No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Distribution of Catechins, Theaflavins, Caffeine, and Theobromine in 77 Teas Consumed in the United States
Journal of Food Science
Abstract
To help define the composition of commercial teas consumed in the United States, we have developed and validated an high-performance liquid chromatography (HPLC) method to analyze levels of catechins, theaflavins, and alkaloids in 77 commercial black, green, specialty (brown rice, white, oolong), and herbal teas extracted with hot water to simulate home use. The following 13 compounds were separated in a single analysis on an Inertsil ODS-3v column with acetonitrile/potassium dihydrogen phosphate as the mobile phase: (−)-epigallocatechin, (+)-catechin, (−)-epicatechin, (−)-epigallocatechin-3-gallate, (−)-gallocatechin-3-gallate, (−)-epicatechin-3-gallate, (−)-catechin-3-gallate, theaflavin, theaflavin-3-gallate, theaflavin-3′-gallate, theaflavin-3, 3′-digallate, caffeine, and theobromine. The data show that (1) extraction time from 3 min to 20 min did not significantly affect measured levels of tea compounds and (2) there was a wide variation in the composition of the tea compounds both within each tea category and among categories: black teas contained both theaflavins and catechins, green and white teas contained catechins and trace amounts of theaflavins, herbal teas contained very low amounts of all tea compounds. A statistical profile of the distribution of catechins, theaflavins, caffeine, and theobromine in the evaluated teas offers consumers a choice of teas containing high levels of health-promoting compounds.
... The range of total catechins levels in green teas (34.61 -204.55 mg/g tea bag) is of a similar order to what has been reported elsewhere by (Khokhar and Magnusdottir, 2002;Henning et al. 2003;Friedman et al., 2005, Yao et al., 2006, Friedman et al., 2006, Al-zubaidi et al., 2017. Profiles of the four epi-structured catechins for the ten types of green tea are presented in Table 2; Figures 4 and 5. ...
... Furthermore, for these results (see Tables 1and 2; Figures; 4 and 5), there exists a trend in which the order regarding quantities of the epi-structure catechins is: EGCG > EGC > EC > ECG (42-54, 31-46, 6-19 and 4-7) % of the total catechins in green tea respectively. These results are largely in agreement with those of other researchers (Khokhar and Magnusdottir, 2002;Henning et al. 2003;Friedman et al., 2005, Yao et al., 2006Friedman et al., 2006, andAl-zubaidi, 2015 and2017). ...
... The range of total catechins levels in green teas (53.82 -116.23 mg/g tea bag) is of a similar order to what has been reported elsewhere by (Khokhar and Magnusdottir, 2002;Henning et al. 2003;Friedman et al., 2005, Yao et al., 2006, Friedman et al., 2006, Al-zubaidi et al., 2017. Profiles of the four epi-structured catechins for the three types of decaffeinated green tea bags are presented in Table 2; Figures 4 and 5. ...
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.
... Friedman et al. analyzed green tea raw material samples sold in the U.S. market and reported the extractable catechin concentrations after brewing the tea under standard conditions with hot water and other samples of green tea [34,35]. The results showed that there are considerable differences in catechin content of green tea on the market. ...
... Other studies show that extraction methods determine the constituents of green tea extracts [36]. GTEs contain much higher concentrations of catechins than brewed green tea beverages as shown in the examples of Polyphenon, a popular GTE on the market (Table 3: columns 2 and 3 in the table show concentration of catechins in GTE whereas column 4 shows the concentration of catechins in cut green tea leaves used in beverages/infusions). Green tea aqueous extracts can be further concentrated or purified to obtain a high-catechin fraction with some claiming to contain 80-95 % EGCG by weight [34,35].The high-catechin fraction can be prepared by extracting the leaves with organic solvents such as 80 % acetone or 70 % ethanol with or without prior extraction with water [37][38][39][40][41]. In the early 2000s, one of the most popular commercial GTE containing products in France and Spain was Exolise, an 80 % ethanolic dry extract standardized at 25 % catechins expressed as EGCG. ...
... ppm, and two of the 28 extracts contained traces of a mixture of solvents (e.g., chloroform, dichloromethane, and ethyl acetate). Of the 32 finished products tested (GTE supplements), 17 contained traces of chloroform ranging Table 3 Relative percentages of catechins in dried green tea leaves (column 2) and GTE extracts ingredients (column 3) and GTE extracts in dosage forms (capsules and extracts) (column 4) on the market [34,37] and in a popular GTE on the market known as Polyphenon, e.g., Poly 30, Poly 60. These levels of solvent residues are within the permissible limits stated in the USP General Chapter < 467 > Residual Solvents [44]. ...
As part of the United States Pharmacopeia’s ongoing review of dietary supplement safety data, a new comprehensive systematic review on green tea extracts (GTE) has been completed. GTEs may contain hepatotoxic solvent residues, pesticide residues, pyrrolizidine alkaloids and elemental impurities, but no evidence of their involvement in GTE-induced liver injury was found during this review. GTE catechin profiles vary significantly with manufacturing processes. Animal and human data indicate that repeated oral administration of bolus doses of GTE during fasting significantly increases bioavailability of catechins, specifically EGCG, possibly involving saturation of first-pass elimination mechanisms. Toxicological studies show a hepatocellular pattern of liver injury. Published adverse event case reports associate hepatotoxicity with EGCG intake amounts from 140 mg to ∼1000 mg/day and substantial inter-individual variability in susceptibility, possibly due to genetic factors. Based on these findings, USP included a cautionary labeling requirement in its Powdered Decaffeinated Green Tea Extract monograph that reads as follows: “Do not take on an empty stomach. Take with food. Do not use if you have a liver problem and discontinue use and consult a healthcare practitioner if you develop symptoms of liver trouble, such as abdominal pain, dark urine, or jaundice (yellowing of the skin or eyes).” Keywords: Green tea, Camellia sinensis, Dietary supplements, Hepatotoxicity, Liver injury, Green tea extract
... Green tea leaves for the evaluation of extraction methods were proce optimum roasting temperature and time from the previous experiment. Ex echin is the major step required for human consumption of tea [34]. It ha that a higher temperature (100 °C) and prolonged extraction (2 h) leads to the bioactive molecules in tea [35]. ...
... Green tea leaves for the evaluation of extraction methods were processed using the optimum roasting temperature and time from the previous experiment. Extraction of catechin is the major step required for human consumption of tea [34]. It has been proved that a higher temperature (100 • C) and prolonged extraction (2 h) leads to degradation of the bioactive molecules in tea [35]. ...
The aim of this study was to investigate the catechin levels and antioxidant activities as manipulated by roasting temperature and roasting time of green tea. Roasting temperature and time varied between 100–300 °C and 60–240 s in green tea production. The main interactions measured were effects on the antioxidant activities, total phenolic content, DPPH, ABTS, FRAP and catechin content (catechin (C), epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG) and epicatechin (EC)). Optimum roasting conditions were determined as 270 °C for 240 s, since this enabled high catechin contents, antioxidant activities and production yield. The extraction methods for green tea including traditional extraction (TDE), microwave-assisted extraction (MAE) and ultrasonic-assisted extraction (UAE) using 60% ethanol as solvent were investigated to evaluate the highest bioactive compound and yield of extraction. MAE was found to be more efficient in green tea extraction compared to UAE and TDE. The extracts showed significant cytotoxic potential against the Huh-7 cell line, in concentrations ranging from 31.25 to 1000 µg/mL. The results are useful in understanding the relationship between thermal treatment and extraction conditions on the chemical and nutritional properties of tea catechins, making it possible to select the production and extraction conditions that maximize the levels of beneficial tea ingredients.
... is of a similar order to what has been reported elsewhere by (Khokhar and Magnusdottir, 2002;Henning et al. 2003;Friedman et al., 2005Friedman et al., , 2006Friedman et al., , and 2009Yao et al., 2006).Profiles of the four epi-structured catechins for the fourteen types of green tea are presented in Table 2; Figures 3and 4.These epi-structured catechins divided into two groups, i.e. EGCG and ECG, EGC and EC. ...
... EGCG > EGC > ECG > EC (44-56, 21-47, 4-15 and 5-10) % of the total catechins in green tearespectively.Again, this order of epi-structured catechinsis very similar, if not identical, to those obtained by (Khokhar and Magnusdottir, 2002;Henning et al. 2003;Friedman et al., 2005Friedman et al., , 2006Friedman et al., , and 2009Yao et al., 2006 andAl-zubaidi, 2015).In contrast, the Tesco Green Tea (Tables 1and 2; Figures 3 and 4)contained higher levels of EGC (58.66 mg/g)followed by EGCG (57.94 mg/g tea bag), EC (10.22 mg/g tea bag), and ECG (9.97 mg/g tea bags)with an overalltrend of EGC > EGCG > EC > ECG.These results seem to concur with the findings of Lin et al. (1998) who reported higher levels of EGC in Japanese green teas.However, EGC was the highest at 67.46mg/g tea bagin Organic Pure Green ...
The level content of the main flavanols in green tea (i.e. epi-structured catechins) in regular commercial green tea bags commonly consumed in the United Kingdom (UK)have been examined using reversed-phasehigh-pressure liquid chromatography (RP-HPLC). Tea bags 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 fourteen types of green teawere separated and determinedby HPLC analysis,i.e. ()-epigallocatechin (EGC), ()-epicatechin (EC), ()-epigallocatechin-3-gallate (EGCG) and ()-epicatechingallate (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 96.38 to 205.03 mg/g, 1097.30-3421.14Trolox equivalents/g tea bags for fourteen types of green teas respectively.It was evident from the results of this study that there was significant linear and positive correlation (r = 0.932, df = 13, p < 0.05) is found to 05 exist between the total catechins contents and ORACvalues.It couldbe concluded that the developed HPLC method gave reliable results for catechins measurementscoupled to this; the well-known ORAC assay was successfully adapted to measure the antioxidant capacity of the green tea extracts throughout this study. Moreover, the higher the level of catechins the greater is the antioxidant capacity of the tea. However,the differences between the studied brands are owing to production, shelf life and storage conditions.
... is of a similar order to what has been reported elsewhere by (Khokhar and Magnusdottir, 2002;Henning et al. 2003;Friedman et al., 2005Friedman et al., , 2006Friedman et al., , and 2009Yao et al., 2006).Profiles of the four epi-structured catechins for the fourteen types of green tea are presented in Table 2; Figures 3and 4.These epi-structured catechins divided into two groups, i.e. EGCG and ECG, EGC and EC. ...
... EGCG > EGC > ECG > EC (44-56, 21-47, 4-15 and 5-10) % of the total catechins in green tearespectively.Again, this order of epi-structured catechinsis very similar, if not identical, to those obtained by (Khokhar and Magnusdottir, 2002;Henning et al. 2003;Friedman et al., 2005Friedman et al., , 2006Friedman et al., , and 2009Yao et al., 2006 andAl-zubaidi, 2015).In contrast, the Tesco Green Tea (Tables 1and 2; Figures 3 and 4)contained higher levels of EGC (58.66 mg/g)followed by EGCG (57.94 mg/g tea bag), EC (10.22 mg/g tea bag), and ECG (9.97 mg/g tea bags)with an overalltrend of EGC > EGCG > EC > ECG.These results seem to concur with the findings of Lin et al. (1998) who reported higher levels of EGC in Japanese green teas.However, EGC was the highest at 67.46mg/g tea bagin Organic Pure Green ...
The level content of the main flavanols in green tea (i.e. epi-structured catechins) in regular commercial green tea bags commonly consumed in the United Kingdom (UK)have been examined using reversed-phase high-pressure liquid chromatography (RP-HPLC). Tea bags 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 fourteen 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 96.38 to 205.03 mg/g, 1097.30 - 3421.14Trolox equivalents/g tea bags for fourteen types of green teas respectively. It was evident from the results of this study that there was significant linear and positive correlation (r = 0.932, df = 13, p < 0.05) is found to
... Black tea usually has lower levels of catechins than green tea, due to the oxidation and polymerization of catechins during fermentation in the manufacturing process. Black tea has a high level of theaflavins for extensive fermentation (1). Catechins and theaflavins are the major polyphenols in black tea and they are used as index polyphenols to estimate the quality of black tea. ...
... Catechins constitute 0.54-11.1% of the dry weight of black tea leave (2). The four major theaflavins in black tea are theaflavin (TF1), theaflavin 3-monogallate (TF2a), theaflavin 3′-monogallate (TF2b) and theaflavin 3,3′-digallate (TF3), which typically constitute 0.1-2.1% of the dry weight of black tea leaves (1,3). Many studies have shown that catechins and theaflavins are the major effective components in teas, e.g., antioxidation (4), anti-carcinoma (5), anti-obesity (6), arteriosclerosis prevention (7), Alzheimer and Parkinson diseases (8). ...
A fast ultrahigh performance liquid chromatography (UPLC) method has been developed for simultaneous analysis of caffeine and 13 index polyphenols-gallic acid, 8 primary catechins and 4 primary theaflavins in black tea. The method was evaluated in terms of linearity, precision, accuracy and recovery. The lower limits of detection and quantification were in the range of 0.05–0.91 and 0.15–3.00 mg/L, respectively. Satisfactory linearity with correlation coefficient (R² > 0.9992), interday and intraday precision with the relative standard deviations (<2.94% and <5.06%, respectively), interday and intraday accuracy with relative errors (REs, −5.34% < REs < 4.36% and −5.36% < REs < 7.07%, respectively) and recovery (95.81–104.48%) were achieved for all target compounds. The UPLC method was applied for the analysis of the 14 compounds in 6 black tea samples.
... Coffee infusions are mainly a source of phenolic acids and the most abundant are 5-caffeoylquinic acid (70.03 mg/100 mL), 4-caffeoylquinic acid (59.60 mg/100 mL), and 3-caffeoylquinic acid (51.80 mg/100 mL; Mattila and Kumpulainen 2002;Nardini et al. 2002a,b;Fujioka and Shibamoto 2006). Herb infusions are, in turn, good sources of both flavan-3-ols and phenolic acids (Friedman et al. 2005;Proestos et al. 2005;Horzic et al. 2009). The most abundant phenolics in lemon balm are in turn phenolic acids (caffeic 13.8 mg/100 g and ferulic 48 mg/100 g of dry mass) and the flavonoid (1)-catechin (21 mg/100 g of dry mass; Proestos et al. 2005). ...
... The most abundant phenolics in lemon balm are in turn phenolic acids (caffeic 13.8 mg/100 g and ferulic 48 mg/100 g of dry mass) and the flavonoid (1)-catechin (21 mg/100 g of dry mass; Proestos et al. 2005). The main polyphenols found in peppermint infusion are (1)-catechin (0.3 mg/100 mL), (1)-catechin 3-O-gallate (0.45 mg/100 mL), (2)-epicatechin 3-O-gallate (9.24 mg/100 mL), and (2)epigallocatechin (0.24 mg/100 mL; Friedman et al. 2005). Flavan-3-ols are also the main polyphenols in lime infusion (127.04-191.66 ...
In this study, we describe a method of total phenolic compounds determination based on CdTe quantum dot (QD) fluorescence recovery in the presence of analyte. Polyphenols present in the solution were reducing agents, acting as electron donors to the CdTe–sodium periodate system, thus leading to perturbation of the transfer of excited electrons from QD to the acceptor molecules occurring in the absence of polyphenols. Using the developed technique the polyphenol content in green tea, black tea, Pu‐Erh tea, lemon balm, peppermint, lime, chamomile, and coffee infusions was successfully determined. The limit of detection of the method amounted to 0.63 nM of (+)‐catechin equivalent, which makes this technique nearly one order of magnitude more sensitive than the commonly used Folin–Ciocalteu method. Additionally, lack of impact of interference from proteins and reducing sugars on the results makes this technique an advantageous alternative to the Folin–Ciocalteu assay.
Practical Applications
The developed method for total phenolic compound determination, thanks to higher specificity and a low detection limit may be a beneficial alternative to the popular Folin–Ciocalteu assay. The applications of the described technique include plant raw material and product nutritional quality assessment as well as studying the effects of a polyphenol‐rich diet on human health. The assay is easy to use both in industry laboratories as well as in research and development.
... The primary components of the raw materials are substances like TFs, phenolic acids, pigments, gallic acid, catechins, and caffeine. The proportion of gallic acid, main catechins, caffeine, and the four major theaflavins, which account for a relatively large proportion [26], is shown in Table 3. The total catechins accounted for 42.64 ± 0.56%, and the four major theaflavins accounted for 14.28 ± 0.05%. ...
Theaflavins, as products of tea fermentation, exhibit significant applications in the fields of functional food, medicine, and others. This study aimed to screen ideal resin, further investigate its adsorption mechanisms, and optimize the dynamic purification process of ideal resin. Through static adsorption/desorption studies, LX-20B resin with great adsorption and desorption ability was screened from six macroporous resins. The adsorption mechanism of LX-20B resin was studied through static adsorption kinetics and thermodynamic experiments. The results showed that the adsorption of TFs on LX-20B resin corresponded to the pseudo-second-order kinetic model and Langmuir kinetic model, indicating that the adsorption is a high-temperature spontaneous, and monolayer adsorption process. After studying the adsorption mechanism of LX-20B resin, the process parameters for purifying TFs using LX-20B resin were further optimized. At a sample concentration of 150 mg/mL and a sample loading flow rate of 1.0 BV/h, sequential elution with 3.0 BV water, 4.0 BV of 30% (v/v) ethanol, and 2.0 BV of 60% (v/v) ethanol at a flow rate of 1.0 BV/h led to a significant increase in TFs purity from 14.28 ± 0.05% to 62.48 ± 0.37%, with a recovery rate of 52.98 ± 2.01%. The purity was 4.4 times greater than that of the crude material.
... In our preliminary screening, polyphenol yield did not change after 60 min of HAE. Friedman et al. [78] and Vergara-Salinas et al. [79] showed that extended extraction time could result in a decrease in polyphenol content due to the sensitivity of phenolic components, especially during heating, as well as the occurrence of their degradation, oxidation, and polymerization. In the case of MAE, 1 min was too little time for a complete polyphenol release, while a longer irradiation time (3 min) can destroy polyphenols, as well as cause the excessive recovery of proteins, lipids, and carbohydrates as ballast compounds [11,80], therefore, the TPC was the highest at the intermediate extraction time used (2 min). ...
Citation: Elferjane, M.R.; Milutinović, V.; Jovanović Krivokuća, M.; Taherzadeh, M.J.; Pietrzak, W.; Marinković, A.; Jovanović, A.A. Abstract: The aims of the present research include (1) optimization of extraction from Vaccinium myrtillus leaf waste via investigation of plant material:medium ratio, extraction medium, and extraction period, employing extractions at room and high temperatures, or using ultrasound and microwaves (M, HAE, UAE, and MAE, respectively), (2) physicochemical characterization, and (3) investigation of extract biological potential. The statistical analysis revealed that optimal levels of parameters for the greatest polyphenolic yield were a proportion of 1:30 g/mL, ethyl alcohol 50% (v/v) during 2 min of microwave irradiation. By LC-MS analysis, 29 phenolic components were detected; HAE showed the highest richness of almost all determined polyphenols, while chlorogenic acid and quercetin 3-O-glucuronide were dominant. All extracts showed a high inhibition of Staphylococcus aureus growth. The effect of different parameters on extracts' antioxidant capacity depended on the used tests. The extracts also showed a stimulative influence on keratinocyte viability and anti-inflammatory activity (proven in cell-based ELISA and erythrocyte stabilization assays). The extraction procedure significantly affected the extraction yield (MAE ≥ maceration ≥ UAE ≥ HAE), whereas conductivity, density, surface tension, and viscosity varied in a narrow range. The presented research provides evidence on the optimal extraction conditions and technique, chemical composition, and antioxidant, antimicrobial, anti-inflammatory, and keratinocyte viability properties of bilberry extracts for potential applications in pharmacy and cosmetics.
... The most common HPLC methods for caffeine determination in the prepared sample basis on reversed-phase liquid chromatography using C18 stationary phases. As the mobile phase water-acetonitrile or water-methanol mixtures are used, organic solvent content is usually low at around 10-15% but may be as high as 40% or gradient elution is applied [10,[18][19][20]. These are the most common organic solvents used in HPLC; unfortunately, both exhibit toxicity [17]. ...
This study presents an innovative method for caffeine determination in tea, employing ethanol as the sole organic solvent for both SPE sample preparation and chromatographic analysis. This approach aligns with green chemistry principles, as confirmed by a comparative study highlighting ethanol’s safety and eco-friendliness compared to traditional solvents. The experiments validate ethanol’s efficacy in caffeine extraction and chromatographic analysis, minimizing environmental impact and eliminating toxicity risks. Utilizing a reduced chromatography column enhances the method’s efficiency and sustainability, resulting in a low limit of quantitation (0.125 μg/mL) and good reproducibility (RSD < 2.5%). Based on tea from the Polish market, the findings reveal the caffeine content (19.29–37.69 mg/g) and endorse ethanol’s role in enhancing sustainable chemical analysis in food science.
... The catechin consist of a group of four major constituents that are epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC), epigallocatechin gallate (EGCG) and the four minor catechins constituents are, catechin (C), catechin gallate (CG), gallocatechin (GC) and gallocatechin gallate (GCG) are the epimers of the mentioned major catechins (Fig. 3) (Gramza et al. 2005;Friedman et al. 2005). These catechins are responsible for the characteristic bitterness and astringent taste to the tea decoction Narukawa et al. 2010). ...
Catechin is one of the prestigious phytoconstituent obtained from the divine wealth of nature. It is a polyphenolic constituent which is broadly distributed in plant kingdom and tea, legumes and rubeaceous plants are rich sources of it. Various research groups have extracted and isolated it by using different analytical techniques due to its diverse pharmacological profile. It is evident in nature that catechin possesses promising anti-inflammatory, neuroprotective, antioxidant, antibacterial, anticancer and anti-viral properties. There are several formulations reported which are intended for multiple uses where catechins are important ingredient. This review discusses the various analytical techniques employed for the extraction and isolation of catechins from various sources, as well as a summary of various reported formulations. The authors also discuss the various pharmacological activities exhibited by catechins, along with the significant outcomes and plausible mode of action. In addition, the review provides an insight into various synthetic and biosynthetic procedures for catechins, along with a description of various clinical trials and patents. In the lateral sections of this compilation, an insight to various synthetic/biosynthetic procedures for catechins has been provided along with description to various clinical trials and patents. Although a lot of progress has been made towards exploration of catechins, still these are associated with some issues of bioavailability and unclear modes of action, which need to be resolved in upcoming times. This review is more comprehensive on catechins, as it covers a wider range of topic includings; analytical techniques for the extraction and isolations of catechins, formulations containing catechins, pharmacological activities, synthetic and biosynthetic procedure, clinical trials as well as patents. The review also provide a more in-depth discussion of the pharmacological activities of catechins, including the significant outcomes and plausible mode of action. The article also highlights the need for the further research to address the issues of bioavailability and unclear modes of action associated with the catechin. This is an important area of research, as it is essential to understand the ADME to develop effective catechin-based therapies.
... According to Owuor and Orchard [25], an increase in caffeine content in tea appears to be related to the breakdown of proteins into amino acids and their metabolism. Similar results have also been observed by other authors [48,49], both for individual and total catechins; however, for caffeine, the results were different, with higher values observed in Azorean tea samples. ...
The objective of this study was to investigate the variability of natural bioactive compounds, such as catechin, theaflavin, total phenolic content (TPC), and total flavonoid content (TFC), of Azorean black tea (Camellia sinensis L., O. Kuntze) as well as its antioxidant activities according to different withering times. The TPC, TFC, free radical scavenging activity (FRSA), ferric reducing antioxidant power (FRAP), and ferrous-ion-chelating (FIC) activities were determined by colorimetric methods, and catechin and theaflavin contents were analyzed by high-pressure liquid chromatography (HPLC). The FRSA shows similar results for the withering range of 6 to 16 h (hours). For FRAP, the best results were observed at 16 h, and for FIC, the highest value was at 20 h. The TPC and TFC showed the highest value at 9 h and the lowest at 20 h. For the total theaflavins, the highest results were obtained after 12 h of withering, and the lowest values were obtained at 16 and 20 h. According to the different withering times, the highest value of total catechin levels was at 12 h, while the lowest value was observed at 20 h. Regarding caffeine content, all samples presented similar results, with the exception of the 12 h time point. In conclusion, the best withering times were observed in the range of 9 to 16 h, showing decreased values at 20 h, with the exception of FIC.
... Also, the TPCs in tea liquors increased rapidly from 3 to 15 min (brewed at 90 • C), then the rising rate was slower during the remaining 15 min. Such results indicated that short brewing durations (3-15 min) in combination with high brewing temperature of infusion water exhibited the most favorable results in the extraction of phenolic compounds as bioactive components in tea products (Friedman et al., 2005;Jakubczyk et al., 2020). The temperature has strong extraction efficiency since it can accelerate the extraction of internal compounds, especially the easily soluble substances (flavonoids, phenolic compounds, and catechins) from the tea products into their liquors. ...
The total phenolic contents (TPCs) represent the bioactive substances and antioxidant capacities of flora products. The present study employed digital images from a smartphone to determine the TPCs in tea products and their liquors. Various parameters related to the portable home-made colorimetric analysis box design were optimized to achieve the most favorable capturing condition. The proposed method performance was evaluated, which agreed with the Appendix F of AOAC (2016). In comparison with the standard UV–vis, no statistical differences (t-tests, P = 95 %) were observed, and there were advantages of simplicity, portability, sample volume reduction, decreased analysis time, low-cost operation, especially the potential to be used by tea producers, managers, and consumers to quickly analyze the TPCs. The results demonstrate the descending TPCs orders of green > white > oolong > black teas (recoveries of 95–98 %) and the increase of TPCs in tea liquors regarding the rising brewing temperature and duration.
... In addition to caffeine, tea also contains high levels of antioxidants, such as flavonoids, catechins and tannins, although levels vary among the various types of teas. 57 While the effect of green tea on the risk of breast cancer tended to be protective, black tea was observed to have no effect or even be a risk factor for breast cancer in epidemiological studies, 58 probably because many catechins in black tea are less bioavailable due to fermentation. 15 We did not observe significant association between overall tea consumption and invasive breast cancer among postmenopausal women; however, we observed a potential positive association limited to ERÀ/PRÀ breast cancer in the current study. ...
Research findings remain inconsistent whether caffeine consumption is associated with invasive breast cancer. We aimed to examine the association between caffeine intake from coffee and tea and incident invasive breast cancer among postmenopausal women. We included 79 871 participants in the Women's Health Initiative Observational Study in the current analysis. Incident invasive breast cancers were identified through September 30, 2015. Caffeine intake (mg/day) from caffeinated and decaffeinated coffee and tea was estimated based on self‐reported frequency (cups/day) and average caffeine amount in each beverage. Cox proportional hazards regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Subgroup analyses were conducted to explore whether associations of caffeine intake from coffee and tea with invasive breast cancer were different by age, race and ethnicity, smoking status, body mass index, history of hormone therapy use, alcohol intake and subtypes of breast cancer. During a median follow‐up of 16.0 years, 4719 incident invasive breast cancers were identified. No significant association was found between caffeine intake from coffee and tea and invasive breast cancer incidence after adjusting for demographic, lifestyle and reproductive factors: HRs (95% CIs) for increasing quartiles of caffeine intake compared to the lowest were 1.03 (0.94, 1.12), 1.04 (0.95, 1.13) and 1.03 (0.94, 1.13), respectively (P‐for‐trend = .54). No significant associations of coffee and tea intake (cups/day) with overall breast cancer risk were found. Our findings are consistent with others showing no clear association of caffeine consumption with invasive breast cancer among postmenopausal women.
... The tea health benefits are typically related to the antioxidant character of tea and its catechin content. 3,4 Green tea that is higher in catechins and has a higher antioxidant character is typically credited with more health benefits. 10,11 A poor correlation was previously reported between the catechin content and ORAC values 1 of tea infusion. ...
The present study measured the antioxidant properties of 15 commercial tea samples as expressed by the oxygen radical absorbance capacity (ORAC) hydro, ORAC lipo, and ferric reducing antioxidant power (FRAP) indexes. The main antioxidant compounds known to be present in tea are several catechins and catechin gallates, gallic acid, theaflavin and some theaflavin gallates, and theogallin. In this study, only gallic acid and the four most common catechins (epicatechin, epigallocatechin, epicatechin gallate, and epigallocatechin gallate) were analyzed in the tea samples. In addition, caffeine levels were measured. The ORAC and FRAP values for these compounds were also determined. The levels of theaflavin, theaflavin gallates, and theogallin were not measured since these compounds are present at relatively low levels in tea. The ORAC (and FRAP) indexes for each tea sample were also calculated based on the content of individual antioxidant compounds and their ORAC and FRAP indexes. Correlations between the experimental ORAC (and FRAP) and the calculated values were further obtained. The correlations were poor, with R² = 0.3657 for ORAC hydro, R² = 0.2794 for ORAC lipo, and R² = 0.6929 for FRAP. The poor correlation between the overall catechin content and the experimental ORAC values in tea infusions was previously reported in the literature. The present study directly calculated the expected ORAC index from individual antioxidant components and reached the same result of poor correlation. For FRAP values, no comparison was previously reported in the literature. The poor correlations were not well explained, indicating that the cause of the antioxidant character of tea is more complex than simply produced by the main catechins.
... The sample solution was filtered through a 0.45 µm syringe filter (Sartorius) prior to HPLC analysis. For the teabag samples, the extraction was conducted as reported by [56][57][58]. Briefly, 250 mg of teabag contents were placed into a 100 mL conical flask containing 10 mL of ethanol 70% (v/v) which was brought to boiling point for 5 min. ...
Labisia pumila is a precious herb in Southeast Asia that is traditionally used as a health supplement and has been extensively commercialized due to its claimed therapeutic properties in boosting a healthy female reproductive system. Indigenous people used these plants by boiling the leaves; however, in recent years it has been marketed as powdered or capsuled products. Accordingly, accuracy in determination of the authenticity of these modern herbal products has faced great challenges. Lack of authenticity is a public health risk because incorrectly used herbal species can cause adverse effects. Hence, any measures that may aid product authentication would be beneficial. Given the widespread use of Labisia herbal products, the current study focuses on authenticity testing via an integral approach of DNA barcoding and qualitative analysis using HPLC. This study successfully generated DNA reference barcodes (ITS2 and rbcL) for L.pumila var. alata and pumila. The DNA barcode that was generated was then used to identify species of Labisia pumila in herbal medicinal products, while HPLC was utilized to determine their quality. The findings through the synergistic approach (DNA barcode and HPLC) implemented in this study indicate the importance of both methods in providing the strong evidence required for the identification of true species and to examine the authenticity of such herbal medicinal products.
... Cada uno de estos a su vez poseen dos isómeros ópticos: (+) catequina y (-)catequina, (-) epicatequina y (+)epicatequina, respectiva mente. La (-)catequina puede ser modificada por medio de una esterificación con ácido gálico para formar (-)catequina3galato, (-) epicatequina3galato, (-)epigalocatequina3 galato y (-)galocatequina3galato (Friedman et al., 2005). ...
El presente estudio evaluó la capacidad antioxidante y contenido de compuestos fenólicos de la hoja cruda y seca de la Guaviduca (Piper carpunya Ruiz & Pav.), siendo la capacidad antioxidante determinada por el método FRAP (Ferric ion reducing antioxidant Power) y ABTS (Ácido 2,2 –azinobis (3etilbenzotiazolin) 6sulfónico), y el contenido de compuestos fenólicos totales usando el método FolinCiocalteau, como resultado evidenciamos que existe una elevada actividad fenólica en aceites esencial obtenido de las hojas húmedas así como la actividad antioxidante total por el método FRAP y ABTS. En conclusión, determinamos que la capacidad antioxidante obtenida por los 2 métodos FRAP Y ABTS esta correlacionada con el contenido de fenoles totales.
... The authors suggest that black tea and its bioactive theaflavin compounds merit further human clinical studies with T. vaginalis. Related studies show that individual green tea catechins and black theaflavins and tea extracts inhibited the growth of pathogenic bacteria and viruses [62,63], and multiple human cancer cells [64], and that the theaflavin and catechin content of 77 commercial green and black teas varied widely [65,66], suggesting that clinicians and tea consumers should select teas with the highest content of the bioactive compounds. Three publications by Sirk et al. [67][68][69] describe studies on molecular-dynamics computer simulations of green tea catechins and black tea theaflavins and lipid bilayers of cell membranes. ...
Human trichomoniasis, caused by the pathogenic parasitic protozoan Trichomonas vaginalis, is the most common non-viral sexually transmitted disease that contributes to reproductive morbidity in affected women and possibly to prostate cancer in men. Tritrichomonas foetus strains cause the disease trichomoniasis in farm animals (cattle, bulls, pigs) and diarrhea in domestic animals (cats and dogs). Because some T. vaginalis strains have become resistant to the widely used drug metronidazole, there is a need to develop alternative treatments, based on safe natural products that have the potential to replace and/or enhance the activity of lower doses of metronidazole. To help meet this need, this overview collates and interprets worldwide reported studies on the efficacy of structurally different classes of food, marine, and medicinal plant extracts and some of their bioactive pure compounds against T. vaginalis and T. foetus in vitro and in infected mice and women. Active food extracts include potato peels and their glycoalkaloids α-chaconine and α-solanine, caffeic and chlorogenic acids, and quercetin; the tomato glycoalkaloid α-tomatine; theaflavin-rich black tea extracts and bioactive theaflavins; plant essential oils and their compounds (+)-α-bisabolol and eugenol; the grape skin compound resveratrol; the kidney bean lectin, marine extracts from algae, seaweeds, and fungi and compounds that are derived from fungi; medicinal extracts and about 30 isolated pure compounds. Also covered are the inactivation of drug-resistant T. vaginalis and T. foetus strains by sensitized light; anti-trichomonad effects in mice and women; beneficial effects of probiotics in women; and mechanisms that govern cell death. The summarized findings will hopefully stimulate additional research, including molecular-mechanism-guided inactivations and human clinical studies, that will help ameliorate adverse effects of pathogenic protozoa.
... Mint herbal tea is used as a hot beverage that is naturally caffeine free (24). Nowadays, consumption of functional food is increasing. ...
Background and Objectives: Due to the health concerns of people about caffeine, several techniques have been developed to remove caffeine from tea; however, these techniques include limitations. The objective of the present study was to remove caffeine from dried tea leaves using hot water treatment. Materials and Methods: Hot water treatment was used to decaffeinate green and black tea leaves using two stages of brewing. Caffeine of the tea infusions was extracted using liquid-liquid extraction technique and quantified using high performance liquid chromatography. Furthermore, pH, total polyphenol content and antioxidant activity were assessed using electronic pH meter, Folin-Ciocalteu method and ABTS method, respectively. Sensory evaluation was carried out using 5-point hedonic scale test. Tea infusions were prepared within two stages of brewing at 1, 3 and 5 min as primary and 7 min as total brewing times. Results: After 3 min of primary brewing time, decaffeination rates of Ceylon black, China green and Iranian green teas were assessed as 47.7, 81.55 and 85.99%. Antioxidant activity of these samples included 87.7, 85.99 and 81.55%, while total polyphenol content included 83.03, 44.44 and 37.7%, respectively. In general, pH and total polyphenol content of decaffeinated tea-mint infusions increased significantly. Conclusions: Effects of brewing time on caffeine concentration of the tea infusions were revealed in this study. In conclusion, hot water treatment is a safe method and includes a high efficiency for the decaffeination of green and black teas.
... It is favourable 140 • C (pre-treated for 30 min by US) with a total phenolic compounds release of 124 mg/g extract. This behaviour has been explained taking into account that the sensitivity of the total phenolic content is higher at longed extraction time especially when higher temperatures are involved in the process (Friedman et al., 2006; Horžić et al., 2012). The authors are not aware that a sequential extraction of 3 techniques has been carried out on tea leaves or other agro-industrial waste. ...
This study deals with the valorisation of tea leaves from the agricultural pruning remains using clean technologies with low environmental impact. Leaves with null commercial interest were dismissed during the pruning season, however with a sequential combination of microwave hydrodiffusion and gravity (MHG), ultrasound-assisted (US) and pressurized hot water (AH) extractions was possible to recover bioactive compounds. An initial pre-treatment was performed using MHG at selected irradiation powers to facilitate the liberation of antioxidants through the cell membrane. The solid phases were processed by three ways: i) ultrasound bath system (80 °C, 80 KHz, from 15 to 60 min); ii) AH technology (non-isothermal treatment with maximum temperature from 140 to 200 °C); and iii) a sequence of the three aforementioned technologies. Both raw material and liquors were analysed to determine fundamental physicochemical, phytochemical or biological properties. Leaves debris showed positive results in bioactive compounds with a maximum value of total phenolic around 130 mg GAE/g extract in the sequential combination. Antioxidant capacity ranged from 0.3 to 0.9 g Trolox/g extract. The combination of green extraction technologies guarantees an efficient recovery of bioactive compounds, creating the possibility of new products that improve the wellbeing.
... The highest content of polyphenols was observed when the tea was brewed at 90 • C for 10 min, which was similar to the result achieved by other researchers who observed that the highest content of bioactive compounds of tea infusions was at 80 • C during a relatively short brewing time (5-10 min) [9,38]. These results point to the fact that short brewing time in combination with high brewing temperature of water yield the best results when extracting tea compounds [39]. Komes et al. [9] analyzed the content of polyphenol compounds in various forms (leaves, tea bags, powder) of green teas. ...
Matcha green tea (Camellia sinensis), which originates from Japan, is commonly considered as particularly beneficial to health. A large content of polyphenols, amino acids (mainly tannins) and caffeine potentially increase the antioxidant properties of the drink. The aim of the study was to determine the antioxidant potential and the content of substances with an antioxidant effect-vitamin C, total polyphenol content including flavonoids-in infusions made from Traditional Matcha (from the first and second harvests) and Daily Matcha (from the second and third harvests) at different temperatures. The infusions were made by pouring 100 mL of distilled water once at various temperatures (25 • C, 70 • C, 80 • C and 90 • C) over 1.75 g of the plant material. Matcha tea is characterized by a high level of antioxidant substances (flavonoids 1968.8 mg/L; polyphenols 1765.1 mg/L; vitamin C 44.8 mg/L) as well as antioxidant potential (41.2% DPPH (10× dilution); 6129.5 µM Fe(II)/dm 3 FRAP). The concentration of these compounds depends on the time at which the plant material was harvested as well as on the temperature of water used to prepare the infusions. For most parameters, the highest values were observed in infusions prepared at 90 • C and from the daily Matcha.
... There are also reports indicating that drinking tea lowers total cholesterol levels, as well as improves the ratio of good cholesterol (HDL) to bad cholesterol (LDL) (Cheng, 2006). These results confirmed with (Friedman et al, 2005) who reported that Catechins, another group of antioxidants, have been found to reduce cholesterol, and white tea is teeming with them. White tea improves good cholesterol while suppressing bad cholesterol. ...
... This is in accordance with the research of Tim Hortons Research and Development (2017) that the caffeine content of green tea infusion varies between 25-60 mg of caffeine/g. Whereas Friedman et al. (2006) showed that the caffeine content of green tea can vary between 1-33 mg/g. According to Tfouni et al. (2018), green tea contains caffeine 18.3-25.3 ...
Insomnia problem can be treated by consuming herbs containing apigenin and EGCG. Chamomile and green tea water extract have been found to containapigenin and EGCG. Optimization of the formulation of those herbs is necessary to obtain the highest hypnotic activity. The purpose of this study was to optimize formulation of chamomile, green tea, and cinnamon to obtain functional beverage containing the highest phenolic and flavonoid content, but the lowest caffeine content. The best formula of the herbs was then tested in caffeine-induced mice to see the hypnotic effect. The research design in this experiment was Response Surface Model (RSM) using Central Composite Design (CCD) method. The in vivo test used Post Test Only Control Group Design. Consisting five groups of 30 male mice divided to 6 mice for each group. The optimum formula for functional beverages suggested by RSM was chamomile: green tea : cinnamon of 70.32 : 30.35 : 4.99. The verification results showed that the actual response of this optimum formula had a total phenol of 23.76 mgGAE/g dry herbs, total flavonoids of 126.43 mgQE/g dry herbs, caffeine content of 29.87 mg caffeine/g dry herbs, apigenin levels of 0.07±0.068 µg/g dry herbs, and EGCG of 6.43±0.218 µg/g dry herbs. Functional beverages showed hypnotic activity in group of mice dosed 26 mL/kg bw, which significantly reduced motor activity to 4.83±0.72 sec. As well as significantly reducing the proinflammatory cytokines
... It has been demonstrated that tea catechins concentration in fresh tea leaves is influenced by cultivation environmental factors, such as more catechins are accumulated in tea leaves with the increasing of sunshine duration to prevent UV rays' damage (Wei et al., 2011). Additionally, catechins accumulation in tea leaves is affected by temperature, rainfall, geographical and other environmental factors (Friedman et al., 2005;Han et al., 2016;Owuor, Obanda, E. Nyirenda, & Mandala, 2008;Szymczycha-Madeja, Welna, & Pohl, 2012). ...
To understand the effects of geographic locations, cultivation altitude, slope, and aspect on secondary metabolites in tea leaves, 78 tea samples were randomly collected from Southern Jiangsu region, China, and catechins, caffeine, and free amino acids were examined. The results showed that samples from the farther north had higher contents of TC, EGCG+GCG, ECG+CG and the ratios of ETC to NTC, while had lower contents of free amino acids, leading to more bitterness and astringency taste in tea. Furthermore, more free amino acids were accumulated in tea cultivated in hilly areas due to shorter sun exposure time and lower intensity than plain areas with the rotation of the earth formed a natural shade management effect, whereas more TC in plain areas. Principal Component Analysis (PCA) grouped the 78 tea samples into three clusters and further confirmed that tea samples from a similar geographical environment exhibited a similar constituent of major secondary metabolites. These results might be useful for providing references to regional tea plantation planning, tea plantations location selection and geographical environment management.
... Interestingly, higher mean contents of caffeine were reported in previous studies that analyzed commercial green and black C. sinensis teas from retail markets in India (2800 -3690 mg/100 g) (Astill et al., 2001), Malaysia (2490 -6920 mg/100 g) (Rahim et al., 2014), China (2160 -2680 mg/100 g) (Zuo et al., 2002), USA (300 -2670 mg/100 g) (Friedman et al., 2005) and UK (1210 -2800 mg/100 g) (Khokhar and Magnusdottir, 2002). Such differences may be due to variations in genotype, agricultural aspects, and processing (Astill et al., 2001). ...
This work investigated the contents of methylxanthines in 25 types of stimulating foods available in the Brazilian market, totaling 199 samples, from which 264 coffee, tea, and chocolate beverages were made using the most common preparation methods in the country. Among solid foods, soluble coffee powders showed the highest mean content of caffeine (2506 ± 477 mg/100 g), while chocolate powders showed the lowest (25 ± 6 mg/100 g). Nevertheless, dark chocolate presented the highest mean contents of theobromine (1036 ± 136 mg/100 g) and theophylline (7.8 ± 2.1 mg/100 g). Regarding beverages, soluble coffees presented the highest content of caffeine (269 ± 12 mg/100 g), followed by espresso coffees (196 ± 37 mg/100 g) and by coffees prepared by electric dripper (120 ± 19 mg/100 g). Among teas, black tea (bulk) and green maté (“chimarrão”) presented the highest caffeine contents (23 ± 8 and 22 ± 3 mg/100 g, respectively). Mean contents in cola soft drinks and energy drinks were 8.3 ± 1.2 and 35 ± 1 mg/100 g, respectively. These results suggest that foods and beverages other than coffee can increase importantly the daily intake of stimulant substances and reveals a large variation in the contents of caffeine in coffee and tea beverages, which is often unknown by the general population. The inclusion of methylxanthines’ contents in food package labels and food composition tables is an important step to increase people´s awareness of methylxanthines existence in certain types of foods.
... The sample solution was filtered through a 0.45 µm syringe filter (Sartorius) prior to HPLC analysis. For the teabag samples, the extraction was conducted as reported by [56][57][58]. Briefly, 250 mg of teabag contents were placed into a 100 mL conical flask containing 10 mL of ethanol 70% (v/v) which was brought to boiling point for 5 min. ...
... The reports of other authors indicate that white and green teas of 3-4 times higher content of polyphenols than black teas also show significantly greater, even 10 times stronger, ability to scavenge free radicals [1,2,9,[20][21][22]. According to Yashin et al. [22], based on the determinations of antioxidant activity of various tea grades, it allows them to be classified in the following order: green > oolong > black > Pu-erh tea, which was also confirmed in our research. ...
Introduction: The leaves of Camellia sinensis (L.) Kuntze are used to produce many types of tea; this variety results from the production process. The extracts, especially from teas rich in polyphenols, are also used in the prevention and treatment of certain diseases, in addition to their application for consumption.
Objective: The aim of the study was to compare the antioxidant activity and total phenolic content in extracts from the following types of tea: white, green, oolong, black and Pu-erh.
Methods: The aqueous and methanolic extracts from the teas were analysed by spectrophotometric methods. The method with the Folin-Ciocalteu reagent was used to determine total phenolic content; the antioxidant activity was investigated by means of the reaction with the DPPH radical.
Results: Total phenolic content and the antioxidant activity of examined extracts differed significantly. The alcoholic and aqueous extracts from white and green tea of the highest content of polyphenols (97.1–84.4 mg GAE/g) showed the greatest antioxidant activity (IC 50 0.263–0.329 mg/ml), similar to that of BHA. The methanolic extracts from black and Pu-erh tea demonstrated much weaker activity.
Conclusions: The antioxidant activity of extracts from investigated teas is closely correlated with content of polyphenolic compounds, which depends on the type of tea and the solvent used for extraction.
... The three main types of tea beverages are black, green and oolong teas (6). Green tea is non-fermented, black tea is completely fermented and oolong tea is partially fermented (7). Kenya is the world's largest producer of black tea in the world (8). ...
Tea quality is manifested in its aroma, flavour and taste properties, which are generated by volatile and non-volatile compounds, mainly catechins and caffeine. Several studies have revealed positive significant relationships between (flavan-3-ols) catechins and caffeine in green leaf and black tea quality. Additionally, the health benefits of tea in management of cancer, arthritis, cardiovascular diseases, diabetes and obesity have been attributed to catechins and caffeine. Eight biochemical traits of tea were used to investigate mid-parent heterosis (MPH), better parent heterosis (BPH) and standard heterosis (SDH) in a 4x4 diallel mating design. Overall, genotype x environment interaction influenced heterosis. For example, mean GA, EGC, C, EC and TC contents were higher at Timbilil compared to Kangaita while mean Caffeine, EGCG and ECG were higher at Kangaita compared to Timbilil. The results also showed that, inbreds (EPK TN14- 3, AHP S15/10 and TRFK 6/8) had improved catechins content and could be used in recurrent selection to develop tea with high catechins content. Crosses, which showed high positive heterosis over the mid-parent, better parent and the standard variety, could be utilized to generate transgressive segregants in the later generations with high catechins and caffeine
... Interestingly, earlier studies also revealed that antioxidant capability of different forms of green tea were similar for steeping time of 5' and 10' at 80 0 C [17][18] . It was also suggested that high water temperature and short steeping time is best for extraction of tea bioactive compounds 18,30,31 . Our investigation was concentrated on short steeping time (5') and high water temperature (95-100 0 C) as these conditions mimic the household method of tea preparation. ...
Green tea is commercially available in three forms: loose leaf, bagged and powdered. The objective of this study was to compare the radical scavenging capacity of different forms of green tea like loose leaf (3), bagged (2) and powdered matcha (2) of various brands. The green tea forms were prepared at 95-100 °C for 5 min., to mimic conditions usually used for tea preparations at home. The comparison of combined IC50 values of different green tea forms (loose leaf, bagged and matcha) showed no significant difference in their radical scavenging activity except bagged tea that exhibited slightly more DPPH radical scavenging potential as compared to matcha. Individually, the Bud white loose leaf demonstrated highest antioxidant activity followed by Laplant bag, Lipton bag, Laplant loose, Gourmet matcha, Wow matcha and Lipton loose. These findings revealed that on the basis of form, it may not be possible to generalize which form of tea whether loose leaf, bagged or matcha, is more effective in scavenging free radicals.
... 7 Amount of caffeine could vary in different kinds of tea. 8 During dim sum lunch, Chinese tea is served with a selection of different kinds of tea from no fermentation to full fermentation. In addition, consumers could determine the taste of tea, which could be regular or strong. ...
... (−)-catechin can be turned into (−)-catechin-3-gallate, epicatechin-3-gallate, (−)-epigallocatechin-3-gallate, and (−)-gallocatechin-3-gallate by esterification with gallic acid. By oxidative coupling, different catechins can form four types of theaflavins including theaflavin (TF), theaflavin-3-gallate (TF3G), theaflavin-3′-gallate (TF3′G) and theaflavin-3, 3′-digallate (TF33′G) (Friedman et al., 2005). ...
Tea polyphenols have been a topic of discussion due to their health benefits. Nevertheless, detailed studies on the antioxidant capacity and polyphenol contents of teas in relation to factors including geographical locations, plantation elevations and leaf grades have been limited. In this study, 53 tea samples were analysed to determine the individual and total catechin and theaflavin contents by HPLC and the total antioxidant capacity by Oxygen Radical Absorbance Capacity (ORAC) methods. Results show that the polyphenol (catechins and theaflavins) contents were significantly influenced by plantation location. Black tea from low plantation elevation contained 22–28% more polyphenols than those from high elevation. Small tea leaves had up to 15% more polyphenols than larger leaves from similar elevation. The results were further confirmed by Principal Composition Analysis (PCA), which grouped the black and green tea samples into 3 different clusters, respectively.
... We previously surveyed the content of bioactive compounds in a variety of teas [21,33,34]. Our results showed that there are large differences in the content of bioactive compounds in widely consumed commercial black and green teas. ...
Background
Plants produce secondary metabolites that often possess widespread bioactivity, and are then known as phytochemicals. We previously determined that several phytochemical-rich food-derived preparations were active against pathogenic foodborne bacteria. Trichomonads produce disease (trichomoniasis) in humans and in certain animals. Trichomonads are increasingly becoming resistant to conventional modes of treatment. It is of interest to test bioactive, natural compounds for efficacy against these pathogens. Methods
Using a cell assay, black tea, green tea, grape, pomegranate, and jujube extracts, as well as whole dried jujube were tested against three trichomonads: Trichomonas vaginalis strain G3 (found in humans), Tritrichomonas foetus strain D1 (found in cattle), and Tritrichomonas foetus-like organism strain C1 (found in cats). The most effective of the test substances was subsequently tested against two metronidazole-resistant Trichomonas vaginalis strains, and on normal mucosal flora. ResultsBlack tea extract inhibited all the tested trichomonads, but was most effective against the T. vaginalis organisms. Inhibition by black tea was correlated with the total and individual theaflavin content of the two tea extracts determined by HPLC. Metronidazole-resistant Trichomonas vaginalis strains were also inhibited by the black tea extract. The response of the organisms to the remaining preparations was variable and unique. We observed no effect of the black tea extract on common normal flora bacteria. Conclusions
The results suggest that the black tea, and to a lesser degree green tea, grape seed, and pomegranate extracts might present possible natural alternative therapeutic agents to treat Trichomonas vaginalis infections in humans and the related trichomonad infections in animals, without negatively affecting the normal flora.
... Within phenolic compounds, phenolic acids and flavanols are the key components of coffee and tea, respectively [8][9][10][11][12][13][14][15][16][17][18][19][20][21] (Table 1). These are the two most important contributors to total phenol intake (hydroxycinnamic acids 27-53% and flavanols 28-48%) in Europe [22 ]. ...
Both postprandial hypotension and hypertension are associated with arteriosclerosis and hypertension. We aimed to review the effects of coffee and tea on postprandial hemodynamic, in light of the pharmacokinetic of phenolic compounds. Phenolic compounds of coffee and teas improve flow-mediated dilation, hypotension or hypertension after meal. O-methylation, microbial metabolism and food matrix effects could account for some contrasting results after meal. In the postprandial reviewed studies, the absence of relationship between cardiovascular and oxidative stress do not support the hypothesis that phenolic compounds improve the cardiovascular changes by increasing the bioavailability of nitric oxide. On the other hand, phenolic compounds and their metabolites could affect sympathetic nervous system, angiotensin I-converting enzyme and postprandial insulin. In conclusion, the beneficial effects of phenolic compounds from coffee and tea on postprandial hemodynamic could be more likely due to pharmacological rather than to antioxidant effects.
... A typical cup of brewed black tea (2.5 g tea leaves in 250 mL) yields approximately 30% water-extractable solids (Yang, et al., 2002). A survey of 32 black tea brands showed that the levels of theaflavin (TF), theaflavin-3-gallate (TF3G), theaflavin-3′-gallate (TF3′G), and theaflavin-3,3′-digallate (TFdiG) in the water-extractable solids were 0.1 -5.4 mg/g, 0.2 -2.1 mg/g, 0.1 -0.8 mg/g, and 0.4 -5.8 mg/g, respectively (Friedman, Kim, Lee, Han, Han, Lee, et al., 2005). Epidemiological and laboratory animal model studies have demonstrated the potential efficacy of tea for weight management and obesity prevention (reviewed in (Grove & Lambert, 2010;). ...
Few studies have examined the effect of black tea (Camellia sinensis) theaflavins on obesity-related targets. Pancreatic lipase (PL) plays a central role in fat metabolism and is a validated target for weight loss. We compared the inhibitory efficacy of individual theaflavins and explored the underlying mechanism. Theaflavin-3,3′-digallate (TFdiG), theaflavin-3′-gallate, theaflavin-3-gallate, and theaflavin inhibited PL with IC50 of 1.9, 4.2, 3.0, and >10 μmol/L. The presence and location of the galloyl ester moiety were essential for inhibitory potency. TFdiG exhibited mixed inhibition with respect to substrate concentration. In silico modeling showed that theaflavins bind to Asn263 and Asp206, which form a pocket adjacent to the active site, and galloyl-containing theaflavins are then predicted to perturb the protonation of His264. These data provide a putative mechanism to explain the anti-obesity effects of tea.
Black rice bran, a waste product from the commercial milling of black rice that removes the bran and germ leaving the starchy endosperm, contains bioactive anthocyanin, phenolic, and phytosteroid compounds that may have health benefits. This study determined the effect of a polysaccharide-rich bioprocessed (fermented) black rice bran and a green tea extract individually and in combination on weight loss in orally fed mice on a high-fat diet and on concurrent changes in blood glucose and insulin as well as in cholesterol, triglyceride, and high-density and low-density lipoproteins (HDL and LDL). At the end of the eight-week feeding study, the combination diet resulted in a 67% lower weight gain than mice on a high-fat diet alone, a greater effect than that of bioprocessed black rice bran or green tea extract individually. The weight loss caused by the combination diet seems to be the result of decreased dietary efficiency. The observed trends in the glucose and insulin data suggest that the combined diet also has anti-diabetic properties, and the corresponding trends in the levels of the serum lipoproteins suggest that the combined diet might also protect against heart disease. Effects on the content, structure, and function of white adipose and liver tissues and on obesity-related biomarkers support the trends in the weight loss data. Based on the observed beneficial effects in 3T3-L1 pre-adipocyte cells and mice, we suggest the need to investigate if the new multifunctional combination food product can also protect against obesity and chronic diseases in humans. Mechanistic aspects that govern the anti-obesity effects and suggestions for future research are discussed.
Certain indigenous African plant materials, including Adansonia digitata (baobab), Moringa oleifera (moringa), and Hibiscus sabdariffa (hibiscus) could be leveraged in food-to-food fortification strategies due to their high content of nutrients, dietary fiber, and phenolic compounds. However, more studies are needed to understand the nutritional composition of commercially available food ingredients. The objective of this study was to examine the phytochemical and polysaccharide compositions of commercially available baobab, moringa, and hibiscus ingredients from Senegal. Characterization of carotenoids, tocopherols, phenolic compounds, monosaccharide composition, and glycosyl linkage was carried out. We observed that moringa contained the greatest content of carotenoids and tocopherols. Moringa also contained significant amounts of the flavonols quercetin 3-O-glucoside and quercetin 3-O-rutinoside, while baobab had greater concentrations of flavan-3-ols. Substantial content of anthocyanins was observed for hibiscus, but not moringa or baobab. The predominant monosaccharide in baobab was xylose, while hibiscus was a combination of xylose, galactose, and glucose. The primary monosaccharides in moringa were galactose and glucose. Based on our glycosyl linkage analysis, (1 → 2)- and (1 → 2,4)-linked rhamnose were attributed to rhamnogalacturonan-I, while (1 → 4)-linked glucose and (Terminal →)-linked xylose were attributed to xyloglucans. The phytochemical and polysaccharide characterization of baobab, moringa, and hibiscus suggested that delivery of micronutrients, such as iron and carotenoids, could be impacted when applied as functional food ingredients.
Tea (Camellia sinensis) is the most widely consumed beverage in the world, with an excellent source of bioactive compounds such as catechins, caffeine, and epigallocatechin. There is an increasing trend to extract these bioactive compounds to deliver them as value-added products. Generally, the extraction of polyphenols and other functional compounds from different parts of tea is carried out using different solvents (e.g., water, water–ethanol, ethanol, methanol, acetone, ethyl acetate, and acetonitrile). The extraction efficiency of functional compounds from tea depends on the type and polarity of the solvent as well as the applied process. Several conventional techniques, such as boiling, heating, Soxhlet, and cold extraction, are used to extract bioactive ingredients. However, these procedures are unsuitable for achieving high yields and biological activities due to the long extraction times of cold brewing and the high temperatures in other heating methods. Many efforts have been carried out in food and pharmaceutical industries to replace conventional extraction techniques with innovative technologies (e.g., microwave (MAE), ultrasonic (UAE), pressurized liquid (PLE), pulsed electric field (PEF), and supercritical fluid (SFE)), which are fast, safe, energy-saving, and can present eco-friendly characteristics. These innovative extraction techniques have proven to improve the recovery rate of phenolic-based antioxidant compounds from tea and increase their extraction efficiency. In this review, the application of novel processing technologies for the extraction of value-added compounds from tea leaves is reviewed. The advantages and drawbacks of using these technologies are also highlighted.
Due to the widespread applications of metal nanoparticles (NPs), green synthesis strategies have recently advanced, e.g., methods that utilize extracts made from different plant wastes. A particularly innovative approach to reducing large amounts of available household/agricultural green wastes is their application in nanoparticle generation. Regarding this, the aim of our work was to examine the possibility of upgrading green nanoparticle syntheses from an innovative economic and environmental point of view, namely by investigating the multiple recyclabilities of green tea (GT), coffee arabica (CA), and Virginia creeper ( Parthenocissus quinquefolia ) (VC) waste residues for iron nanoparticle (FeNPs) synthesis. The plant extracts obtained by each extraction round were analyzed individually to determine the amount of main components anticipated to be involved in NPs synthesis. The synthesized FeNPs were characterized by X-ray powder diffraction and transmission electron microscopy. The activity of the generated FeNPs in degrading chlorinated volatile organic compounds (VOC) and thus their future applicability for remediation purposes were also assessed. We have found that VC and especially GT residues could be reutilized in multiple extraction rounds; however, only the first extract of CA was suitable for FeNPs’ generation. All of the obtained FeNPs could degrade VOC with efficiencies GT1-Fe 91.0%, GT2-Fe 83.2%, GT3-Fe 68.5%; CA1-Fe 76.2%; VC1-Fe 88.2%, VC2-Fe 79.7%, respectively, where the number (as in GT3) marked the extraction round. These results indicate that the adequately selected green waste material can be reutilized in multiple rounds for nanoparticle synthesis, thus offering a clean, sustainable, straightforward alternative to chemical methods.
Graphical abstract
Tea is not only just a beverage in Turkey, it is but also a considerable part of the Turkish culture. You can meet a cup of tea anytime, anywhere in Turkey. The place of tea in Turkish culture has also attracted the attention of foreigners. It is important that the tea served well-infused and, the infusion time plays a decisive role in consumer’s preference.
With this paper, depending on the three criterion of evaluation that contain quality parameters, minerals and sensory parameters, the ideal infusion time was determined according to the traditional Turkish type black tea infusion method.
This study investigates the effects of in vitro digestion on the antioxidant activity and release of phenolics, xanthine alkaloids, and L-theanine contents of matcha. It establishes digestibility values between 61.2–65.8%. Considering native matcha, the rutin content (303–479 µg/g) reached higher values than catechin (10.2–23.1 µg/g). Chlorogenic acid (2090–2460 µg/g) was determined as predominant. Rutin, quercetin, ferulic, ellagic, and caffeic acid were the least-released phenolics, and their remaining residues reached 76–84%. Protocatechuic, hydroxybenzoic acid, epigallocatechin, and epigallocatechin-3-gallate were the best-released phenolics, with the remaining residues under 1%. Caffeine, L-theanine, and theobromine contents in native matcha reached 16.1, 9.85, and 0.27 mg/g, respectively. Only caffeine (3.66–5.26 mg/g) and L-theanine (0.09–0.15 mg/g) were monitored in the undigested residue, representing 13 and 0.1% of the remaining part, respectively. A chemiluminescence assay showed that water-soluble antioxidants showed significant antioxidant activity in native matcha, while lipid-soluble compounds showed higher antioxidant activity in the undigested samples. Cinnamic and neochlorogenic acids were determined as the main contributors to the ACW values in the undigested matcha, epicatechin, and quercetin in the ACL fraction. The application of the digestion process reduced the antioxidant activity by more than 94%. SEM has proved specific digestion patterns of in vitro digestibility of matcha.
This study was conducted to investigate the effect of ethanol acidification
on the antioxidant properties of Morinda citrifolia leaf (MCL) extract and its catechin
derivatives. Four different ethanol (100%, 99.5%, 70%, 50%) with or without 0.5%
acetic acid were used for extraction. The antioxidant profile was studied with DPPH
radical scavenging activity, FRAP and TPC. The quantification of catechins in MCL
was performed using HPLC, and the identification of catechins derivatives was
performed with Ultra UPLC-TWIMS-QTOF. The results showed that an extraction
solvent composed of 70% ethanol: 29.5% water: 0.5 % acetic acid exhibited the
highest DPPH percentage of inhibition (86.12±2.96%) and highest TPC value with
97.80±0.25 mg GAE/g extract, while 100% ethanol acidified with 0.5% acetic acid
showed highest FRAP antioxidant power with 1.31±0.05mg FSE/g extract. All eight
types of catechins were identified in MCL and the most total catechins were
quantified in 70% ethanol: 29.5% water: 0.5 % acetic acid at 153.57mg/g. The
catechin derivatives identified included epigallocatechin-3-O-gallate (EGCG),
epigallocatechin (4β, 8)-gallocatechin, gallocatechin (4α→8)-epicatechin, catechin-3-
O-gallate (CG) and epigallocatechin (EGC). The results suggest that acidification
improves the extraction of polyphenols as well as catechin content.
Keywords: “Acidification, Antioxidant, Catechin, Morinda citrifolia, UPLC-TWIMS-
QTOF”
In present study, different tea and coffee brands were analyzed and compared for their phenol, tannin and caffeine content.
The product having highest phenol contents was Red label (21.8%). The products having least tannin contents were; Red label (2.6%),
Parivar (1.08%). Remaining product as: Tata agni, bru and Nescafe showed almost same percentage of tannins in range 2.8%-
.3.0%Among various tea and coffee brands, Nescafe had maximum quantity (3.0%) of tannin. Parivar was containing highest quantity
(4.2%) of caffeine among all the studied products
Se realizó un análisis fitoquímico de la especie Ilex guayusa que incluyó determinar la capacidad antioxidante mediante el ensayo del poder antioxidante reductor férrico (FRAP, por sus siglas en inglés) y determinación de la cantidad de cafeína y teobromina mediante cromatografía líquida de alta eficiencia (HPLC, por sus siglas en inglés). Las muestras de Ilex guayusa consistieron en hojas que fueron recolectadas en diferentes lugares geográficos de la amazonía ecuatoriana, con el fin de obtener resultados más amplios. Los métodos empleados para los análisis cuantitativos y cualitativos demostraron ser de alta precisión y de buena reproducibilidad, ya que los resultados mostraron ser comparables a los obtenidos con plantas similares como Camellia sinensis. La capacidad antioxidante resultó ser relativamente alta y los contenidos de cafeína y teobromina presentaron valores máximos de 16.64 y 0.56 mg/g de peso de hoja fresca respectivamente.
Different teas from everywhere are very useful and have been extensively studied. We studied the antioxidant activity of herbal teas and green teas from Hainan, Mallotus oblongifolius Muell. Arg. (MO), Ilex kudingcha C.J. Tseng (KD), Camellia sinensis var. assamica (J. W. Mast.) Kitam. Hainan Dayezhong (DY), and Camellia sinensis (L.) O. Ktze. (produced from Hainan Baisha (BS)). The total phenol content and total flavonoid content from water extracts, resin extracts and fractions of herbal teas and green teas were compared. Later, eight fractions of herbal teas and green teas were subjected to UPLC-PDA-ESI-(−)-HRMS. We determined 1-diphenyl -2-picryl-hydrazyl radical and hydroxyl free radical scavenging activity by electron paramagnetic resonance spectroscopy. We subjected Saccharomyces cerevisiae to hydrogen peroxide, stress and evaluated antioxidant activity of herbal teas and green teas in cellulo. The experiment identified more than 14 potential antioxidant compounds from herbal teas and green teas. The herbal teas and green teas had a clearance rate higher than ferulic acid at the same concentrations. MO best reduced intracellular oxidation levels and increased catalase, glutathione reductase activities, glutathione reduced and glutathione oxidized content. KD had the highest cell survival rate and reduced cell lipid peroxidation. DY best improved superoxide dismutase activity and BS was the most active in the halo test. Therefore, we concluded that MO had stronger antioxidant activity than other herbal teas and green teas from Hainan, especially, which reduce S. cerevisiae oxidative stress under H2O2 stress.
To answer the question “How much caffeine do I have in my cup of tea?” we have developed a simple isocratic HPLC method with UV detection for determination of caffeine. The optimized method exhibits high repeatability; the retention time RSD was lower than 0.4% and RSD of the peak area was lower than 3.5%. The method was applied to five types of tea in loose leaf form differing in level of fermentation (black, pu-erh, oolong, green, and white). The brewing conditions were chosen to be as close as possible to domestic preparation of tea. In this study, we have focused on two important culinary factors: infusion time and brewing temperature. The results show that both investigated factors significantly influence the final content of caffeine in a cup of tea. Increase in caffeine content was up to 29% when the tea infusion was overextracted by 1 min. Increase was even higher (up to 66%) when boiling water was used instead of water of recommended temperature. It indicates that careful attitude to preparation of each type of tea is essential for caffeine content.
Graphical abstract
Open image in new window
A large scale isolation and purification of theaflavin (TF) and epigallocatechin (EGC) has been successfully developed by tannase-mediated biotransformation combining high-speed countercurrent chromatography. After tannase hydrolysis of a commercially available theaflavins extract (TE), the content of TF and EGC in tannase-mediated biotransformation product (TBP) achieved approximately 3 times enrichment. SEM studies revealed smooth tannase biotransformation and the possibility of recovery of the tannase. A single 1.5 hours' HSCCC separation for TF and EGC employing a two-phase solvent system could simultaneously produce 180.8 mg of 97.3% purity TF and 87.5 mg of 97.3% purity EGC. However, a preparative HPLC separation of maximum injection volume containing 120 mg TBP prepared 11.2 mg TF of 94.9% purity and 7.7 mg EGC of 89.9% purity. HSCCC separation demonstrated significant advantages over Prep HPLC in terms of sample loading size, separation time, environmental friendly solvent systems, and the production.
The popularity of caffeine as a psychoactive drug is due to its stimulant properties, which depend on its ability to reduce adenosine transmission in the brain. Adenosine A(1) and A(2A) receptors are expressed in the basal ganglia, a group of structures involved in various aspects of motor control. Caffeine acts as an antagonist to both types of receptors. Increasing evidence indicates that the psychomotor stimulant effect of caffeine is generated by affecting a particular group of projection neurons located in the striatum, the main receiving area of the basal ganglia. These cells express high levels of adenosine A(2A) receptors, which are involved in various intracellular processes, including the expression of immediate early genes and regulation of the dopamine- and cyclic AMP-regulated 32-kDa phosphoprotein DARPP-32. The present review focuses on the effects of caffeine on striatal signal transduction and on their involvement in caffeine-mediated motor stimulation.
Tea is the most widely consumed beverage in the world, second only to water. Most laypersons and scientists believe that green tea is healthier than black tea due to the low incidence of heart disease and cancer in the Orient. Here, we report the first dose-response comparison of a green and black tea on normal hamsters after long-term supplementation and on a hamster model of atherosclerosis. Both teas were equally effective in inhibiting atherosclerosis with the lower dose decreasing it 26-46% and the high dose decreasing it 48-63%. Atherosclerosis was inhibited by three mechanisms: hypolipemic, antioxidant, and antifibrinolytic. There was a significant correlation between atherosclerosis and the three mechanisms. In the normal animals, teas also caused some improvement in plasma low density lipoprotein (LDL), LDL/high density lipoprotein ratio, triglycerides, lipid peroxides, lower density lipoprotein lipid peroxides, and fibrinogen. Isolated lower density lipoprotein oxidizability was also reduced in all groups. Green and black teas were equally effective at human equivalent doses, thus confirming human intervention and epidemiology studies and providing mechanisms for teas' benefit.
Objective: To examine the influence of variety and brewing technique on the catechins, theaflavins, and thearubigins in black tea using published data.Methods and materials: Differences due to tea variety were examined by comparing values for the characteristic flavanols that are responsible in part for the distinct flavors of the various teas. These included catechins, theaflavins, and thearubigins in varieties of blended teas (from several regions) and unblended teas (from only one region) in the published literature. Total catechins, theaflavins, and thearubigins were calculated per 180 mL serving of tea for teabags of different weights. For brewing techniques, calculations by infusion strength of 1.25% (2.25 g teabag per 180 mL water) and by an illustrative extraction efficiency were compared to analytical results at a 2 min brewing time.Results: The unblended teas (e.g. Assam, Kenya, Ceylon, China, and Darjeeling) varied greatly in the amount and pattern of their flavonoid content. Compared to unblended teas, the blended teas were lower in total catechins and mid-range in theaflavins. Differences in flavonoid content per tea serving were the result of tea variety, weight of tea used, and, to a lesser extent, brewing technique.Significance: Tea variety, weight of tea or teabag, and brewing techniques all affect estimates of flavonoid intake. Databases that include flavonoid data for different varieties of teas and different brewing techniques will be useful for dietary assessment studies. For research purposes it would be helpful to list tea type (black, green, oolong, pu’er), unblended or blended, and if data suffice, for unblended by region (Assam, China, Darjeeling) and for blended by name (Earl Gray, English Breakfast). More research is needed on the effects of brewing techniques so accurate formulas can be developed to determine flavonoid content.
This paper describes the simultaneous determination of catechins and theaflavins in green and black teas, using reversed-phase high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE). The tea polyphenols analyzed included (+)-catechin, catechin gallate, (−)-epicatechin, epicatechin-3-gallate, epigallocatechin, epigallocatechin-3-gallate, theaflavin, theaflavin-3-monogallate, theaflavin-3′-monogallate and theaflavin-3,3′-gallate. These polyphenols together with six other tea ingredients such as caffeine, adenine, theophylline, quercetin, gallic acid and caffeic acid were separated within 27 min by HPLC and in less than 10 min by CE. The optimal analytical conditions of both chromatographic methods were investigated for the convenience and reliability for routine analysis. Both HPLC and CE were found to be reliable and compatible. The reproducibility of the within-day assay using both methods was generally >90%. The day-to-day variation of retention time was <5% for HPLC, while the variation of migration time for CE was <2%. The analysis time of CE was three-times faster, however it is five-times less sensitive than HPLC, which has detection limits of 0.05 μg/ml and 0.5 μg/ml for catechins and theaflavins, respectively.
Studies in cell culture and laboratory animals have shown that green tea and its major component, epigallocatechin-3-gallate, inhibit cell growth and reduce tumor incidence. However, results of epidemiological studies have generated inconsistent, sometimes conflicting data regarding protection by green tea against human cancers. To clarify the findings of these laboratory studies in application to humans, we conducted a pilot intervention study with three heavy smokers (> 10 cigarettes/day) and three nonsmokers (never smokers) in order to evaluate the molecular and cellular effects of drinking green tea using human oral cells as an investigative tool. Green tea total extract (400-500 mg/cup, 5 cups/day) was administered in drinking water to the subjects for four weeks. Two oral cytology samples were taken weekly for measurements of tobacco carcinogen-induced DNA damage, including bulky adducts and oxidized bases, cell growth, DNA content, and apoptosis. The study showed that during the course of green tea administration smoking-induced DNA damage was decreased, cell growth was inhibited, and the percentage of cells in S phase was reduced, cells accumulated in G1 phase (cyclin D1 positive), DNA content became more diploid and less aneuploid, and p53, Caspase-3, and TUNEL, markers of apoptosis, were increased. The study, although preliminary, indicates that drinking green tea reduced the number of damaged cells in smokers by inducing cell growth arrest and apoptosis, a mechanism similar to that observed in cultured cells and animals. These results warrant a large-scale intervention trial to further verify the role of green tea in the prevention of oral cancer in smokers.
Tea is the most highly consumed beverage in the world, other than water. However, unlike water, tea contains substantial amounts of polyphenols that have unique biological activities and may be responsible for many of the health benefits of tea. As a result, it is essential to be able to measure the various tea-associated polyphenols. Total polyphenol content is currently measured by using methodology based on reducing activity. Several HPLC systems with detectors that, collectively, have wide ranges in sensitivity have been developed for analysis of individual flavonoids in tea and biological samples, and for theaflavins in tea. Catechins also have been measured in plasma by solid phase extraction, addition of a chromophore, and colorimetric quantification. Except for theaflavins in tea, routine and robust methods for the measurement of polyphenol condensation products (dimers and thearubigens) in tea and biological samples have not been developed. Although in vitro and animal studies suggest substantial metabolism of flavonoids in the gastrointestinal tract, only a single HPLC procedure has been assembled for monitoring the metabolic products of quercetin in urine of human subjects.
Tea polyphenols are strong antioxidants and are believed to have beneficial health effects. However, the blood and tissue levels of these compounds are not well characterized because of a lack of suitable analytical methods for the biological resolution of these compounds. Previously, we developed methods for the analysis of three green tea catechins. Now we report an improved method for the measurement of the levels of the different catechins and theaflavins in biological fluids and tissues. The method includes digestion of the plasma, urine, or tissue samples with beta-d-glucuronidase and sulfatase, followed by extraction with ethyl acetate and subsequent separation by reversed-phase high-performance liquid chromatography (HPLC). The polyphenols are identified on the basis of their retention times, spectral analysis, and electrochemical behavior across an array of electrodes. In a single HPLC run, it is possible to determine the major catechins and theaflavins as well as some of the catechin metabolites. The detection limits for catechins and theaflavins are from 5 to 10 ng/ml of saliva, plasma, or urine.
It is not uncommon to treat plant-derived foods and feeds with alkali. Such exposure to high pH is being used to recover proteins from cereals and legumes, to induce the formation of fiber-forming meat analogue vegetable protein, for preparing peeled fruits and vegetables, and for destroying microorganisms. In addition to their profound effects on functional and nutritional properties in such foods, such treatments may also cause other side reactions, including the destruction of natural polyphenolic compounds. Because plants contain a large number of structurally different antioxidant, anticarcinogenic, and antimicrobial polyphenolic compounds, it is of interest to know whether such compounds are stable to heat and to high pH. In this model study, the stability of the following natural polyphenols to pH in the range 3-11 was studied with the aid of ultraviolet spectroscopy: caffeic acid, (-)-catechin, chlorogenic acid, ferulic acid, gallic acid, (-)-epigallocatechin, rutin, and the nonphenolic compound trans-cinnamic acid. This study demonstrates that caffeic, chlorogenic, and gallic acids are not stable to high pH and that the pH- and time-dependent spectral transformations are not reversible. By contrast, chlorogenic acid is stable to acid pH, to heat, and to storage when added to apple juice. (-)-Catechin, (-)-epigallocatechin, ferulic acid, rutin, and trans-cinnamic acid resisted major pH-induced degradation. The results are rationalized in terms of relative resonance stabilization of phenoxide ions and quinone oxidation intermediates. The possible significance of these findings to food chemistry and microbiology is discussed.
Green tea catechins, including (-)-epicatechin (EC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin (EGC) and (-)-epigallocatechin gallate (EGCG), are oxidized and dimerized during the manufacture of black tea and oolong tea to form orange-red pigments, theaflavins (TF), a mixture of theaflavin (TF1), theaflavin-3-gallate (TF2A), theaflavin-3'-gallate (TF2B) and theaflavin-3,3'-digallate (TF3). The present study was designed to compare the antioxidant activities of individual TF with that of each catechin using human LDL oxidation as a model. All catechins and TF tested inhibited Cu(+2)-mediated LDL oxidation. Analysis of the thiobarbituric acid-reactive substances (TBARS) and conjugated dienes produced during LDL oxidation revealed that the antioxidant activity was in the order: TF3 > ECG > EGCG > or = TF2B > or = TF2A > TF1 > or = EC > EGC. Four TF derivatives also demonstrated a dose-dependent antioxidant activity in Cu(+2)-mediated LDL oxidation at concentrations of 5-40 micromol/L. These results demonstrate that the TF present in black tea possess at least the same antioxidant potency as catechins present in green tea, and that the conversion of catechins to TF during fermentation in making black tea does not alter significantly their free radical-scavenging activity.
Levels of total phenol, catechins, and caffeine in teas commonly consumed in the United Kingdom have been determined using reversed phase high-performance liquid chromatography. Tea bags or tea leaves were purchased from local supermarkets and extracted in boiling water for 5 min. The resulting data showed considerable variability in both total phenols [80.5-134.9 mg/g of dry matter (DM) in black teas and 87-106.2 mg/g of DM in green teas] and catechins (5.6-47.5, 51.5-84.3, and 8.5-13.9 mg/g of DM in black, green, and fruit teas, respectively); this was most probably a result of differing agronomic conditions, leaf age, and storage during and after transport, as well as the degree of fermentation. Caffeine contents of black teas (22-28 mg/g of DM) were significantly higher than in less fermented green teas (11-20 mg/g of DM). The relative concentration of the five major tea catechins ranked EGCG > ECG > EC > EGC > C. The estimated U.K. dietary intakes of total tea catechins, calculated on the basis of an average tea consumption of three cups of tea (200 mL cup, 1% tea leaves w/v), were 61.5, 92.7, and 405.5 mg/day from fruit teas, black teas, and green teas, respectively. The coefficients of variation were 19.4, 88.6, and 17.3%, respectively, indicating the wide variation in these intakes. The calculated caffeine intake ranged between 92 and 146 mg/day. In addition, many individuals will consume much larger quantities of tea, of various strengths (as determined by the brewing conditions employed). This broad spread of U.K. daily intakes further emphasizes the need for additional research to relate intake and effect in various population groups.
The contents of gallic acid, epigallocatechin gallate, epigallocatechin, epicatechin, epicatechin gallate, catechin, caffeine, theophylline, and theobromine were determined in a set of 45 tea samples, including fermented (black and red) and nonfermented (green) teas of different geographical origins (i.e., China, Japan, Kenya, Sri Lanka, and India). A reversed-phase high performance liquid chromatographic method with gradient elution and photometric detection at 275 nm was used to carry out the analysis. Before the HPLC determination, an extraction step was developed using a mixture of acetonitrile and water (60:40, v/v). Pattern recognition techniques involving principal component analysis (PCA) and linear discriminant analysis (LDA) were applied to differentiate the tea samples according to their geographical origins. Catechins, gallic acid, and tea alkaloids are adequate chemical descriptors to distinguish between fermented and nonfermented tea samples cultivated in different geographical areas.
The phenolic composition and antioxidant activities [TEAC, ORAC, FRAP] of consumer brews (1 tea bag in 230 ml for 1 min) of seven different brands of black tea from the British market were investigated. The main phenolic compounds identified were epigallocatechin gallate, four theaflavins, as well as epicatechin gallate, theogallin (tentative assignment), quercetin-3-rutinoside and 4-caffeoyl quinic acid. Thearubigins represented an estimated 75-82% of the total phenolics. Further, polyphenol fractions were in decreasing order theaflavins, flavan-3-ols, flavonols, gallic acids and hydroxycinnamates. On average, a cup of a consumer brew of black tea is providing polyphenols at the level of 262mg GAE/serving, of which 65 mg were assigned to individual polyphenols. The antioxidant activity of black tea preparations is higher than that of most reported dietary agents on a daily basis. Correlations were observed between the antioxidant activities and the sum of all quantified polyphenols by HPLC analysis as well as with the total phenolics. Treatment of the black tea brew with simulated gastric juice resulted in a significant increase of the identified theaflavins implying a partial cleavage of thearubigins in the environment of the gastric lumen. Therefore, black tea can be considered to be a rich source of polyphenols and/or antioxidants.
Polyphenols, which have beneficial effects on health and occur ubiquitously in plant foods, are extremely diverse. We developed a method for simultaneously determining all the polyphenols in foodstuffs, using HPLC and a photodiode array to construct a library comprising retention times, spectra of aglycons, and respective calibration curves for 100 standard chemicals. The food was homogenized in liquid nitrogen, lyophilized, extracted with 90% methanol, and subjected to HPLC without hydrolysis. The recovery was 68-92%, and the variation in reproducibility ranged between 1 and 9%. The HPLC eluted polyphenols with good resolution within 95 min in the following order: simple polyphenols, catechins, anthocyanins, glycosides of flavones, flavonols, isoflavones and flavanones, their aglycons, anthraquinones, chalcones, and theaflavins. All the polyphenols in 63 vegetables, fruits, and teas were then examined in terms of content and class. The present method offers accuracy by avoiding the decomposition of polyphenols during hydrolysis, the ability to determine aglycons separately from glycosides, and information on simple polyphenol levels simultaneously.
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.
Antioxidant properties and stimulating effects of green tea are related to its content of cathechins and xanthines; tea quality evaluation is based on organoleptic tests and on the presence of those components. In this work, by a MEKC method, eight cathechins and three xanthines were quantified in some tea-based beverages. The best separation was realized using a phosphate-borate running buffer, with sodium dodecyl sulfate as micellar agent. A 40 cm capillary, a temperature of 29 degrees C, a voltage of 30 kV, and UV detection at 200 nm were used. The method showed a very good sensitivity (limit of detection ranging from 0.0011 to 0.0051 microg/mL) and was applied to real tea samples to characterize their antioxidant content. Statistical studies were performed and showed a satisfactory reliability of the data.
Diverse procedures have been reported for the separation and analysis by HPLC of the two major glycoalkaloids present in potatoes, alpha-chaconine and alpha-solanine. To further improve the usefulness of the HPLC method, studies were carried out on the influence of several salient parameters on the analysis of the two potato glycoalkaloids. Effects on retention (elution, separation) times of the (a) composition and pH of the mobile phase (acetonitrile and phosphate buffer), (b) concentration of the phosphate buffer, (c) capacity values of column packing of four commercial HPLC amino columns, (d) column temperature were studied. Except for pH, all of the variables significantly influenced the retention times. The results make it possible to select analysis conditions that produce well-separated as well as symmetrical peaks of the two glycoalkaloids. This improved HPLC method (limit of detection of approximately 150 ng) was evaluated with extracts from the cortex of one whole potato variety (May Queen) grown in Japan and the freeze-dried peel and flesh from the following eight cultivars grown in the United States: Atlantic, Dark Red Norland, Ranger Russet, Red Lasoda, Russet Burbank, Russet Norkota, Shepody, and Snowden. In addition, the same samples were analyzed by GC-MS for the presence of two water-soluble nortropane alkaloids, calystegine A(3) and calystegine B(2), reported to be potent glycosidase inhibitors. The following ranges for the eight varieties of total glycoalkaloid and calystegine levels were observed: dry flesh, 5-592 and 6-316 mg/kg; dry peel, 84-2226 and 218-2581 mg/kg; dry whole potatoes, 40-883 and 34-326 mg/kg; wet flesh, 1-148 and 1-68 mg/kg; wet peel, 12-429 and 35-467 mg/kg; wet whole potatoes, 7-187 and 5-68 mg/kg. The possible significance of the results to plant and food sciences is discussed.
The anticancer properties of tea catechins are most frequently attributed to the principal catechin (-)-epigallocatechin-3-gallate (EGCg). Efficacy was evaluated using growth of cultured HeLa cells and inhibition of the enzymatic activity of a putative cell surface tea target enzyme, a cancer-associated cell surface-located NADH oxidase (ECTO-NOX) designated tNOX. The amounts of EGCg required to inhibit by both criteria was reduced 10 times by combination with inactive catechins such as (-)-epicatechin (EC), (-)-epigallocatechin (EGC) or (-)-epicatechin-3-gallate (ECG). Various synthetic mixtures based on purified catechins and decaffeinated tea extracts treated enzymatically to reduce the ester bond-containing catechins varying in EGCg content from 0.065 to 40% were of comparable efficacy to decaffeinated green tea extracts as long as EGCg was present and the ratio of total catechins to EGCg + EGC was about 1.5. Such mixtures appear to offer potential cancer protection and therapeutic advantages over those of EGCg alone through lowered toxicity of the mixture to normal cells and for more efficient blood delivery of orally-administered catechins to a tumour site.
Tea consumption has been associated with decreased cardiovascular risk, but potential mechanisms of benefit are ill-defined. While epidemiologic studies suggest that drinking multiple cups of tea per day lowers low-density lipoprotein cholesterol (LDL-C), previous trials of tea drinking and administration of green tea extract have failed to show any impact on lipids and lipoproteins in humans. Our objective was to study the impact of a theaflavin-enriched green tea extract on the lipids and lipoproteins of subjects with mild to moderate hypercholesterolemia.
Double-blind, randomized, placebo-controlled, parallel-group trial set in outpatient clinics in 6 urban hospitals in China. A total of 240 men and women 18 years or older on a low-fat diet with mild to moderate hypercholesterolemia were randomly assigned to receive a daily capsule containing theaflavin-enriched green tea extract (375 mg) or placebo for 12 weeks. Main outcome measures were mean percentage changes in total cholesterol, LDL-C, high-density lipoprotein cholesterol (HDL-C), and triglyceride levels compared with baseline.
After 12 weeks, the mean +/- SEM changes from baseline in total cholesterol, LDL-C, HDL-C, and triglyceride levels were -11.3% +/- 0.9% (P =.01), -16.4% +/- 1.1% (P =.01), 2.3% +/- 2.1% (P =.27), and 2.6% +/- 3.5% (P =.47), respectively, in the tea extract group. The mean levels of total cholesterol, LDL-C, HDL-C, and triglycerides did not change significantly in the placebo group. No significant adverse events were observed.
The theaflavin-enriched green tea extract we studied is an effective adjunct to a low-saturated-fat diet to reduce LDL-C in hypercholesterolemic adults and is well tolerated.
Levels of essential elements with antioxidant activity, as well as catechins, gallic acid, and caffeine levels, in a total of 45 samples of different teas commercialized in Spain have been evaluated. Chromium, manganese, selenium, and zinc were determined in the samples mineralized with HNO(3) and V(2)O(5), using ETAAS as the analytical technique. The reliability of the procedure was checked by analysis of a certified reference material. Large variations in the trace element composition of teas were observed. The levels ranged from 50.6 to 371.4 ng/g for Cr, from 76.1 to 987.6 microg/g for Mn, from 48.5 to 114.6 ng/g for Se, and from 56.3 to 78.6 ng/g for Zn. The four major catechins [(-)-epigallocatechin gallate (EGCG), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epicatechin (EC)], gallic acid (GA), and caffeine were simultaneously determined by a simple and fast HPLC method using a photodiode array detector. In all analyzed samples, EGCG ranged from 1.4 to 103.5 mg/g, EGC from 3.9 to 45.3 mg/g, ECG from 0.2 to 45.6 mg/g, and EC ranged from 0.6 to 21.2 mg/g. These results indicated that green tea has a higher content of catechins than both oolong and fermented teas (red and black teas); the fermentation process during tea manufacturing reduces the levels of catechins significantly. Gallic acid content ranged from 0.039 to 6.7 mg/g; the fermentation process also elevated remarkably gallic acid levels in black teas (mean level of 3.9 +/- 1.5 mg/g). The amount of caffeine in the analyzed samples ranged from 7.5 to 86.6 mg/g, and the lower values were detected in green and oolong teas. This study will be useful for the appraisal of trace elements and antioxidant components in various teas, and it will also be of interest for people who like drinking this beverage.
Flavonoids and their polymers constitute a large class of food constituents, many of which alter metabolic processes and have a positive impact on health. Flavonoids are a subclass of polyphenols. They generally consist of two aromatic rings, each containing at least one hydroxyl, which are connected through a three-carbon "bridge" and become part of a six-member heterocyclic ring. The flavonoids are further divided into subclasses based on the connection of an aromatic ring to the heterocyclic ring, as well as the oxidation state and functional groups of the heterocyclic ring. Within each subclass, individual compounds are characterized by specific hydroxylation and conjugation patterns. Many flavonoids in foods also occur as large molecules (tannins). These include condensed tannins (proanthocyanidins), derived tannins and hydrolysable tannins. For proanthocyanidins, three subclasses (15 characterized) have been identified in foods. Monomers are connected through specific carbon-carbon and ether linkages to form polymers. Derived tannins are formed during food handling and processing, and found primarily in black and oolong teas. Flavonoids are widely distributed in nature, albeit not uniformly. As a result, specific groups of foods are often rich sources of one or more subclasses of these polyphenols. The polyphenolic structure of flavonoids and tannins renders them quite sensitive to oxidative enzymes and cooking conditions. Scientists in several countries have estimated intakes of a few subclasses of flavonoids from limited food composition databases. These observations suggest large differences in consumption, due in part to cultural and food preferences among populations of each country.
Black tea, green tea, red wine, and cocoa are high in phenolic phytochemicals, among which theaflavin, epigallocatechin gallate, resveratrol, and procyanidin, respectively, have been extensively investigated due to their possible role as chemopreventive agents based on their antioxidant capacities. The present study compared the phenolic and flavonoid contents and total antioxidant capacities of cocoa, black tea, green tea, and red wine. Cocoa contained much higher levels of total phenolics (611 mg of gallic acid equivalents, GAE) and flavonoids (564 mg of epicatechin equivalents, ECE) per serving than black tea (124 mg of GAE and 34 mg of ECE, respectively), green tea (165 mg of GAE and 47 mg of ECE), and red wine (340 mg of GAE and 163 mg of ECE). Total antioxidant activities were measured using the 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays and are expressed as vitamin C equivalent antioxidant capacities (VCEACs). Cocoa exhibited the highest antioxidant activity among the samples in ABTS and DPPH assays, with VCEACs of 1128 and 836 mg/serving, respectively. The relative total antioxidant capacities of the samples in both assays were as follows in decreasing order: cocoa > red wine > green tea > black tea. The total antioxidant capacities from ABTS and DPPH assays were highly correlated with phenolic content (r2 = 0.981 and 0.967, respectively) and flavonoid content (r2 = 0.949 and 0.915). These results suggest that cocoa is more beneficial to health than teas and red wine in terms of its higher antioxidant capacity.
Derivatives based on a benzotropolone skeleton (9-26) have been prepared by the enzymatic coupling (horseradish peroxidase/H2O2) of selected pairs of compounds (1-8), one with a vic-trihydroxyphenyl moiety, and the other with an ortho-dihydroxyphenyl structure. Some of these compounds have been found to inhibit TPA-induced mice ear edema, nitric oxide (NO) synthesis, and arachidonic acid release by LPS-stimulated RAW 264.7 cells. Their cytotoxic activities against KYSE 150 and 510 human esophageal squamous cell carcinoma and HT 29 human colon cancer cells were also evaluated.
We examined the antibacterial effects of epigallocatechin gallate (EGCg, the main constituent of tea catechins) against various strains of Staphylococcus and Gram-negative rods. Compared to the minimum inhibitory concentrations (MICs) of EGCg against S. aureus, S. epidermidis, S. hominis, and S. haemolyticus (50-100 micro g/ml), higher MICs (>or=800 micro g/ml) were observed against Gram-negative rods, including Escherichia coli, Klebsiella pneumoniae, Salmonella typhi, Proteus mirabilis, Pseudomonas aeruginosa, and Serratia marcescens. And difference was observed between the binding abilities of EGCg with viable S. aureus and with E. coli. The bactericidal activity of EGCg for S. aureus was blocked dose-dependently by purified peptidoglycan but not by lipopolysaccharide or dextran. It was also found that peptone and protein, but not amino acids, in the culture medium greatly affected the antibacterial activity of EGCg. These results indicate that the structure of the bacterial cell wall and the different affinities of EGCg with the various cell wall components are responsible for the different susceptibilities of Staphylococcus and Gram-negative rods to EGCg.
Tomato plants (Lycopersicon esculentum) synthesize the glycoalkaloids dehydrotomatine and alpha-tomatine, possibly as a defense against bacteria, fungi, viruses, and insects. We used a high-performance liquid chromatography method with UV detection at 208 nm for the analysis of these compounds in various tissues. An Inertsil ODS-2 column with a mobile phase of acetonitrile/20 mM KH2PO4 (24/76, v/v) afforded good separation of the two glycoalkaloids in mini-tomato extracts, fruit harvested at different stages of maturity, and calyxes, flowers, leaves, roots, and stems. The two peaks appeared at approximately 17 and approximately 21 min. Recoveries from tomato fruit extracts spiked with dehydrotomatine and alpha-tomatine were 87.7 +/- 6.8 and 89.8 +/- 3.4% (n = 5), respectively. The detection limit is estimated to be 0.39 microg for dehydrotomatine and 0.94 microg for alpha-tomatine. The dehydrotomatine and alpha-tomatine content of tomatoes varied from 42 to 1498 and 521 to 16 285 microg/g of fresh weight, respectively. The ratio of alpha-tomatine to dehydrotomatine ranged from 10.9 to 12.5 in tomatoes and from 2.3 to 7.8 in the other plant tissues. These results suggest that the biosynthesis of the glycoalkaloids is under separate genetic control in each plant part. Degradation of both glycoalkaloids occurred at approximately the same rate during maturation of the tomatoes on the vine. An Inertsil NH2 column, with acetonitrile/1 mM KH2PO4 (96/4, v/v) as the eluent, enabled the fractionation of commercial tomatidine into tomatidenol and tomatidine, the aglycons of dehydrotomatine and alpha-tomatine, respectively. The information should be useful for evaluating tomatoes and vegetative tissues for dehydrotomatine/alpha-tomatine content during fruit development and their respective roles in host-plant resistance and the diet.
Black tea contains two major groups of pigments, theaflavins (TFs) and thearubigins (TRs). TFs contain a bis-flavan substituted 1,2-dihydroxy-3,4-benzotropolone moiety. Unlike the TFs, TRs have not yet been characterized. The chemical structure of the TRs remains a mystery. The present paper reports our effort to study the structure of TFs and TRs using delayed pulsed ion extraction of ions generated via the matrix-assisted laser desorption ionization (MALDI) technique, on line with a Linear time-of-flight (TOF) mass spectrometer. Spectra of standard TFs show not only pseudomolecular ions but also ions resulting from fragmentation. The analysis of MALDI-TOF spectra of black tea fractions shows the structure of some TRs, which are similar to those of TFs because the same loss of mass is observed.
A reverse phase high performance liquid chromatography (RP-HPLC) separation coupled with photo diode array detection (DAD) and electrospray ionization mass spectrometry (ESI-MS) detection was established for the analyzing of multiple bioactive compounds in tea and tea extracts. Theanine, chlorogenic acid, purine alkaloids and catechins were identified with authentic standard compounds and with MS-spectra. The content of theanine and catechins was measured by employing DAD and caffeine, chlorogenic acid, theobromine and theopylline by protonated molecular ion on selective ion recording (SIR) mode. The unity of LC/ESI-MS provides more qualitative and quantitative information comparing with general HPLC in the analysis of multi-components in tea, and complex extraction or sample pretreatment is unnecessary. The chromatogram acquired by using this method can be used as a bioactive components fingerprint for the quality control of tea and its extracts. With the help of multi-dimension information of HPLC-DAD-ESIMS, the compounds owning different chemical structure such as amino acid, catechins, etc. in tea and its extracts could be identified and determined in one run successfully.
Tea is a complex mixture containing a range of compounds from simple phenolics to complex thearubigins, many of which have well-recognized antioxidant properties. This paper describes the application of high-performance liquid chromatography-mass spectrometry (HPLC-MS(n)) methods for the rapid and routine analysis of more than 30 phenolics in tea. Green and black tea infusions were injected directly onto a reversed phase HPLC column, and the phenolics eluted using two different mobile phase gradients, one optimized to resolve catechin derivatives and the other, flavonols and theaflavins. Compounds, identified on the basis of their retention time, absorbance spectrum, and MS fragmentation pattern, included (+)-catechin, (-)-epicatechin, theaflavin and their various gallate derivatives, quercetin and kaempferol mono-, di-, and triglycosides, quinic acid esters of gallic acid and hydroxycinnamates, and the purine alkaloids, caffeine and theobromine.
Green tea catechins possess potent antioxidative properties, and the preventive effects against various oxidative diseases have been reported. The purpose of this study is to examine preventive and protective effects of green tea catechins on various deteriorative processes following stroke.
Male Wistar rats were given ad libitum water with or without 0.25 and 0.5% tea catechin extract for 5 days prior to the operation and during the experiment. Right middle cerebral artery was occluded for 2 h, then reperfused for 22 h. Brain slices were stained with triphenyltetrazolim chloride to assess infarct area. Concentrations of plasma EGCg, and serum NOx were analyzed by HPLC. Detection of iNOS expression, neutrophil infiltration and peroxynitrite formation in the penumbra was performed by immunostain. Neurologic deficit was scored by posture reflex.
Tea catechins dose-dependently reduced the brain infarct area and volume. Infarct volume was inversely correlated with plasma EGCg concentration. Dark staining for iNOS, neutrophils and peroxynitrite were observed in vessel wall of small arteries in control ischemic hemisphere, while in catechins (0.5%)-treated rats iNOS was detected slightly, and staining for neutrophils and peroxynitrite was not seen. Catechin ingestion blocked a 3-fold increase in serum NOx concentration in the jugular vein, and also reduced by 35% a 2-fold increase of plasma lipid peroxide level seen in control rats after reperfusion. Neurologic deficits were significantly alleviated by 0.5% catechin ingestion.
Daily intake of green tea catechins efficiently protects the penumbra from irreversible damage due to cerebral ischemia, and consequent neurologic deficits.
A new spectrophotometric enzymatic method for the determination of total phenol content in tea and wine has been developed. The method is based on the peroxidase-catalyzed oxidation, by hydrogen peroxide, of phenols to phenoxyl radicals, which can react with aromatic substrates to form intensely colored adducts. In comparison with the widely used Folin-Ciocalteu method, this method appears to be more specific and more rapid and as a whole is not affected by the common interfering substances such as ascorbate, citrate, and sulfite. Numerous samples of teas and wines were analyzed by using the new method, and the results compared with those obtained by using the Folin and scavenging of DPPH methods. The differences of the total phenols content found by applying the three methods are discussed in terms of the different specificities of the analytical basis.
A green tea extract (GTE) was incorporated into bread as a source of tea catechins. The stability of tea catechins in the breadmaking process including unfrozen and frozen dough was studied. A method was developed for the separation and quantification of tea catechins in GTE, dough, and bread samples using a RP-HPLC system. The separation system consisted of a C18 reversed-phase column, a gradient elution system of water/methanol and formic acid, and a photodiode array UV detector. Tea catechins were detected at 275 nm. GTEs at 50, 100, and 150 mg per 100 g of flour were formulated. The results obtained showed that green tea catechins were relatively stable in dough during freezing and frozen storage at -20 degrees C for up to 9 weeks. There were no further detectable losses of tea catechins in bread during a storage of 4 days at room temperature. It was also revealed that (-)-epigallocatechin gallate (EGCG) and (-)-epigallocatechin (EGC) were more susceptible to degradation than (-)-epicatechin gallate (ECG) and (-)-epicatechin (EC). (-)-EGCG and (-)-ECG were normally selected as the quality indices of green tea catechins, and their retention levels in freshly baked bread were ca. 83 and 91%, respectively. One piece of bread (53 g) containing 150 mg of GTE/100 g of flour will provide 28 mg of tea catechins, which is approximately 35% of those infused from one green tea bag (2 g).
Frequent coffee consumption has been associated with a reduced risk of colorectal cancer in a number of case-control studies. Cohort studies have not revealed such an association but were limited in size. We explored the association between consumption of coffee and tea and the incidence of colorectal cancer in two large prospective cohorts of women and men.
We used data from the Nurses' Health Study (women) and the Health Professionals' Follow-up Study (men). Consumption of coffee and tea and total caffeine intake were assessed and updated in 1980, 1984, 1986, 1990, and 1994 among women and in 1986, 1990, and 1994 among men. The incidence of cancer of the colon or rectum was ascertained through 1998. Hazard ratios were calculated using Cox proportional hazards models that adjusted for potential confounders. All tests of statistical significance were two-sided.
During almost 2 million person-years of follow-up, 1438 cases of colorectal cancer were observed. Consumption of caffeinated coffee or tea with caffeine or caffeine intake was not associated with the incidence of colon or rectal cancer in either cohort. For both cohorts combined, the covariate-adjusted hazard ratio for colorectal cancer associated with consumption of each additional cup of caffeinated coffee was 0.99 (95% confidence interval [CI] = 0.96 to 1.03). However, participants who regularly consumed two or more cups of decaffeinated coffee per day had a 52% (95% CI = 19% to 71%) lower incidence of rectal cancer than those who never consumed decaffeinated coffee.
Consumption of caffeinated coffee, tea with caffeine, or caffeine was not associated with incidence of colon of rectal cancer, whereas regular consumption of decaffeinated coffee was associated with a reduced incidence of rectal cancer.
Green and black teas were given at 1.25% in the drinking water to streptozotocin-induced diabetic rats for 3 months. Normal and diabetic control groups were also studied. As expected, diabetic animals had significantly increased glucose in lens and plasma. Lens and red blood cell sorbitol were significantly increased as a result of the aldose reductase pathway activation. Plasma and lens lipid thiobarbituric acid-reactive substances and protein glycation were also significantly elevated. Both teas significantly inhibited diabetic cataracts and caused significant reductions in the biochemical pathway implicated in the development of the pathology. After corrections for glucose, it was found that the teas retard the development of diabetic cataracts by a hypoglycemic effect that in turn inhibits the biochemical indicators of pathology. There were significant correlations between glucose, cataract score, and these indicators. Green tea but not black tea caused a significant decline in triglycerides in the diabetic animals. Tea may be a simple, inexpensive means of preventing or retarding human diabetes and the ensuing complications. Tea also should be investigated as an adjunct therapy for diabetes treatment.
OF FOOD SCIENCE C559 URLs and E-mail addresses are active links at www.ift.org C: Food Chemistry & Toxicology HPLC analysis of teas . . . catechins in green tea are equally effective antioxidants
- Leung
- Lk
- Chen Y R Su
- Z Zhang
- Y Huang
- Chen
- Zy
Leung LK, Su Y, Chen R, Zhang Z, Huang Y, Chen ZY. 2001. Theaflavins in black tea and Vol. 70, Nr. 9, 2005—JOURNAL OF FOOD SCIENCE C559 URLs and E-mail addresses are active links at www.ift.org C: Food Chemistry & Toxicology HPLC analysis of teas... catechins in green tea are equally effective antioxidants. J Nutr 131:2248–51.
Antibiotic activities of tea catechins and teas against the foodborne pathogen Bacillus cereus
- M Friedman
- Henika
- Levin Ce Pr
- Mandrell Re
- Kozukue
Friedman M, Henika PR, Levin CE, Mandrell RE, Kozukue N. 2005. Antibiotic activities of tea catechins and teas against the foodborne pathogen Bacillus cereus. San Francisco, Calif.: Am Soc Microbiol Abstr ASM1235.
Phenolic Compounds of Beverages. Phenolics in Food and Neutraceuticals
- F Shahidi
- Naczk
Shahidi F, Naczk M. 2004. Phenolic Compounds of Beverages. Phenolics in Food and Neutraceuticals. Boca Raton, Fla.: CRC Press. p 241–8.
Desirable enzymatic browning In: Handbook of food enzy-mology
- S Schwimmer
Schwimmer S. 1981. Desirable enzymatic browning. In: Handbook of food enzy-mology. Westport, Conn.: AVI. p 291–7.
Analysis of tea polyphenols
- Beecher
Antibiotic activities of tea catechins and teas against the foodborne pathogen Bacillus cereus
- M Friedman
- C E Henika Pr Levin
- R E Mandrell
- N Kozukue
- November