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Copyright of Journal of Advanced Research in Health Sciences (JARHS) / Sağlık Bilimlerinde İleri Araştırmalar Dergisi (SABİAD) is the property of Journal of Advanced Research in Health Sciences (JARHS) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Tea is a rich source of functional components called polyphenols which impart it antioxidant properties. Tea is categorized as green or black tea according to the processing method used. Tea is widely consumed beverage, and it is often prepared with the addition of milk and sugar in many parts of the world including India. The present study was conducted to compare the effect of addition of milk and/or sugar, in both black and green teas of two brands (1 and 2), on the antioxidant properties of teas. The total polyphenol, flavonoid and catechin contents along with antioxidant activity were significantly (p < 0.05) higher in green teas then in black teas but the tannin content of black teas was higher than that of green teas. The addition of milk in both black and green teas significantly (p < 0.05) reduced total polyphenol, flavonoid, catechin and tannin contents as well as antioxidant activity. The addition of sugar had significant (p < 0.05) adverse effect on flavonoid and catechin contents, and antioxidant activity. Further, the combined addition of milk and sugar caused significant (p < 0.05) additive/synergistic reductions in flavonoid content of teas of both brands, and in catechin content, tannin content and antioxidant activity of black and green teas of brand 2 only. [ABSTRACT FROM AUTHOR]

Abstract Background Catechins, polyphenols derived from tea leaves, have been shown to have antibacterial properties, through direct killing of bacteria as well as through inhibition of bacterial toxin activity. In particular, certain catechins have been shown to have bactericidal effects on the oral bacterium, Aggregatibacter actinomycetemcomitans , as well as the ability to inhibit a key virulence factor of this organism, leukotoxin (LtxA). The mechanism of catechin-mediated inhibition of LtxA has not been shown. Methods In this work, we studied the ability of six catechins to inhibit LtxA-mediated cytotoxicity in human white blood cells, using Trypan blue staining, and investigated the mechanism of action using a combination of techniques, including fluorescence and circular dichroism spectroscopy, confocal microscopy, and surface plasmon resonance. Results We found that all the catechins except (−)-catechin inhibited the activity of this protein, with the galloylated catechins having the strongest effect. Pre-incubation of the toxin with the catechins increased the inhibitory action, indicating that the catechins act on the protein, rather than the cell. The secondary structure of LtxA was dramatically altered in the presence of catechin, which resulted in an inhibition of toxin binding to cholesterol, an important initial step in the cytotoxic mechanism of the toxin. Conclusions These results demonstrate that the catechins inhibit LtxA activity by altering its structure to prevent interaction with specific molecules present on the host cell surface. General significance Galloylated catechins modify protein toxin structure, inhibiting the toxin from binding to the requisite molecules on the host cell surface. Graphical abstract Unlabelled Image Highlights • Galloylated catechins alter the structure of A. actinomycetemcomitans leukotoxin. • Galloylated catechins prevent leukotoxin from binding to cholesterol. • Leukotoxin activity is thus greatly inhibited by galloylated catechins. [ABSTRACT FROM AUTHOR]

Tea polyphenols (TP) were emulsified with corn oil and polysorbate 80 by high-pressure homogenization. The oil in water (O/W) TP nanoemulsion had droplet sizes of 99.42 ± 1.25 nm after preparation. The TP nanoemulsion was stable during storage at 4, 25 or 40 °C for 20 days. An in vitro simulated digestion assay showed that the bioaccessibility of (−)-epigallocatechin gallate (EGCG) was increased in the nanoemulsion compared to that in aqueous solution, but that the bioaccessibilities of (−)-epigallocatechin (EGC), (−)-epicatechin (EC) and (−)-gallocatechin gallate (GCG) were greatly decreased. Compared with rats fed an aqueous TP solution, rats fed the TP nanoemulsion had significantly lower maximum plasma concentrations (C max ) of EGCG and EGC, but the area under the plasma concentration-time curve (AUC 0–t ) was increased. The data show that use of a nanoemulsion system to deliver tea polyphenols may enhance the absorption of EGCG through controlled release. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effect of the addition of β-cyclodextrin, catechin or inclusion complexes (catechin: β-CD) (physical mixture or with supercritical carbon dioxide) on prebiotic green tea beverage characteristics during storage at ambient temperature (90 days/25 °C). The prebiotic (oligofructose) stability was also evaluated. The addition of cyclodextrin and/orcatechin resulted in products with higher acidity. The physical process of complexation, which is simple and cheap, gave the best results in relation to the stability of the phenolic compounds content in the product. The supercritical carbon dioxide did not improve the protection of the phenolic compounds. A portion of 200 mL of the green tea had sufficient oligofructose content to be considered a prebiotic product during 90 days of storage. It was possible to formulate green tea beverages with high total phenolic compounds (2525–3307 mg CE/L) and oligofructose content (3.1 g/200 mL) sufficient to consider them prebiotic products, being recommended the physical process of complexation (catechin: β-CD). The green teas would maintain the beneficial effects for 90 days at ambient temperature (25 °C). [ABSTRACT FROM AUTHOR]

Tea contains characteristic volatile organic compounds, polyphenols, caffeine and catechins, and is therefore among the most widely consumed beverages all over the world. In this study, fresh Jukro tea leaves collected from Damyang-gun (Jeollanam-do) at 40, 60 and 90 day growth stages, were semi-fermented. The volatile organic compounds (VOCs) were extracted by simultaneous distillation-solvent extraction (SDE) and analyzed by gas chromatography/mass spectrometry (GC/MS). Catechins, caffeine and theanine were analyzed by high performance liquid chromatography (HPLC). A total of 159 VOCs were identified in the analyzed Jukro tea leaves. Comparatively, the increase in the concentrations of VOCs was high in 60 day leaves. The content of catechins increased along the three growth stages, whereas caffeine, compared to 90 day leaves, was higher for 40 and 60 day leaves. Based on the results, the 60 day leaves were found to be the most suitable and useful for making semi-fermented Jukro tea. [ABSTRACT FROM AUTHOR]

Main conclusion : Functional allelic variants of the flavonoid 3′,5′-hydroxylase (F3′5′H) gene provides new information of F3′5′H function of tea plant and its relatives. This insight may serve as the foundation upon which to advance molecular breeding in the tea plant. Catechins are the active components of tea that determine its quality and health attributes. This study established the first integrated genomic strategy for deciphering the genetic basis of catechin traits of tea plant. With the RNA-sequencing analysis of bulked segregants representing the tails of a F1 population segregated for total catechin content, we identified a flavonoid 3′,5′-hydroxylase (F3′5′H) gene. F3′5′H had one copy in the genomic DNA of tea plant. Among 202 tea accessions, we identified 120 single nucleotide polymorphisms (SNPs) at F3′5′H locus. Seventeen significant marker-trait associations were identified by association mapping in multiple environments, which were involved in 10 SNP markers, and the traits including the ratio of di/tri-hydroxylated catechins and catechin contents. The associated individual and combination of SNPs explained 4.5-25.2 and 53.0-63.0% phenotypic variations, respectively. In the F1 population (validation population), the catechin trait variation percentages explained by F3′5′H diplotype were 6.9-74.3%. The genotype effects of ten functional SNPs in the F1 population were all consistent with the association population. Furthermore, the function of SNP−711/−655 within F3′5′H was validated by gene expression analysis. Altogether, our work indicated functional SNP allelic variants within F3′5′H governing the ratio of di/tri-hydroxylated catechins and catechin contents. The strong catechin-associated SNPs identified in this study can be used for future marker-assisted selection to improve tea quality. [ABSTRACT FROM AUTHOR]

MicroRNAs are endogenous non-coding small RNAs playing crucial regulatory roles in plants. Tea, a globally popular non-alcoholic drink, is rich in health-enhancing catechins. In this study, 69 conserved and 47 novel miRNAs targeting 644 genes were identified by high-throughout sequencing. Predicted target genes of miRNAs were mainly involved in plant growth, signal transduction, morphogenesis and defense. To further identify targets of tea miRNAs, degradome sequencing and RNA ligase-mediated rapid amplification of 5’cDNA ends (RLM-RACE) were applied. Using degradome sequencing, 26 genes mainly involved in transcription factor, resistance protein and signal transduction protein synthesis were identified as potential miRNA targets, with 5 genes subsequently verified. Quantitative real-time PCR (qRT-PCR) revealed that the expression patterns of novel-miR1, novel-miR2, csn-miR160a, csn-miR162a, csn-miR394 and csn-miR396a were negatively correlated with catechin content. The expression of six miRNAs (csn-miRNA167a, csn-miR2593e, csn-miR4380a, csn-miR3444b, csn-miR5251 and csn-miR7777-5p.1) and their target genes involved in catechin biosynthesis were also analyzed by qRT-PCR. Negative and positive correlations were found between these miRNAs and catechin contents, while positive correlations were found between their target genes and catechin content. This result suggests that these miRNAs may negatively regulate catechin biosynthesis by down-regulating their biosynthesis-related target genes. Taken together, our results indicate that miRNAs are crucial regulators in tea, with the results of 5’-RLM-RACE and expression analyses revealing the important role of miRNAs in catechin anabolism. Our findings should facilitate future research to elucidate the function of miRNAs in catechin biosynthesis. [ABSTRACT FROM AUTHOR]

Background: Catechins are the main polyphenol compounds in tea ( Camellia sinensis). To understand the relationship between gene expression and product accumulation, the levels of catechins and relative expressions of key genes in tea leaves of different developmental stages were analyzed. Results: The amounts of catechins differed significantly in leaves of different stages, except for gallocatechin gallate. Close correlations between the expression of synthesis genes and the accumulation of catechins were identified. Correlation analysis showed that the expressions of chalcone synthase 1, chalcone synthase 3, anthocyanidin reductase 1, anthocyanidin reductase 2 and leucoanthocyanidin reductase genes were significantly and positively correlated with total catechin contents, suggesting their expression may largely affect total catechin accumulation. Anthocyanidin synthase was significantly correlated with catechin. While both ANRs and LAR were significantly and positively correlated with the contents of (−)-epigallocatechin gallate and (−)-epicatechin gallate. Conclusion: Our results suggest synergistic changes between the expression of synthetic genes and the accumulation of catechins. Based on our findings, anthocyanidin synthase may regulate earlier steps in the conversion of catechin, while the anthocyanidin reductase and leucoanthocyanidin reductase genes may both play important roles in the biosynthesis of galloylated catechins. [ABSTRACT FROM AUTHOR]

The article offers information on the Standard Method Performance Requirements (SMPRs®) by the Association of Official Analytical Chemists (AOAC) for identification of methyl xanthines, theaflavins, and catechins in tea (Camellia sinensis) dietary supplements and ingredients. Topics mentioned include the importance of tea dietary ingredients, the chemical structures for catechins and theaflavins, and the green tea analysis.

Tea Catechins associate with proline rich proteins such as caseins. In this work, the interactions between epigallocatechin-gallate (EGCG), one of the main tea catechins, and caseins at an oil water interface were studied. The association of EGCG with sodium caseinate was quantified by measuring the amount of EGCG adsorbed on the emulsion droplets. In addition, the viscoelastic properties of the protein and EGCG–protein layers formed at the interface were studied using drop tensiometry. Different concentrations of EGCG were added to a model emulsion to obtain final concentrations of 10% soybean oil, 0.5% sodium caseinate and 0–9 mg/mL EGCG. At concentrations < 2 mg/mL EGCG, more than 90% was adsorbed at the interface. At higher concentrations, below 5 mg/mL, about 70% of EGCG was adsorbed. The surface load reached about 1 mg/m 2 at 9 mg/mL of EGCG. The dissociation constant for the complex formed, was estimated using schatchard plot, and was 3.7 × 10 −5 M for less than 20 mol bound EGCG/protein. The interactions of EGCG with sodium caseinate did not affect the interfacial tension but increased the dilational modulus of the EGCG-protein layer at the interface. This study demonstrated that sodium caseinate emulsions could be employed as carriers for EGCG, and that the complexes formed at the interface are affecting the physico-chemical properties of the emulsions. The results are of significance in the development of dairy based beverages containing tea polyphenols. [ABSTRACT FROM AUTHOR]

Tea flavonoids bind to variety of enzymes and inhibit their activities. In the present study, binding and inhibition of catalase activity by catechins with respect to their structure-affinity relationship has been elucidated. Fluorimetrically determined binding constants for (−)-epigallocatechin gallate (EGCG) and (−)-epicatechin gallate (ECG) with catalase were observed to be 2.27×106 M−1 and 1.66×106 M−1, respectively. Thermodynamic parameters evidence exothermic and spontaneous interaction between catechins and catalase. Major forces of interaction are suggested to be through hydrogen bonding along with electrostatic contributions and conformational changes. Distinct loss of α-helical structure of catalase by interaction with EGCG was captured in circular dichroism (CD) spectra. Gallated catechins demonstrated higher binding constants and inhibition efficacy than non-gallated catechins. EGCG exhibited maximum inhibition of pure catalase. It also inhibited cellular catalase in K562 cancer cells with significant increase in cellular ROS and suppression of cell viability (IC50 54.5 µM). These results decipher the molecular mechanism by which tea catechins interact with catalase and highlight the potential of gallated catechin like EGCG as an anticancer drug. EGCG may have other non-specific targets in the cell, but its anticancer property is mainly defined by ROS accumulation due to catalase inhibition. [ABSTRACT FROM AUTHOR]

Highlights: [•] Development of a rapid HPLC procedure based on the use of monolithic column. [•] The use of microwave assisted extraction for the isolation of the catechin compounds. [•] Application of the methods for the determination of catechins in various types of teas. [ABSTRACT FROM AUTHOR]

Highlights: [•] Antioxidant activity (AA) of different grades of white tea was studied. [•] Cold white tea infusions have higher AA than hot infusions. [•] AA correlates with total phenol, flavonoid and catechin content. [•] African white teas may have potential health benefits comparable to Chinese teas. [•] White tea AA does not correlate with type of cultivar, grade or geographical area. [ABSTRACT FROM AUTHOR]

Eight compounds were isolated from the water extract of Pu-erh tea and their structures were elucidated by NMR and MS as gallic acid (1), (+)-catechin (2), (-)-epicatechin (3), (-)-epicatechin-3-O-gallate (4), (-)-epigallocatechin-3-O-gallate (5), (-)-epiafzelechin- 3-O-gallate (6), kaempferol (7), and quercetin (8). Their in vitro antioxidant activities were assessed by the DPPH and ABTS scavenging methods with microplate assays. The relative order of DPPH scavenging capacity for these compounds was compound 8 > compound 7 > compound 1 > compound 6 > compound 4 ≈ compound 5 > compound 2 > VC (reference) > compound 3, and that of ABTS scavenging capacity was compound 1 > compound 2 > compound 7 ≈ compound 8 > compound 6 > compound 5 > compound 4 > VC (reference) > compound 3. The results showed that these phenolic compounds contributed to the antioxidant activity of Pu-erh tea. [ABSTRACT FROM AUTHOR]

The use of etched, chemically modified, capillaries with a rectangular inner channel for open tubular electrochromatography is investigated. Comparisons of separation capabilities are made between circular and rectangular capillaries undergoing the same etching and chemical modification processes. With the long dimension of the rectangular column aligned in the direction of the optical light path, the relative sensitivities of the two capillary geometries are evaluated. The electrochromatographic properties of two catechins found in tea are investigated on the rectangular etched octadecyl-modified capillary. [ABSTRACT FROM AUTHOR]