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PubMed1976

Effects of azotemia on renal extraction and clearance of PAH and TEA.

Dogs were made azotemic by bilateral ureteral-venous anastomosis. Subsequently, the left ureter, a systemic artery, and the left renal vein were cannulated. Left renal blood flow (RBF) was measured by an electromagnetic flowmeter. Left renal clearances and extractions of [14C]tetraethylammonium ([14C]TEA) and p-aminohippuric acid (PAH) were determined at five 40-min intervals after administraiton of loading doses and institution of a maintenance infusion containing PAH and [14C]TEA. The renal extraction of TEA was independent of blood urea nitrogen (BUN), whereas the extraction of PAH correlated inversely with BUN. Renal plasma flows calculated from urinary clearances and renal extractions agreed with renal plasma flows calculated from flowmeter data. The extraction of TEA remained constant over the 200-min experimental period, whereas the extraction of PAH increases progressively as a function of time. It is probable that those organic acids which accumulate in azotemia, and interfered with renal tubular secretion of PAH, were themselves eliminated after opening the ureteral-venous anastomosis. Thus, TEA is superior to PAH for evaluation of the renal circulation in azotemia.

Aminohippuric Acids↗

PubMed2026

Microbial diversity, functional activities, and safety risks in fermented tea: a comprehensive review.

Microbial fermented teas are gaining global popularity due to their unique sensory profiles and health benefits. The quality and safety of these products are governed by complex microbial ecosystems that orchestrate the biotransformation of tea leaf components. This review addresses a critical paradox in the field: the same microbial activities that generate desirable bioactive metabolites, such as theabrownins and organic acids, also create ecological niches for mycotoxigenic fungi, posing significant health risks from contaminants like ochratoxin A, citrinin, and aflatoxins. While extensive research has cataloged the microbial diversity in these systems, a comprehensive framework linking processing environments to microbial community assembly, functional outcomes, and quantifiable safety risks remains elusive. This review systematically bridges this gap by synthesizing current knowledge on the microbial consortia-dominated by Aspergillus, Penicillium, Bacillus, and Lactiplantibacillus species-that drive tea fermentation. We critically analyze their functional roles in enhancing flavor, bioactivity, and potential probiotic activity while simultaneously evaluating the mechanisms of mycotoxin production and accumulation. By integrating microbial ecology, biochemistry, and food safety, we propose a forward-looking perspective focused on transitioning the industry from traditional, spontaneous fermentation to modern, controlled biotechnological processes. This approach, centered on the use of defined starter cultures, predictive modeling, and active biocontrol strategies, provides a roadmap for ensuring the consistent quality and safety of fermented tea products, ultimately unlocking their full potential as high-quality functional foods.

Tea↗

PubMed1975

Biosynthesis of caffeine by tea-leaf extracts. Enzymic formation of theobromine from 7-methylxanthine and of caffeine from theobromine.

1. Extracts prepared from tea leaves with Polyclar AT (insoluble polyvinylpyrrolidine) contained two methyltransferase activities catalysing the transfer of methyl groups from S-adenosylmethionine to 7-methylxanthine, producing theobromine, and to theobromine, producing caffeine. 2. The methyltransferases exhibited the same pH optimum (8.4) and a similar pattern of effects by metal ions, thiol inhibitors and metal-chelating reagents, both for theobromine and caffeine synthesis. Mg2+, Mn2+ and Ca2+ slightly stimulated enzyme activity but they were not essential. Paraxanthine was shown to be most active among methylxanthines, as the methyl acceptor. However, the formation of paraxanthine from 1-methylxanthine was very low and that from 7-methylxanthine was nil, suggesting that the synthesis of caffeine from paraxanthine is of little importance in intact plants. Xanthine, xanthosine, XMP and hypoxanthine were all inactive as methyl acceptors, whereas [2(-14)C]xanthine and [8(-14)C]hypoxanthine were catabolized to allantoin and urea by tea-leaf extracts. The apparent Km values are as follows: 7-methylxanthine, 1.0 times 10(-14)M; theobromine, 1.0 times 10(-3)M; paraxanthine, 0.2 times 10(-3)M; S-adenosylmethionine, 0.25 times 10(-4)M (with each of the three substrates). 3. The results suggest that the pathway for caffeine biosynthesis is as follows: 7-methylxanthine leads to theobromine leads to caffeine. In contrast, it is suggested that theophylline is synthesized from 1-methylxanthine. The methyl groups of the purine ring of caffeine are all derived directly from the methyl group of S-adenosylmethionine. Little is known about the pathways leading to the formation of 7-methylxanthine. 4. A good correlation between caffeine synthesis and shoot formation or growth of tea seedlings was shown, suggesting that the methylating systems in caffeine synthesis are closely associated with purine nucleotide and nucleic acid metabolism in tea plants.

Caffeine↗

PubMed1976

Metabolism of methionine and biosynthesis of caffeine in the tea plant (Camellia sinensis L.).

1. Caffeine biosynthesis was studied by following the incorporation of 14C into the products of L-[Me-14C]methionine metabolism in tea shoot tips. 2. After administration of a 'pulse' of L-[Me-14C]methionine, almost all of the L-[Me-14C]methionine supplied disappeared within 1 h, and 14C-labelled caffeine synthesis increased throughout the experimental periods, whereas the radioactivities of an unknown compound and theobromine were highest at 3 h after the uptake of L-[Me-14C]methionine, followed by a steady decrease. There was also slight incorporation of the label into 7-methylxanthine, serine, glutamate and aspartate, disappearing by 36 h after the absorption of L-[Me-14C]methionine. 3. The radioactivities of nucleic acids derived from L-[Me-14C]methionine increased rapidly during the first 12 h incubation period and then decreased steadily. Sedimentation analysis of nucleic acids by sucrose-gradient centrifugation showed that methylation of nucleic acids in tea shoot tips occurred mainly in the tRNA fraction. The main product among the methylated bases in tea shoot tips was identified as 1-methyladenine. 4. The results indicated that the purine ring in caffeine is derived from the purine nucleotides in the nucleotide pool rather than in nucleic acids. A metabolic scheme to show the production of caffeine and related methylxanthines from the nucleotides in tea plants is discussed.

Adenosine Monophosphate↗

PubMed1977

A colorimetric study of coffee and tea staining of four composite resins.

Colorimetric measurements were made on four composite resins before and after controlled immersion treatments. The four composite resins were: Adaptic (Johnson and Johnson), Prestige (Lee Pharmaceuticals), Addent XV (3M Mfg. Co.) and Smile (Kerr Mfg. Co.). Specimens of each material were prepared with mylar surfaces and with abraded finished surfaces. Separate groups of specimens of the four materials were immersed in three separate solutions for 12 days at 55c. The three solutions used were: a control solution of distilled water and coffee and a solution of distilled water and tea. For all materials and surface finishes, immersion in coffee and tea produced significantly greater colour changes than distilled water. Coffee produced significantly greater colour changes than tea with the exception of 'Prestige' and 'Addent XV' with finished surfaces. When immersed in a tea solution, specimens of the same material with differing surface finishes showed greater differences in colour change than when immersed in control and coffee solutions. The relative colour changes of the four materials due to the immersion procedures were as follows: 'Adaptic' showed the least colour changes and "Smile' showed the most. 'Addent XV' and 'Prestige' tended to vary between the former two. Comparison and correlation of colorimetry results with visual assessment scores allowed for the expression of the objective measures in subjective terms suitable for clinical purposes.

Coffee↗

PubMed1975

Tea-gruel as a possible factor for cancer for the esophagus.

Specific death rates for esophageal cancer by each city and county in Japan were calculated. Nara and Wakayama Prefectures formed a high death-rate area with some neighboring cities and counties in other perfectures. Inhabitants of these area are known by the custom of taking "Chagayu", tea-cooked rice gruel. According to this survey on the habit of taking hot tea-gruel, with over 5,000 teachers and their families aged over 50 years old, the distribution of the precentages of taking tea-gruel among surveyed subjects by cities and counties was similar to that of the death rates for esophageal cancer. Also, in Yamaguchi Prefecture, western-most prefecture of the main island (Honshu), there was an area which showed a similar condition. The result of this survey suggests that taking hot tea-gruel is one of possible factors for esophageal cancer in these districts.

Esophageal Neoplasms↗

PubMed1979

[TEA-resistant outward current in the somatic membrane of perfused nerve cells].

The outward currents remaining after addition of 20-50 mM tetraethylammonium (TEA) to the extracellular solution were studied on perfused isolated neurons from Helix pomatia. A potassium-carried noninactivating outward current with potential-dependence and kinetics different from those of TEA-sensitive potassium currents was found. This TEA-resistant current includes a component depending on the presence of the inward calcium current. It could be abolished by replacing extracellular calcium by magnesium ions, by blocking the calcium channels with extracellular cadmium ions and their distruction by intracellular fluorid ions. An increase in the level of intracellular free carcium (by perfusing the cell with solutions containing Ca-EGTA buffer) potentiated the TEA-resistant component of the outward current and the removal of free calcium by EGTA decreased it. A conclusion is made that the somatic membrane contains outward current channels which can be activated only when calcium ions are bound to its inner surface.

Animals↗

PubMed2026

Metagenomic Insights Into Microbial Diversity of Tea Rhizosphere of the Kangra Valley.

This study provides the first metagenomic assessment of microbial diversity from the tea rhizosphere of the Kangra valley. Tea rhizosphere soil samples were collected from 4 locations (Dharamshala, Baijnath, Palampur, and Joginder Nagar) of the Kangra valley. DNA extracts of rhizosphere samples were analysed for bacterial and Archaeal diversity using amplicon sequencing (V3-V4) region of the 16S rRNA gene and Fungal diversity using ITS1 and ITS2 regions. Baijnath and Palampur samples showed the highest bacterial richness, while Dharamshala and Palampur had the highest fungal richness. Proteobacteria was a dominant phylum in all the rhizosphere samples, followed by Firmicutes, Actinobacteria, Acidobacteria, and Bacteroidetes. A total of 11 fungal phyla were identified among all the locations, with abundance of Ascomycota and Basidiomycota. For the Archaea domain, uncultured archaeon and Aeropyrum camini were the most common found among all the locations. A small fraction (< 0.5%) of Bacillus and Pseudomonas species were observed among all the locations. Alpha and beta diversity indices displayed notable differences within and between microbial diversities. Soil factors were variably associated with microbial diversity, with nitrogen positively aligned with fungal diversity, while EC and K were associated with Archaeal diversity. Soil pH and OM% showed moderate associations with bacterial diversity. These findings provided valuable and comprehensive insights into tea rhizosphere microbial ecology and could be used to better understand microbial functions and their role in plant health.

Rhizosphere↗

PubMed1979

Iron absorption in the thalassemia syndromes and its inhibition by tea.

To determine the hemoglobin concentration at which iron absorption is minimal, five subjects with thalassemia major and one with thalassemia intermedia underwent a series of iron-absorption studies. The effect of tea as an inhibitor of non-heme iron absorption was also tested. Iron absorption increased as the hemoglobin concentration decreased, although iron absorption was much higher at any given hemoglobin level in the subject with thalassemia intermedia. In the subjects with thalassemia major, iron absorption averaged 10 per cent at hemoglobin concentrations between 9 and 10 and 2.7 per cent between 11 and 13 g per deciliter. The percentage of iron absorbed could be accurately predicted from the nucleated red-cell count (r = 0.91, P less than 0.001). Tea produced a 41 to 95 per cent inhibition of iron absorption. Since patients with thalassemia intermedia may absorb a large percentage of dietary iron, inhibitors of iron absorption, such as tea, may be useful in their management.

Adolescent↗

PubMed1992

[Experimental study on tea in inhibiting mutational specificity of 6 antineoplastic drugs].

According to the principles of SOS response, the authors tested the mutational specificity of tea and its inhibitory effects to the mutational specificity of 6 antineoplastic drugs by using the method of mutational and anti-mutational synchronous test. The results revealed that the tea had no mutational toxicity but anti-mutation effect. It also had the inhibitory effect on mutational toxicity of 6 antineoplastic drugs, including Mitomycin C, Bleomycin, Fluorouracil, Cisdiaminodichoroplatinum, Arabinosylcytosin and Mustargen. These results have provided referential basis for further study on anti-cancer effect and clinical use of tea.

Antimutagenic Agents↗

PubMed1976

[Purification and properties of peroxidase from tea leaves].

Purification of fractions of tea leaves peroxidase is described. During ion-exchange chromatography on DEAE- and CM-cellulose peroxidase is eluted into six fractions, differing in their electrophoretic properties. The enzyme showed optimal activity at pH 4.1-5.0, when the enzyme fractions of guaiacol adsorbed on DEAE-cellulose were used as a substrate; in case of enzyme fractions adsorbed on CM-cellulose it was observed within pH range of 5.4-6.2. The dependence curves of the initial rate of the reaction on the substrate concentration were S-shaped in case of the latter fractions. Peroxidase is shown to catalyze the oxidation of tea catechins; its activity is inhibited by the products of their condensation. The catalytic effect of the enzyme on the oxidation of phenolic acids, e.g. chlorogenic, caffeic and gallic, was far stronger than on that of tea catechins, pyrogallol and pyrocatechin. It was established that two fractions of the enzyme possess predominantly the phloroglucinol oxidase activity, whereas the other fractions do not catalyze the oxidation of phloroglucin. The molecular weights of some peroxidase fractions estimated by polyacryl amide gel electrophoresis are 26.000+/-1.100, 45.00+/-1.200 and 50.000+/-1.500.

Catechin↗

PubMed1979

[Efficacy and tolerance of Uroflux, a bladder and kidney tea, in the treatment of urinary tract infections, especially in diabetes mellitus].

In an open study the use of Uroflux tea and sugar coated tablets individually and in combination with chemotherapeutic or antibiotic therapy in 52 patients is described. Urine analysis showed improvement rates of 92 and 93 per cent respectively. A blind trial was carried out separately in diabetic patients over a period of 14 days in order to evaluate the effects on daily blood sugar levels of Uroflux tea against a comparative product. It was clearly shown, that the patients on Uroflux tea showed no changes in daily blood sugar profiles. Contrary to this is was noteworthy that blood sugar concentrations in patients receiving the comparative product were elevated in the morning before breakfast as well as one hour after the midday meal. There were no side effects observed with any of the Uroflux dosage forms; even patients complaining of "sensitive stomach" reported excellent tolerance.

Aged↗

PubMed2026

Enhancement flavor quality in Zhao'an Baxian oolong tea through enhanced turning-over process.

A systematical investigation on the effects of turning-over intensity on the flavor formation of Zhao'an Baxian oolong tea (ZBT) was performed, through a comparative analysis of heavy turning-over (HT) and light turning-over (LT) treatments in this study. The tea samples were subjected to proteomic and metabolomic analyses, combined with quantitative descriptive analysis (QDA) and electronic sensory (E-tongue/E-nose) evaluation. The results demonstrate that HT significantly reduced the content of bitter and astringent compounds, such as catechins and flavonol glycosides, while promoting the accumulation of umami-related amino acids. Concurrently, HT enhanced the biosynthesis of key floral and fruity volatiles, such as β-ocimene, geraniol, benzaldehyde, jasmone by activating stress-responsive metabolic pathways. These coordinated biochemical changes, driven by enzyme-catalyzed reactions in response to prolonged mechanical wounding and environmental stress, collectively improved the overall sensory profile of ZBT. These findings provide a mechanistic foundation for improving ZBT production, with clear implications for quality control and flavor-oriented product development.

Tea↗

PubMed1977

Toxicity from tea ingestion in an infant: a computer simulation analysis.

A seven-week-old infant presented with tonic posturing and nervous irritability after concentrated tea ingestion. The tea was analyzed and found to contain caffeine, a methylxanthine central nervous system stimulant. With the aid of a computer, projected blood levels were calculated over a thirty-hour time period and comared to the infant's clinical status. It is recommended that beverages containing xanthines be given to infants and small children with caution.

Caffeine↗

PubMed2026

Cis-regulatory evolution of CsANS1 drives cultivar variation in anthocyanin accumulation in tea plants.

Anthocyanins, a ubiquitous class of water-soluble phytochemicals renowned for their chromatic diversity and potent bioactivity, are integral to the phenotypic and metabolic plasticity of higher plants. Using an integrative multi-omics approach that combines transcriptomic and metabolomic profiling, we identified anthocyanin synthase (CsANS1) as the key genetic determinant responsible for interspecific variation in anthocyanin accumulation among tea plants. Architectural comparison of promoter regions revealed a 192-bp variation insertion in the CsANS1 cis-regulatory region with potential functional significance. This insertion was strictly conserved in anthocyanin-rich (purple-leaf) cultivars, including both natural and hybrid genotypes, but entirely missing in anthocyanin-deficient (green-leaf) cultivars. Dual-luciferase assays confirmed that this insertion enhances promoter activity. Additionally, we delineated a tripartite regulatory axis comprising CsmiR156b, CsSPL9, and CsMYB75 which orchestrates the spatiotemporal modulation of CsANS1 expression and, consequently, anthocyanin biosynthesis. Collectively, these findings provide a mechanistic paradigm for anthocyanin polymorphism in tea plants, implicating both cis-regulatory evolution and transcriptional network synergy as pivotal drivers of phytochemical diversification.

Anthocyanins↗

PubMed1975

The effect of tea on iron absorption.

The effect of tea on iron absorption was studied in human volunteers. Absorption from solutions of FeCl3 and FeSO4, bread, a meal of rice with potato and onion soup, and uncooked haemoglobin was inhibited whether ascorbic acid was present or not. No inhibition was noted if the haemoglobin was cooked. The effect on the absorption of non-haem iron was ascribed to the formation of insoluble iron tannate complexes. Drinking tannin-containing beverages such as tea with meals may contribute to the pathogenesis of iron deficiency if the diet consists largely of vegetable foodstuffs.

Adult↗

PubMed2026

Network pharmacology-based prediction and experimental validation of the anti-hyperuricemic effects of oolong tea polyphenols.

OBJECTIVE: This study aimed to identify candidate therapeutic targets of oolong tea polyphenols (TP) against hyperuricemia (HUA) using network pharmacology and bioinformatics, and to validate the predicted molecular mechanism through in vivo experimentation. METHODS: Drug and disease targets were retrieved from public databases, and overlapping targets were identified by Venn diagram analysis. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed on the shared targets, and a protein-protein interaction (PPI) network was constructed to identify hub genes. For in vivo validation, an HUA mouse model was established by 15 days of oral potassium oxonate (PO) administration. Model mice then received TP by gavage at low (0.5 g⋅kg-1⋅d-1), medium (1 g⋅kg-1⋅d-1), or high (2 g⋅kg-1⋅d-1) doses for an additional 15 days. Serum biochemical markers, histopathological changes, and pathway-related protein expression were assessed by enzyme-linked immunosorbent assay (ELISA), hematoxylin and eosin (HE) staining, and western blot analysis, respectively. RESULTS: Network pharmacology analysis identified 59 overlapping targets between TP and HUA; GO and KEGG enrichment analyses revealed that these targets were primarily associated with hormone metabolism and the PI3K-AKT signaling pathway. In the animal experiment, TP dose-dependently reduced serum uric acid (SUA) levels in hyperuricemic mice. At the molecular level, low and medium doses of TP suppressed phosphorylation of phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT), and mammalian target of rapamycin (mTOR), whereas the high dose paradoxically activated this pathway and concomitantly elevated interleukin-1β levels. These findings indicate that TP modulates uric acid metabolism through a non-monotonic, dose-dependent mechanism. CONCLUSION: By combining network pharmacology with animal experiments, this study identified the PI3K/AKT/mTOR signaling pathway as a likely mediator of the anti-hyperuricemic action of oolong tea polyphenols (TP). A medium dose of TP achieved the most balanced outcome, attenuating inflammation and preserving hepatic and renal architecture; the high dose, by contrast, paradoxically elevated interleukin-1β (IL-1β) and overactivated PI3K/AKT/mTOR signaling, underscoring the importance of dose calibration. These data suggest that a medium dose of TP may represent a feasible dietary strategy against hyperuricemia. Further work-including monomer identification, direct target validation, and clinical evaluation-is warranted to confirm and extend these preclinical findings.

PI3K/Akt/mTOR signaling pathway↗

PubMed1975

Liver dysfunction and tea eating.

A case report is presented of a patient who had liver fibrosis, splenomegaly and ascites, associated with the habit of nibbling tea leaves. The splenomegaly and the ascites remitted when she ceased eating tea, but liver fibrosis is still present 15 years later. No other cause for the liver disorder was found.

Female↗