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PubMed2000

Flavor compounds of pine sprout tea and pine needle tea.

Flavor compounds of pine sprout tea and pine needle tea were analyzed and identified in this study. Eighty-one and 39 kinds of flavor compounds were detected in pine sprout tea and pine needle tea by GC, respectively. Among them, 55 and 29 flavor compounds were identified by GC-MS, respectively. Major flavor compounds of pine sprout tea were alpha-pinene, myrcene, beta-thujene, terpinene-4-ol, and delta-cadinene, and major flavor compounds of pine needle tea were alpha-pinene, isoamyl alcohol, trans-caryophyllene, terpinene-4-ol, alpha-terpineol, and delta-cadinene.

Beverages↗

PubMed1998

In-vitro activity of essential oils, in particular Melaleuca alternifolia (tea tree) oil and tea tree oil products, against Candida spp.

The in-vitro activity of a range of essential oils, including tea tree oil, against the yeast candida was examined. Of the 24 essential oils tested by the agar dilution method against Candida albicans ATCC 10231, three did not inhibit C. albicans at the highest concentration tested, which was 2.0% (v/v) oil. Sandalwood oil had the lowest MIC, inhibiting C. albicans at 0.06%. Melaleuca alternifolia (tea tree) oil was investigated for activity against 81 C. albicans isolates and 33 non-albicans Candida isolates. By the broth microdilution method, the minimum concentration of oil inhibiting 90% of isolates for both C. albicans and non-albicans Candida species was 0.25% (v/v). The minimum concentration of oil killing 90% of isolates was 0.25% for C. albicans and 0.5% for non-albicans Candida species. Fifty-seven Candida isolates were tested for sensitivity to tea tree oil by the agar dilution method; the minimum concentration of oil inhibiting 90% of isolates was 0.5%. Tests on three intra-vaginal tea tree oil products showed these products to have MICs and minimum fungicidal concentrations comparable to those of non-formulated tea tree oil, indicating that the tea tree oil contained in these products has retained its anticandidal activity. These data indicate that some essential oils are active against Candida spp., suggesting that they may be useful in the topical treatment of superficial candida infections.

Antifungal Agents↗

PubMed2005

Oxidation of tea extracts and tea catechins by molecular oxygen.

Tea polyphenols (PP) are known as potent antioxidants. At the same time, PP have been repeatedly reported to oxidize by molecular oxygen with the formation of active forms of oxygen. In this work, the Clark electrode technique was applied to study the kinetics of the autoxidation of tea extracts and individual tea PP as well as model PP, catechol, gallic acid, and pyrogallol. Aqueous extracts of both green and black teas were found to undergo extensive autoxidation under physiological conditions. The addition of superoxide dismutase (SOD) and milk resulted in a significant decrease in the rate of oxidation. Studied individually, PP were found to autoxidize at a rate, which increased with pH, proportional to PP concentration and nearly proportional to oxygen concentration. The collected data were used for the extrapolation/interpolation of the starting rates of oxidation to the standard conditions (at pH 7.40, 100 microM PP, 200 microM O2). PP oxidizability is basically determined by that of the key PP fragment (pyrogallol > gallate > catechol). Meta-OH groups do not contribute to the oxidation even at pH 13.0. Similar to tea brew, the oxidation of individual PP was inhibited by milk and SOD addition, with catechol being the only exception (the oxidation of catechol was accelerated when SOD was added). Comparison of the autoxidation of PP (o-hydroquinones) with that of p-hydroquinones (Roginsky, V.; Barsukova, T. K. J. Chem. Soc., Perkin Trans. 2 2000, 1575-1582) displays the dramatic difference both in the oxidizability and in the kinetic regularities. The difference in the kinetics has been suggested to be due to the difference in the initiation of the chain process. Whereas for p-hydroquinones the oxidation is initiated by the reaction between hydroquinone and a corresponding quinone, the oxidation of o-hydroquinones is likely started by direct interaction between substrate and molecular oxygen. As the second process is much slower, this may explain the relatively low oxidizability of PP as compared to p-hydroquinones.

Catechols↗

PubMed2006

Characterization of the key aroma compounds in the beverage prepared from Darjeeling black tea: quantitative differences between tea leaves and infusion.

By application of the aroma extract dilution analysis on the volatile fraction isolated from a black tea infusion (Darjeeling Gold Selection), vanillin (vanilla-like), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (caramel), 2-phenylethanol (flowery), and (E,E,Z)-2,4,6-nonatrienal (oat-flake-like) were identified with the highest flavor dilution (FD) factors among the 24 odor-active compounds detected in the FD factor range of 4-128. Quantitative measurements performed by means of stable isotope dilution assays and a calculation of odor activity values (OAVs; ratio of concentration to odor threshold in water) revealed, in particular, the previously unknown tea constituent (E,E,Z)-2,4,6-nonatrienal as a key odorant in the infusion and confirmed the important role of linalool and geraniol for the tea aroma. An aroma recombinate performed by the 18 odorants for which OAVs > 1 were determined in their "natural" concentrations matched the overall aroma of the tea beverage. In the black tea leaves, a total of 42 odorants were identified, most of which were identical with those in the beverage prepared thereof. However, quantitative measurements indicated that, in particular, geraniol, but also eight further odorants were significantly increased in the infusion as compared to their concentration in the leaves.

Acyclic Monoterpenes↗

PubMed1978

A study of caffeine in tea. I. A new spectrophotometric micro-method. II. Concentration of caffeine in various strengths, brands, blends, and types of teas.

A new spectrophotometric micro-method for the determination of caffeine in tea is described. This method is then used to evaluate the caffeine content of a variety of brands and blends of bagged and loose hot tea prepared in different strengths and by different brewing methods. In addition, the caffeine content of instant tea, ice tea, and Mr. Coffee automatic tea is evaluated.

Caffeine↗

PubMed1998

Tea tree oil allergy: what is the offending agent? Report of three cases of tea tree oil allergy and review of the literature.

Tea tree oil is currently enjoying popularity as a 'cure-all' for a variety of skin conditions, from infections to psoriasis, and many household and personal products containing Melaleuca oil are available. However, despite its chemical complexities and enthusiastic use, there have been only a few reports of allergic reactions to tea tree oil. At the Skin and Cancer Foundation (Sydney, NSW, Australia), three of 28 normal volunteers tested strongly positive to patch testing with tea tree oil. Following further patch testing with tea tree oil constituents, all three patients reacted strongly to two preparations containing sesquiterpenoid fractions of the oil. Because patients often neglect to mention that they have used 'natural' remedies, it is important that physicians are aware of the potential adverse effects of these products. Furthermore, identification of the allergenic ingredients in tea tree oil may assist the growing industry to produce safer products.

Adult↗

PubMed2005

Heat-epimerized tea catechins have the same cholesterol-lowering activity as green tea catechins in cholesterol-fed rats.

Tea catechins are known to be epimerized by heat treatment. The effect of heat-epimerized tea catechins on serum cholesterol concentration was compared with that of green tea catechins. Our observations strongly suggest that both tea catechins and heat-epimerized tea catechins lower serum cholesterol concentration by inhibiting cholesterol absorption in the intestine. There was no differential effect between the two catechin preparations.

Animals↗

PubMed1998

[Simultaneous extraction of tea-polyphenols and caffeine from green tea].

Tea-polyphenols and caffeine were extracted simultaneously from green tea. The factors influencing on the process of impregnation and extraction were studied. The result indicated that the content of tea-polyphenols and caffeine in tea was increased with the duration of extraction and decreased with the frequency of extraction. The authors discuss the effect of pH on the precipition of calcium-tea-polyphenols.

Caffeine↗

PubMed2005

[Determination of catechins and caffeine in tea and tea beverages by high-performance liquid chromatography].

OBJECTIVE: A high-performance liquid chromatography method was developed for the determination of total tea catechin and caffeine. METHODS: The catechins needed to be determined are: (-)-catechin, (-)-epigallocatechin, (-)-epigallocatechin gallate, (-)-epicatechin, (-)-epicatechin gallate, (-)-gallocatechin, (-)-gallocatechin gallate, (-)-catechin gallate and caffeine. The catechins in the tea was extracted with water:ethanol (3:7) by sonication for 20 min. After the extraction solution was centrifuged, it was analyzed by HPLC. The column used was a CAPCELL PAK C18 MG (4.6mm I.D. x 150mm) and gradient elution at constant column temperature with 30 degrees C under UV detector with 210nm. Mobile phase A was 0.1% H3PO4 in water, mobile phase B was 0.1% H3PO4 in methanol with the flow rate 1ml/min. RESULTS: The results showed that the concentration of the catechins and caffeine and their peak areas achieved good linear relation, r > 0.999. The recoveries were between 61.7%-117.3%. RSD was below 10%. With this method, some tea samples were determined, the results were favorable. CONCLUSION: The method can be applied for determination of catechin and caffeine in tea and tea beverages.

Caffeine↗

PubMed2005

[Studies on ANN models of determination of tea polyphenol and amylose in tea by near-infrared spectroscopy].

The objectives of the present paper were to build the models for the determination of tea polyphenol (TP) and tea amylose (TA) in tea by near-infrared spectroscopy (NIR). According to the range of 7432.3-6155.7 cm(-1) and 5484.6-4192.5 cm(-1) of NIR spectra, the models are built for determining the contents of TP and TA in tea with the input layer, hidden layer and node ((8, 4, 1) and (7, 5, 1) respectively) in network structure by the artificial neural network. The correlation coefficient (r), the root mean square error of cross validation (RMSECV) and the root mean square error of prediction (RMSEP) were selected as the indexes for evaluating the performance of calibration models. The results show that r, RMSECV and RSECV by the model samples for TP and TA are 0.9847, 0.460 and 0.123, and 0.9470, 0.136 and 0.224 respectively, and r, RMSEP and RSEP by the prediction samples for TP and TA are 0.9804, 0.529 and 0.017, and 0.9682, 0.111 and 0.0298 respectively. These indicated that the NIRANN models can be used to determine the contents of TP and TA in tea.

Algorithms↗

PubMed1997

Antimutagenicity of Tochu tea (an aqueous extract of Eucommia ulmoides leaves): 1. The clastogen-suppressing effects of Tochu tea in CHO cells and mice.

The suppressing effect of crude extracts of Tochu tea, an aqueous extract of Eucommia ulmoides leaves and a popular beverage in Japan, on the induction of chromosome aberrations in CHO cells and mice was studied. When CHO cells were treated with Tochu tea crude extract after MMC treatment, the frequency of chromosome aberrations was reduced. Out of 17 Tochu tea components, 5 irridoids (geniposidic acid, geniposide, asperulosidic acid, deacetyl asperulosidic acid, and asperuloside) and 3 phenols (pyrogallol, protocatechuic acid, and p-trans-coumaric acid) were found to have anticlastogenic activity. Since the anticlastogenic irridoids had an alpha-unsaturated carbonyl group, this structure was considered to play an important role in the anticlastogenicity. The anticlastogenic effect of Tochu tea extracts was examined in mice using a micronucleus assay. When mice received 1.0 ml 4% Tochu tea extract by oral gavage 6 h before intraperitoneal injection of MMC, a decrease in the frequency of micronuclei was observed. This decrease was not due to a delay in the maturation of micronucleated reticulocytes.

Animals↗

PubMed2003

A combination of tea (Camellia senensis) catechins is required for optimal inhibition of induced CYP1A expression by green tea extract.

It was previously demonstrated that the commercial green tea extract Polyphenon 100 (P100), and to a lesser extent (-)-epigallocatechin-3-gallate (EGCG), partially antagonizes 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced transcription of human CYP1A1 (Williams, S. N.; Shih, H.; Guenette, D. K.; Brackney, W.; Denison, M. S.; Pickwell, G. V.; Quattrochi, L. C. Chem.-Biol. Interact. 2000, 128, 211-229). Here, P100 is compared to a reconstituted mixture of the four major tea catechins (referred to as P100R) to determine whether inhibition was due to additional polyphenols in the extract or from synergistic interactions among the tea catechins. It was found that cotreatment of cells with TCDD and either P100 or P100R inhibited TCDD-induced CYP1A promoter-driven luciferase reporter activity (HepG2 cells) and CYP1A expression (HepG2 and primary human hepatocytes), similarly. These results indicate that modulation of human CYP1A expression by P100 can be attributed entirely to the combination of the four tea catechins. These findings may be important in the evaluation of future chemoprevention strategies using green tea and single catechin agents.

Bacterial Proteins↗

PubMed2004

Total phenolics and antioxidant activities of fenugreek, green tea, black tea, grape seed, ginger, rosemary, gotu kola, and ginkgo extracts, vitamin E, and tert-butylhydroquinone.

The total phenolics and antioxidant activities of fenugreek, green tea, black tea, grape seed, ginger, rosemary, gotu kola, and ginkgo extracts, vitamin E, and tert-butylhydroquinone, were determined. Grape seed and green tea were analyzed for their phenolic constituents using high-performance liquid chromatography. The total phenolics of the plant extracts, determined by the Folin-Ciocalteu method, ranged from 24.8 to 92.5 mg of chlorogenic acid equivalent/g dry material. The antioxidant activities of methanolic extracts determined by conjugated diene measurement of methyl linoleate were 3.4-86.3%. The antioxidant activity of the extracts using chicken fat by an oxidative stability instrument (4.6-10.2 h of induction time) followed a similar trend in antioxidant activity as determined by the Folin-Ciocalteu method. Seven phenolics in grape seed and green tea extracts were identified that ranged from 15.38 to 1158.49 and 18.3 to 1087.02 mg/100 g of extract, respectively. Plant extracts such as green tea and grape seed extracts can be used to retard lipid oxidation in a variety of food products.

Antioxidants↗

PubMed2006

Mechanisms of hypolipidemic and anti-obesity effects of tea and tea polyphenols.

Among the health-promoting effects of tea and tea polyphenols, the cancer-chemopreventive effects in various animal model systems have been intensively investigated; meanwhile, the hypolipidemic and antiobesity effects in animals and humans have also become a hot issue for molecular nutrition and food research. It has been demonstrated that the body weights of rats and their plasma triglyceride, cholesterol, and LDL-cholesterol have been significantly reduced by feedings of oolong, black, pu-erh, and green tea leaves to the animals. It has been suggested that the inhibition of growth and suppression of lipogenesis in MCF-7 breast cancer cells may be through down-regulation of fatty acid synthase gene expression in the nucleus and stimulation of cell energy expenditure in the mitochondria. The experimental data indicated that the molecular mechanisms of fatty acid synthase gene suppression by tea polyphenols (EGCG, theaflavins) may invite down-regulation of EGFR/PI3K/Akt/Sp-1 signal transduction pathways.

Animals↗

PubMed1978

[Nickel, cobalt, iron, manganese, zinc and chromium content of black tea and the distribution of these metals between prepared infusion and the extracted tea leaves (author's transl)].

Twentytwo samples of black tea were examined for nickel, cobalt, iron, manganese and chromium by atomic absorption spectro-photometry. The amounts of these metals in the tea beverage as well as the amount remaining in the tea leaf residue was determined in duplicate experiments. From these results the proportion of each metal extracted may be calculated, as well as its concentration in the tea beverage prepared under defined conditions.

Chromium↗

PubMed2006

Dynamic hollow fiber protected liquid phase microextraction and quantification using gas chromatography combined with electron capture detection of organochlorine pesticides in green tea leaves and ready-to-drink tea.

The dynamic hollow fiber protected liquid phase microextraction (DHFP-LPME) technique was evaluated for the extraction of organochlorine pesticides (OCPs) in green tea leaves and ready-to-drink tea prior to gas chromatography combined-electron capture detection (GC-ECD) analysis. A conventional microsyringe with a 1.5 cm length of hollow fiber attached to its needle was connected to a syringe pump to perform the extraction. The microsyringe was used as both the microextraction device and the sample introduction device for GC-ECD analysis. In this work, the organochlorine pesticides were extracted and condensed to a volume of 3 microl of organic extracting solvent (1-octanol) confined within a 1.5 cm length of hollow fiber. The effects of extraction solvent, extraction time, sample agitation, plunger speed, and extraction temperature and salt concentration content on the extraction performance were also investigated. Good enrichments were achieved (34-297-fold) with this method, and good repeatabilities of extraction were obtained, with full name (RSDs) below 12.57%. Detection limits were much below 1 microg l(-1) for ready-to-drink tea and much below 1 microg g(-1) for green tea leaves.

1-Octanol↗

PubMed2001

Degradation of green tea catechins in tea drinks.

Green tea cateachins (GTC). namely (-) epicatechin (EC), (-) epicatechin gallate (ECG), (-) epigallocatechin (EGC), and (-) epigallocatechin gallate (EGCG), have been studied extensively for their wide-ranging biological activities. The goal of the present study was to examine the stability of GTC as a mixture under various processing conditions. The stability study demonstrated that GTC was stable in water at room temperature. When it was brewed at 98 degrees C for 7 h, longjing GTC degraded by 20%. When longjing GTC and pure EGCG were autoclaved at 120 degrees C for 20 min, the epimerization of EGCG to (-) gallocatechin gallate (GCG) was observed. The relatively high amount of GCG found in some tea drinks was most likely the epimerization product of EGCG during autoclaving. If other ingredients were absent, the GTC in aqueous solutions was pH-sensitive: the lower the pH, the more stable the GTC during storage. When it was added into commercially available soft drinks or sucrose solutions containing citric acid and ascorbic acid, longjing GTC exhibited varying stability irrespective of low pH value. This suggested that other ingredients used in production of tea drinks might interact with GTC and affect its stability. When canned and bottled tea drinks are produced, stored, and transported, the degradation of GTC must be taken into consideration.

Beverages↗

PubMed2005

Oxidative deamination of benzylamine and lysine residue in bovine serum albumin by green tea, black tea, and coffee.

Oxidative deamination by various polyphenolic compounds is presumed to be due to the oxidative conversion of polyphenols to the corresponding quinones through autoxidation. Here we examined the oxidative deamination by the polyphenol-rich beverages green tea, black tea, and coffee at a physiological pH and temperature. Green tea, black tea, and coffee extracts oxidatively deaminated benzylamine and the lysine residues of bovine serum albumin to benzaldehyde and alpha-aminoadipic delta-semialdehyde residues, respectively, in sodium phosphate buffer (pH 7.4) at 37 degrees C in both the presence and absence of Cu2+, indicating the occurrence of an amine (lysyl) oxidase-like reaction. We also examined the effects of pH and metal ions on the reaction. The possible biological effects of drinking polyphenol-rich beverages on human are also discussed.

Benzylamines↗