhaeticus and gluconobacter roseus), was inoculated at 20% (v/v), and fermented statically at 29 ± 1°c for 12 days. the results showed that the total phenolic ... | 2015 | 28911487 |
| concentrations and solubility of selected trace metals in leaf and bagged black teas commercialized in poland. | the objective of this study was to determine the concentrations of heavy metals in bagged and leaf black teas of the same brand and evaluate the percentage transfer of metals to tea infusion to assess the consumer exposure. ten leaf black teas and 10 bagged black teas of the same brand available in poland were analyzed for zn, mn, cd, pb, ni, co, cr, al, and fe concentrations both in dry material and their infusion. the bagged teas contained higher amounts of pb, mn, fe, ni, al, and cr compared ... | 2015 | 28911707 |
| beverage-induced enhanced bioavailability of carbamazepine and its consequent effect on antiepileptic activity and toxicity. | the present study was undertaken to investigate the food-drug interaction of carbamazepine (cbz). common fruit juices [grapefruit juice (gfj), lime juice (lj)], known to inhibit the enzyme cytochrome p450 3a4 (cyp3a4), and some widely consumed beverages [milk (m), black tea (bt)] were involved in this study in the presence of cbz, as might happen during clinical therapy. the effects of the beverages on the pharmacokinetics and drug-induced toxicity of cbz was observed after concomitant administr ... | 2015 | 28911389 |
| development and validation of uhplc-ms/ms method for determination of eight naturally occurring catechin derivatives in various tea samples and the role of matrix effects. | a complete analytical procedure combining optimized tea infusion preparation and validated uhplc-ms/ms method was developed for routine quantification of eight naturally occurring catechin derivatives in various tea samples. the preparation of tea infusions was optimized in terms of temperature, time and water-to-tea ratio in green, white and black teas. the catechins were analyzed using ultra-high performance liquid chromatography coupled with triple quadrupole mass spectrometry in a run of onl ... | 2015 | 26025813 |
| rapid determination of total polyphenolic content in tea samples based on caffeic acid voltammetric behaviour on a disposable graphite electrode. | the present paper describes the voltammetric behaviour and the quantitative determination of caffeic acid (ca) on a disposable pencil graphite electrode (pge). the anodic peak current of ca recorded by differential pulse voltammetry (dpv) varies linearly with ca concentration in the range 1×10(-7)-3×10(-3) m. the detection and quantification limits were 8.83×10(-8) m and 2.94×10(-7) m caffeic acid, respectively. the mean recoveries of ca from turkish green, white and black teas were 98.30%, 99.5 ... | 2015 | 25466125 |
| antioxidant effects of camellia sinensis l. extract in patients with type 2 diabetes. | the prevalence of diabetes mellitus (dm) has dramatically increased in the past decade. furthermore, increasing evidence from research shows that oxidative stress (os) plays a crucial role in the pathogenesis of diabetes and in its complications. a search for ways to reduce oxidative damage has become the focus of interest for the majority of scientists. in this study, we determined the radical scavenging activity of single green tea constituents by using an on-line high performance liquid chrom ... | 2014 | 28911467 |
| development of sts and caps markers for variety identification and genetic diversity analysis of tea germplasm in taiwan. | tea (camellia sinensis) is an important economic crop in taiwan. particularly, two major commercial types of tea (paochong tea and oolong tea) which are produced in taiwan are famous around the world, and they must be manufactured with specific cultivars. nevertheless, many elite cultivars have been illegally introduced to foreign countries. because of the lower cost, large amount of "taiwan-type tea" are produced and imported to taiwan, causing a dramatic damage in the tea industry. it is very ... | 2014 | 28510923 |
| cloning of a new glutathione peroxidase gene from tea plant (camellia sinensis) and expression analysis under biotic and abiotic stresses. | tea plant, camellia sinensis (l.) o. kuntze, a well-known heavy metal hyperaccumulator, possesses a powerful tolerance to heavy metals. the heavy metal stresses lead to reactive oxygen species (ros) production, and high concentration of ros is harmful to plants. the glutathione peroxidase gene has positive function to damage induced by ros. to understand the mechanism of tolerance to deferent stresses in tea plant, a new glutathione peroxidase gene of tea plant was cloned and its expression patt ... | 2014 | 28510910 |
| catechin content and the degree of its galloylation in oolong tea are inversely correlated with cultivation altitude. | the taste quality of oolong tea generated from leaves of camellia sinensis l. cultivated in the same mountain area is positively correlated to the cultivation altitude, partly due to the inverse correlation with the astringency of the tea infusion. the astringency of oolong tea mostly results from the presence of polyphenolic compounds, mainly catechins and their derivatives. four catechins, (-)-epicatechin (ec) and (-)-epigallocatechin (egc) together with their gallate derivatives (with relativ ... | 2014 | 28911419 |
| green synthesis of iron nanoparticles by various tea extracts: comparative study of the reactivity. | iron nanoparticles (fe nps) are often synthesized using sodium borohydride with aggregation, which is a high cost process and environmentally toxic. to address these issues, fe nps were synthesized using green methods based on tea extracts, including green, oolong and black teas. the best method for degrading malachite green (mg) was fe nps synthesized by green tea extracts because it contains a high concentration of caffeine/polyphenols which act as both reducing and capping agents in the synth ... | 2014 | 24793479 |
| green tea and type 2 diabetes. | green tea and coffee consumption have been widely popular worldwide. these beverages contain caffeine to activate the central nervous system by adenosine receptor blockade, and due to the caffeine, addiction or tolerance may occur. in addition to this caffeine effect, green tea and coffee consumption have always been at the center of discussions about human health, disease, and longevity. in particular, green tea catechins are involved in many biological activities such as antioxidation and modu ... | 2014 | 28664072 |
| the benefits and risks of consuming brewed tea: beware of toxic element contamination. | background. increasing concern is evident about contamination of foodstuffs and natural health products. methods. common off-the-shelf varieties of black, green, white, and oolong teas sold in tea bags were used for analysis in this study. toxic element testing was performed on 30 different teas by analyzing (i) tea leaves, (ii) tea steeped for 3-4 minutes, and (iii) tea steeped for 15-17 minutes. results were compared to existing preferred endpoints. results. all brewed teas contained lead with ... | 2013 | 24260033 |
| determination of polycyclic aromatic hydrocarbons in smoked and non-smoked black teas and tea infusions. | this study describes the occurrence of polycyclic aromatic hydrocarbons (pahs) in smoked tea and tea infusions, via the monitoring of benzo(a)anthracene, chrysene, benzo(b)fluoranthene and benzo(a)pyrene (pah4) that have been chosen as indicators for the occurrence of pahs in food by the european food safety agency. the concentrations ranged from 1.2 μg/kg for benzo(b)fluoranthene to 125.0 μg/kg for benzo(a)anthracene in smoked tea leaves, and from 0.6 μg/l for benzo(a)anthracene to 1.2 μg/l for ... | 2014 | 24128549 |
| neurobiological effects of the green tea constituent theanine and its potential role in the treatment of psychiatric and neurodegenerative disorders. | theanine (n-ethylglutamic acid), a non-proteinaceous amino acid component of green and black teas, has received growing attention in recent years due to its reported effects on the central nervous system. it readily crosses the blood-brain barrier where it exerts a variety of neurophysiological and pharmacological effects. its most well-documented effect has been its apparent anxiolytic and calming effect due to its up-regulation of inhibitory neurotransmitters and possible modulation of seroton ... | 2014 | 23883567 |
| compositional, nutritional, and functional characteristics of instant teas produced from low- and high-quality black teas. | two types of instant teas produced from low- and high-quality black teas were examined for their proximate composition, dietary fiber, minerals, water-soluble vitamins, total phenolic content, various antioxidant assays, phenolics (flavanols, condensed phenolics, and phenolic acids), alkaloids, and carotenoids as well as taste-active compounds (sugars, organic acids, and free amino acids). some variations, albeit to different extents, were observed (p < 0.05) among these parameters between insta ... | 2013 | 23837397 |
| antimicrobial polyphenols from small tropical fruits, tea and spice oilseeds. | the polyphenolic fractions of fruits: terminalia catappa, carissa carandas, ziziphus nummularia; spice oilseeds: thymol, mustard, fenugreek and poppy seeds; and herb: green and black teas were analyzed for their total phenolics, flavonoids and antimicrobial potential. all fractions from fruits, except anthocyanin of c. carandas, displayed substantial antibacterial activity in accordance to their phenolic contents, the difference in activity being quite significant (p < 0.05), highest for t. cata ... | 2014 | 23703103 |
| discrimination of sri lankan black teas using fluorescence spectroscopy and linear discriminant analysis. | the quality of teas is currently graded using trained tea tasters, whose evaluation can sometimes be subjective. in this study the simple fluorescence-based technique of total luminescence spectroscopy (tls) in conjunction with data classification using principal component analysis (pca) was applied to discriminate between teas from 11 different sri lankan plantations. solvent extraction of the tea samples was followed by tls to record excitation-emission matrices in the excitation range 250-590 ... | 2013 | 23371833 |
| effects of addition of egg ovotransferrin-derived peptides on the oxygen radical absorbance capacity of different teas. | ovotransferrin-derived peptides showed synergistic effects with vitamin c, epigallocatechin gallate (egcg), and caffeic acid, but not quercetin in our previous report. in this study, we further investigated the interactions between ovotransferrin-derived peptides and teas, based on the oxygen radical absorbance capacity (orac) assay. our results showed that there was no significant difference in orac values among green, oolong, and black teas. for all the samples, 80% methanol extracts possessed ... | 2012 | 22953899 |
| rapid and selective quantification of l-theanine in ready-to-drink teas from chinese market using spe and uplc-uv. | an ultra performance liquid chromatography (uplc) method combined with solid phase extraction (spe) sample pre-treatment was developed and validated for the rapid quantification of l-theanine in ready-to-drink (rtd) teas. uplc analysis of twenty-seven rtd teas from the chinese market revealed that the l-theanine levels in various types of rtd teas were significantly different. rtd green teas were found to contain highest mean l-theanine level (37.85±20.54 mg/l), followed by jasmine teas (36.60±1 ... | 2012 | 22868106 |
| simultaneous determination of procymidone, pyridaben and beta-cypermethrin residues in tea solution by gc-ecd. | a sensitive and effective method for the simultaneous quantitative determination of procymidone, pyridaben and beta-cypermethrin residues in tea solutions was developed and validated using a gas chromatograph (gc) equipped with an electron capture detector (ecd). the analysis of the three pesticides in tea solutions involved extraction with petroleum ether-ethyl acetate (3:1, v/v), cleanup using a florisil solid-phase extraction cartridge and subsequent determination by gc-ecd. recovery studies ... | 2016 | 22689906 |
| evaluation of soluble oxalates content in infusions of different kinds of tea and coffee available on the polish market. | tea and coffee are the potentially rich source of oxalic acid, which can act as a antinutrient. | 2012 | 22642066 |
| structural annotation and elucidation of conjugated phenolic compounds in black, green, and white tea extracts. | advanced analytical approaches consisting of both lc-ltq-orbitrap fourier transformed (ft)-ms and lc-time-of-flight-(tof)-ms coupled to solid-phase extraction (spe) nmr were used to obtain more insight into the complex phenolic composition of tea. on the basis of the combined structural information from (i) accurate mass fragmentation spectra, derived by using lc-orbitrap ftms(n), and (ii) proton nmr spectra, derived after lc-tofms triggered spe trapping of selected compounds, 177 phenolic compo ... | 2012 | 22468624 |
| reactions of green and black teas with cu(ii). | electron paramagnetic resonance (epr) measurements of the products of reactions between cu(ii) and samples of green and black teas showed spectral components from at least six different cu(ii) complexes with both tea types. several of these complexes were common to both teas in spite of major differences in their polyphenol compositions. the ph range observed for complex formation, and the total signal intensity in the ph range 4-8, were greatly different from those for the reactions of cu(ii) w ... | 2012 | 22159216 |
| assessment of sample cleanup and matrix effects in the pesticide residue analysis of foods using postcolumn infusion in liquid chromatography-tandem mass spectrometry. | matrix effect profiles can be used to visualize the effect of the sample matrix to the data signals occurring in a chromatogram. in the present study these profiles were generated by postcolumn infusion of a standard pesticide mix with extracts of different food matrices prepared by the quechers method. complete raw extracts as well as individual clean-up steps were analyzed. this allowed for a detailed comparison of the interferences caused by the matrix effects from various food samples. it al ... | 2011 | 21999915 |
| determination and comparison of γ-aminobutyric acid (gaba) content in pu-erh and other types of chinese tea. | two previous studies have reported that pu-erh tea contains a high level of γ-aminobutyric acid (gaba), which is the major inhibitory neurotransmitter in the central nervous system and has several physiological functions. however, two other researchers have demonstrated that the gaba content of several pu-erh teas was low. due to the high value and health benefits of gaba, analysis of mass-produced pu-erh tea is necessary to determine whether it is actually enriched with gaba. a high-performance ... | 2011 | 21395338 |
| amp-activated protein kinase: 'a cup of tea' against cholesterol-induced neurotoxicity. | disturbances in brain cholesterol metabolism have been linked to alzheimer's disease (ad) pathology. a high-cholesterol diet increases fibrillar amyloid β peptide (aβ) deposition, inflammation, and apoptosis that eventually results in neurodegeneration and learning and memory impairments. in the october 2010 issue of the journal of pathology, lu and colleagues provided a novel and interesting mechanism that explains how quercetin, a flavonoid found at high concentrations in green and black teas, ... | 2010 | 20922714 |
| simultaneous determination of pyrethrins residues in teas by ultra-performance liquid chromatography/tandem mass spectrometry. | a sensitive and effective method for the simultaneous quantitative determination of pyrethrin residues in teas was developed and validated using ultra-performance liquid chromatography coupled with tandem mass spectrometry (uplc-ms/ms). the six major constituents of the pyrethrins (pyrethrin i and ii, jasmolin i and ii, and cinerin i and ii) were successfully separated and independently confirmed in a single run within approximately 5 min. the multi-residue analysis of pyrethrins in teas involve ... | 2010 | 20869505 |
| tea flavonoids and cardiovascular health. | the two main types of tea are green and black. both green and black teas are rich dietary sources of flavonoids. available evidence suggests that regular tea consumption may reduce the risk of cardiovascular disease. the cardiovascular health benefits of drinking tea are thought to be largely due to flavonoids. tea intake and intake of flavonoids found in tea have been associated with reduced risk of cardiovascular disease in cross-sectional and prospective population studies. isolated flavonoid ... | 2010 | 20837049 |
| detection of total phenol in green and black teas by flow injection system and unmodified screen printed electrode. | a flow injection system using an unmodified gold screen-printed electrode was employed for total phenol determination in black and green teas. in order to avoid passivation of the electrode surface due to the redox reaction, preoxidation of the sample was realized by hexacyanoferrate(iii) followed by addition of an edta solution. the complex formed in the presence of edta minimizes or avoids polymerization of the oxidized phenols. the previously filtered tea sample and hexacyanoferrate(iii) reag ... | 2010 | 21461407 |
| caffeine content of brewed teas. | caffeine is the world's most popular drug and can be found in many beverages including tea. it is a psychostimulant that is widely used to enhance alertness and improve performance. this study was conducted to determine the concentration of caffeine in 20 assorted commercial tea products. the teas were brewed under a variety of conditions including different serving sizes and steep-times. caffeine was isolated from the teas with liquid-liquid extraction and quantitated by gas chromatography with ... | 2008 | 19007524 |
| simultaneous determination of catechins, caffeine and gallic acids in green, oolong, black and pu-erh teas using hplc with a photodiode array detector. | a simple and fast hplc method using a photodiode array detector was developed for simultaneous determination of four major catechins, gallic acid and caffeine. after multiple extractions with aqueous methanol and acidic methanol solutions, tea extract was separated within 20 min using a methanol-acetate-water buffer gradient elution system on a c(18) column. the sample extraction data demonstrated that the single extraction used in the previous studies with aqueous acetonitrile or methanol is no ... | 2002 | 18968631 |
| discrimination of teas with different degrees of fermentation by spme-gc analysis of the characteristic volatile flavour compounds. | as tea is traded all over the world, it is necessary for both customs officers and business investigators to develop an easy and reliable method to discriminate teas from each other. a total of 56 kinds of various green, oolong, and black teas were collected from different countries and markets, and their catechin contents and volatile flavour compounds (vfc) were compared by analyses, using hplc and solid-phase microextraction-gas chromatograph (spme-gc). it was found that neither total catechi ... | 2008 | 26054281 |
| coffee, tea, colas, and risk of epithelial ovarian cancer. | associations of coffee, tea, and other caffeinated beverages with ovarian cancer risk remain uncertain. in a population-based study in washington state, 781 women with epithelial ovarian cancer diagnosed in 2002 to 2005 and 1,263 controls completed self-administered questionnaires detailing consumption of caffeinated and noncaffeinated coffee, teas, and colas and in-person interviews regarding reproductive and hormonal exposures. we assessed risk associated with coffee, tea, and cola drinking an ... | 2008 | 18349292 |
| identification and comparison of phenolic compounds in the preparation of oolong tea manufactured by semifermentation and drying processes. | oolong tea manufactured via a semifermentation process possesses a taste and color somewhere between green and black teas. alteration of constituents, particularly phenolic compounds, in the infusion of oolong tea resulting from its manufacture, was analyzed by high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry. the identified constituents contained 2 alkaloids, 11 flavan-3-ols, 8 organic acids and esters, 11 proanthocyanidin dimers, 3 theaflavins, ... | 2007 | 17696450 |
| dynamic ultrasound-assisted extraction of catechins and caffeine in some tea samples. | a novel dynamic ultrasound-assisted extraction (duae) device has been constructed for extraction of five catechins and caffeine in solid sample. the accurate, simple, reproducible and sensitive method for the determination of five catechins and caffeine has been developed and validated. a comparison has been made of the efficiencies by employing duae and conventionally static ultrasound-assisted extraction (uae). the proposed method can not only improve extraction efficiency but also decrease ti ... | 2016 | 17696011 |