Levels Of Total Catechins Research Articles

Comprehensive investigation on non-volatile and volatile metabolites in four types of green teas obtained from the same tea cultivar of Longjing 43 (Camellia sinensis var. sinensis) using the widely targeted metabolomics

In this study, we produced roasted, baked, steamed, and sun-dried green tea products using the same batch of fresh tea leaves (FTL) of Longjing 43 (Camellia sinensis var. sinensis), and explored processing effects on the metabolic profiles of four types of green teas (FGTs) using the widely targeted metabolomics. Results showed that 146 differential metabolites including flavonoids, amino acids, lipids, and phenolic acids were screened among 1034 non-volatiles. In addition, nineteen differential metabolites were screened among 79 volatiles. Most of non-volatiles and volatiles metabolites changed notably in different manufacturing processes, whereas there were no significant differences (p＞0.05) in the levels of total catechins between FGTs and FTL. The transformation of metabolites was the dominant trend during green tea processing. The results contribute to a better understanding of how the manufacturing process influences green tea quality, and provide useful information for the enrichment of tea biochemistry theory.

The catechins profile and antioxidant activity in different types of green tea bags

Tea and mainly green tea as a rich source of antioxidants has been widely known for some time. The antioxidant capacity of tea including green tea is mainly due to its catechins content. The objective of this study was to determine the relationship between the ORAC value and the catechins content. Regular and decaffeinated commercial green tea bags commonly consumed in the United Kingdom (UK) have been examined using Reversed-Phase High-pressure Liquid Chromatography (RP-HPLC). Teabags were purchased from different local supermarkets in the UK and extracted with natural mineral water at temperature 100°C for 9 minutes at the pre-adjusted pH 4. The level of four catechins (Epi-structured) for the thirteen types of green tea were separated and determined by HPLC analysis, i.e. ()-epigallocatechin (EGC), ()-epicatechin (EC), ()-epigallocatechin-3-gallate (EGCG) and ()-epicatechin gallate (ECG). The standard graphs were validated using certified reference catechins supplied by the Laboratory of the Government Chemist (LGC). The levels of total catechins and oxygen radical absorbance capacity (ORAC) values varied from 34.61to 204.55 mg/g, 830.19- 4197.81 Trolox equivalents/g tea bags for thirteen types of green teas respectively. It was clear from the results of this study that there was a significant linear and positive correlation (r = 0.951, df = 12, p < 0.05) is found to exist between the total catechins contents and ORAC values. It can be concluded that the results of catechins measurements coupled to this; the well-known ORAC assay was successfully modified to measure the antioxidant capacity of the green tea extracts throughout this study. Furthermore, the higher the level of catechins the higher is the antioxidant capacity of the tea. This may stimulus consumers in selecting the type of tea and tea brewing times, exhibiting more health benefits. Nevertheless, the differences between the studied brands are owing to shelf life, production and storage conditions.
 

Correlation of major components and radical scavenging activity of commercial tea drinks in Taiwan

Correlation of major components with free radical scavenging activities of 27 commercial tea drinks prepared from green, Oolong, and black teas in Taiwan were investigated. Green tea drinks contained the highest level of total catechins including epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin (EC), epicatechin gallate (ECG), and gallocatechin gallate (GCG), while these components were low in black tea drinks and moderate in Oolong tea drinks. EGC and EGCG were the major catechins in the three types of tea drinks, and gallic acid showed the highest abundance in black tea drinks. Caffeine concentrations were comparable in the three types of tea drinks. All black tea drinks contained sugars, and sucrose was the main sweetener added. The scavenging abilities against l,l-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radicals were used to determine the antioxidant potential of tea drinks, and the ranked order of potency was green tea > Oolong tea > black tea. Total phenolics, total catechins, and EGC of tea drinks were positively and significantly (r > 0.8) correlated to the scavenging abilities against DPPH and ABTS radicals. Our results show that green tea drinks have higher free radical scavenging activity than black and Oolong tea drinks may be related to their high levels of total phenolics and catechins.

Antioxidant activity and effects of Kenyan Tea (Camellia sinensis) on the liver function and serum biochemistry in male Wistar rats

Background: Tea is a beverage that is most widely consumed worldwide. Studies have shown that oral consumption of tea has health benefits however, there is paucity of data in Kenya detailing the biochemical effects of tea in the liver and elucidation of its mechanism of action.Methods: The polyphenol composition and antioxidant capacity of tea were determined by HPLC and the Folins Ciocalteu spectrophotometric methods. Metal levels were determined using flame Atomic Absorption Spectrometer (AAS). Aqueous black and green tea extracts were administered to the rats at dosages of 400mg/kg b.w.t. The effect of tea on total blood proteins, Albumin, ZHX1, TBARS, AST, ALP and ALT were determined by spectrophotometric methods. The body weight of each rat was also determined at one week interval.Results: Total Polyphenols (TP), Total Catechins (TC) and Antioxidant Activity (AA) between the black and green teas were significantly (P<0.05) different. Green tea had the highest levels of TP (19.70-26.12%), TC (8.51%-17.60%) and AA (86.65%-94.50%). Tea did not have a significant (P>0.05) effect on TP, ALB, ALT, AST, ALP, MDA and ZHX1 in the test animals compared with the controls. This data indicates that green tea is rich in catechins while black tea being rich in Theaflavins (TFs) and Thearubigins (TRs). Both tea products possess essential and non-essential metals well within the maximum permissible concentrations.Conclusions: Findings from this study indicate both green and black tea aqueous extracts have polyphenols and high antioxidant activity. Administration of the aqueous tea extracts have no toxicological effect on the liver.

Polyphenolics Profile and their Seasonal Variation in Fresh Shoots of Kangra tea[Camellia sinensis(L) O Kuntze] Grown in North Western India

Fresh shoots (two leaves and a bud) of Kangra tea collected at seven day intervals throughout the plucking seasons (April to Octo-ber) during three consecutive years. In fresh tea shoots the variations in the levels of total poly-phenols in the range: 124.800 to 207.600gkg-1 (2006), 192.421 to 304.144gkg-1 (2007), 131.842 to 231.750gkg-1 (2008); and total catechins in the range: 60.070 to 163. 900gkg-1 (2006), 65.557 to 146.808gkg-1 (2007), 59.710 to 80.122gkg-1 (2008); were significant throughout the plucking seasons. Correlations among total polyphenols, total catechins and six weather pa-rameters were worked out. The catechins con-tent of tea powders obtained by lyophilizing aqueous extracts of fresh tea shoots always var-ied in the order (−)-epigallocatechin gallate > (−)-epigallocatechin > (−)-epicatechin > (+)-catechin. Tea powders of summer season had higher levels of total catechins, (+)-catechin, (−)-epicatechin and (−)-epigallocatechin compared to rest of the plucking seasons.

Biosynthesis of catechin components is differentially regulated in dark-treated tea (Camellia sinensis L.)

Tea (Camellia sinensis L.) is a crop with both commercial and medicinal value with remarkably high polyphenol content in the form of catechins. To understand the molecular regulation of catechin biosynthesis in tea, we treated the tea plants with darkness. We used qRT-PCR to validate the expression of genes involved in catechin biosynthesis. It indicated that dark treatment displayed different effects on the genes participating in tea flavonoid (FL) pathway. The early genes of FL biosynthesis pathway, CHSI, F3H and DFR, remained at steady expression levels when treated by darkness. It is noteworthy that the expression level of LAR increased and the level of ANS decreased under dark conditions. The vanillin assay showed that the dark-treated plants contained lower levels of total catechins than those grown under normal conditions. The HPLC analysis further demonstrated the changes in biosynthesis of catechins under these conditions. In accordance with the gene expression pattern, the content of epicatechins (ECs) declined and that of catechins (Cs) was elevated in response to the darkness. Our study uncovered the molecular mechanisms and biochemical changes of shading in tea cultivation.

Factors affecting the levels of catechins and caffeine in tea beverage: estimated daily intakes and antioxidant activity

AbstractIncreased public awareness of health benefits of green tea is generally based on the high polyphenol content of tea leaves and the resulting beverage. A number of factors, such as species, season, agronomic condition and age of the leaves, are known to affect the composition of commercial teas. In the present study the effects of factors associated with domestic preparation and analytical methods, such as brewing time, concentration, solvent and type of tea product, on levels of catechins and caffeine, antioxidant activity and estimated daily intakes were investigated. There were large variations in the levels of total catechins: 43 and 117 mg g−1 dry matter (DM) (brewed for 30 s and 5 min respectively); 72 and 161 mg g−1 DM (extracted in boiling water and 50% acetonitrile respectively); 72 and 117 mg g−1 DM (a tea bag and tea leaves respectively). The effects on caffeine content were comparatively smaller. These variations consequently led to considerable variations in estimated daily intakes based on three cups (600 ml), ranging between 538 and 2014 mg g−1 DM of total catechins and between 103 and 466 mg g−1 DM of caffeine. The antioxidant activity was highest (26 680 µmol g−1 DM) for tea leaves brewed for 5 min and lowest (10 110 µmol g−1 DM) for a tea bag product brewed for 1 min. Copyright © 2005 Society of Chemical Industry

Determination of tea polyphenols and caffeine in tea flowers (Camellia sinensis) and their hydroxyl radical scavenging and nitric oxide suppressing effects.

The native occurrence of tea polyphenols, namely, (-)-epicatechin, (+)-catechin, (-)-epigallocatechin 3-gallate, (-)-epicatechin, and (-)-epicatechin 3-gallate, and caffeine in tea flowers was assessed by an isocratic HPLC procedure. The levels of total catechins and caffeine were determined in tea flowers collected from 10 different species of Camellia sinensis. The results showed the levels of total catechin ranged from 10 to 38 mg/g, whereas the level of caffeine ranged from 3 to 8 mg/g. Levels of catechins and caffeine in tea leaves and various teas were also determined and ranged from 2 to 126 mg/g and from 23 to 49 mg/g, respectively. Both tea flower and tea leaf extracts exert their strong hydroxyl radical scavenging effects in the Fenton reaction system and nitric oxide suppressing effects in LPS-induced RAW 264.7 cells. Most tea flowers contain less caffeine, but comparable amounts of total catechins, compared to tea leaves and teas. The present study demonstrates that both tea flowers and tea leaves contain appreciable amounts of catechins and caffeine. It is likely that tea flowers might be useful for making alternative tea beverages.

Analysis of catechins from green and black tea in humans: a specific and sensitive colorimetric assay of total catechins in biological fluids

Catechins are a group of flavonoids widely occurring in fruits, wine and tea, which are strong antioxidants with demonstrated anticarcinogenic effects in animal models. There is currently little knowledge on the bioavailability of catechins due to a lack of suitable analytical methods. Therefore a simple colorimetric assay was developed for the determination of the concentration of catechins in plasma. Following precipitation of proteins with methanol, tea flavonoids were accumulated by solid phase adsorption to alumina. Reactions of adsorbed catechins with 4-dimethyl amino cinnamaldehyde under strong acidic conditions results in desorption and development of a highly selective coloured complex (λ = 637 nm). The method is highly specific for catechins with equimolar responses for catechin, epicatechin, epigallocatechin, epicatechin gallate and epigallocatechin gallate. The detection limit in plasma is 0.05 μmol/L and the within and between day variation was 1.1% and 2.6%, respectively. Following consumption of a single dose of green tea, equivalent to six cups of tea, plasma levels of total catechins of 2.36 ± 0.55 μmol/L (n = 5) were reached after 60 min. This novel method is a rapid and sensitive way to gain more insight in the bioavailability of catechins from tea, wine and foods.