| risk factors for renal cell cancer in a japanese population. | the incidence of renal cell cancer has been increasing worldwide. although the incidence of renal cell cancer in japan is lower than the rates in the other industrialized countries, there is no doubt that it is increasing. in this paper, we would like to introduce the result of our studies, which evaluate the risk factors for renal cell cancer in japan. hypertension, diabetes mellitus, kidney diseases, fondness for fatty food and black tea showed an increased risk of renal cell carcinoma while a ... | 2009 | 20689612 |
| delayed effects of coffee, tea and sucrose on postprandial glycemia in lean, young, healthy adults. | in observational studies, habitual coffee consumption has been linked to a lower risk of type 2 diabetes. we hy-pothesized that the mechanism may be related to delayed effects on postprandial glycemia. the aim of this study is to investigate the glycemic and insulinemic effects of consumption of caffeinated and decaffeinated coffee, sweetened and unsweetened, tea and sucrose, 1 h prior to a high carbohydrate meal. on separate occasions in random order, lean young healthy subjects (n = 8) consume ... | 2008 | 19114405 |
| higher regular coffee and tea consumption is associated with reduced endometrial cancer risk. | several studies have investigated the associations between diet and endometrial cancer, but few have focused specifically on coffee and tea. in a hospital-based case-control study, we examined the associations between endometrial cancer risk and usual consumption of coffee, decaffeinated coffee, and black tea among 541 women with endometrial cancer and 541 women with an intact uterus but without a cancer diagnosis seen at roswell park cancer institute (buffalo, new york) between 1982 and 1998. d ... | 2009 | 19107932 |
| epigallocatechin gallate from green tea (camellia sinensis) increases lifespan and stress resistance in caenorhabditis elegans. | epigallocatechin gallate (egcg) is a major green tea polyphenol with pronounced antioxidative activity. the effects of egcg on lifespan and stress resistance in wild-type n2 and transgenic strains of caenorhabditis elegans [ hsp-16.2/gfp, mev-1(kn1), fem-1(hc17)] were investigated. the expression of hsp-16.2 (induced by the pro-oxidant juglone) and the intracellular levels of h (2)o (2) were inhibited by egcg treatment. daily administration of 220 mum egcg increased the mean lifespan by 10.14 % ... | 2009 | 19085685 |
| accumulation of catechins in tea in relation to accumulation of mrna from genes involved in catechin biosynthesis. | catechins are a group of polyphenols found in tea (camellia sinensis var. sinensis) at high levels. they are beneficial for health. from the study on accumulation of catechins in shoots and mature leaves of a tea cultivar, oolong no. 17, using high-performance liquid chromatography (hplc), it was found that the amounts of most catechins in the shoots were higher than those in the mature leaves, with an exception of catechins gallate (cg) that was found in trace amounts in both the shoots and mat ... | 2009 | 19081728 |
| insect pests of tea and their management. | globally, 1031 species of arthropods are associated with the intensively managed tea camellia sinensis (l.) o. kuntze monoculture. all parts of the plant, leaf, stem, root, flower, and seed, are fed upon by at least one pest species, resulting in an 11%-55% loss in yield if left unchecked. there has been heavy use of organosynthetic pesticides since the 1950s to defend the plant against these pests, leading to rapid conversion of innocuous species into pests, development of resistance, and undes ... | 2009 | 19067632 |
| green tea, soy, and mammographic density in singapore chinese women. | there is increasing evidence from observational studies that breast cancer risk is inversely associated with soy and green tea consumption. we investigated the effects of these two dietary agents on mammographic density, a well-established biomarker for breast cancer risk, in a cross-sectional analysis of mammograms and validated food frequency questionnaires from 3,315 chinese women in singapore. percent mammographic density (pmd) was assessed using a reproducible computer-assisted method. we u ... | 2008 | 19064551 |
| inhibition of mammalian thioredoxin reductase by black tea and its constituents: implications for anticancer actions. | black tea is recently reported to have anti-carcinogenic effects through pro-oxidant property, but the underlying mechanisms remain unclear. mammalian cytosolic thioredoxin reductase (trxr1) is well -known for its anti-oxidation activity. in this study, we found that black tea extract (bte) and theaflavins (tfs), the major black tea polyphenols, inhibited the purified trxr1 with ic(50) 44 microg/ml and 21+/-1 microg/ml, respectively. kinetics of tfs exhibited a mixed type of competitive and non- ... | 2009 | 19059456 |
| theaflavins from black tea, especially theaflavin-3-gallate, reduce the incorporation of cholesterol into mixed micelles. | tea is one of the most widely consumed beverages in the world and may be associated with reduced heart disease rates. theaflavins, which are formed in the production of black tea, have been suggested being responsible for the blood-cholesterol-lowering (bcl) effects of tea. we hypothesized that the effect of theaflavins on bcl could be through interference in the formation of dietary mixed micelles, which could result in reduced intestinal cholesterol absorption. micelles were produced by mixing ... | 2008 | 19049290 |
| soft drink intake is associated with diet quality even among young japanese women with low soft drink intake. | unsweetened traditional japanese tea has long been the main beverage consumed in japan, with soft drinks only recently forming a part of people's diets. evidence suggests an association between soft drink intake and poor diet quality among youth in the united states. the association is not yet fully examined in the population with relatively low intake level of soft drinks such as the current japanese population. | 2008 | 19027402 |
| antioxidative and anti-carcinogenic activities of tea polyphenols. | tea (camellia sinensis, theaceace), a popular beverage consumed world-wide, has been studied for its preventive effects against cancer as well as cardiovascular, neurodegenerative, and other diseases. most of the proposed beneficial effects have been attributed to the polyphenolic compounds in tea, but the nature of these activities and the molecular mechanisms of their actions remain unclear. tea polyphenols are known to be strong antioxidants. prevention of oxidative stress, modulation of carc ... | 2009 | 19002670 |
| microwave heating of tea residue yields polysaccharides, polyphenols, and plant biopolyester. | microwave heating was used to produce aqueous-soluble components from green, oolong, and black tea residues. heating at 200-230 degrees c for 2 min extracted 40-50% of polysaccharides and 60-70% of the polyphenols. solubilization of arabinose and galactose by autohydrolysis occurred with heating above 170 degrees c, whereas heating above 200 degrees c was necessary to solubilize xylose. catechins were soluble in water by heating at low temperature (110 degrees c); however, new polyphenols having ... | 2008 | 18998700 |
| an epidemiologic study of tongue lesions in 1901 iranian dental outpatients. | the aim of this study was to assess the frequency of nine tongue conditions and evaluate their relationship to oral hygiene status and personal habits in a northern iranian population. | 2008 | 18997919 |
| a study on the determination of chromium as chromate at a carbon paste electrode modified with surfactants. | a procedure for the determination of chromium is described based on synergistic pre-concentration of the chromate anion at a carbon paste electrode modified in situ with quarternary ammonium salts such as 1-ethoxycarbonylpentadecyltrimethylammonium bromide (septonex((r))), cetyltrimethylammonium bromide (ctab) or cetylpyridinium bromide (cpb). the proper electrochemical detection utilises the reduction cr(vi) --> cr(iii) performed in the differential pulse cathodic voltammetric mode. in discussi ... | 2004 | 18969679 |
| identification of green tea's (camellia sinensis (l.)) quality level according to measurement of main catechins and caffeine contents by hplc and support vector classification pattern recognition. | high performance liquid chromatography (hplc) was identified green tea's quality level by measurement of catechins and caffeine content. four grades of roast green teas were attempted in this work. five main catechins ((-)-epigallocatechin gallate (egcg), (-)-epigallocatechin (egc), (-)-epicatechin gallate (ecg), (-)-epicatechin (ec), and (+)-catechin (c)) and caffeine contents were measured simultaneously by hplc. as a new chemical pattern recognition, support vector classification (svc) was ap ... | 2008 | 18952392 |
| green tea (camellia sinensis) and cancer prevention: a systematic review of randomized trials and epidemiological studies. | green tea is one of the most popular beverages worldwide. this review summarizes the beneficial effects of green tea on cancer prevention. | 2008 | 18940008 |
| p-coumarate:coa ligase as a key gene in the yield of catechins in tea [camellia sinensis (l.) o. kuntze]. | tea is an important crop known for its beverage and antioxidant polyphenols -- catechins and its derivatives. catechins are synthesized through flavonoid (fl) pathway and stored in the vacuole. a metabolic flux for the operation of fl pathway is maintained through the supply of 4-coumaroyl-coa of phenylpropanoid pathway. 4-coumaroyl-coa is synthesized through the catalytic activity of p-coumarate:coa ligase (4cl) using 4-coumaric acid and acetyl-coa as the substrates. the present manuscript repo ... | 2009 | 18931865 |
| phenolic content and antioxidative capacity of green and white tea extracts depending on extraction conditions and the solvent used. | the efficiencies of different solvents in the extraction of phenolics from bagged and loose leaves of white and green tea, after different extraction times, as well as the antioxidative capacity of the obtained extracts, were investigated. the developed hplc method has the potential to separate and determinate 17 phenolics widely distributed in plants, but in investigated tea extracts only four catechins and traces of three flavonols and one flavone were separated and detected based on compariso ... | 2008 | 26047270 |
| standardized capsule of camellia sinensis lowers cardiovascular risk factors in a randomized, double-blind, placebo-controlled study. | previous studies examining the effect of tea drinking on cardiovascular health have produced mixed results due to their observational nature and qualitatively and quantitatively imprecise definitions of active tea components. the objective of this study was to determine if a standardized and defined decaffeinated green tea (camellia sinensis) product lowers blood pressure, serum lipids, oxidative stress, and markers of chronic inflammation. | 2009 | 18848434 |
| coffee, tea, and incident type 2 diabetes: the singapore chinese health study. | increasing coffee intake was inversely associated with risk of type 2 diabetes in populations of european descent; however, data from high-risk asian populations are lacking as are data on tea intake in general. | 2008 | 18842784 |
| screening of dhfr-binding drugs by maldi-tofms. | the class of antimetabolite chemotherapeutical agents has been used to treat cancers in humans for almost 50 years and gives significant results by binding dihydrofolate reductase (dhfr), a key enzyme in dna synthesis. therefore, finding new active compounds inhibiting dna synthesis through their binding to dhfr is of prime interest. the aim of this work is to describe a protocol designed to study the binding of compounds to dhfr. this screening protocol involves matrix-assisted laser desorption ... | 2008 | 18841351 |
| total polyphenol content and antioxidant capacity of commercially available tea (camellia sinensis) in argentina. | tea, camellia sinensis (l.) o. kuntze (theaceae) is cultivated in argentina in the northeastern region (provinces of misiones and corrientes), between 26 degrees and 28 degrees south latitude, the southernmost area of the world where tea is cultivated. the objective of this work was to determine the total polyphenol content and the in vitro antioxidant capacity of green and black tea cultivated and industrialized in argentina. twelve samples of eight brands were analyzed. the total polyphenol co ... | 2008 | 18778031 |
| medicinal flowers. xxii. structures of chakasaponins v and vi, chakanoside i, and chakaflavonoside a from flower buds of chinese tea plant (camellia sinensis). | two acylated oleanane-type triterpene oligoglycosides, chakasaponins v and vi, an aromatic glycoside, chakanoside i, and an acylated flavonol oligoglycoside, chakaflavonoside a, were isolated from the flower buds of chinese tea plant [camellia sinensis (l.) o. kuntze]. the chemical structures of those new glycosides were elucidated on the basis of chemical and physicochemical evidence. | 2008 | 18758105 |
| a population-based, case-control study of green tea consumption and leukemia risk in southwestern taiwan. | this study investigated the association between green tea consumption and leukemia. | 2009 | 18752033 |
| new phenolic components and chromatographic profiles of green and fermented teas. | a standardized profiling method based on liquid chromatography with diode array and electrospray ionization mass spectrometric detection (lc-dad-esi/ms) was applied to establish the phenolic profiles of 41 green teas and 25 fermented teas. more than 96 phenolic compounds were identified that allowed the teas to be organized into five groups. epigallocatechin gallate (egcg) was the major phenolic component of green tea made from mature leaves (group 2), while green tea made from the younger buds ... | 2008 | 18686968 |
| the effects of sour tea (hibiscus sabdariffa) on hypertension in patients with type ii diabetes. | to compare the antihypertensive effectiveness of sour tea (st; hibiscus sabdariffa) with black tea (bt) infusion in diabetic patients, this double-blind randomized controlled trial was carried out. sixty diabetic patients with mild hypertension, without taking antihypertensive or antihyperlipidaemic medicines, were recruited in the study. the patients were randomly allocated to the st and bt groups and instructed to drink st and bt infusions two times a day for 1 month. their blood pressure (bp) ... | 2009 | 18685605 |
| determination of theanine, gaba, and other amino acids in green, oolong, black, and pu-erh teas with dabsylation and high-performance liquid chromatography. | dabsyl chloride (dimethylaminoazobenzene sulfonyl chloride), a useful chromophoric labeling reagent for amino acids and amines, was developed in this laboratory in 1975. although several methods have been developed to determine various types of amino acids, a quick and easy method of determining theanine, gaba, and other amino acids has not been developed in one hplc system. in this paper are analyzed the free amino acid contents of theanine and gaba in different teas (green tea, black tea, oolo ... | 2008 | 18652476 |
| beverage consumption and the prevalence of tooth loss in pregnant japanese women: the osaka maternal and child health study. | recently, there has been growing interest in the impact of beverage consumption on dental health because changes have occurred in the types and quantities of beverage consumed. this cross-sectional study investigated the relationship between consumption frequencies of various beverages and the prevalence of tooth loss among young adult women. study subjects were 1002 pregnant japanese women. tooth loss was defined as previous extraction of one or more teeth. dietary habits were evaluated by a va ... | 2008 | 18646593 |
| nongallated compared with gallated flavan-3-ols in green and black tea are more bioavailable. | green tea and black tea (bt) contain gallated [(-)-epigallocatechin-3-gallate (egcg), (-)-epicatechin-3-gallate] and nongallated [(-)-epicatechin, (-)-epigallocatechin (egc)] tea polyphenols (pp). during bt production, pp undergo oxidation and form larger polymers such as theaflavins (the) and thearubigins, which contribute to the health benefit of bt. this article gives an overview of the role of chemical characteristics and endogenous metabolism of tea pp and their bioavailability in humans an ... | 2008 | 18641202 |
| flavonoids, flavonoid-rich foods, and cardiovascular risk: a meta-analysis of randomized controlled trials. | the beneficial effects of flavonoid consumption on cardiovascular risk are supported by mechanistic and epidemiologic evidence. | 2008 | 18614722 |
| a physiological model of tea-induced astringency. | the mechanism by which solutions containing polyphenols are perceived as astringent is not clearly understood. salivary proline-rich proteins and histatins are products of salivary glands and rapidly bind polyphenols - thought to be the main astringent compound in such as tea and wine. however it is unclear how this interaction leads to the altered oral mouthfeel known as astringency which is characterised by a dry, puckered feeling all around the mouth. to determine the role of saliva in the pe ... | 2008 | 18590751 |
| [toxic hepatitis due to camellia sinensis]. | | 2016 | 18570823 |
| influence of green and black tea on folic acid pharmacokinetics in healthy volunteers: potential risk of diminished folic acid bioavailability. | previous in vitro studies using caco-2 cell monolayers suggested a possible interaction between green and black tea and folic acid at the level of intestinal absorption. the main purpose of the present study was to investigate a possible pharmacokinetic interaction between tea and folic acid in healthy volunteers. in an open-labeled randomized cross-over study, the pharmacokinetic interaction between tea and folic acid (0.4 mg and 5 mg) was investigated in healthy volunteers. water was used as t ... | 2008 | 18551467 |
| expression of caffeine biosynthesis genes in tea (camellia sinensis). | using semi-quantitative reverse transcription-pcr, we studied the expression of genes encoding caffeine synthase (tcs1), inosine-5'-monophosphate dehydrogenase (tidh), s-adenosyl-l-methionine synthase (sams), phenylalanine ammonia-lyase (pal) and alpha-tubulin (tua1) in young and mature leaves, stems and roots of 4-month-old tea seedlings and young and old tea tissue cultures. the amounts of transcripts of tcs1 were much higher in young leaves than in other parts of the plant. expression of tidh ... | 2013 | 18533472 |
| the acute effect of green tea consumption on endothelial function in healthy individuals. | tea consumption is associated with decreased cardiovascular risk. flow-mediated dilatation (fmd) of the brachial artery is related to coronary endothelial function and it is an independent predictor of cardiovascular risk. black tea has a beneficial effect on endothelial function; the effect, however, of green tea on brachial artery reactivity has not been defined yet. | 2008 | 18525384 |
| structural determination and dpph radical-scavenging activity of two acylated flavonoid tetraglycosides in oolong tea (camellia sinensis). | two major acylated flavonoid tetraglycosides were isolated from the methanol extract of oolong tea. their structures were elucidated by spectroscopic methods as quercetin 3-o-[2(g)-(e)-coumaroyl-3(g)-o-beta-d-glucosyl-3(r)-o-beta-d-glucosylrutinoside] (1) and kaempferol 3-o-[2(g)-(e)-coumaroyl-3(g)-o-beta-d-glucosyl-3(r)-o-beta-d-glucosylrutinoside] (2). compounds 1 and 2 exhibited scavenging activity against dpph radical with ec(50) values of 30.5 and 487.2 microm, respectively. | 2008 | 18520094 |
| effect of sucrose concentration on the products of kombucha fermentation on molasses. | fermentation of 1.5g/l of indian black tea, sweetened with adequate quantities of molasses (containing approx. 70g/l, 50g/l and 35g/l of sucrose), was conducted using domestic kombucha. inoculation was performed with 10% of fermentation broth from a previous process. the fermentation in cylindrical vessels containing 2l of liquid phase, was carried out at 22±1°c for 14 days, with periodical sampling, to measure ph, content of acids (total, acetic and l-lactic), content of remaining sucrose, and ... | 2008 | 26065754 |
| methylglyoxal: its presence and potential scavengers. | hyperglycemia is the most important factor for the onset and progress of diabetic complications. a growing body of evidence indicates that the increase in reactive carbonyl intermediates such as methylglyoxal (mg) is a consequence of hyperglycemia in diabetes. several studies have shown that higher levels of mg are present in diabetic patients' plasma compared to non-diabetics. glyoxal (go) and mg, the two major alpha-dicarbonyl compounds found in humans, are very reactive and lead to nonenzymat ... | 2008 | 18296351 |
| evaluation of black tea gel and its protection potential against uv. | in this study, aqueous and alcoholic extracts of black tea were obtained. the black tea extracts were tested in vitro for their ultraviolet (uv) absorption profile. it was found that both extracts showed uv absorption and followed the same path based on the wavelength. aqueous extract showed a stronger absorptivity per weight basis than the alcoholic extract of black tea. a peak was obtained between 250 and 300 nm. after 300 nm, uv absorption decreased fast towards 400 nm with a low absorptivity ... | 2007 | 18489382 |
| shoot epicatechin and epigallocatechin contents respond to water stress in tea [camellia sinensis (l.) o. kuntze]. | an experiment was conducted to determine the association of tea catechins to water stress in tea, with the objective of determining their suitability as indicators for predicting drought tolerance in tea (camellia sinensis). the study consisted of six tea clones (bbk 35, trfk 6/8, trfk 76/1, trfk 395/2, trfk 31/30, and trfk 311/287) and four levels of soil water content (38, 30, 22, and 14% v/v), which were arranged in a complete randomized design and replicated 3 times. the treatments were main ... | 2008 | 18460799 |
| association between soy and green tea (camellia sinensis) diminishes hypercholesterolemia and increases total plasma antioxidant potential in dyslipidemic subjects. | to evaluate the hypolipemic and antioxidant effects of soy and green tea alone and/or in association in dyslipidemic subjects. | 2008 | 18455656 |
| contribution of p53-mediated bax transactivation in theaflavin-induced mammary epithelial carcinoma cell apoptosis. | theaflavins, the bioactive flavonoids of black tea, have been demonstrated to inhibit proliferation and induce apoptosis in a variety of cancer cells. however, the contribution of p53 in mammary epithelial carcinoma cell apoptosis by theaflavins remains unclear. it has been reported that p53 triggers apoptosis by inducing mitochondrial outer membrane permeabilization through transcription-dependent and -independent mechanisms. using wild-type and mutant p53-expressing as well as p53-null cells w ... | 2008 | 18454316 |
| preparative isolation and purification of theaflavins and catechins by high-speed countercurrent chromatography. | high-speed countercurrent chromatography (hsccc) has been applied for the separation of theaflavins and catechins. the hsccc run was carried out with a two-phase solvent system composed of hexane-ethyl acetate-methanol-water-acetic acid (1:5:1:5:0.25, v/v) by eluting the lower aqueous phase at 2 ml/min at 700 rpm. the results indicated that pure theaflavin, theaflavins-3-gallate, theaflavins-3'-gallate and theaflavin-3,3'-digallate could be obtained from crude theaflavins sample and black tea. t ... | 2008 | 18436487 |
| potential anthelmintics: polyphenols from the tea plant camellia sinensis l. are lethally toxic to caenorhabditis elegans. | a novel gallate of tannin, (-)-epigallocatechin-(2 beta-->o-->7',4 beta-->8')-epicatechin-3'-o-gallate (8), together with (-)-epicatechin-3-o-gallate (4), (-)-epigallocatechin (5), (-)-epigallocatechin-3-o-gallate (6), and (+)-gallocatechin-(4 alpha-->8')-epigallocatechin (7), were isolated from the tea plant camellia sinensis (l.) o. kuntze var. sinensis (cv., yabukita). the structure of 8, including stereochemistry, was elucidated by spectroscopic methods and hydrolysis. the compounds, along w ... | 2008 | 18404315 |
| iron absorption in young indian women: the interaction of iron status with the influence of tea and ascorbic acid. | ascorbic acid (aa) enhances and tea inhibits iron absorption. it is unclear whether iron status influences the magnitude of this effect. | 2008 | 18400710 |
| a case-control study of lifestyle and lung cancer associations by histological types. | the objective of the study was to investigate the contribution of dietary factors and physical exercise to the variation in the risk of lung cancer and its major histological types among men and women in the czech republic, and reveal interactions between smoking and diet/physical exercise, if any. in a hospital based case-control study, data collected by in-person interviews from 1096 microscopically confirmed lung cancer cases (587 women, 509 men) and 2966 controls were analyzed using uncondit ... | 2008 | 18348651 |
| polymer-like polyphenols of black tea and their lipase and amylase inhibitory activities. | lipase and amylase inhibitory activities of black tea were examined. after solvent partitioning of a black tea extract with the ethyl acetate and n-butanol, the two soluble fractions showed comparable inhibitory activities. activity in the ethyl acetate fraction was mainly attributable to polyphenols with low-molecular weights, such as theaflavin gallates. on the other hand, the active substance in the n-butanol layer was ascertained to be a polymer-like substance. 1h- and 13c-nmr spectra showed ... | 2008 | 18310934 |
| element composition of tea leaves and tea infusions and its impact on health. | tea infusion is the most frequently consumed beverage worldwide next to water, with about 20 billion cups consumed daily. in taiwan, daily consumption averages 2.5 cups of tea infusion per person. many studies have concluded that tea has numerous beneficial effects on health. however, some undesirable trace elements, such as arsenic, chromium, cadmium, lead, etc., are a concern. this study has three aims: (1) to measure the concentrations of arsenic and heavy metal elements, such as chromium, ca ... | 2008 | 18309449 |
| the influence of different food and drink on tics in tourette syndrome. | tourette syndrome (ts) is characterized by waxing and waning motor and vocal tics. because standard medication often remains unsatisfactory, many patients seek alternative medicine. the aim of this study was to increase experience about the influence of food and drinks in ts. | 2008 | 18307557 |
| association between consumption of black tea and iron status in adult africans in the north west province: the thusa study. | the association between black tea consumption and iron status was investigated in a sample of african adults participating in the cross-sectional thusa (transition and health during urbanization of south africans) study in the north west province, south africa. data were analysed from 1605 apparently healthy adults aged 15-65 years by demographic and ffq, anthropometric measurements and biochemical analyses. the main outcome measures were hb and serum ferritin concentrations. no associations wer ... | 2008 | 18275622 |
| immobilized proanthocyanidins for the capture of bacterial lipopolysaccharides. | proanthocyanidins (pacs) are an abundant class of compounds found in a variety of plant materials. here we demonstrate the application of these materials as capture molecules for the removal of bacterial lipopolysaccharide (lps) from solution. pacs from whole cranberries, grape juice, black tea, and cranberry juice were purified and immobilized onto thiol-activated sepharose beads. this material was used in pull-down type assays for the capture of lps. the binding of lps by pacs has been shown t ... | 2008 | 18257561 |
| gas chromatographic method for the determination of hexaconazole residues in black tea. | a highly reliable, quantitative and sensitive analytical method for determining the residues of the fungicide, hexaconazole in black tea is described. the proposed method is based on liquid-liquid extraction followed by gas chromatographic determination, using nitrogen phosphorus detector (gc-npd) for the identification and quantitation of hexaconazole. the most appropriate solvent mixture for extracting hexaconazole residues from black tea was n-hexane:acetone at 1:1 (v/v). the extract was clea ... | 2008 | 18257139 |
| expression and biochemical characterization of beta-primeverosidase and application of beta-primeverosylamidine to affinity purification. | beta-primeverosidase (pd) is a family 1 glycosidase catalyzing the hydrolysis of beta-primeverosides (6-o-beta-d-xylopyranosyl-beta-d-glucopyranosides) to release a disaccharide primeverose. to investigate how pd recognizes the disaccharide moiety of beta-primeverosides, the recombinant pd was expressed by a baculovirus-insect cell system. the recombinant pd was secreted from high five cells and was properly modified with n-glycosylation and correct cleavage at the n-terminal signal peptide. the ... | 2008 | 18256510 |
| simple and rapid uv spectrophotometry of caffeine in tea coupled with sample pre-treatment using a cartridge column filled with polyvinylpolypyrrolidone (pvpp). | we have applied a sample pre-treatment method with a cartridge column filled with polyvinylpolypyrrolidone (pvpp) to the effective removal of polyphenols and simple uv spectrophotometry of caffeine in tea. the absorption maximum length (lambda(max)) for caffeine was close to those for tea catechins in aqueous 1% acetic acid; therefore, the uv spectrum of a non-treated green tea sample had a large absorption wave. in contrast, the absorbance of the green tea sample was gradually reduced by pvpp c ... | 2008 | 18239305 |
| immunostimulating activity of a crude polysaccharide derived from green tea (camellia sinensis) extract. | green tea extract is well-known to reduce the risk of a variety of diseases. here, we investigated the immunostimulating activity of tea polysaccharide (tps), one of the main components in green tea extract. the water extracts from mature or immature tea leaves were precipitated by using ethanol at room temperature. the sediment was washed with ethanol and acetone alternately and then dried. we used the phagocytic activity of macrophage-like cells as an indicator of immune function activation. c ... | 2008 | 18232634 |
| tea polyphenols, their biological effects and potential molecular targets. | tea is the most popular beverage in the world, second only to water. tea contains an infusion of the leaves from the camellia sinensis plant rich in polyphenolic compounds known as catechins, the most abundant of which is (-)-egcg. although tea has been consumed for centuries, it has only recently been studied extensively as a health-promoting beverage that may act to prevent a number of chronic diseases and cancers. the results of several investigations indicate that green tea consumption may b ... | 2008 | 18228206 |
| differential expression of histone h3 gene in tea (camellia sinensis (l.) o. kuntze) suggests its role in growing tissue. | histone proteins are integral part of chromatin and their expression is typically linked to dna replication in the s phase of cell cycle. histone h3 is one of the four histones, along with h2a, h2b and h4, which forms the eukaryotic nucleosome octomer core. using differential display of mrna and rapid amplification of cdna ends (race), a full-length histone h3.1 cdna (csh3) was isolated from tea leaves. the open reading frame consisted of 411 nucleotides and deduced amino acid sequence comprised ... | 2009 | 18224457 |
| comparison of antioxidant potency of commonly consumed polyphenol-rich beverages in the united states. | a number of different beverage products claim to have antioxidant potency due to their perceived high content of polyphenols. basic and applied research indicates that pomegranate juice (pj), produced from the wonderful variety of punica granatum fruits, has strong antioxidant activity and related health benefits. although consumers are familiar with the concept of free radicals and antioxidants, they are often misled by claims of superior antioxidant activity of different beverages, which are u ... | 2008 | 18220345 |
| role of quercetin (a natural herbal compound) in allergy and inflammation. | an investigated flavonoid, quercetin, is reviewed in this article. quercetin is a bioflavonoid found in red wine, grapefruit, onions, apples, black tea, and, in lesser amounts, in leafy green vegetables and beans. quercetin has an antioxidant and anti-inflammatory activity and prevents cancer. quercitin inhibits the growth of certain malignant cells in vitro, and histamine and most cyclin-dependent kinases and also displays unique anticancer properties. quercetin is a natural compound that block ... | 2008 | 18187018 |
| combination of hsccc and sephadex lh-20 methods an approach to isolation and purification of the main individual theaflavins from black tea. | in order to separate the main individual theaflavin monomers from black tea, high-speed countercurrent chromatography (hsccc) and sephadex lh-20 column chromatography were applied. the results showed that theaflavin (tf1), theaflavin-3-gallate (tf2a), theaflavin-3'-gallate (tf2b) and theaflavin-3,3'-digallate (tf3) can be obtained by hsccc using a solvent system composed of n-hexane-ethyl acetate-methanol-water (1:3:1:6, v/v/v/v), but the tf1 was containing epicatechin-3-gallate (ecg). similarly ... | 2008 | 18063426 |
| structures of epicatechin gallate trimer and tetramer produced by enzymatic oxidation. | during black tea production, catechins and their galloyl esters are enzymatically oxidized to generate a complex mixture of black tea polyphenols. the role of galloyl ester groups in this process has yet to be determined. enzymatic oxidation of epicatechin 3-o-gallate (1) yielded two new oxidation products, theaflavate c and bistheaflavate a, along with theaflavate a (2), a known dimer of 1 generated by coupling of the b-ring with the galloyl group. theaflavate c is a trimer of 1 and possesses t ... | 2007 | 18057757 |
| quasi-flow injection analysis for rapid determination of caffeine in tea using the sample pre-treatment method with a cartridge column filled with polyvinylpolypyrrolidone. | the sample pre-treatment method using a polyvinylpolypyrrolidone (pvpp) cartridge column combined with a quasi-flow injection analysis (quasi-fia) system realized the rapid determination of caffeine in three types of tea, green, oolong and black tea. the measurement time for each tea sample pre-treated using a pvpp cartridge column was shortened to 20s. in the present system, the limits of detection and quantification were 0.3 microm (1.5 pmol injected) and 0.7 microm (3.5 pmol injected), respec ... | 2008 | 18054948 |
| comparative evaluation of antiproliferative, antiangiogenic and apoptosis inducing potential of black tea polyphenols in the hamster buccal pouch carcinogenesis model. | to evaluate the relative chemopreventive efficacy of two black tea polyphenols, polyphenon-b [p-b] and btf-35 on 7,12-dimethylbenz [a]anthracene (dmba)-induced hamster buccal pouch (hbp) carcinogenesis. | 2007 | 18053169 |
| biotransformation of green tea polyphenols and the biological activities of those metabolites. | green tea ( camellia sinensis, theaceae) and its major polyphenol constituents, the catechins, have been reported to have many health benefits including the prevention of cancer and heart disease. many mechanisms of action have been proposed based on in vitro models; however, the importance of most of these mechanisms remains to be determined in vivo. the bioavailability and biotransformation of tea catechins play a key role in determining the importance of various mechanisms in vivo. likewise, ... | 2013 | 17963356 |
| characterization of the constituents and antioxidant activity of brazilian green tea (camellia sinensis var. assamica iac-259 cultivar) extracts. | freeze-dried extracts from camellia sinensis var. assamica iac-259 cultivar named brazilian green tea were prepared by hot water and ultrasound-assisted extractions using leaves harvested in spring and summer. their caffeine and catechin contents were measured by high performance liquid chromatography-diode array detector. the antioxidant activity of the major green tea compounds and brazilian green tea extracts was evaluated using a 2,2-diphenyl-1-picrylhydrazyl (dpph) assay. the levels of caff ... | 2007 | 17937477 |
| immobilised tyrosinase-based biosensor for the detection of tea polyphenols. | an amperometric principle-based biosensor containing immobilized enzyme tyrosinase has been used for detection of polyphenols in tea. the immobilized tyrosinase-based biosensor could detect tea polyphenols in the concentration range 10-80 mmol l(-1). immobilization of the enzyme by the crosslinking method gave good stable response to tea polyphenols. the biosensor response reached the steady state within 5 min. the voltage response was found to have a direct linear relationship with the concentr ... | 2007 | 17928999 |
| the effect of consuming instant black tea on postprandial plasma glucose and insulin concentrations in healthy humans. | to determine the effects of black tea on postprandial plasma glucose and insulin concentrations in healthy humans in response to an oral glucose load. | 2007 | 17914136 |
| chemical composition of green tea (camellia sinensis) infusions commercialized in portugal. | to evaluate the potential benefits and risks associated with tea consumption it is important to identify the constituents of this beverage. levels of some minerals, caffeine and catechins in green tea samples commercialized in portugal were evaluated. potassium is the metal present in larger amount (92-151 mg/l). the content of sodium, calcium, fluoride, aluminium, manganese and iron were 35-69, 1.9-3.5, 0.80-2.0, 1.0-2.2, 0.52-1.9, 0.020-0.128 mg/l, respectively. chromium and selenium were not ... | 2007 | 17899383 |
| a 6-month randomized pilot study of black tea and cardiovascular risk factors. | the effects of black tea consumption on cardiovascular risk factors have been inconsistent in previous randomized trials, all of which have been limited to a few weeks duration. | 2007 | 17892999 |
| arsenic species and leaching characters in tea (camellia sinensis). | tea is one of the most popular non-alcoholic beverages consumed in the world. arsenic including species totalling to 47 chinese tea samples from 18 tea-producing provinces in china were analyzed. by simulating the infusion process, leaching characters, effects of extraction time and temperature on arsenic extraction were investigated. total amount of arsenic in tea leaf samples was in the range below the detection limit to 4.81 microg/g. leaching of arsenic was strongly affected by extraction ti ... | 2007 | 17892910 |
| enzymatic oxidation of gallocatechin and epigallocatechin: effects of c-ring configuration on the reaction products. | tea leaf is rich in pyrogallol-type catechins, and their oxidation is important in the generation of black tea polyphenols. in the present study, the enzymatic oxidation of three pyrogallol-type catechins, (+)- and (-)-gallocatechins and (-)-epigallocatechin, was compared. the reactions yielded unstable quinone products, which were trapped as condensation products with o-phenylenediamine. the oxidation of (+)-gallocatechin proceeded very slowly compared to the reaction of (-)-epigallocatechin, a ... | 2008 | 17888464 |
| the effect of an extract of green and black tea on glucose control in adults with type 2 diabetes mellitus: double-blind randomized study. | recent evidence suggests that tea from camellia sinensis (eg, green, oolong, and black tea) may have a hypoglycemic effect. we evaluated the ability of an extract of green and black tea to improve glucose control over a 3-month period. a double-blind, placebo-controlled, randomized multiple-dose (0, 375, or 750 mg per day for 3 months) study in adults with type 2 diabetes mellitus not taking insulin was performed. the primary end point was change in glycosylated hemoglobin at 3 months. the 49 su ... | 2007 | 17884442 |
| improved sample pre-treatment for determination of caffeine in tea using a cartridge filled with polyvinylpolypyrroridone (pvpp). | we have improved sample pre-treatment for the effective removal of polyphenols and simple analysis of caffeine in tea using a cartridge filled with polyvinylpolypyrroridone (pvpp). nearly 100% of catechins were removed from the green tea sample and caffeine was completely recovered in the range of 98.2-101.3% by sample pre-treatment with a pvpp cartridge. reproducibility of preparing pvpp pre-treatment cartridges was sufficient for quantitative analysis, because rsds of analytical values for caf ... | 2007 | 17827770 |
| green tea and black tea consumption in relation to colorectal cancer risk: the singapore chinese health study. | the relationships between green tea and black tea consumption and colorectal cancer risk were examined within the singapore chinese health study, a prospective cohort study of diet and cancer involving >60,000 men and women. intake of green tea and black tea was assessed through in-person interviews. incident cancer cases and deaths among cohort members were identified through record linkage of the cohort database with respective databases from the nationwide singapore cancer registry and the si ... | 2007 | 17724377 |
| flow injection potentiometric determination of total antioxidant activity of plant extracts. | a new flow injection potentiometric (fip) method, rapid, reproducible and simple to apply, has been developed for the in vitro evaluation of antioxidative capacity of aqueous plant extracts. this method is based on the transient negative signal measurements with a flow-type platinum electrode detector due to the composition change of a [fe(cn)6]3-/[fe(cn)6]4- redox-reagent solution. the variables affecting the signal height such as composition and concentration of redox-reagent, injected sample ... | 2006 | 17723555 |
| tea and coffee as the main sources of oxalate in diets of patients with kidney oxalate stones. | we analyzed nutritional habits of 22 stone formers with special regard to oxalate content as one of the main nutritional lithogenic factors associated with kidney stones. daily dietary oxalate intake was 354 +/- 261 mg and 406 +/- 265 mg in men and women respectively. these values were much higher than those found by other researches. the main sources of oxalate in diets were regular tea and coffee (80-85%). only 15-20% of oxalate was derived from other plant foods. patients did not adhere to hi ... | 2007 | 17711092 |
| determination of theaflavins including methylated theaflavins in black tea leaves by solid-phase extraction and hplc analysis. | a quantitative method for four theaflavins and two methylated theaflavin derivatives in black tea leaves was developed by solid-phase extraction and a high-performance liquid chromatographic method with photodiode array detection. the theaflavins in black tea leaves were extracted three times with 40 vol 50% aqueous ethanol (mg dry tea powder/ml) containing 2% ascorbic acid. the ethanol extracts were diluted 4-fold with distilled water. all diluted extracts were directly applied to the solid-pha ... | 2007 | 17696441 |
| food interaction of oral uptake of iron / a clinical trial using 59fe. | a primary objective of the study was to evaluate how food as well as a specific enhancer or an inhibitor of iron uptake affect erythrocyte iron uptake after oral administration of iron(iii)-hydroxide polymaltose complex (ipc, maltofer) in subjects with or without iron deficiency. secondary objectives of the study were 1. to compare the uptake of 59fe in erythrocytes between subjects with or without iron deficiency, 2. to evaluate the 59fe activity in plasma after oral administration of ipc and 3 ... | 2007 | 17691590 |
| tea polyphenols for health promotion. | people have been consuming brewed tea from the leaves of the camellia sinensis plant for almost 50 centuries. although health benefits have been attributed to tea, especially green tea consumption since the beginning of its history, scientific investigations of this beverage and its constituents have been underway for less than three decades. currently, tea, in the form of green or black tea, next to water, is the most widely consumed beverage in the world. in vitro and animal studies provide st ... | 2007 | 17655876 |
| mechanism for the detoxification of aluminum in roots of tea plant (camellia sinensis (l.) kuntze). | to determine the mechanism of aluminum (al) detoxification in the roots of tea plants (camellia sinensis (l.) kuntze), the amounts of al and al-chelating compounds (fluoride (f), organic acids and catechins) were measured and the chemical forms of al in root cell extracts were identified by the application of 27al-nuclear magnetic resonance (nmr) spectroscopy. tea plants were cultivated in nutrient solutions containing 0, 4, 1.0 and 4.0 mm of al at ph 4.2 for approximately 10 weeks. the levels o ... | 2008 | 17643454 |
| cadmium induced oxidative stress influence on glutathione metabolic genes of camellia sinensis (l.) o. kuntze. | glutathione, a tripeptide with sulfhydryl (-sh) group is a very crucial compound primarily involved in redox balance maintenance of the cellular environment. in this study, we monitored the influence of cd exposure on the transcript levels of glutathione metabolic genes in bud tissues, the youngest leaf, of camellia sinensis l. in addition, some physiochemical parameters were also studied. cd exposure decreased chlorophyll and protein contents, while increase was observed in lipid peroxidation u ... | 2007 | 17607728 |
| mixture-mixture design for the fingerprint optimization of chromatographic mobile phases and extraction solutions for camellia sinensis. | a composite simplex centroid-simplex centroid mixture design is proposed for simultaneously optimizing two mixture systems. the complementary model is formed by multiplying special cubic models for the two systems. the design was applied to the simultaneous optimization of both mobile phase chromatographic mixtures and extraction mixtures for the camellia sinensis chinese tea plant. the extraction mixtures investigated contained varying proportions of ethyl acetate, ethanol and dichloromethane w ... | 2007 | 17605980 |
| effects of lifestyle on urinary 1-hydroxypyrene concentration. | this study aimed to clarify the variation of urinary excretion of 1-hydroxypyrene, which is a major metabolite of pyrene, in relation to lifestyle, including factors such as diet and smoking. the study subjects were 251 workers (male: 196, female: 55, mean age: 44.3) who were not occupationally exposed to pahs. urine specimens were collected from 8:00 a.m. to 11:00 a.m. and their 1-hydroxypyrene concentrations were determined by hplc. a questionnaire was distributed in order to learn gross aspec ... | 2007 | 17575398 |
| polyamines in tea processing. | the distribution of dietary polyamines, putrescine, spermidine and spermine, was determined during processing of camellia sinensis. black tea manufacture is carried by a series of processes on fresh tea leaves involving withering, rolling, fermentation, drying and sieving. the aim of this research was to determine the effect of tea processing on the polyamine content in relation with antioxidant enzymes, superoxide dismutase, lipid peroxidase and glutathione peroxidase. before processing, the sp ... | 2007 | 17566892 |
| tea (camellia sinensis) clones with shorter periods of winter dormancy exhibit lower accumulation of reactive oxygen species. | tea (camellia sinensis (l.) o. kuntze) is a perennial crop grown throughout the world. during winter, tea undergoes a dormancy period when growth of apical buds almost ceases, severely reducing the commercial yield of tea. low temperatures prevail during the period of winter dormancy, which alone or in combination with high solar irradiance have the potential to induce oxidative stress in plants. we studied six tea clones under field conditions to test whether a relationship exists between oxida ... | 2007 | 17545125 |
| black tea improves endothelial function in renal transplant recipients. | endothelial damage and dysfunction are commonplace in renal transplant recipients. impaired endothelial function is an important contributor to cardiovascular diseases. we hypothesized that short-term black tea consumption may improve endothelium-dependent arterial dilation in kidney recipients. | 2007 | 17524915 |
| activation of endothelial nitric oxide synthase by dietary isoflavones: role of no in nrf2-mediated antioxidant gene expression. | the endothelium plays a key role in the maintenance of vascular homeostasis, and increased oxidative stress in vascular disease leads to reduced nitric oxide bioavailability and impaired endothelium-dependent relaxation of resistance vessels. although epidemiological evidence suggests that diets containing high amounts of natural antioxidants afford protection against coronary heart disease (chd), antioxidant supplementation trials have largely reported only marginal health benefits. there is co ... | 2007 | 17498676 |
| genetic base of tea (camellia sinensis l.) cultivars in sri lanka as revealed by pedigree analysis. | an understanding of genetic diversity and relationships among breeding materials is a prerequisite for crop improvement. coefficient of parentage (cop) can be used to measure the genetic diversity among genotypes on the basis of pedigree information. in the present study, cop was estimated for 56 cultivars, including commercial tea cultivars developed by the tea research institute of sri lanka and their parental lines. mean cop of the 56 accessions studied was 0.097 and the value was raised up t ... | 2007 | 17495345 |
| effects of infusion time and addition of milk on content and absorption of polyphenols from black tea. | epidemiological studies assessing the health benefits of drinking black tea are equivocal. such disparity may reflect an inability of semiquantitative assessment to consider how infusion time and addition of milk affect the bioavailability of potentially beneficial antioxidant polyphenols. six brands of tea demonstrated similar increases in antioxidant capacity and total phenolic and catechin contents with increasing infusion time. these results were unaffected by the addition of milk. consumpti ... | 2007 | 17489604 |
| the structure of two n-methyltransferases from the caffeine biosynthetic pathway. | caffeine (1,3,7-trimethylxanthine) is a secondary metabolite produced by certain plant species and an important component of coffee (coffea arabica and coffea canephora) and tea (camellia sinensis). here we describe the structures of two s-adenosyl-l-methionine-dependent n-methyltransferases that mediate caffeine biosynthesis in c. canephora 'robusta', xanthosine (xr) methyltransferase (xmt), and 1,7-dimethylxanthine methyltransferase (dxmt). both were cocrystallized with the demethylated cofact ... | 2007 | 17434991 |
| potential exposure and risk of fluoride intakes from tea drinks produced in taiwan. | tea is the second most commonly consumed drink in the world. excess fluoride intakes from tea drinks may cause health effects. this work assesses infusible fluoride levels in popular tea sold in taiwan and evaluates potential exposure factors. lungjing, pouchong, tienguanyin, oolong, pureh, and black tea specimens were purchased from different counties in taiwan. fluoride levels were evaluated in one complete cycle of tea making as well as at different calcium carbonate contents in water, with g ... | 2008 | 17410113 |
| study on the antioxidant activity of tea flowers (camellia sinensis). | major chemical compounds in different extracts from tea flowers (camellia sinensis) were analyzed. distilled water or 70% ethanol extracts were then fractionated with chloroform, ethyl acetate and n-butanol, respectively. each extract fraction was tested its scavenging activities on 2,2-diphenyl-1-picrylhydrazyl (dpph) and hydroxyl free radicals. the results showed that ethyl acetate fraction of ethanol-extract of tea flower (eea) exhibited the highest quenching activity to hydroxyl radicals (sc ... | 2007 | 17392094 |
| high-molecular-weight polyphenols from oolong tea and black tea: purification, some properties, and role in increasing mitochondrial membrane potential. | high-molecular-weight polyphenols from oolong and black teas increased mitochondrial membrane potential, as measured by a method using ciliated protozoan tetrahymena and rhodamine 123. these polyphenols, referred to as mitochondrial activation factors (mafs), were purified from oolong and black teas by solvent extraction and toyopearl column chromatography. the number-average molecular weights of the mafs were 9,000 to 18,000, and the weight-average molecular weights were 15,000 to 25,000. the m ... | 2007 | 17341825 |
| oxidative coupling of the pyrogallol b-ring with a galloyl group during enzymatic oxidation of epigallocatechin 3-o-gallate. | in order to clarify the mechanism for formation of catechin oligomers during the fermentation stage of black tea manufacture, epigallocatechin-3-o-gallate, the most abundant tea flavanol in fresh tea leaves, was enzymatically oxidized and the resulting unstable quinone metabolites were converted to phenazine derivatives by treatment with o-phenylenediamine. in addition to formation of monomeric and dimeric derivatives, four trimeric derivatives were isolated whose structures were determined by a ... | 2007 | 17320123 |
| antioxidant capacity of 55 medicinal herbs traditionally used to treat the urinary system: a comparison using a sequential three-solvent extraction process. | the prevalence of chronic renal disease exceeds 10% in industrialized societies. oxidative damage is thought to be one of the main mechanisms involved in nearly all chronic renal pathologies. | 2014 | 17309384 |
| dissipation kinetics of spiromesifen on tea (camellia sinensis) under tropical conditions. | spiromesifen (oberon) is a new insecticide and miticide of chemical class ketoenol active against white flies (bemisia spp., trialeuroides spp.) and spider mites (tetranychus and panonychus spp.). due to its potential significance in insect resistance management, it is important to establish its behaviour on crop and environment. in the present study, the degradation/dissipation of spiromesifen on tea crop under tropical environmental conditions was studied and its dt(50) (t(1/2)), and dt(90) (t ... | 2007 | 17307225 |
| consumption of black tea or coffee and risk of ovarian cancer. | the goal of this study was to investigate the associations between ovarian cancer risk and usual consumption of black tea, regular coffee, or decaffeinated coffee. using a hospital-based case-control design, participants included 414 women with primary epithelial ovarian, fallopian, or peritoneal cancer and 868 age- and region-matched women with nonneoplastic conditions. all participants completed a comprehensive epidemiologic questionnaire. black tea consumption was associated with a linear dec ... | 2013 | 17291231 |
| [studies on tea plants (camellia sinensis) germplasms using est-ssr marker]. | forty two tea varieties were analyzed by using 16 ssr primer sets derived from tea ests in this study, and 13 of the primer sets produced clear bands and 10 of them showed polymorphism, accounting for 76.9%. the pic (polymorphism information content) for each polymorphic primer set varied from 0.522 to 0.866, with a average about 0.73. totally 84 genotypes and 74 alleles were detected in all materials by 10 polymorphic markers, with the range from 4 to 12 and from 3 to 10 for each polymorphic pr ... | 2007 | 17284433 |
| fatty acids in tea shoots (camellia sinensis (l.) o. kuntze) and their effects on the growth of retinal rf/6a endothelial cell lines. | chemo-protective effects of tea on ocular diseases were recorded in chinese pharmacopoeia about 2000 years ago by eating tea. in the present study, contents of fatty acids (fas) in tea shoots were determined by capillary gc; and the growth of rf/6a cells was also investigated by exposure to various representative fas existing in tea shoots with pathologically relevant concentrations (40-500 microm) by ameliorated mtt assay and flow cytometry. electron spin resonance (esr) was used to measure oxy ... | 2007 | 17262883 |
| effect of nitrogen form and root-zone ph on growth and nitrogen uptake of tea (camellia sinensis) plants. | tea (camellia sinensis) is considered to be acid tolerant and prefers ammonium nutrition, but the interaction between root zone acidity and n form is not properly understood. the present study was performed to characterize their interaction with respect to growth and mineral nutrition. | 2007 | 17204540 |