RESUMEN
Both regular and decaffeinated coffees were found to have cholinomimetic actions when tested in urethane-anesthetized rats. These actions were distinct from those of caffeine and reversible by atropine. The bioactive fraction was purified from alcoholic extracts of instant decaffeinated coffee by liquid column chromatography and preparative TLC. The purified compound showed similar pharmacological actions as the starting material. Chromatographic behavior was further characterized by analytical TLC and HPLC. Chromatographic analyses of extracts of green coffee beans and roasted ground coffees showed that the cardioactive compound was only present in roasted coffees. Similar analyses of other commonly consumed beverages, including teas and cocoa, showed that this compound was not present in beverages besides coffee.
Asunto(s)
Café/análisis , Parasimpaticomiméticos/aislamiento & purificación , Acetilcolina/análisis , Animales , Atropina/farmacología , Presión Sanguínea/efectos de los fármacos , Cacao/análisis , Cromatografía Líquida de Alta Presión , Cromatografía en Capa Delgada , Masculino , Parasimpaticomiméticos/análisis , Ratas , Ratas Endogámicas , Espectrofotometría Ultravioleta , Té/análisisRESUMEN
The isolation and structural elucidation of new quercetin and kaempferol triglycosides from Camellia sinensis is described. Their structures were determined as quercetin and kaempferol 3-glucosyl(1----3) rhamnosyl(1----6)galactosides. The content of quercetin glucosylrhamnosylgalactoside ranged between 0 and 87 mg per 100 g, and that of the kaempferol homologue between 0 and 119 mg per 100 g dry wt.
Asunto(s)
Quempferoles , Quercetina/análogos & derivados , Té/análisis , Trisacáridos/aislamiento & purificación , Secuencia de Carbohidratos , Cromatografía Líquida de Alta Presión , Hidrólisis , Espectroscopía de Resonancia Magnética , Datos de Secuencia Molecular , Quercetina/química , Quercetina/aislamiento & purificación , Trisacáridos/químicaAsunto(s)
Carcinógenos , Té/efectos adversos , Animales , Humanos , Factores de Riesgo , Té/análisis , Té/provisión & distribuciónRESUMEN
Epicatechin complex was given to diethylnitrosamine-initiated male Wistar rats concomitantly with the administration of phenobarbitol during hepatocarcinogenesis. The epicatechin complex was extracted from Longjing green tea and its concentration of whole epicatechin was 87.5%. The results denoted that epicatechin efficiently inhibited the promotive effect of phenobarbitol. High performance liquid chromatography analysis proved that the chemical properties of phenobarbitol and epicatechin were still well preserved when these two substances were dissolved together in distilled water. It was noted that there was no direct chemical reaction between these two substances. The inhibition mechanism and need of further studies concerning the effect of epicatechin on cell metabolism are discussed.
Asunto(s)
Catequina/análogos & derivados , Flavonoides/farmacología , Neoplasias Hepáticas/patología , Fenobarbital/antagonistas & inhibidores , Lesiones Precancerosas/patología , Animales , Catequina/farmacología , Dietilnitrosamina , Neoplasias Hepáticas/inducido químicamente , Masculino , Lesiones Precancerosas/inducido químicamente , Ratas , Ratas Endogámicas , Té/análisisRESUMEN
A ninhydrin positive compound (L2) now identified as 2-amino-5-(N-ethylcarboxyamido)-pentanoic acid, from unprocessed tea leaves was a potent inhibitor of thrombin-stimulated thromboxane formation in rabbit whole blood (Ali and Afzal; Prostaglandins, Leukotrienes and Medicine, 27: 9, 1987). In the present study, processed and unprocessed tea leaf extracts were given to rats to consume for a period of eight weeks. Cholesterol and thromboxane levels were measured in the serum obtained from clotting the blood at 37 degrees C. A significant reduction in thromboxane levels was observed in rats taking unprocessed tea extract. This reduction was equally distributed in adult as well as in juvenile rats. However no appreciable changes in the levels of thromboxane were noticed in the serum of rats taking processed tea extracts. This might be due to the presence of a labile component which is destroyed during the processing of green tea leaves. A decreased level of cholesterol was observed in rats consuming unprocessed tea extract. This decrease could be linked to the decrease in thromboxane levels as observed. Processed tea refers to commercially available tea of different brands while unprocessed tea refers to dried green tea leaves.
Asunto(s)
Té , Tromboxano B2/biosíntesis , Aminoácidos/aislamiento & purificación , Aminoácidos/farmacología , Animales , Colesterol/sangre , Femenino , Manipulación de Alimentos , Ratas , Ratas Endogámicas , Té/análisis , Tromboembolia/prevención & control , Tromboxano B2/sangreRESUMEN
We extended the study of oxalate bioavailability by testing 7 additional food items: brewed tea, tea with milk, turnip greens, okra, peanuts and almonds. Nine normal subjects ingested a large serving of each of these items. The bioavailable oxalate was calculated from the increment in urinary oxalate during 8 hours after ingestion and bioavailability was determined as the percentage of total oxalate content in a given food item represented by bioavailable oxalate. Brewed tea and tea with milk, with a high oxalate content, had a low bioavailable oxalate level (1.17 and 0.44 mg. per load) because of the low oxalate availability (bioavailability of 0.08 and 0.03%). Turnip greens, with a satisfactory oxalate bioavailability (5.8%), had a negligible effect on urinary oxalate excretion, since oxalate content was relatively low (12 mg. per load). Okra, with a moderate oxalate content (264 mg. per load) had a negligible bioavailable oxalate (0.28 mg. per load). Only peanuts and almonds provided a moderate increase in oxalate excretion (3 to 5 mg. per load) due to the modest oxalate content (116 and 131 mg. per load) and oxalate bioavailability (3.8 and 2.8%). Thus, the ability of various oxalate-rich foods to augment urinary oxalate excretion depends not only on oxalate content but on the bioavailability.
Asunto(s)
Alimentos , Oxalatos/farmacocinética , Adulto , Disponibilidad Biológica , Femenino , Humanos , Masculino , Nueces/análisis , Oxalatos/análisis , Oxalatos/orina , Té/análisis , Verduras/análisisRESUMEN
A method for determining the Al levels in tea leaf digests and tea infusions by means of 27Al nuclear magnetic resonance (NMR) spectroscopy is described. Quantitative results down to 2.0 micrograms cm-3 of Al in 0.5-cm-3 acidified samples are readily obtainable in standard 5-mm NMR tubes. An acceptable quantitative determination is achieved by using an internal Al standard in a 1-mm capillary in conjunction with europium nitrate as a shift reagent.
Asunto(s)
Aluminio/análisis , Té/análisis , Espectroscopía de Resonancia Magnética , RadioisótoposRESUMEN
Counter-current chromatography using a multilayer coil planet centrifuge, with solvent system ethyl acetate-butanol-water, permits the separation of black tea infusions into fractions which include pure SII and a mixture of SI and SIa thearubigins. Good resolution of several components of the infusion may be achieved in elution times of 1 to 2 h. The appearance of chromatograms is altered on decaffeinating the infusion. The effect of stationary phase composition is considered. Resolution of the peaks improves with butanol content.
Asunto(s)
Té/análisis , Cromatografía Liquida/métodos , Extractos Vegetales/análisisRESUMEN
The extent to which tea, cocoa and carob (foods rich in polyphenols) influence fecal nitrogen (N) excretion was investigated in rats. The studies took into account the methylxanthine contents of tea and cocoa as well as the poor digestibility of cocoa nitrogen. Balance measurements indicated that all three food sources significantly increased fecal nitrogen excretion relative to methylxanthine-matched control diets (p less than 0.01). In the case of cocoa, virtually all the increase could be attributed to the poor digestibility of cocoa protein itself (estimated to be only 28-30% of total N in cocoa powder). There appeared to be no other effects. With extracts of tea and carob, however, the increased excretion of N in feces resulted either from a decreased digestibility of other dietary protein, through interaction with their polyphenols, or from a stimulation of the excretion of endogenous (body) nitrogen. With respect to the latter possibility, a preliminary investigation with the stable isotope of nitrogen (15N) showed that tea produced a marked increase in the excretion of endogenous nitrogen. These studies, therefore, indicate that foods rich in polyphenols have varying effects on N excretion in feces and that, in the case of tea at least, the loss of endogenous nitrogen may be a major contributing factor.
Asunto(s)
Dieta , Heces/análisis , Flavonoides , Nitrógeno/análisis , Fenómenos Fisiológicos de la Nutrición , Fenoles/farmacología , Polímeros/farmacología , Animales , Peso Corporal , Cacao/análisis , Proteínas en la Dieta/análisis , Interacciones Farmacológicas , Ingestión de Energía , Galactanos , Masculino , Mananos , Nitrógeno/orina , Fenoles/administración & dosificación , Fenoles/aislamiento & purificación , Extractos Vegetales/administración & dosificación , Gomas de Plantas , Polímeros/administración & dosificación , Polímeros/aislamiento & purificación , Polifenoles , Polisacáridos/análisis , Ratas , Ratas Endogámicas , Té/análisis , Xantinas/análisisRESUMEN
In the course of our studies on the development of anti-plaque agents for prevention of dental caries, we investigated effects of some of tea preparations and their individual components on the glucan synthesis catalyzed by glucosyltransferase (GTF) from Streptococcus mutans. Extracts of green tea and black tea, and polyphenol mixtures showed appreciable inhibition in the synthesis of insoluble glucan. Among the components isolated from tea infusions, theaflavin and its mono- and digallates had potent inhibitory activities at concentrations of 1-10 mM against GTF. (+)-Catechin, (-)-epicatechin and their enantiomers had moderate inhibitory activities at these concentrations, while galloyl esters of (-)-epicatechin, (-)-epigallocatechin and (-)-gallocatechin had increased inhibitory activities.
Asunto(s)
Glucanos/biosíntesis , Glucosiltransferasas/metabolismo , Fenoles/farmacología , Streptococcus mutans/enzimología , Té/análisisRESUMEN
We have studied and found antitumor effects in Chinese green tea extracts (T-8750). By pharmacologic test, it showed anticancer actions against several kinds of tumors in NIH mice evidently. Clinical trials on the therapeutics effects against early stomach cancer showed very effective. In order to prove it's function to prevent cancer. The research results as follows: (1) In vitro, T-8750 (0.5-1 mg/ml) could inhibit the cell growth of SGC (stomach gastric cancer) significantly. The inhibition action are obviously within 12-24 hr. (2) T-8750 traversed the migration of cell line L1210 from G1 phase to S phase, the rate were (63%). (3) In vitro, the blocking effect of T-8750 on the nitrosation of morpholine-nitrite was (92.4%). (4) the effect of T-8750 scavenger harmful free radicals was (63%).
Asunto(s)
Adenocarcinoma/patología , Antineoplásicos , Extractos Vegetales/farmacología , Neoplasias Gástricas/patología , Té , Animales , Humanos , Leucemia L1210/patología , Té/análisis , Células Tumorales Cultivadas/efectos de los fármacosRESUMEN
The effect of hot water extract of green tea on the collagen-induced aggregation of washed rabbit platelets was examined. The extract lowered submaximal aggregation and prolonged the lag time in a dose-dependent manner. After fractionation of the extract, it was revealed that the tea catechins (tannins) are active principles for inhibition and that ester-type catechins are more effective than free-type catechins. One of the ester type catechins, epigallocatechin gallate (EGCG), suppressed the collagen-induced platelet aggregation completely at the concentration of 0.2 mg/ml (= 0.45 mM). Comparing IC50 values of EGCG and aspirin it was found that the potency of EGCG is comparable to that of aspirin. Thrombin- and platelet activating factor (PAF)-induced aggregation was also inhibited by EGCG. The elevation of cyclic adenosine 3',5'-monophosphate (cAMP) level was not observed in EGCG treated platelets.
Asunto(s)
Catequina/análogos & derivados , Extractos Vegetales/farmacología , Inhibidores de Agregación Plaquetaria , Té/análisis , Animales , Flavonoides/aislamiento & purificación , Flavonoides/farmacología , Técnicas In Vitro , Masculino , ConejosRESUMEN
The two components of Camellia sinensis (tea plant) [i.e., (-)-epicatechin gallate and (-)-epigallocatechin gallate] were found to differentially inhibit the activities of reverse transcriptase and cellular DNA and RNA polymerases. Under the assay conditions optimized for each enzyme species, the strongest inhibition by these compounds was observed with reverse transcriptase. The concentrations of (-)-epicatechin gallate and (-)-epigallocatechin gallate required for 50% inhibition of the activity of human immunodeficiency virus (HIV) reverse transcriptase were in the range of 0.01-0.02 microgram/mL. On the other hand, neither (-)-epicatechin, (-)-epigallocatechin, nor gallic acid, the constituents of (-)-epicatechin gallate and (-)-epigallocatechin gallate, was inhibitory to the activity of HIV reverse transcriptase at concentrations up to 1 microgram/mL. The mode of inhibition of reverse transcriptase and other DNA polymerases by these compounds was competitive with respect to the template-primer, whereas the mode of inhibition of RNA polymerase was competitive with respect to the nucleotide substrate. The Ki values of HIV reverse transcriptase for (-)-epicatechin gallate and (-)-epigallocatechin gallate were determined to be 7.2 and 2.8 nM, respectively, which are smaller by 1-2 orders of magnitude than the Ki's of other DNA and RNA polymerases for these compounds.
Asunto(s)
Catequina/análogos & derivados , Catequina/farmacología , ARN Polimerasas Dirigidas por ADN/antagonistas & inhibidores , VIH/enzimología , Inhibidores de la Síntesis del Ácido Nucleico , Inhibidores de la Transcriptasa Inversa , Animales , Bovinos , Línea Celular , ADN Polimerasa Dirigida por ADN/metabolismo , ARN Polimerasas Dirigidas por ADN/metabolismo , Cinética , ADN Polimerasa Dirigida por ARN/metabolismo , Té/análisis , Timo/enzimologíaRESUMEN
A method for the simultaneous determination of pantothenic acid and hopantenic acid in plasma samples was developed using gas chromatography-mass spectrometry with multiple ion detection. Plasma samples were directly purified without deproteinization on an ion-exchange resin, and the eluate was extracted with ethyl acetate under acidic conditions. The organic layer was evaporated to dryness under a stream of nitrogen, and the residue was dissolved in an internal standard solution. Pantothenic and hopantenic acids were converted into their trimethylsilyl derivatives by treating with bis(trimethylsilyl)trifluoroacetamide. Aliquots of this solution were injected into the gas chromatograph-mass spectrometer, which was equipped with a wide-bore fused-silica column (DB-17) and analysed by the multiple ion detection method. The detection limits for pantothenic acid and hopantenic acid in plasma were 1 ng/ml each at a signal-to-noise ratio of 5. This method was applied to a study of the assay of pantothenic acid and hopantenic acid in biological samples and natural products.
Asunto(s)
Cromatografía de Gases y Espectrometría de Masas , Ácido Pantoténico/análogos & derivados , Ácido Pantoténico/análisis , Ácido gamma-Aminobutírico/análogos & derivados , Animales , Química Encefálica , Pollos , Perros , Análisis de los Alimentos , Haplorrinos , Humanos , Indicadores y Reactivos , Ratones , Estructura Molecular , Oryza/análisis , Ácido Pantoténico/sangre , Conejos , Ratas , Porcinos , Té/análisis , Tortugas , Levadura Seca/análisis , Ácido gamma-Aminobutírico/análisis , Ácido gamma-Aminobutírico/sangreRESUMEN
EGCG, the main constituent of green tea, and sarcophytols A and B, isolated from a soft coral, inhibited tumor promotion by teleocidin in a two-stage carcinogenesis experiment on mouse skin. EGCG and sarcophytols showed inhibition of tumor development by chemical carcinogenesis. A possibility of developing these compounds as cancer chemopreventives for human beings is discussed.
Asunto(s)
Catequina/análogos & derivados , Diterpenos/uso terapéutico , Flavonoides/uso terapéutico , Neoplasias Mamarias Experimentales/prevención & control , Neoplasias Cutáneas/prevención & control , Té/análisis , 9,10-Dimetil-1,2-benzantraceno , Animales , Cnidarios/análisis , Cocarcinogénesis , Diterpenos/aislamiento & purificación , Femenino , Flavonoides/aislamiento & purificación , Toxinas de Lyngbya/toxicidad , Ratones , Neoplasias Cutáneas/inducido químicamenteRESUMEN
The paper is concerned with the results of a study of behavior of artificial radionuclides in Georgian tea technological products after the accident at the Chernobyl Nuclear Station. A partial contribution of the activity of radionuclides 141Ce, 140La, 103Ru, 106Ru, 140Ba, 137Cs, 95Zr, 95Nb, 134Cs and 90Sr to the total activity to Georgian tea samples. Maximum tolerated concentrations of radionuclides were assessed provided average annual tea consumption per capita was 1 kg. The maximum of solubility in the water phase falls on Cs radionuclides. The regularities of migration of half-lived radionuclides 3 yrs. After the Chernobyl accident were established.
Asunto(s)
Contaminación Radiactiva de Alimentos , Radioisótopos/análisis , Té/análisis , Accidentes , Georgia (República) , Reactores Nucleares , Centrales Eléctricas , Radioisótopos/farmacocinética , Solubilidad , Espectrometría gamma , Té/metabolismo , UcraniaRESUMEN
Tea and infant formulae have been examined for the presence of aluminium. Concentrations in 13 different tea infusions ranged from 2.2 mg/l to 4.5 mg/l. In cow's milk-based infant formulae as made up for consumption, aluminium levels of between 0.03 mg/l and 0.20 mg/l were detected. Higher amounts were present in soya-based formulae with concentrations ranging from 0.64 mg/l to 1.34 mg/l.