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Chung S Yang - One of the best experts on this subject based on the ideXlab platform.
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Cancer Preventive Activities of Tea Catechins.
Molecules (Basel Switzerland), 2016Co-Authors: Chung S Yang, Hong WangAbstract:Catechins are widely occurring in our diet and beverages. The cancer-preventive activities of Catechins have been extensively studied. Of these, (−)-epigalloCatechin-3-gallate (EGCG), the principal Catechin in green tea, has received the most attention. The inhibitory activities of tea Catechins against carcinogenesis and cancer cell growth have been demonstrated in a large number of laboratory studies. Many mechanisms for modulating cancer signaling and metabolic pathways have been proposed based on numerous studies in cell lines with EGCG, the most active tea Catechin. Nevertheless, it is not known whether many of these mechanisms indeed contribute to the anti-cancer activities in animals and in humans. Human studies have provided some results for the cancer preventive activities of tea Catechins; however, the activities are not strong. This article reviews the cancer preventive activities and mechanisms of action of tea Catechins involving their redox activities, biochemical properties and binding to key enzymes or signal transduction proteins. These mechanisms lead to suppression of cell proliferation, increased apoptosis and inhibition of angiogenesis. The relevance of the proposed mechanisms for cancer prevention are assessed in the light of the situation in vivo. The potential and possible problems in the application of tea and tea-derived products for cancer prevention are discussed.
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delivery of tea polyphenols to the oral cavity by green tea leaves and black tea extract
Cancer Epidemiology Biomarkers & Prevention, 2004Co-Authors: Joshua D Lambert, Pius Maliakal, Saileta Prabhu, Xiaofeng Meng, Chitang Ho, Hong Lu, Chung S YangAbstract:Catechins and theaflavins, polyphenolic compounds derived from tea ( Camellia sinensis , fam. Theaceae), have been reported to have a wide range of biological activities including prevention of tooth decay and oral cancer. The present study was undertaken to determine the usefulness of green tea leaves and black tea extract for the delivery of Catechins and theaflavins to the oral cavity. After holding either green tea leaves (2 g) or brewed black tea (2 g of black tea leaves in 100 ml) in the mouth for 2–5 min and thoroughly rinsing the mouth, high concentrations of Catechins ( C max = 131.0–2.2 μm) and theaflavins ( C max = 1.8–0.6 μm) were observed in saliva in the 1st hour. Whereas there was significant interindividual variation in the peak levels of Catechins and theaflavins, the overall kinetic profile was similar, with t 1/2 = 25–44 min and 49–76 min for Catechins and theaflavins, respectively (average coefficient of variation in t 1/2 was 23.4%). In addition to the parent Catechin and theaflavin peaks, five unidentified peaks were also observed in saliva after black tea treatment. Hydrolysis of theaflavin gallates, apparently by salivary esterases, was observed in vitro and in vivo . These results indicate that tea leaves can be used as a convenient, slow-release source of Catechins and theaflavins and provide information for the possible use of tea in the prevention of oral cancer and dental caries.
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chemical studies on antioxidant mechanism of tea Catechins analysis of radical reaction products of Catechin and epiCatechin with 2 2 diphenyl 1 picrylhydrazyl
Bioorganic & Medicinal Chemistry, 2002Co-Authors: Shengmin Sang, Xiaofang Cheng, Ruth E Stark, Robert T Rosen, Chung S YangAbstract:Abstract Tea Catechins, an important class of polyphenols, have been shown to have wide spectrum of antitumor activity believed to be due mainly to their antioxidative effect. In this study, the radical scavenging behavior of Catechins on 2,2-diphenyl-1-picrylhydrazyl (DPPH) was studied. Two reaction products of (+)-Catechin, and two reaction products of (−)-epiCatechin were purified and identified. Their structures were determined on the basis of detailed high-field 1-D and 2-D NMR spectral analysis. Structure elucidation of these products can provide insights into specific mechanisms of antioxidant reactions. A possible mechanism of the formation of reaction products is suggested.
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Identification of oxidation products of (-)-epigalloCatechin gallate and (-)-epigalloCatechin with H2O2.
Journal of Agricultural and Food Chemistry, 2000Co-Authors: Tzou-chi Huang, Younong Yu, Edmond J. Lavoie, Chung S YangAbstract:(−)-EpigalloCatechin gallate (EGCG) and (−)-epigalloCatechin (EGC) are two important antioxidants in tea. They also display some antitumor activities, and these activities are believed to be mainly due to their antioxidative effects. However, the specific mechanisms of antioxidant action of tea Catechins remain unclear. In this study are isolated and identified two novel reaction products of EGCG and one product of EGC when they were reacted separately with H2O2. These products are formed by the oxidation and decarboxylation of the A ring in the Catechin molecule. This study provides unequivocal proof that the A ring of EGCG and EGC may also be an antioxidant site. This study also indicates an additional reaction pathway for the oxidation chemistry of tea Catechins. Keywords: Catechins; EGCG; EGC; antioxidants; H2O2
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human salivary tea Catechin levels and Catechin esterase activities implication in human cancer prevention studies
Cancer Epidemiology Biomarkers & Prevention, 1999Co-Authors: Chung S Yang, Maojung Lee, Laishun ChenAbstract:Because of the possible application of tea in the prevention of oral and esophageal cancers, the salivary levels of tea Catechins were determined in six human volunteers after drinking tea. Saliva samples were collected after thoroughly rinsing the mouth with water. After drinking green tea preparations equivalent to two to three cups of tea, peak saliva levels of (-)-epigalloCatechin (EGC; 11.7-43.9 microg/ml), EGC-3-gallate (EGCG; 4.8-22 microg/ml), and (-)-epiCatechin (EC; 1.8-7.5 microg/ml) were observed after a few minutes. These levels were 2 orders of magnitude higher than those in the plasma. The elimination half-life (t(1/2)) of the salivary Catechins was 10-20 min, much shorter than that of the plasma. Holding a tea solution in the mouth for a few minutes without swallowing produced even higher salivary Catechin levels, but taking tea solids in capsules resulted in no detectable salivary Catechin level. Holding an EGCG solution in the mouth resulted in EGCG and EGC in the saliva and, subsequently, EGC in the urine. The results suggest that EGCG was converted to EGC in the oral cavity, and both Catechins were absorbed through the oral mucosa. A Catechin esterase activity that converts EGCG to EGC was found in the saliva. The enzyme was likely of human origin, but the activity was not inhibited by common human esterase inhibitor. The present results suggest that slowly drinking tea is a very effective way of delivering rather high concentrations of Catechins to the oral cavity and then the esophagus.
Peter C H Hollman - One of the best experts on this subject based on the ideXlab platform.
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Catechin intake might explain the inverse relation between tea consumption and ischemic heart disease the zutphen elderly study
The American Journal of Clinical Nutrition, 2001Co-Authors: Ilja C W Arts, Peter C H Hollman, Edith J M Feskens, Bas Bueno H De Mesquita, Daan KromhoutAbstract:Background Epidemiologic studies suggest that tea consumption may reduce the risk of cardiovascular diseases, but results are inconsistent. Catechins, which belong to the flavonoid family, are the main components of tea and may be responsible for the alleged protective effect. Taking Catechin sources other than tea into account might clarify the reported associations. Objective The objective was to evaluate the association between Catechin intake and the incidence of and mortality from ischemic heart disease and stroke. Design We evaluated the effect of a high Catechin intake by using data from the Zutphen Elderly Study, a prospective cohort study of 806 men aged 65-84 y at baseline in 1985. Results The mean (+/-SD) Catechin intake at baseline was 72 +/- 47.8 mg, mainly from black tea, apples, and chocolate. A total of 90 deaths from ischemic heart disease were documented. Catechin intake was inversely associated with ischemic heart disease mortality; the multivariate-adjusted risk ratio in the highest tertile of intake was 0.49 (95% CI: 0.27, 0.88; P for trend: 0.017). After multivariate adjustment, Catechin intake was not associated with the incidence of myocardial infarction (risk ratio in the highest tertile of intake: 0.70; 95% CI: 0.39, 1.26; P for trend: 0.232). After adjustment for tea consumption and flavonol intake, a 7.5-mg increase in Catechin intake from sources other than tea was associated with a tendency for a 20% reduction in ischemic heart disease mortality risk (P = 0.114). There was no association between Catechin intake and stroke incidence or mortality. Conclusion Catechins, whether from tea or other sources, may reduce the risk of ischemic heart disease mortality but not of stroke.
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Catechin contents of foods commonly consumed in the netherlands 2 tea wine fruit juices and chocolate milk
Journal of Agricultural and Food Chemistry, 2000Co-Authors: Ilja C W Arts, B Van De Putte, Peter C H HollmanAbstract:Catechins, compounds that belong to the flavonoid class, are potentially beneficial to human health. To enable an epidemiological evaluation of Catechins, data on their contents in foods are required. HPLC with UV and fluorescence detection was used to determine the levels of (+)-Catechin, (−)-epiCatechin, (+)-galloCatechin (GC), (−)-epigalloCatechin (EGC), (−)-epiCatechin gallate (ECg), and (−)-epigalloCatechin gallate (EGCg) in 8 types of black tea, 18 types of red and white wines, apple juice, grape juice, iced tea, beer, chocolate milk, and coffee. Tea infusions contained high levels of Catechins (102−418 mg of total Catechins/L), and tea was the only beverage that contained GC, EGC, ECg, and EGCg in addition to (+)-Catechin and (−)-epiCatechin. Catechin concentrations were still substantial in red wine (27−96 mg/L), but low to negligible amounts were found in white wine, commercially available fruit juices, iced tea, and chocolate milk. Catechins were absent from beer and coffee. The data reported he...
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Catechin contents of foods commonly consumed in the netherlands 1 fruits vegetables staple foods and processed foods
Journal of Agricultural and Food Chemistry, 2000Co-Authors: Ilja C W Arts, B Van De Putte, Peter C H HollmanAbstract:Catechins, compounds that belong to the flavonoid class, are potentially beneficial to human health. To enable epidemiological evaluation of these compounds, data on their contents in foods are required. HPLC with UV and fluorescence detection was used to determine the levels of (+)-Catechin, (-)-epiCatechin, (+)-galloCatechin (GC), (-)-epigalloCatechin (EGC), (-)-epiCatechin gallate (ECg), and (-)-epigalloCatechin gallate (EGCg) in 24 types of fruits, 27 types of vegetables and legumes, some staple foods, and processed foods commonly consumed in The Netherlands. Most fruits, chocolate, and some legumes contained Catechins. Levels varied to a large extent: from 4.5 mg/kg in kiwi fruit to 610 mg/kg in black chocolate. (+)-Catechin and (-)-epiCatechin were the predominant Catechins; GC, EGC, and ECg were detected in some foods, but none of the foods contained EGCg. The data reported here provide a base for the epidemiological evaluation of the effect of Catechins on the risk for chronic diseases.
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A RP-HPLC method for the determination of tea Catechins
Cancer Letters, 1997Co-Authors: Santosh Khokhar, Peter C H Hollman, Dini Venema, Matthijs Dekker, Wim M.f. JongenAbstract:An HPLC method with gradient elution for the quantification of Catechins ((-)-epigalloCatechin (EGC), (+)-Catechin (C), (-)-epiCatechin (EC), (-)-epigalloCatechingallate (EGCg) and (-)-epiCatechingallate (ECg)) in tea was developed. The method was used to determine Catechins in black tea, green tea and oolong tea. Sample preparation was simple because only filtration and adjustment of pH was required. The levels of Catechins in different teas varied between
Takami Kakuda - One of the best experts on this subject based on the ideXlab platform.
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Heat-epimerized tea Catechins have the same cholesterol-lowering activity as green tea Catechins in cholesterol-fed rats.
Bioscience biotechnology and biochemistry, 2005Co-Authors: Makoto Kobayashi, Ayumu Nozawa, Takami Kakuda, Tomonori Unno, Yuko Suzuki, Yuko M. Sagesaka, Ikuo IkedaAbstract:Tea Catechins are known to be epimerized by heat treatment. The effect of heat-epimerized tea Catechins on serum cholesterol concentration was compared with that of green tea Catechins. Our observations strongly suggest that both tea Catechins and heat-epimerized tea Catechins lower serum cholesterol concentration by inhibiting cholesterol absorption in the intestine. There was no differential effect between the two Catechin preparations.
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Heat-epimerized tea Catechins rich in galloCatechin gallate and Catechin gallate are more effective to inhibit cholesterol absorption than tea Catechins rich in epigalloCatechin gallate and epiCatechin gallate.
Journal of Agricultural and Food Chemistry, 2003Co-Authors: Ikuo Ikeda, Tadateru Hamada, Koichi Tsuda, Hitomi Goto, Ayumu Nozawa, And Akio Sugimoto, Katsumi Imaizumi, Makoto Kobayashi, Takami KakudaAbstract:It has been known that tea Catechins, (−)-epiCatechin (1), (−)-epigalloCatechin (2), (−)-epiCatechin gallate (3), and (−)-epigalloCatechin gallate (4) are epimerized to(−)-Catechin (5), (−)-galloCatechin (6), (−)-Catechin gallate (7), and (−)-galloCatechin gallate (8), respectively, during retort pasteurization. We previously reported that tea Catechins, mainly composed of 3 and 4, effectively inhibit cholesterol absorption in rats. In this study, the effect of heat-epimerized Catechins on cholesterol absorption was compared with tea Catechins. Both tea Catechins and heat-epimerized Catechins lowered lymphatic recovery of cholesterol in rats cannulated in the thoracic duct and epimerized Catechins were more effective than tea Catechins. The effect of purified Catechins on micellar solubility of cholesterol was examined in an in vitro study. The addition of gallate esters of Catechins reduced micellar solubility of cholesterol by precipitating cholesterol from bile salt micelles. Compounds 7 and 8 were mor...
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Heat-epimerized tea Catechins rich in galloCatechin gallate and Catechin gallate are more effective to inhibit cholesterol absorption than tea Catechins rich in epigalloCatechin gallate and epiCatechin gallate.
Journal of agricultural and food chemistry, 2003Co-Authors: Ikuo Ikeda, Tadateru Hamada, Koichi Tsuda, Hitomi Goto, Ayumu Nozawa, And Akio Sugimoto, Katsumi Imaizumi, Makoto Kobayashi, Takami KakudaAbstract:It has been known that tea Catechins, (-)-epiCatechin (1), (-)-epigalloCatechin (2), (-)-epiCatechin gallate (3), and (-)-epigalloCatechin gallate (4) are epimerized to(-)-Catechin (5), (-)-galloCatechin (6), (-)-Catechin gallate (7), and (-)-galloCatechin gallate (8), respectively, during retort pasteurization. We previously reported that tea Catechins, mainly composed of 3 and 4, effectively inhibit cholesterol absorption in rats. In this study, the effect of heat-epimerized Catechins on cholesterol absorption was compared with tea Catechins. Both tea Catechins and heat-epimerized Catechins lowered lymphatic recovery of cholesterol in rats cannulated in the thoracic duct and epimerized Catechins were more effective than tea Catechins. The effect of purified Catechins on micellar solubility of cholesterol was examined in an in vitro study. The addition of gallate esters of Catechins reduced micellar solubility of cholesterol by precipitating cholesterol from bile salt micelles. Compounds 7 and 8 were more effective to precipitate cholesterol than 3 and 4, respectively. These observations strongly suggest that heat-epimerized Catechins may be more hypocholesterolemic than tea Catechins.
Ikuo Ikeda - One of the best experts on this subject based on the ideXlab platform.
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Heat-epimerized tea Catechins have the same cholesterol-lowering activity as green tea Catechins in cholesterol-fed rats.
Bioscience biotechnology and biochemistry, 2005Co-Authors: Makoto Kobayashi, Ayumu Nozawa, Takami Kakuda, Tomonori Unno, Yuko Suzuki, Yuko M. Sagesaka, Ikuo IkedaAbstract:Tea Catechins are known to be epimerized by heat treatment. The effect of heat-epimerized tea Catechins on serum cholesterol concentration was compared with that of green tea Catechins. Our observations strongly suggest that both tea Catechins and heat-epimerized tea Catechins lower serum cholesterol concentration by inhibiting cholesterol absorption in the intestine. There was no differential effect between the two Catechin preparations.
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Heat-epimerized tea Catechins rich in galloCatechin gallate and Catechin gallate are more effective to inhibit cholesterol absorption than tea Catechins rich in epigalloCatechin gallate and epiCatechin gallate.
Journal of Agricultural and Food Chemistry, 2003Co-Authors: Ikuo Ikeda, Tadateru Hamada, Koichi Tsuda, Hitomi Goto, Ayumu Nozawa, And Akio Sugimoto, Katsumi Imaizumi, Makoto Kobayashi, Takami KakudaAbstract:It has been known that tea Catechins, (−)-epiCatechin (1), (−)-epigalloCatechin (2), (−)-epiCatechin gallate (3), and (−)-epigalloCatechin gallate (4) are epimerized to(−)-Catechin (5), (−)-galloCatechin (6), (−)-Catechin gallate (7), and (−)-galloCatechin gallate (8), respectively, during retort pasteurization. We previously reported that tea Catechins, mainly composed of 3 and 4, effectively inhibit cholesterol absorption in rats. In this study, the effect of heat-epimerized Catechins on cholesterol absorption was compared with tea Catechins. Both tea Catechins and heat-epimerized Catechins lowered lymphatic recovery of cholesterol in rats cannulated in the thoracic duct and epimerized Catechins were more effective than tea Catechins. The effect of purified Catechins on micellar solubility of cholesterol was examined in an in vitro study. The addition of gallate esters of Catechins reduced micellar solubility of cholesterol by precipitating cholesterol from bile salt micelles. Compounds 7 and 8 were mor...
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Heat-epimerized tea Catechins rich in galloCatechin gallate and Catechin gallate are more effective to inhibit cholesterol absorption than tea Catechins rich in epigalloCatechin gallate and epiCatechin gallate.
Journal of agricultural and food chemistry, 2003Co-Authors: Ikuo Ikeda, Tadateru Hamada, Koichi Tsuda, Hitomi Goto, Ayumu Nozawa, And Akio Sugimoto, Katsumi Imaizumi, Makoto Kobayashi, Takami KakudaAbstract:It has been known that tea Catechins, (-)-epiCatechin (1), (-)-epigalloCatechin (2), (-)-epiCatechin gallate (3), and (-)-epigalloCatechin gallate (4) are epimerized to(-)-Catechin (5), (-)-galloCatechin (6), (-)-Catechin gallate (7), and (-)-galloCatechin gallate (8), respectively, during retort pasteurization. We previously reported that tea Catechins, mainly composed of 3 and 4, effectively inhibit cholesterol absorption in rats. In this study, the effect of heat-epimerized Catechins on cholesterol absorption was compared with tea Catechins. Both tea Catechins and heat-epimerized Catechins lowered lymphatic recovery of cholesterol in rats cannulated in the thoracic duct and epimerized Catechins were more effective than tea Catechins. The effect of purified Catechins on micellar solubility of cholesterol was examined in an in vitro study. The addition of gallate esters of Catechins reduced micellar solubility of cholesterol by precipitating cholesterol from bile salt micelles. Compounds 7 and 8 were more effective to precipitate cholesterol than 3 and 4, respectively. These observations strongly suggest that heat-epimerized Catechins may be more hypocholesterolemic than tea Catechins.
Ilja C W Arts - One of the best experts on this subject based on the ideXlab platform.
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Catechin intake might explain the inverse relation between tea consumption and ischemic heart disease the zutphen elderly study
The American Journal of Clinical Nutrition, 2001Co-Authors: Ilja C W Arts, Peter C H Hollman, Edith J M Feskens, Bas Bueno H De Mesquita, Daan KromhoutAbstract:Background Epidemiologic studies suggest that tea consumption may reduce the risk of cardiovascular diseases, but results are inconsistent. Catechins, which belong to the flavonoid family, are the main components of tea and may be responsible for the alleged protective effect. Taking Catechin sources other than tea into account might clarify the reported associations. Objective The objective was to evaluate the association between Catechin intake and the incidence of and mortality from ischemic heart disease and stroke. Design We evaluated the effect of a high Catechin intake by using data from the Zutphen Elderly Study, a prospective cohort study of 806 men aged 65-84 y at baseline in 1985. Results The mean (+/-SD) Catechin intake at baseline was 72 +/- 47.8 mg, mainly from black tea, apples, and chocolate. A total of 90 deaths from ischemic heart disease were documented. Catechin intake was inversely associated with ischemic heart disease mortality; the multivariate-adjusted risk ratio in the highest tertile of intake was 0.49 (95% CI: 0.27, 0.88; P for trend: 0.017). After multivariate adjustment, Catechin intake was not associated with the incidence of myocardial infarction (risk ratio in the highest tertile of intake: 0.70; 95% CI: 0.39, 1.26; P for trend: 0.232). After adjustment for tea consumption and flavonol intake, a 7.5-mg increase in Catechin intake from sources other than tea was associated with a tendency for a 20% reduction in ischemic heart disease mortality risk (P = 0.114). There was no association between Catechin intake and stroke incidence or mortality. Conclusion Catechins, whether from tea or other sources, may reduce the risk of ischemic heart disease mortality but not of stroke.
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chronic obstructive pulmonary disease and intake of Catechins flavonols and flavones the morgen study
American Journal of Respiratory and Critical Care Medicine, 2001Co-Authors: Cora Tabak, Henriette A Smit, Ilja C W Arts, Dick Heederik, Daan KromhoutAbstract:Flavonoids have been suggested to protect against chronic lung disease. We studied intake of Catechins, flavonols, and flavones in relation to pulmonary function and COPD symptoms in 13,651 adults from three Dutch cities examined from 1994 to 1997. Dietary intake was estimated using a food frequency questionnaire, and flavonoid intake was calculated using specific food composition tables. Pulmonary function (FEV1) was determined by spirometry and COPD symptoms by questionnaire. Associations were presented for the fifth versus the first quintile of intake (Q5-Q1), adjusted for age, height (for FEV1 only), sex, smoking, BMI, and energy intake. Smoking was strongly associated with COPD, independent of dietary effects. Average Catechin, flavonol, and flavone intake was 58 mg/d (SD = 46) with tea and apples as main sources. Total Catechin, flavonol, and flavone intake was positively associated with FEV1 ( βQ5-Q1 = 44 ml, 95% CI = 18–69) and inversely associated with chronic cough (ORQ5-Q1 = 0.80, 95% CI = 0.66...
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Catechin contents of foods commonly consumed in the netherlands 2 tea wine fruit juices and chocolate milk
Journal of Agricultural and Food Chemistry, 2000Co-Authors: Ilja C W Arts, B Van De Putte, Peter C H HollmanAbstract:Catechins, compounds that belong to the flavonoid class, are potentially beneficial to human health. To enable an epidemiological evaluation of Catechins, data on their contents in foods are required. HPLC with UV and fluorescence detection was used to determine the levels of (+)-Catechin, (−)-epiCatechin, (+)-galloCatechin (GC), (−)-epigalloCatechin (EGC), (−)-epiCatechin gallate (ECg), and (−)-epigalloCatechin gallate (EGCg) in 8 types of black tea, 18 types of red and white wines, apple juice, grape juice, iced tea, beer, chocolate milk, and coffee. Tea infusions contained high levels of Catechins (102−418 mg of total Catechins/L), and tea was the only beverage that contained GC, EGC, ECg, and EGCg in addition to (+)-Catechin and (−)-epiCatechin. Catechin concentrations were still substantial in red wine (27−96 mg/L), but low to negligible amounts were found in white wine, commercially available fruit juices, iced tea, and chocolate milk. Catechins were absent from beer and coffee. The data reported he...
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Catechin contents of foods commonly consumed in the netherlands 1 fruits vegetables staple foods and processed foods
Journal of Agricultural and Food Chemistry, 2000Co-Authors: Ilja C W Arts, B Van De Putte, Peter C H HollmanAbstract:Catechins, compounds that belong to the flavonoid class, are potentially beneficial to human health. To enable epidemiological evaluation of these compounds, data on their contents in foods are required. HPLC with UV and fluorescence detection was used to determine the levels of (+)-Catechin, (-)-epiCatechin, (+)-galloCatechin (GC), (-)-epigalloCatechin (EGC), (-)-epiCatechin gallate (ECg), and (-)-epigalloCatechin gallate (EGCg) in 24 types of fruits, 27 types of vegetables and legumes, some staple foods, and processed foods commonly consumed in The Netherlands. Most fruits, chocolate, and some legumes contained Catechins. Levels varied to a large extent: from 4.5 mg/kg in kiwi fruit to 610 mg/kg in black chocolate. (+)-Catechin and (-)-epiCatechin were the predominant Catechins; GC, EGC, and ECg were detected in some foods, but none of the foods contained EGCg. The data reported here provide a base for the epidemiological evaluation of the effect of Catechins on the risk for chronic diseases.