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Rezaeian FM, Zimmermann BF. Simplified analysis of flavanols in matcha tea. Food Chem 2022; 373:131628. [PMID: 34863606 DOI: 10.1016/j.foodchem.2021.131628] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 11/14/2021] [Indexed: 11/04/2022]
Abstract
Matcha tea contains only the softer parts of the tea leaves and is finely ground. Therefore, extraction of the flavanols for analysis by HPLC is possible by a simpler protocol compared to the ISO 14502-2 method. 21 different simplified extraction methods were screened and five of them gave equal results as the ISO 14502-2 method. The simplest and fastest method consists of extraction by ethanol + water (7 + 3, v + v) at room temperature with ultrasonication. This method was validated by determining accuracy, intraday and interday repeatability. The simplified method was successfully applied to four traditional matcha teas and two powdered green teas from Japan. This method paves the way for time-saving, energy-saving and accurate analyses of flavanols in matcha tea.
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Affiliation(s)
- Flora M Rezaeian
- Department of Nutritional and Food Sciences - Food Science, University of Bonn, Meckenheimer Allee 166a, 53115 Bonn, Germany.
| | - Benno F Zimmermann
- Department of Nutritional and Food Sciences - Food Science, University of Bonn, Meckenheimer Allee 166a, 53115 Bonn, Germany.
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Wakamatsu M, Yamanouchi H, Sahara H, Iwanaga T, Kuroda R, Yamamoto A, Minami Y, Sekijima M, Yamada K, Kajiya K. Catechin and caffeine contents in green tea at different harvest periods and their metabolism in miniature swine. Food Sci Nutr 2019; 7:2769-2778. [PMID: 31428365 PMCID: PMC6694591 DOI: 10.1002/fsn3.1143] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 05/30/2019] [Accepted: 06/04/2019] [Indexed: 12/15/2022] Open
Abstract
The catechin content in green tea leaves varies according to cultivation conditions such as intensity of solar radiation, temperature, and precipitation, and thus, there is ambiguity about the best harvest time for obtaining optimal functional effects. In this study, the Yabukita (ordinary) and Benifuki varieties, which contain methylated catechin, were used to determine the difference in green tea catechins according to harvest times and tea manufacturing processes. Caffeine determination was also carried out to provide information about green tea intake for all age-groups of children and pregnant women. Determining the quantity of each catechin was difficult because of degradation, polymerization, and isomerization that had occurred during heat-drying in the refining process. In addition, the absorption of catechin compounds was tested using miniature swine because of their functional and physiological similarity to humans. Benifuki tea leaves contained epigallocatechin-3-(3"-O-methyl) gallate (EGCg3"Me) instead of epigallocatechin-3-(4"-O-methyl) gallate (EGCg4"Me). However, EGCg4"Me was detected during the entire intake period, but EGCg3"Me was not detected in the blood of miniature swine fed Benifuki tea. It is possible that the position of the methyl group was modified by the pig metabolism. Furthermore, caffeine from both Yabukita and Benifuki tea varieties was found to be easily accumulated in miniature swine. These results suggest that nonrefined September-October picking tea (autumn and winter tea) of the Benifuki variety is preferable over the Yabukita variety for consumption by children and pregnant women owing to its lower caffeine content and higher content of methylated catechin.
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Affiliation(s)
- Misato Wakamatsu
- Biochemical Science & Technology, Graduate School of AgricultureKagoshima UniversityKagoshimaJapan
| | - Hiroki Yamanouchi
- Biochemical Science & Technology, Graduate School of AgricultureKagoshima UniversityKagoshimaJapan
| | - Hisashi Sahara
- Division of Organ Replacement and Xenotransplantation Surgery, Center for Advanced Biomedical Science and Swine ResearchKagoshima UniversityKagoshimaJapan
| | - Takehiro Iwanaga
- Division of Organ Replacement and Xenotransplantation Surgery, Center for Advanced Biomedical Science and Swine ResearchKagoshima UniversityKagoshimaJapan
| | - Rei Kuroda
- Biochemical Science & Technology, Graduate School of AgricultureKagoshima UniversityKagoshimaJapan
| | - Ayaka Yamamoto
- Department of Food Science & Biotechnology, Faculty of AgricultureKagoshima UniversityKagoshimaJapan
| | - Yuji Minami
- Department of Food Science & Biotechnology, Faculty of AgricultureKagoshima UniversityKagoshimaJapan
| | - Mitsuhiro Sekijima
- Division of Organ Replacement and Xenotransplantation Surgery, Center for Advanced Biomedical Science and Swine ResearchKagoshima UniversityKagoshimaJapan
| | - Kazuhiko Yamada
- Division of Organ Replacement and Xenotransplantation Surgery, Center for Advanced Biomedical Science and Swine ResearchKagoshima UniversityKagoshimaJapan
| | - Katsuko Kajiya
- Department of Food Science & Biotechnology, Faculty of AgricultureKagoshima UniversityKagoshimaJapan
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Monobe M, Nomura S, Ema K, Horie H. Influence of continued ingestion of matcha on emotional behaviors after social stress in mice. Biosci Biotechnol Biochem 2019; 83:2121-2127. [PMID: 31267836 DOI: 10.1080/09168451.2019.1637713] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Matcha has high contents of theanine, caffeine, and epigallocatechin gallate (EGCG). Among these, theanine reduces psychological and physiological stress responses, although this effect is disturbed by caffeine and EGCG. It was reported that the continued ingestion of high-quality matcha, whose molar ratio of caffeine and EGCG to theanine and arginine was kept at less than two, reduces stress responses. However, most matcha on the market has an inadequate ratio. Therefore, we investigated the influence of continued ingestion of matcha with a ratio of over two, on emotional behaviors after stress. Continued ingestion of matcha was suggested to reduce the anxiety-like behaviors induced by psychological and physiological stresses.
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Affiliation(s)
- Manami Monobe
- Tea Research Division, Institute of Fruit Tree and Tea Science, National Agriculture and Food Research Organization (NARO) , Shizuoka , Japan
| | - Sachiko Nomura
- Tea Research Division, Institute of Fruit Tree and Tea Science, National Agriculture and Food Research Organization (NARO) , Shizuoka , Japan
| | - Kaori Ema
- Tea Research Division, Institute of Fruit Tree and Tea Science, National Agriculture and Food Research Organization (NARO) , Shizuoka , Japan
| | - Hideki Horie
- Tea Research Division, Institute of Fruit Tree and Tea Science, National Agriculture and Food Research Organization (NARO) , Shizuoka , Japan
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Sano T, Horie H, Matsunaga A, Hirono Y. Effect of shading intensity on morphological and color traits and on chemical components of new tea (Camellia sinensis L.) shoots under direct covering cultivation. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2018; 98:5666-5676. [PMID: 29722013 DOI: 10.1002/jsfa.9112] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 12/10/2017] [Accepted: 04/30/2018] [Indexed: 05/18/2023]
Abstract
BACKGROUND Use of covering cultivation to shade tea (Camellia sinensis L.) trees to produce high-quality, high-priced green tea has recently increased in Japan. Knowledge of shading effects on morphological and color traits and on chemical components of new tea shoots is important for product quality and productivity. We assessed these traits of tea shoots and their relationships under covering cultivation of various radiation intensities. RESULTS Leaf thickness, leaf mass per area, and leaf density of new tea leaves were smaller under covering culture than under open-field culture. SPAD values and chlorophyll contents were larger under covering culture than under open culture. The derived exponential equation for estimating chlorophyll contents from SPAD values was improved by considering leaf thickness. Covering culture decreased epicatechin and epigallocatechin contents, and increased theanine and caffeine contents. Principal component analysis on shoot and leaf traits indicated that leaf mass per area, chlorophyll, epicatechin, and epigallocatechin contents were strongly associated with shading effects. CONCLUSION The morphological traits, color traits, and chemical components of new tea shoots and leaves varied depending on radiation intensity, shoot growth, and cropping season. These findings are useful for covering cultivation with high quality and high productivity in tea gardens. © 2018 Society of Chemical Industry.
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Affiliation(s)
- Tomohito Sano
- Division of Tea Research, Institute of Fruit Tree and Tea Science, National Agriculture and Food Research Organization (NARO), Shimada, Japan
| | - Hideki Horie
- Division of Tea Research, Institute of Fruit Tree and Tea Science, National Agriculture and Food Research Organization (NARO), Shimada, Japan
| | - Akiko Matsunaga
- Division of Tea Research, Institute of Fruit Tree and Tea Science, National Agriculture and Food Research Organization (NARO), Shimada, Japan
- Department of Planning and General Administration, Institute of Vegetable and Floriculture Science, National Agriculture and Food Research Organization (NARO), Tsukuba, Japan
| | - Yuhei Hirono
- Division of Tea Research, Institute of Fruit Tree and Tea Science, National Agriculture and Food Research Organization (NARO), Shimada, Japan
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Homura Y, Hiejima Y, Kodama T, Tanaka M, Horie H, Suzuki T, Yasui A. Validation of Method for Determining <i>O</i>-methylated Catechin in ‘Benifuuki’ Green Tea (<i>Camellia sinensis </i>L.) by Interlaboratory Study. J JPN SOC FOOD SCI 2016. [DOI: 10.3136/nskkk.63.312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Yuji Homura
- Food and Agricultural Materials Inspection Center
| | | | | | | | - Hideki Horie
- NARO Institute of Vegetable and Tea Science, National Agriculture and Food Research Organization
| | - Tadanao Suzuki
- Food and Agricultural Materials Inspection Center
- National Food Research Institute, National Agriculture and Food Research Organization
| | - Akemi Yasui
- National Food Research Institute, National Agriculture and Food Research Organization
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Effect on the Epigallocatechin Gallate/Epigallocatechin Ratio in a Green Tea (Camellia sinensisL.) Extract of Different Extraction Temperatures and Its Effect on IgA Production in Mice. Biosci Biotechnol Biochem 2014; 74:2501-3. [DOI: 10.1271/bbb.100498] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Maeda-Yamamoto M, Okuda Y, Ohsuge T, Monobe M. Examination of Conditions for the Efficient Extraction of Various Functional Ingredients from Tea Leaves ( Camellia sinensis L.) using a Tea Infuser, ‘Rich plus’ (RICH+ ®). J JPN SOC FOOD SCI 2014. [DOI: 10.3136/nskkk.61.586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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MIYASHITA T, ETOH H. Improvement of the Bitterness and Astringency of Green Tea by Sub-Critical Water Extraction. FOOD SCIENCE AND TECHNOLOGY RESEARCH 2013. [DOI: 10.3136/fstr.19.471] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Maeda-Yamamoto M, Saito T, Nesumi A, Tokuda Y, Ema K, Honma D, Ogino A, Monobe M, Murakami A, Murakami A, Tachibana H. Chemical analysis and acetylcholinesterase inhibitory effect of anthocyanin-rich red leaf tea (cv. Sunrouge). JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2012; 92:2379-86. [PMID: 22419270 DOI: 10.1002/jsfa.5644] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Revised: 02/01/2012] [Accepted: 02/01/2012] [Indexed: 05/24/2023]
Abstract
BACKGROUND The purpose of this study was to evaluate the effects of leaf order or crop season on anthocyanins and other chemicals in the anthocyanin-rich tea cultivar 'Sunrouge' (Camellia sinensis x C. taliensis) by using high-performance liquid chromatography, and to study the effect of 'Sunrouge' extract on acetylcholinesterase (AChE) activity in human neuroblastoma SK-N-SH cells. RESULTS The total anthocyanin content was higher in the third (3.09 mg g⁻¹) than in the second (2.24 mg g⁻¹) or first crop season (1.79 mg g⁻¹). The amount of anthocyanins contained in the stem was high (1.61 mg g⁻¹). In the third crop season, the concentrations of delphinidin-3-O-β-D-(6-(E)-p-coumaroyl)galactopyranoside (DCGa), cyanidin-3-O-β-D-(6-(E)-p-coumaroyl)galactopyranoside, delphinidin-3-O-β-D-galactopyranoside, delphinidin-3-O-β-D-(6-O-(Z)-p-coumaroyl)galactopyranoside, cyanidin-3-O-β-D-galactoside, and delphinidin-3-O-β-D-glucoside were 1.57 mg g⁻¹, 0.52 mg g⁻¹, 0.40 mg g⁻¹, 0.22 mg g⁻¹, 0.14 mg g⁻¹, and 0.11 mg g⁻¹, respectively. DCGa accounted for about 50% of the anthocyanins present. The suppressive effect of 'Sunrouge' water extract on AChE activity in human neuroblastoma SK-N-SH cells was the strongest among the three tea cultivars ('Sunrouge', 'Yabukita' and 'Benifuuki'). CONCLUSION These results suggested that 'Sunrouge' might protect humans from humans from AChE-related diseases by suppressing AChE activity. To obtain sufficient amounts of anthocyanins, catechins and/or caffeine for a functional food material, 'Sunrouge' from the third crop season should be used.
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Affiliation(s)
- Mari Maeda-Yamamoto
- NARO Institute of Vegetable and Tea Science, Shizuoka, Makurazaki, Kagoshima, Japan.
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Maeda-Yamamoto M, Ema K, Tokuda Y, Monobe M, Tachibana H, Sameshima Y, Kuriyama S. Effect of green tea powder (Camellia sinensis L. cv. Benifuuki) particle size on O-methylated EGCG absorption in rats; The Kakegawa Study. Cytotechnology 2011; 63:171-9. [PMID: 21207145 DOI: 10.1007/s10616-010-9331-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Accepted: 12/17/2010] [Indexed: 11/27/2022] Open
Abstract
Tea polyphenols, e.g., (-)-epigallocatechin-3-O-(3-O-methyl gallate (EGCG3"Me), (-)-epigallocatechin-3-O-gallate (EGCG), (-)-epigallocatechin (EGC), (-)-epicatechin-3-O-gallate (ECG), and (-)-epicatechin (EC), are believed to be responsible for the beneficial effects of tea. 'Benifuuki', a tea (Camellia sinensis L.) cultivar grown in Japan, is rich in the anti-allergic molecule epigallocatechin-3-O-(3-O-methyl) gallate (EGCG3"Me). Pulverized Benifuuki green tea powder (BGP) is more widely distributed than leaf tea in Japan. Japanese people mix their pulverized tea with water directly, whereas it is common to drink leaf tea after extraction. However, few studies of the effects of BGP particle size on polyphenol bioavailability have been performed. This study was conducted to investigate the absorption of catechins in rats after the intragastric administration of Benifuuki green tea. Therefore, we assessed the plasma concentrations of catechins following the ingestion of BGP with different mean particle sizes (2.86, 18.6, and 76.1 μm) or Benifuuki green tea infusion (BGI) as a control in rats. The bioavailabilities of EGCG3"Me, EGCG, ECG, EGC, and EC were analyzed after the oral administration of a single dose of Benifuuki green tea (125 mg/rat) to rats. The plasma concentrations of tea catechins were determined by HPLC analysis combined with of electrochemical detection (ECD) using a coulometric array. The AUC (area under the drug concentration versus time curve; min μg/mL) of ester-type catechins (EGCG3"Me, EGCG, and ECG) for the BGP 2.86 μm were significantly higher than those in the infusion and 18.6 and 76.1 μm BGP groups, but the AUC of free-type catechins (EGC and EC) showed no differences between these groups. Regarding the peak plasma level of EGCG3"Me adjusted for intake, BGP 2.86 μm and BGI showed higher values than the BGP 18.6 and 76.1 μm groups, and the peak plasma levels of the other catechins displayed the same tendency. The present study demonstrates that the bioavailability of ester-type catechins (EGCG and ECG) can be improved by reducing the particle size of green tea, but the plasma level of EGCG3"Me in the BGI group was similar to that in the BGP 2.86 μm group. This result suggests that drinking Benifuuki green tea with a particle size of around 2 μm would deliver the anti-allergic EGCG3"Me and the anti-oxidant EGCG efficiently.
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Affiliation(s)
- Mari Maeda-Yamamoto
- National Institute of Vegetable and Tea Sciences, National Agriculture and Food Research Organization, 2769 Kanaya-Shishidoi, Shimada, Shizuoka, 428-8501, Japan,
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Honma D, Tagashira M, Kanda T, Maeda-Yamamoto M. Identifications of inhibitors of IgE production by human lymphocytes isolated from 'Cha Chuukanbohon Nou 6' tea leaves. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2010; 90:168-174. [PMID: 20355027 DOI: 10.1002/jsfa.3807] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
BACKGROUND Tea (Camellia sinensis L.) is consumed all over the world and in especially large quantities in Japan and China, where it has been used not only as a daily beverage but also for medicinal purposes for thousands of years. Tea has been found to exhibit various bioregulatory activities, including antiallergic, anticarcinogenic, antimetastatic, antioxidative, antihypertensive, antihypercholesterolemic, anti-dental caries and antibacterial effects, and to influence intestinal flora. RESULTS Cha Chuukanbohon Nou 6 is a tea cultivar improved by the National Institute of Vegetable and Tea Science (NIVTS) in Japan. On comparing chemical constituents of 11 varieties of tea leaves by high-performance liquid chromatography, we found two new major compounds in Cha Chuukanbohon Nou 6. Nuclear magnetic resonance spectroscopy revealed these compounds to be theogallin and 1,2-di-O-galloyl-4,6-O-(S)-hexahydroxydiphenoyl-beta-D-glucopyranose. The two were similar in chemical structure to strictinin, an inhibitor of immunoglobulin (Ig) production. Thus their effects on the production of Igs by peripheral blood lymphocytes were tested. Both compounds, like strictinin, inhibited IgE production. CONCLUSION The results suggest Cha Chuukanbohon Nou 6 to be the basis of an antiallergic beverage.
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Affiliation(s)
- Daiki Honma
- Research Laboratory for Health and Gustatory Science, Asahi Breweries Ltd, Ibaraki 302-0106, Japan.
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Inagaki H, Sugitani M, Setoguchi Y, Ito R, Oritani Y, Nishimura E, Sato S, Kato M, Sai M, Maeda-Yamamoto M, Kamei M. Effective Suppression of Adipose Tissue Weight Gain in High-fat Diet-fed Mice by 'Benifuuki' Green Tea Consumption. J JPN SOC FOOD SCI 2009. [DOI: 10.3136/nskkk.56.403] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Monobe M, Ema K, Kato F, Maeda-Yamamoto M. Immunostimulating activity of a crude polysaccharide derived from green tea (Camellia sinensis) extract. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2008; 56:1423-1427. [PMID: 18232634 DOI: 10.1021/jf073127h] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Green tea extract is well-known to reduce the risk of a variety of diseases. Here, we investigated the immunostimulating activity of tea polysaccharide (TPS), one of the main components in green tea extract. The water extracts from mature or immature tea leaves were precipitated by using ethanol at room temperature. The sediment was washed with ethanol and acetone alternately and then dried. We used the phagocytic activity of macrophage-like cells as an indicator of immune function activation. Chemical components were analyzed by HPLC. The immunostimulating activity of TPS from immature leaves extract was higher than that of TPS from mature leaves, and its activities were dependent on the content of strictinin in the leaf extract. Futhermore, a mixture of catechin and TPS that removed polyphenols did not increase the immunostimulating activity. These results suggest that the catechin-polysaccharide complex is a very important molecule in the immunomodulating activity of tea extracts.
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Affiliation(s)
- Manami Monobe
- National Institute of Vegetable and Tea Science, NARO, Shizuoka, Japan.
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Mizukami Y, Sawai Y, Yamaguchi Y. Simultaneous analysis of catechins, gallic acid, strictinin, and purine alkaloids in green tea by using catechol as an internal standard. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2007; 55:4957-64. [PMID: 17530772 DOI: 10.1021/jf070323f] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
We developed a high-performance liquid chromatography-based method for simultaneous analysis of nine catechins, gallic acid, strictinin, caffeine, and theobromine in green tea by using catechol as an internal standard. Although the high cost and instability of the catechin reference standards limit the application of this method, the addition of ascorbic acid to the standard stock solution preserved the stability of the reference standards in the solution for 1 year when stored at -30 degrees C. Furthermore, we found that the slopes of the calibration curves plotted were stable for a run time of 2000 h. Our method proved to be appropriate for quantification and yielded good correlation coefficients, detection levels, repeatability, reproducibility, and recovery rates. Quantitative data revealed that the contribution of only 200 mL of brewed tea to the total dietary catechins was approximately 220-420 mg, while that of 500 mL of bottled tea was approximately 170-900 mg.
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Affiliation(s)
- Yuzo Mizukami
- National Institute of Vegetable and Tea Science, 2769 Kanaya, Shimada, Shizuoka 428-8501, Japan.
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Turkmen N, Velioglu YS, Sari F, Polat G. Effect of extraction conditions on measured total polyphenol contents and antioxidant and antibacterial activities of black tea. Molecules 2007; 12:484-96. [PMID: 17851405 PMCID: PMC6149426 DOI: 10.3390/12030484] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2007] [Revised: 03/06/2007] [Accepted: 03/12/2007] [Indexed: 11/16/2022] Open
Abstract
Black tea was extracted for 2, 8 and 18 h with absolute acetone, N,N-dimethyl-formamide (DMF), ethanol and methanol and their 50% aqueous solutions. The extracts were screened for total polyphenol contents, antioxidant and antibacterial activities. The polyphenol content of the extracts was found to be in the range of 0.44-114.01 mg gallic acid equivalents (GAE)/g dry weight tea, depending on the solvent used and the length of the extraction process. In general, aqueous acetone or DMF extracts displayed the highest polyphenol contents and antioxidant activity, while absolute acetone was the least efficient solvent. Antioxidant activities of tea extracts tested using the reducing power and 2,2-diphenyl-1-picryhydrazyl (DPPH) radical methods ranged from 0.09 to 1.18 and from 2.60 to 95.42 %, respectively, depending on the extraction conditions and the antioxidant activities correlated well with the polyphenol concentrations. Aqueous solvent black tea extracts also possessed antibacterial activity, depending on the solvent used and bacterial species tested. Staphylococcus aureus was found to be the most sensitive to all tea extracts, except for the methanol extract. Tea extracts were not effective against Y. enterocolitica, L. monocytogenes and E. coli O157:H7.
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Affiliation(s)
- Nihal Turkmen
- Ankara University, Faculty of Engineering, Department of Food Engineering, 06110-Diskapi-Ankara, Turkey.
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