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Cho SK, Abd El-Aty AM, Choi JH, Jeong YM, Shin HC, Chang BJ, Lee C, Shim JH. Effectiveness of pressurized liquid extraction and solvent extraction for the simultaneous quantification of 14 pesticide residues in green tea using GC. J Sep Sci 2008; 31:1750-60. [DOI: 10.1002/jssc.200800010] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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303
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Optimization of calcium pectinate gel beads for sustained-release of catechin using response surface methodology. Int J Biol Macromol 2008; 42:340-7. [DOI: 10.1016/j.ijbiomac.2008.01.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 01/11/2008] [Accepted: 01/11/2008] [Indexed: 11/24/2022]
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304
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Farabegoli F, Barbi C, Lambertini E, Piva R. (-)-Epigallocatechin-3-gallate downregulates estrogen receptor alpha function in MCF-7 breast carcinoma cells. ACTA ACUST UNITED AC 2008; 31:499-504. [PMID: 18061364 DOI: 10.1016/j.cdp.2007.10.018] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/31/2007] [Indexed: 12/11/2022]
Abstract
BACKGROUND (-)-Epigallocatechin-3-gallate (EGCG) is the most active catechin present in green tea, demonstrated to have chemopreventive action and to kill cancer cells selectively. As a previous study found that catechins could compete with 17-beta-estradiol for binding to estrogen receptor alpha (ERalpha), we asked whether EGCG could regulate ERalpha action. METHODS We used MCF-7, a breast carcinoma cell line having a high level of ERalpha expression. The cells were treated with various EGCG concentrations and cell viability was evaluated by MTT assay. ERalpha and pS2 expression were analyzed by RT-PCR after RNA extraction. To better define EGCG action in relation to ERalpha, we studied EGCG cytotoxicity on MCF-7 resistant to tamoxifen (MCF-7tam), MCF-7 treated with 10(-7)M ICI 182,780 for 8 days and on MDA-MB-231, a cell line that lacked ERalpha by flow cytometry (FCM). RESULTS Both ERalpha and pS2 mRNA were expressed in samples treated with low EGCG concentration (30 microg/ml). At this concentration, no cell change was detectable. In contrast, pS2 expression was lost in samples treated with 100 microg/ml EGCG for 24h, indicating ERalpha alteration. EGCG cytotoxicity was lower when ERalpha was not present (MDA-MB-231) or inactivated (by tamoxifen or ICI 182,780). CONCLUSIONS Functionally active ERalpha may have a role in EGCG cytotoxicity, increasing the sensitivity to the drug. As higher EGCG concentrations also killed cells resistant to tamoxifen or treated by 10(-7)M ICI 182,780, EGCG ought to be better investigated in breast carcinoma cells treated with drugs targeted to steroid receptors, as a potential complement of therapy.
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Affiliation(s)
- Fulvia Farabegoli
- Department of Experimental Pathology, University of Bologna, V.S. Giacomo 14, 40126 Bologna, Italy.
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305
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Hays NP, Galassetti PR, Coker RH. Prevention and treatment of type 2 diabetes: current role of lifestyle, natural product, and pharmacological interventions. Pharmacol Ther 2008; 118:181-91. [PMID: 18423879 DOI: 10.1016/j.pharmthera.2008.02.003] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2008] [Accepted: 02/07/2008] [Indexed: 02/07/2023]
Abstract
Common complications of type 2 diabetes (T2D) are eye, kidney and nerve diseases, as well as an increased risk for the development of cardiovascular disease and cancer. The overwhelming influence of these conditions contributes to a decreased quality of life and life span, as well as significant economic consequences. Although obesity once served as a surrogate marker for the risk of T2D, we know now that excess adipose tissue secretes inflammatory cytokines that left unchecked, accelerate the progression to insulin resistance and T2D. In addition, excess alcohol consumption may also increase the risk of T2D. From a therapeutic standpoint, lifestyle interventions such as dietary modification and/or exercise training have been shown to improve glucose homeostasis but may not normalize the disease process unless weight loss is achieved and increased physical activity patterns are established. Furthermore, utilization of natural products may serve as a significant adjunct in the fight against insulin resistance but further research is needed to ascertain their validity. Since it is clear that pharmaceutical therapy plays a significant role in the treatment of insulin resistance, this review will also discuss some of the newly developed pharmaceutical therapies that may work in conjunction with lifestyle interventions, and lessen the burden of behavioral change as the only strategy against the development of T2D.
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Affiliation(s)
- Nicholas P Hays
- Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, AR 72205, United States
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306
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Lee JS, Chung D, Lee HG. Preparation and characterization of calcium pectinate gel beads entrapping catechin-loaded liposomes. Int J Biol Macromol 2008; 42:178-84. [DOI: 10.1016/j.ijbiomac.2007.10.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2007] [Revised: 09/11/2007] [Accepted: 10/11/2007] [Indexed: 02/08/2023]
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307
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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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308
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Verschoyle RD, Steward WP, Gescher AJ. Putative cancer chemopreventive agents of dietary origin-how safe are they? Nutr Cancer 2008; 59:152-62. [PMID: 18001209 DOI: 10.1080/01635580701458186] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
As cancer chemopreventive agents are intended for use by healthy individuals as prophylactics to prevent or retard the development of cancer, they must be amenable to ingestion over prolonged periods without toxicity. Therefore, putative chemopreventive agents need to undergo stringent testing to ensure their safety with regard to chronic exposure in humans. The diet is thought to be a source of chemopreventive agents, and dietary compounds are generally considered to be of low hazard, albeit this notion has not often been put to the test. Here the safety information available for 5 dietary putative chemopreventive compounds, indole-3-carbinol (I3C), curcumin, quercetin, epigallocatechin gallate (EGCG), and capsaicin is reviewed. For these agents, normal dietary intake, doses used in clinical trials, efficacious doses in rodents, and where available, toxic doses are compared. For curcumin, quercetin and capsaicin, toxicological data is only available from studies in rodents. Information on long-term effects in animals beyond 28 or 90 days is lacking for EGCG. Capsaicin and quercetin are suspected carcinogens. I3C and quercetin can modulate the absorption of other drugs given concomitantly. Without further investigation of their toxicology, it is difficult to recommend any of these agents for long-term use in the healthy population.
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Affiliation(s)
- Richard D Verschoyle
- Cancer Biomarkers and Prevention Group, Department of Cancer Studies and Molecular Medicine, University of Leicester, RKCSB, Leicester Royal Infirmary, Leicester LE2 7LX
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309
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Burckhardt IC, Gozal D, Dayyat E, Cheng Y, Li RC, Goldbart AD, Row BW. Green tea catechin polyphenols attenuate behavioral and oxidative responses to intermittent hypoxia. Am J Respir Crit Care Med 2008; 177:1135-41. [PMID: 18276944 DOI: 10.1164/rccm.200701-110oc] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE The intermittent hypoxia (IH) that characterizes sleep-disordered breathing impairs spatial learning and increases NADPH oxidase activity and oxidative stress in rodents. We hypothesized that green tea catechin polyphenols (GTPs) may attenuate IH-induced neurobehavioral deficits by reducing IH-induced NADPH oxidase expression, lipid peroxidation, and inflammation. OBJECTIVES To assess the effects of GTP administered in drinking water on the cognitive, inflammatory, and oxidative responses to long-term (>14 d) IH during sleep in male Sprague-Dawley rats. METHODS Cognitive assessments were conducted in the Morris water maze. We measured levels and expression of malondialdehyde (MDA), prostaglandin E(2), p47(phox) subunit of NADPH oxidase, receptor for advanced glycation end products (RAGE), and glial fibrillary acidic protein expression in rodent brain tissue. MEASUREMENTS AND MAIN RESULTS GTP treatment prevented IH-induced decreases in spatial bias for the hidden platform during the Morris water maze probe trails as well as IH-induced increases in p47phox expression within the hippocampal CA1 region. In untreated animals, IH exposure was associated with doubling of cortical MDA levels in comparison to room air control animals, and GTP-treated animals exposed to IH showed a 40% reduction in MDA levels. Increases in brain RAGE and glial fibrillary acidic protein expression were observed in IH-exposed animals, and these increases were attenuated in animals treated with GTP. CONCLUSIONS Oral GTP attenuates IH-induced spatial learning deficits and mitigates IH-induced oxidative stress through multiple beneficial effects on oxidant pathways. Because oxidative processes underlie neurocognitive deficits associated with IH, the potential therapeutic role of GTP in sleep-disordered breathing deserves further exploration.
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Affiliation(s)
- Isabel C Burckhardt
- Kosair Children's Hospital Research Institute, University of Louisville, 570 South Preston Street, Suite 204, Louisville, KY 40202, USA
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311
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Effects of black and green tea consumption on blood glucose levels in non-obese elderly men and women from Mediterranean Islands (MEDIS epidemiological study). Eur J Nutr 2008; 47:10-6. [PMID: 18204918 DOI: 10.1007/s00394-007-0690-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2007] [Accepted: 11/28/2007] [Indexed: 10/22/2022]
Abstract
BACKGROUND Obesity and diabetes are metabolic disorders that affect a large amount of the elderly population and are related to increased cardiovascular risk. Tea intake has been associated with lower risk of mortality and morbidity in some, but not all studies. We evaluated the association between tea intake, blood glucose levels, in a sample of elderly adults. METHODS During 2005-2006, 300 men and women from Cyprus, 142 from Mitilini and 100 from Samothraki islands (aged 65-100 years) were enrolled. Dietary habits (including tea consumption) were assessed through a food frequency questionnaire. Among various factors, fasting blood glucose and body mass index (BMI) were measured. RESULTS Fifty-four percent of the participants reported that they consume tea at least once a week (mean intake 1.6 +/- 1.1 cup/day). A significant interaction was observed between tea intake, obesity status on glucose levels (P < 0.001). After adjusting for various confounders, tea intake was associated with lower blood glucose levels in non-obese (P for trend <0.001), but not in obese people (P = 0.24). Multiple logistic regression analysis revealed that moderate tea consumption (1-2 cups/day) was associated with 88% (95% CI 76-98%) lower odds of having diabetes among non-obese participants, irrespective of age, sex, smoking, physical activity status, dietary habits and other clinical characteristics. CONCLUSION Tea consumption is associated with reduced levels of fasting blood glucose only among non-obese elderly people.
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Abstract
The present paper explores the level of evidence required to justify giving dietary advice to the public. There are important practical differences between the development of public health nutrition guidelines and guidelines for clinical practice. While the gold standard for evidence for clinical practice guidelines is a meta-analysis of a number of randomised controlled trials, this is often unrealistic and sometimes unethical for the evaluation of public health nutrition interventions. Hence, epidemiological studies make up the bulk of evidence for nutrition guidelines. Tea and coffee are an interesting case study in relation to this issue. They are two of the most commonly consumed beverages worldwide, yet there is little dietary advice on their use. The evidence for a relationship between coffee or tea consumption and several diseases is discussed. The available studies, predominantly epidemiological, together with animal and in vitro studies, indicate that coffee and tea are both safe beverages. However, tea is the healthier option because it has a possible role in the prevention of several cancers and CVD. While the evidence for such relationships is not strong, the public will continue to drink both tea and coffee, and will continue to ask nutritionists to make recommendations. It is therefore argued that advice should be given on the best available data, as waiting for complete data to become available could have severe consequences for public health.
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Antiplatelet Activity of Epigallocatechin Gallate Is Mediated by the Inhibition of PLCγ2 Phosphorylation, Elevation of PGD2 Production, and Maintaining Calcium-ATPase Activity. J Cardiovasc Pharmacol 2008; 51:45-54. [DOI: 10.1097/fjc.0b013e31815ab4b6] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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314
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Li W, Ashok M, Li J, Yang H, Sama AE, Wang H. A major ingredient of green tea rescues mice from lethal sepsis partly by inhibiting HMGB1. PLoS One 2007; 2:e1153. [PMID: 17987129 PMCID: PMC2048740 DOI: 10.1371/journal.pone.0001153] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2007] [Accepted: 10/16/2007] [Indexed: 11/18/2022] Open
Abstract
Background The pathogenesis of sepsis is mediated in part by bacterial endotoxin, which stimulates macrophages/monocytes to sequentially release early (e.g., TNF, IL-1, and IFN-γ) and late (e.g., HMGB1) pro-inflammatory cytokines. Our recent discovery of HMGB1 as a late mediator of lethal sepsis has prompted investigation for development of new experimental therapeutics. We previously reported that green tea brewed from the leaves of the plant Camellia sinensis is effective in inhibiting endotoxin-induced HMGB1 release. Methods and Findings Here we demonstrate that its major component, (-)-epigallocatechin-3-gallate (EGCG), but not catechin or ethyl gallate, dose-dependently abrogated HMGB1 release in macrophage/monocyte cultures, even when given 2–6 hours post LPS stimulation. Intraperitoneal administration of EGCG protected mice against lethal endotoxemia, and rescued mice from lethal sepsis even when the first dose was given 24 hours after cecal ligation and puncture. The therapeutic effects were partly attributable to: 1) attenuation of systemic accumulation of proinflammatory mediator (e.g., HMGB1) and surrogate marker (e.g., IL-6 and KC) of lethal sepsis; and 2) suppression of HMGB1-mediated inflammatory responses by preventing clustering of exogenous HMGB1 on macrophage cell surface. Conclusions Taken together, these data suggest a novel mechanism by which the major green tea component, EGCG, protects against lethal endotoxemia and sepsis.
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Affiliation(s)
- Wei Li
- Department of Emergency Medicine, North Shore University Hospital-New York University School of Medicine, Manhasset, New York, United States of America
| | - Mala Ashok
- Department of Emergency Medicine, North Shore University Hospital-New York University School of Medicine, Manhasset, New York, United States of America
| | - Jianhua Li
- The Feinstein Institute for Medical Research, Manhasset, New York, United States of America
| | - Huan Yang
- The Feinstein Institute for Medical Research, Manhasset, New York, United States of America
| | - Andrew E. Sama
- Department of Emergency Medicine, North Shore University Hospital-New York University School of Medicine, Manhasset, New York, United States of America
| | - Haichao Wang
- Department of Emergency Medicine, North Shore University Hospital-New York University School of Medicine, Manhasset, New York, United States of America
- The Feinstein Institute for Medical Research, Manhasset, New York, United States of America
- * To whom correspondence should be addressed. E-mail:
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315
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Neilson AP, Hopf AS, Cooper BR, Pereira MA, Bomser JA, Ferruzzi MG. Catechin degradation with concurrent formation of homo- and heterocatechin dimers during in vitro digestion. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2007; 55:8941-9. [PMID: 17924707 DOI: 10.1021/jf071645m] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Catechins were subjected to in vitro gastric and small intestinal digestion. EGCG, EGC, and ECG were significantly degraded at all concentrations tested, with losses of 71-91, 72-100, and 60-61%, respectively. EC and C were comparatively stable, with losses of 8-11 and 7-8%, respectively. HLPC-ESI-MS/MS indicated that EGCG degradation under simulated digestion resulted in production of theasinensins (THSNs) A and D (m/z 913) and P-2 (m/z 883), its autoxidation homodimers. EGC dimerization produced the homodimers THSN C and E (m/z 609) and homodimers analogous to P-2 (m/z 579). ECG homodimers were not observed. EGCG and EGC formed heterodimers analogous to the THSNs (m/z 761) and P-2 (m/z 731). EGCG and ECG formed homodimers analogous to the THSNs (m/z 897). This study provides an expanded profile of catechin dimers of digestive origin that may potentially form following consumption of catechins. These data provide a logical basis for initial screening to detect catechin digestive products in vivo.
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Affiliation(s)
- Andrew P Neilson
- Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, Indiana 47907, USA
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316
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Shinada K, Tagashira M, Watanabe H, Sopapornamorn P, Kanayama A, Kanda T, Ikeda M, Kawaguchi Y. Hop bract polyphenols reduced three-day dental plaque regrowth. J Dent Res 2007; 86:848-51. [PMID: 17720853 DOI: 10.1177/154405910708600908] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Previous research has shown the inhibitory effects of hop bract polyphenols (HBP) on cariogenic streptococci in vitro, but their effects in humans have not been investigated. This double-blind, crossover clinical study tested the hypothesis that HBP delivered in a mouthrinse suppresses plaque regrowth in humans. Twenty-nine healthy male volunteers had all plaque removed, and refrained from all oral hygiene for 3 days, except for rinsing with a mouthrinse containing 0.1% HBP or a placebo. The results showed that the mean amount of plaque assessed by the Patient Hygiene Performance score after the volunteers used the HBP mouthrinse was significantly less than that after they used the placebo (p < 0.001). The number of mutans streptococci in the plaque samples after volunteers used the HBP mouthrinse was significantly lower than that after they used the placebo (p < 0.05). These findings suggested that HBP, delivered in a mouthrinse, successfully reduced dental plaque regrowth in humans.
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Affiliation(s)
- K Shinada
- Department of Oral Health Promotion, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Tokyo, Japan.
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317
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Kelemen K, Kiesecker C, Zitron E, Bauer A, Scholz E, Bloehs R, Thomas D, Greten J, Remppis A, Schoels W, Katus HA, Karle CA. Green tea flavonoid epigallocatechin-3-gallate (EGCG) inhibits cardiac hERG potassium channels. Biochem Biophys Res Commun 2007; 364:429-35. [PMID: 17961513 DOI: 10.1016/j.bbrc.2007.10.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2007] [Accepted: 10/02/2007] [Indexed: 11/25/2022]
Abstract
The catechin EGCG is the main flavonoid compound of green tea and has received enormous pharmacological attention because of its putative beneficial health effects. This study investigated for the first time the effect of EGCG on hERG channels, the main pharmacological target of drugs that cause acquired long QT syndrome. Cloned hERG channels were expressed in Xenopus oocytes and in HEK293 cells. Heterologous hERG currents were inhibited by EGCG with an IC50 of 6.0 micromol/l in HEK293 cells and an IC50 of 20.5 micromol/l in Xenopus laevis oocytes. Onset of effect was slow and only little recovery from inhibition was observed upon washout. In X. laevis oocytes EGCG inhibited hERG channels in the open and inactivated states, but not in the closed states. The half-maximal activation voltage of hERG currents was shifted by EGCG towards more positive potentials. In conclusion, EGCG is a low-affinity inhibitor of hERG sharing major electrophysiological features with pharmaceutical hERG antagonists.
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Affiliation(s)
- Kamilla Kelemen
- Department of Internal Medicine III-Cardiology, Medical University Hospital Heidelberg, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany.
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318
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Yang G, Shu XO, Li H, Chow WH, Ji BT, Zhang X, Gao YT, Zheng W. Prospective cohort study of green tea consumption and colorectal cancer risk in women. Cancer Epidemiol Biomarkers Prev 2007; 16:1219-23. [PMID: 17548688 DOI: 10.1158/1055-9965.epi-07-0097] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Tea and its constituents have shown anticarcinogenic activities in in vitro and animal studies. Epidemiologic studies, however, have been inconsistent. We prospectively evaluated the association between green tea consumption and colorectal cancer (CRC) risk in a cohort of 69,710 Chinese women aged 40 to 70 years. Information on tea consumption was assessed through in-person interviews at baseline and reassessed 2 to 3 years later in a follow-up survey. During 6 years of follow-up, 256 incident cases of CRC were identified. The multivariate relative risk of CRC was 0.63 (95% confidence interval, 0.45-0.88) for women who reported drinking green tea regularly at baseline compared with nonregular tea drinkers. A significant dose-response relationship was found for both the amount of tea consumed (Ptrend = 0.01) and duration in years of lifetime tea consumption (Ptrend = 0.006). The reduction in risk was most evident among those who consistently reported to drink tea regularly at both the baseline and follow-up surveys (relative risk, 0.43; 95% confidence interval, 0.24-0.77). The inverse association with regular tea drinking was observed for both colon and rectal cancers. This study suggests that regular consumption of green tea may reduce CRC risk in women.
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Affiliation(s)
- Gong Yang
- Department of Medicine, Vanderbilt Epidemiology Center and Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville TN 37232-2587, USA.
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Schamberger GP, Labuza TP. Effect of green tea flavonoids on Maillard browning in UHT milk. Lebensm Wiss Technol 2007. [DOI: 10.1016/j.lwt.2006.09.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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320
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Osada K, Suzuki T, Kawakami Y, Senda M, Kasai A, Sami M, Ohta Y, Kanda T, Ikeda M. Dose-dependent hypocholesterolemic actions of dietary apple polyphenol in rats fed cholesterol. Lipids 2007; 41:133-9. [PMID: 17707979 DOI: 10.1007/s11745-006-5081-y] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The dose-dependent hypocholesterolemic and antiatherogenic effects of dietary apple polyphenol (AP) from unripe apple, which contains approximately 85% catechin oligomers (procyanidins), were examined in male Sprague-Dawley rats (4 wk of age) given a purified diet containing 0.5% cholesterol. Dietary AP at 0.5 and 1.0% levels significantly decreased the liver cholesterol level compared with that in the control (AP-free diet-fed) group. Dietary AP also significantly lowered the serum cholesterol level compared with that in the control group. However, the HDL cholesterol level was significantly higher in the 1.0% AP-fed group than in the control group. Accordingly, the ratio of HDL-cholesterol/total cholesterol was significantly higher in the 0.5% AP-fed group and 1.0% AP-fed group than in the control group. Moreover, the atherogenic indices in the 0.5 and 1.0% AP-fed groups were significantly lower than those in the control group. The activity of hepatic cholesterol 7alpha-hydroxylase tended to be increased by dietary AP in a dose-dependent manner. In accord with this observation, dietary AP increased the excretion of acidic steroids in feces. Dietary AP also significantly promoted the fecal excretion of neutral steroids in a dose-dependent manner. These observations suggest that dietary AP at a 0.5 or 1.0% level exerts hypocholesterolemic and antiatherogenic effects through the promotion of cholesterol catabolism and inhibition of intestinal absorption of cholesterol.
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Affiliation(s)
- Kyoichi Osada
- Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Aomori 036-8224, Japan.
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321
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Yang Y, Zhou L, Gu Y, Zhang Y, Tang J, Li F, Shang W, Jiang B, Yue X, Chen M. Dietary chickpeas reverse visceral adiposity, dyslipidaemia and insulin resistance in rats induced by a chronic high-fat diet. Br J Nutr 2007; 98:720-6. [PMID: 17666145 DOI: 10.1017/s0007114507750870] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The improved effects of dietary chickpeas on visceral adiposity, dyslipidaemia and insulin resistance were examined. Rats were fed a normal-fat diet (NFD), a high-fat diet (HFD) or a high-fat plus chickpea diet (HFD+CP) for 8 months. The epididymal fat pad weight v. total body weight of rats was higher in the HFD group (0.032 (sd 0.0042) g/g) than in the NFD group (0.015 (sd 0.0064) g/g) and smaller in the HFD+CP group (0.023 (sd 0.0072) g/g) compared with the HFD group (P < 0.05). Chickpea treatment also induced a favourable plasma lipid profile reflecting decreased TAG, LDL-cholesterol (LDL-C) and LDL-C:HDL-cholesterol levels (P < 0.05). HFD-fed rats had higher TAG concentration in muscle and liver, whereas the addition of chickpeas to the HFD drastically lowered TAG concentration (muscle, 39 %; liver, 23 %). The activities of lipoprotein lipase (LPL) in epididymal adipose tissue and hepatic TAG lipase in liver recorded a 40 and 23 % increase respectively in HFD rats compared with those in NFD rats; dietary chickpeas completely normalised the levels. Furthermore, chickpea-treated obese rats also showed a markedly lower leptin and LPL mRNA content in epididymal adipose tissue. An insulin tolerance test, oral glucose tolerance test and insulin-releasing test showed that chickpeas significantly improved insulin resistance, and prevented postprandial hyperglycaemia and hyperinsulinaemia induced by the chronic HFD. The present findings provide a rational basis for the consumption of chickpeas as a functional food ingredient, which may be beneficial for correcting dyslipidaemia and preventing diabetes.
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Affiliation(s)
- Ying Yang
- Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, School of Medicine, Shanghai Jiaotong University, 197 Ruijin Road II, Shanghai 200025, China
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Abstract
Ovarian cancer is the leading cause of death from gynecologic cancer. Tea, especially green tea, has shown promise in the prevention of several cancers. Green tea contains a number of compounds, including polyphenols, that have chemopreventive properties. There is much evidence from in vitro and animal studies suggesting that components of tea are associated with decreased risk or progression of ovarian cancer. However, epidemiologic studies have generated inconsistent results. Recent research conducted in China reported reduced risk of ovarian cancer and increased survival post diagnosis with green tea consumption. This review presents emerging evidence and the authors' perspectives on the role of green tea in ovarian cancer prevention.
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Affiliation(s)
- Andy H Lee
- Curtin University of Technology, School of Public Health, Perth, WA, Australia.
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323
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Ju J, Lu G, Lambert JD, Yang CS. Inhibition of carcinogenesis by tea constituents. Semin Cancer Biol 2007; 17:395-402. [PMID: 17686632 PMCID: PMC2736048 DOI: 10.1016/j.semcancer.2007.06.013] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2007] [Revised: 06/21/2007] [Accepted: 06/27/2007] [Indexed: 10/23/2022]
Abstract
The possible cancer preventive activity of tea has received much attention in recent years. The inhibitory activities of tea and tea constituents against carcinogenesis at different organ sites have been demonstrated in many animal models. The effect of tea consumption on human cancers, however, remains inconclusive. The mechanisms of action of tea polyphenols, especially EGCG, the most abundant and active catechin, have been extensively investigated. Most of the studies, however, were based on cell culture systems, and these mechanisms need to be evaluated and verified in animal models or humans in order to gain more understanding on the effect of tea consumption on human cancer. Human intervention trials are warranted to determine the possible prevention of cancer of specific sites by preparation of tea constituents.
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Affiliation(s)
| | | | | | - Chung S. Yang
- Corresponding author: Dr. Chung S. Yang, Department of Chemical Biology, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, 164 Frelinghuysen Road, Piscataway, NJ 08854-8020, Phone: 732-445-3400 x248; Fax: 732-445-0687, E-mail:
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324
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Kitani K, Osawa T, Yokozawa T. The effects of tetrahydrocurcumin and green tea polyphenol on the survival of male C57BL/6 mice. Biogerontology 2007; 8:567-73. [PMID: 17516143 DOI: 10.1007/s10522-007-9100-z] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2006] [Accepted: 04/11/2007] [Indexed: 01/21/2023]
Abstract
The effect of feeding of two different antioxidants, tetrahydrocurcumin (TC) and green tea polyphenols (PPs) on the survival of male C57BL/6 mice was examined. Mice that started to receive diets containing TC (0.2%) at the age of 13 months had significantly longer average life spans (days, mean +/- SD) than control mice (797.6 +/- 151.2 vs.882 +/- 154.6, both n = 50, controls vs. TC treated, plus 11.7%, P < 0.01). The 10% longest survival was also significantly greater in TC-treated mice (plus 6.5%, P < 0.01). In contrast, in mice that started to receive TC in their 19th month of life, no significant difference from the control mice was found for either the average life span or the 10% longest survival. In mice that received water containing PPs (80 mg/l), the average life span was also significantly longer than in the control mice (801 +/- 121.5 vs. 852.7 +/- 88.2, plus 6.4%, P < 0.05), although the 10% longest survival was not significantly different from that in the control mice (P > 0.05). The body weights of the TC (but not PP) fed mice, were slightly (2-4%) but significantly (P < 0.05) lower than the values for the corresponding ages in the control mice in the first six months of treatment. Thereafter, the difference in average body weight between the control and the TC-fed animals was totally lost. Although an additional contribution of an unintended slight decrease in food intake due to TC feeding (suspected due to the difference in body weight) is not excluded, we suggest that the feeding of nutritional antioxidants such as TC and PPs may have the potential to beneficially modify the life spans of animals.
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Affiliation(s)
- Kenichi Kitani
- National Institute for Longevity Sciences, 36-3, Gengo, Moriokacho, Obu-shi, Aichi 474-8522, Japan.
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325
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Leong H, Mathur PS, Greene GL. Inhibition of mammary tumorigenesis in the C3(1)/SV40 mouse model by green tea. Breast Cancer Res Treat 2007; 107:359-69. [PMID: 17484049 DOI: 10.1007/s10549-007-9568-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2007] [Accepted: 03/12/2007] [Indexed: 12/30/2022]
Abstract
Previous studies show inhibitory effects of green tea in chemically induced mammary tumors or human tumor explants, but not in spontaneous tumor models that are more representative of human breast cancer. The C3(1)/SV40 mouse model is particularly suited for breast cancer prevention studies because it produces spontaneous ductal adenocarcinomas and a predictable time course for mammary tumorigenesis through a multistage progression similar to that occurring in humans. We therefore used this model to test the chemoprotective effects of green tea. Administration of 0.5% Polyphenon E (Poly E) (a standardized preparation of green tea extract) in drinking water delayed tumor onset and suppressed tumor growth by 40%, compared to tap water-fed animals, with no adverse side effects. Histological analysis of mammary glands showed that green tea slowed the progression of ductal lesions to advanced mammary intraepithelial neoplasias and suppressed tumor invasiveness. Green tea inhibited the proliferation of ductal epithelial cells and tumors and, overall, disrupted post-pubertal ductal growth. Immunohistochemical analyses also demonstrated that green tea inhibited angiogenesis through a decrease in both ductal epithelial and stromal VEGF expression and a decrease in intratumoral microvascular density. Our data strongly support the potential use of green tea as a breast cancer chemopreventive agent.
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Affiliation(s)
- Hoyee Leong
- The Ben May Department for Cancer Research, The University of Chicago, GCIS W330, 929 East 57th Street, Chicago, IL 60637, USA
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326
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Kaur S, Greaves P, Cooke DN, Edwards R, Steward WP, Gescher AJ, Marczylo TH. Breast cancer prevention by green tea catechins and black tea theaflavins in the C3(1) SV40 T,t antigen transgenic mouse model is accompanied by increased apoptosis and a decrease in oxidative DNA adducts. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2007; 55:3378-85. [PMID: 17407311 DOI: 10.1021/jf0633342] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Tea consumption is associated with a reduced risk of mammary cancer as reflected by epidemiological studies and experiments in carcinogen-induced rodent models of mammary carcinogenesis. We tested the hypothesis that green tea catechins (GTC) or theaflavins from black tea (BTT) interfere with mammary carcinogenesis in C3(1) SV40 T,t antigen transgenic multiple mammary adenocarcinoma (TAg) mice and that GTC/BTT affect tumor survival or oxidation status. TAg mice received GTC/BTT (0.05%) in drinking water for their lifetime. As compared to control mice, they survived longer and had smaller tumors. On microscopic inspection, the size of the largest tumor per mouse was decreased by 40-42% (p<0.01). GTC (0.01%) and BTT (0.05%) increased levels of cleaved caspase 3 in tumor tissue by 67 and 38%, respectively (p<0.05), intimating increased apoptosis. Tumor levels of the malondialdehyde-DNA adduct M1dG in mice receiving GTC or BTT (0.05%) were reduced by 78 (p<0.001) or 63% (p<0.05), respectively, as compared to controls. The results render the exploration of the breast cancer chemopreventive properties of tea preparations in humans worthwhile.
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Affiliation(s)
- Siminder Kaur
- Department of Cancer Studies and Molecular Medicine, University of Leicester, Leicester LE2 7LX, United Kingdom
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327
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Moon HS, Lee HG, Choi YJ, Kim TG, Cho CS. Proposed mechanisms of (−)-epigallocatechin-3-gallate for anti-obesity. Chem Biol Interact 2007; 167:85-98. [PMID: 17368440 DOI: 10.1016/j.cbi.2007.02.008] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2007] [Revised: 02/11/2007] [Accepted: 02/12/2007] [Indexed: 12/28/2022]
Abstract
Green tea catechins (GTCs) are polyphenolic flavonoids formerly called vitamin P. GTCs, especially (-)-epigallocatechin-3-gallate (EGCG), lower the incidence of cancers, collagen-induced arthritis, oxidative stress-induced neurodegenerative diseases, and streptozotocin-induced diabetes. Also, inhibition of adipogenesis by green tea and green tea extract has been demonstrated in cell lines, animal models, and humans. The obesity-preventive effects of green tea and its main constituent EGCG are widely supported by results from epidemiological, cell culture, animal, and clinical studies in the last decade. Studies with adipocyte cell lines and animal models have demonstrated that EGCG inhibits extracellular signal-related kinases (ERK), activates AMP-activated protein kinase (AMPK), modulates adipocyte marker proteins, and down-regulates lipogenic enzymes as well as other potential targets. Also, the catechin components of green tea have been shown to possess anti-carcinogenic properties possibly related to their anti-oxidant activity. In addition, it was shown that dietary supplementation with EGCG could potentially contribute to nutritional strategies for the prevention and treatment of type 2 diabetes mellitus. In this review, the biological activities and multiple mechanisms of EGCG in cell lines, animal models, and clinical observations are explained.
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Affiliation(s)
- Hyun-Seuk Moon
- School of Agricultural Biotechnology, Seoul National University, Seoul 151-921, South Korea
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328
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Soulat T, Philippe C, Bal dit Sollier C, Brézillon C, Berge N, Teissedre PL, Callebert J, Rabot S, Drouet L. Wine constituents inhibit thrombosis but not atherogenesis in C57BL/6 apolipoprotein E-deficient mice. Br J Nutr 2007; 96:290-8. [PMID: 16923223 DOI: 10.1079/bjn20061818] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Regular and moderate wine consumption is one of the explanations suggested for the lower incidence of cardiovascular events in France compared with other industrialized countries. We evaluated whether alcohol alone or combined with red wine polyphenols reduced plaque size and/or attenuated thrombotic reactivity at the site of advanced atherosclerotic lesions. Red wine extract, or purified (+)-catechin with alcohol, or alcohol alone, was added for 12 weeks to the drinking water of apoE-deficient (apoE−/−) C57B/ mice and wild-type counterparts. In the apoE−/−mice, all alcohol-containing mixtures were associated with a larger size of aortic atherosclerotic lesions. On the other hand, red wine extract and (+)-catechin significantly inhibited blood thrombotic reactivity (P<0·05) as assessed in a cylindrical perfusion chamber model of experimental thrombosis: area reductions in cross-sectional surface of theex vivothrombus were 64% and 63%, respectively. In the wild-type mice, red wine extract and (+)-catechin tended to reduce thrombogenicity, which was on the whole less marked than in the apoE−/−mice. These findings suggest that a moderate and regular consumption of red wine may protect against clinical cardiovascular events, mainly by attenuating the thrombogenic response rather than by reducing the development of atherosclerotic lesions. This antithrombogenic effect may include normalization of the abnormally high thrombogenic responsiveness in apoE−/−mice as well as a direct antithrombotic effect.
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Affiliation(s)
- Thierry Soulat
- Laboratoire de Thrombose et d'Athérosclérose Expérimentales, IVS, Hôpital Lariboisière, 2 rue Ambroise Paré, 75475 Paris Cedex 10, France
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329
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Khallouki F, Haubner R, Hull WE, Erben G, Spiegelhalder B, Bartsch H, Owen RW. Isolation, purification and identification of ellagic acid derivatives, catechins, and procyanidins from the root bark of Anisophyllea dichostyla R. Br. Food Chem Toxicol 2007; 45:472-85. [PMID: 17084499 DOI: 10.1016/j.fct.2006.09.011] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2006] [Revised: 09/15/2006] [Accepted: 09/20/2006] [Indexed: 11/28/2022]
Abstract
The root bark of Anisophyllea dichostyla R. Br. is traditionally used in the Democratic Republic Congo for the treatment of several conditions such as anorexia, fatigue and intestinal infections. We have identified and quantitated several polyphenol antioxidants in the methanol extract of the root bark (120g). The polyphenol content (3.32g/kg) was predominantly ellagitannins (25%) and polyhydroxyflavan-3-ols (catechins and procyanidins, 75%) with 3'-O-methyl-3,4-methylenedioxo ellagic acid 4'-O-beta-d-glucopyranoside and (-)-epicatechin as the major species in each class. These two compounds and the following species were identified unequivocally by NMR spectroscopy: (+)-catechin, (-)-epicatechin 3-O-gallate, 3-O-methyl ellagic acid, 3,3'-di-O-methyl ellagic acid, 3'-O-methyl-3,4-methylenedioxo ellagic acid, 3'-O-methyl-3,4-methylenedioxo ellagic acid 4'-O-beta-d-glucopyranoside, and 3'-O-methyl ellagic acid 4-O-beta-d-xylopyranoside. The following additional compounds were purified by semi-preparative HPLC and tentatively identified on the basis of UV spectra, HPLC-ESI-MS and nano-ESI-MS-MS: (+)-catechin-3-O-beta-d-glucopyranoside, epicatechin-(4beta-->8)-catechin (procyanidin B(1)), epicatechin-(4beta-->8)-epicatechin (procyanidin B(2)), an (epi)catechin trimer, 3-O-methyl ellagic acid 4-O-beta-d-glucopyranoside, (-)-epicatechin 3-O-vanillate, 3,4-methylenedioxo ellagic acid 4'-O- beta-d-glucopyranoside, and 3,3'-di-O-methyl ellagic acid 4-O-beta-d-xylopyranoside. Fractionation of the raw extract by column chromatography on silicic acid yielded 10 fractions. In the hypoxanthine/xanthine oxidase antioxidant assay system, CC-9 which contained a range of polyphenols dominated by (-)-epicatechin-O-gallate proved to be the most potent antioxidant fraction (IC(50)=52 micro g/mL) in terms of ROS scavenging. In terms of XO inhibition CC-8, dominated by (epi)catechin trimer and which also contained appreciable amounts of 3'-O-methyl ellagic acid 4'-O-beta-d-xylopyranoside, as well as the catechins (+)-catechin-3-O-beta-d-glucopyranoside, epicatechin-(4beta-->8)-catechin (procyanidin B(1)), and (-)-epicatechin 3-O-gallate, proved to be the most potent (IC(50)=36 micro g/mL).
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Affiliation(s)
- F Khallouki
- Division of Toxicology and Cancer Risk Factors, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany
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330
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Fraser ML, Mok GS, Lee AH. Green tea and stroke prevention: Emerging evidence. Complement Ther Med 2007; 15:46-53. [PMID: 17352971 DOI: 10.1016/j.ctim.2006.07.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2005] [Accepted: 07/07/2006] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Stroke is a leading cause of morbidity and mortality in many countries. Green tea is a simple and inexpensive beverage that is showing promise in the prevention of several diseases, including stroke. However, epidemiological studies examining the preventive effects of tea on stroke have generated inconsistent results. OBJECTIVE To review the emerging evidence for green tea in stroke prevention. METHODS Published articles were located by searching the PubMed, ProQuest, CINAHL and other databases, using the keywords 'tea' and 'stroke' with no restriction on publication date. Reference lists of identified articles were also searched for relevant publications. RESULTS Two published epidemiological studies on green tea reported positive findings. A large number of studies have also proposed biological mechanisms by which tea or tea components may reduce the stroke risk. Additional studies are required from a variety of populations, assessing duration and different types of tea consumption on subtypes of stroke to provide further evidence. CONCLUSION Green tea is a safe and cheap beverage. Its consumption should be encouraged because it could potentially serve as a practical method for stroke prevention.
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Affiliation(s)
- Michelle L Fraser
- School of Public Health, Curtin University of Technology, GPO Box U 1987, Perth, WA 6845, Australia
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331
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Wessner B, Strasser EM, Koitz N, Schmuckenschlager C, Unger-Manhart N, Roth E. Green tea polyphenol administration partly ameliorates chemotherapy-induced side effects in the small intestine of mice. J Nutr 2007; 137:634-40. [PMID: 17311952 DOI: 10.1093/jn/137.3.634] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The chemotherapeutic agent irinotecan (IT) is highly effective against several types of cancer, although its use is limited due to severe intestinal toxicity. The aim of this study was to evaluate inflammatory and oxidative stress-related processes contributing to small intestinal mucosa damage and to determine the extent to which green tea polyphenols could ameliorate the detrimental effects induced by IT. In Expt. 1, mice were challenged intraperitoneally with IT or saline on 2 consecutive days. For time kinetic measurements, the IT-treated mice were killed at 3, 24, 48, 72, and 96 h after the 2nd dose of IT. Three hours after IT administration, the ileum glutathione concentration dropped significantly. Lipid peroxidation and inflammation, as measured by macrophage inflammatory protein-2 content, myeloperoxidase activity, and nuclear factor-kappaB translocation, were highest between 24 and 48 h after IT treatment. In Expt. 2, green tea polyphenols (1 g/L) were supplied via drinking water for 7 d before and 3 d after treatment with IT. Green tea polyphenols significantly affected the glutathione:glutathione disulfide ratio but not lipid peroxidation, macrophage inflammatory protein-2 levels, myeloperoxidase activity, or nuclear factor-kappaB activation. Our study reveals that IT administration is associated with oxidative stress and inflammation, both occurring simultaneously to IT-induced mucosal damage. The antioxidative defense is affected soon after IT administration. Green tea polyphenols supplied orally protected against oxidation in our experimental model and could be one approach to reducing the risk of IT-induced side effects in the clinical setting.
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Affiliation(s)
- Barbara Wessner
- Department of Surgery, Research Laboratories, Medical University of Vienna, A-1090 Vienna, Austria.
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332
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Abstract
Present study was conducted to clarify whether lower or higher dietary dose of green tea is beneficial for the reduction of risk of type 2 diabetes. Five weeks old male SD rats were fed high fat diet for 2 weeks then divided into 4 groups of 8 animals as Normal Control (NC), Diabetic Control (DBC), Green Tea Low (GTL, 0.5%, Green Tea High (GTH, 2.0%) groups. Diabetes was induced by intra-peritoneal (i.p) injection of STZ (40 mg/kg BW) in all animals except NC group. After 4 weeks feeding of experimental diets, serum fasting blood glucose was not decreased but relatively increased in both green tea fed groups compared to DBC group. Serum insulin concentration was significantly (p< 0.05) increased in GTL group but not in GTH group when compared with DBC group. Serum lipids were significantly decreased in GTH group but not in GTL group compared to DBC group. Intra-peritoneal glucose tolerance test, blood HbA1c, liver weight, and liver glycogen level were not influenced by the feeding of green tea containing diets. Data of this study suggest that lower dose of green tea is insulinotropic when higher dose is hyperglycemic but hypolipidemic at least in this experimental condition.
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MESH Headings
- Animals
- Blood Glucose/analysis
- Body Weight/drug effects
- Cholesterol/blood
- Cholesterol, HDL/blood
- Cholesterol, LDL/blood
- Diabetes Mellitus, Experimental/blood
- Diabetes Mellitus, Experimental/physiopathology
- Diabetes Mellitus, Experimental/prevention & control
- Diabetes Mellitus, Type 2/blood
- Diabetes Mellitus, Type 2/physiopathology
- Diabetes Mellitus, Type 2/prevention & control
- Dietary Fats/administration & dosage
- Dietary Fats/pharmacology
- Dose-Response Relationship, Drug
- Glucose Tolerance Test
- Liver/drug effects
- Liver/pathology
- Male
- Organ Size/drug effects
- Plant Extracts/administration & dosage
- Plant Extracts/pharmacology
- Rats
- Rats, Sprague-Dawley
- Tea/chemistry
- Triglycerides/blood
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Affiliation(s)
- Md Shahidul Islam
- Department of Food and Nutrition, Seoul National University, Seoul 151-742, South Korea.
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333
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Biasutto L, Marotta E, De Marchi U, Zoratti M, Paradisi C. Ester-Based Precursors to Increase the Bioavailability of Quercetin. J Med Chem 2007; 50:241-53. [PMID: 17228866 DOI: 10.1021/jm060912x] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Plant polyphenols exhibit a variety of potentially useful biochemical properties in vitro, but their evaluation and clinical exploitation in vivo is hampered by their limited bioavailability. Precursors exhibiting resistance to phase II metabolism during absorption are therefore desirable. We report here the synthesis as well as stability and solubility studies of several ester derivatives of quercetin (3,3',4',5,7-pentahydroxy flavone), most of which comprise an aminoacyl group. To model transepithelial absorption, we tested transport across supported tight monolayers of MDCK-1, MDCK-2, and Caco-2 cells. Quercetin itself was extensively conjugated by all three types of cells. A few of our precursors did not cross the monolayers, but others did, undergoing partial deacylation. No phase II conjugation was observed during transport of these compounds across MDCK or some Caco-2 clones. With other Caco-2 lines complete deacylation occurred, followed by metabolism of quercetin. Since elimination of residual acyl groups is expected to take place in vivo, ester derivatives of polyphenols may constitute a useful method to increase systemic aglycone concentrations.
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Affiliation(s)
- Lucia Biasutto
- Department of Biomedical Sciences, University of Padova, Padova, Italy
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334
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Ohta Y, Funayama M, Seino H, Sami M, Kanda T, Shoji T, Ohtake Y, Osada K. Apple Polyphenol Improves Lipid Metabolism and Insulin Independence in Obese Rats. J JPN SOC FOOD SCI 2007. [DOI: 10.3136/nskkk.54.287] [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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335
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Kim SY, Jeong SM, Jo SC, Lee SC. Application of far-infrared irradiation in the manufacturing process of green tea. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2006; 54:9943-7. [PMID: 17177525 DOI: 10.1021/jf062524+] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Seven kinds of green tea leaves were manufactured with far-infrared (FIR) irradiation, and the physicochemical characteristics of the green tea were determined. Appropriate FIR irradiation during the manufacturing process significantly increased the polyphenolic content of green tea. FIR irradiation at 90 degrees C for 10 min, replacing the roasting step, and of the fully processed green tea leaves (GTP3) increased the total phenol content of green tea from 475.6 to 811.1 mg/g and the total flavanol content from 175.7 to 208.7 mg/g, as compared to the control. Epigallocatechin and epigallocatechin gallate increased from 57.68 and 9.60 mg/g in a nonirradiated control to 89.88 and 16.33 mg/g in GTP3, respectively. Ascorbic acid, caffeine, and nitrite scavenging activities were also increased in GTP3. However, the overall color change of GTP3 was negligible. These results indicate that the chemical properties of green tea are significantly affected by FIR irradiation at specific stages of the manufacturing process of green tea leaves and that this FIR irradiation results in high-quality green tea.
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Affiliation(s)
- So-Young Kim
- Department of Food Science and Biotechnology, Kyungnam University, Masan 631-701, Korea
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336
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Shoji Y, Nakashima H. Glucose-lowering effect of powder formulation of African black tea extract in KK-A(y)/TaJcl diabetic mouse. Arch Pharm Res 2006; 29:786-94. [PMID: 17024853 DOI: 10.1007/bf02974080] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
We observed the suppressive effect of a powder formulation of African black tea extract prepared from the leaves of Camellia sinensis on type 2 non-insulin dependent diabetic mice, KK-A(y)/TaJcl. Black tea extract significantly showed suppressive effect of the elevation of blood glucose on oral glucose tolerance test of 8 week-old KK-A(y)/TaJcl mice (P < 0.05). Long-term treatment with black tea extract showed significant suppression of post-prandial blood glucose and obesity (P < 0.05). The weight of the intestine of mice treated with black tea extract was significantly reduced (P < 0.05). From these results, African black tea used in this study showed a suppressive effect on the elevation of blood glucose during food intake and the body weight.
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Affiliation(s)
- Yoko Shoji
- Department of Microbiology, St. Marianna University School of Medicine, 2-16-1, Sugao, Miyamae-ku Kawasaki, Kanagawa 216-8511, Japan.
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337
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Coimbra S, Santos-Silva A, Rocha-Pereira P, Rocha S, Castro E. Green tea consumption improves plasma lipid profiles in adults. Nutr Res 2006. [DOI: 10.1016/j.nutres.2006.09.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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338
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Wang S, Noh SK, Koo SI. Epigallocatechin gallate and caffeine differentially inhibit the intestinal absorption of cholesterol and fat in ovariectomized rats. J Nutr 2006; 136:2791-6. [PMID: 17056802 DOI: 10.1093/jn/136.11.2791] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We conducted this study to determine whether green tea constituents, (-)-epigallocatechin gallate (EGCG) and caffeine, affect the intestinal absorption of cholesterol (CH), fat, and other fat-soluble compounds. Ovariectomized rats with lymph cannula were infused intraduodenally with a lipid emulsion containing 14C-labeled CH (14C-CH), alpha-tocopherol (alpha TOH), triolein, and sodium taurocholate, without (control) or with EGCG, caffeine, or EGCG plus caffeine, in PBS, pH 6.5. The lymphatic total 14C-CH was significantly lowered by EGCG (21.1 +/- 2.1% dose), caffeine (27.9 +/- 1.7% dose), and EGCG plus caffeine (19.3 +/- 0.9% dose), compared with the control (32.4 +/- 1.6% dose). The lymphatic output of esterified CH also was significantly lower in rats infused with EGCG (7.9 +/- 0.7 micromol), caffeine (7.6 +/- 0.2 micromol), and EGCG plus caffeine (7.5 +/- 0.6 micromol) than rats in the control group (11.6 +/- 1.7 micromol). Also, EGCG and caffeine significantly lowered the absorption of alpha TOH, another highly hydrophobic lipid. However, the lymphatic outputs of oleic acid (exogenous fatty acid marker) and other fatty acids of endogenous origin were not affected by EGCG but were markedly lowered by caffeine and EGCG plus caffeine. Caffeine significantly lowered the amount of lymph flow, regardless of whether it was infused alone (14.2 +/- 3.9 mL) or with EGCG (18.6 +/- 2.0 mL), compared with EGCG (22.2 +/- 2.2 mL) alone and the control group (23.2 +/- 3.8 mL). The caffeine-induced decline in lymph flow was associated with the lowering of lipid absorption. The results indicate that both EGCG and caffeine inhibit lipid absorption and that the inhibitory effects of the 2 tea constituents are not synergistic but mediated by distinctly different mechanisms.
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Affiliation(s)
- Shu Wang
- Department of Human Nutrition, Kansas State University, Manhattan, KS 66506, USA
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339
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Liang W, Binns CW, Jian L, Lee AH. Does the consumption of green tea reduce the risk of lung cancer among smokers? EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2006; 4:17-22. [PMID: 17342237 PMCID: PMC1810371 DOI: 10.1093/ecam/nel066] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2005] [Accepted: 08/25/2006] [Indexed: 12/24/2022]
Abstract
Experimental and epidemiological studies were reviewed to assess whether the consumption of green tea could reduce the risk of lung cancer in smokers. Articles published since 1990 were located by searching electronic databases PubMed, Ovid and Science Direct, using keywords 'lung cancer', 'tea' and 'smoking' without any restriction on language. After relevant articles had been located, further papers were obtained from their reference lists. Evidence from experimental studies (in vitro animal and human trials) suggested that regular intake of green tea may be protective against tobacco carcinogens. However, the mechanism behind the protective effect is only partly understood. In most of the epidemiological studies reviewed, the green tea exposure was within 5 years of the interview or follow-up, which would coincide with the induction period and latent period of lung cancer. Longer term studies are thus needed to further quantify the cancer risk. There is some evidence suggesting regular intake of green tea at high level (>3 cups per day) may reduce the risk of smokers developing lung cancer. Improvement in measuring green tea intake is required in order to confirm the evidence from epidemiological studies.
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Affiliation(s)
- Wenbin Liang
- School of Public Health, Curtin University of Technology Perth, Australia
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340
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Jang SI, Jun MH, Lillehoj HS, Dalloul RA, Kong IK, Kim S, Min W. Anticoccidial effect of green tea-based diets against Eimeria maxima. Vet Parasitol 2006; 144:172-5. [PMID: 17027157 DOI: 10.1016/j.vetpar.2006.09.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2006] [Revised: 08/14/2006] [Accepted: 09/07/2006] [Indexed: 11/22/2022]
Abstract
Anticoccidial effects of green tea (GT)-based diets were evaluated in chickens following oral infection with Eimeria maxima an ubiquitous intestinal parasite of poultry that impairs the growth and feed efficiency of infected birds. Five-week-old chickens were assigned to four groups (GT 0.5%, GT 2.0%, untreated/infected and non-infected control) and each group consisted of 15 chickens. Chickens were fed a standard diet supplemented with ground green tea for 2 weeks prior to infection with E. maxima (10,000 sporulated oocysts per bird). The effects of green tea on E. maxima infection were assessed by two parameters, fecal oocyst shedding and body weight gain. The green tea-fed chickens produced significantly reduced fecal oocysts (P<0.05) when compared to the E. maxima-infected group fed standard diet. The green tea-based diet, however, did not improve body weight loss caused by E. maxima infection. This study is the first to demonstrate anticoccidial effect of green tea on Eimeria parasites.
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Affiliation(s)
- Seung I Jang
- College of Veterinary Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea
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341
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Van Dorsten FA, Daykin CA, Mulder TPJ, Van Duynhoven JPM. Metabonomics approach to determine metabolic differences between green tea and black tea consumption. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2006; 54:6929-38. [PMID: 16939360 DOI: 10.1021/jf061016x] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The purpose of this study was to compare the effects of black and green tea consumption on human metabolism. Seventeen healthy male volunteers consumed black tea, green tea, or caffeine in a randomized crossover study. Twenty-four-hour urine and blood plasma samples were analyzed by NMR-based metabonomics, that is, high-resolution 1H NMR metabolic profiling combined with multivariate statistics. Green and black tea consumption resulted in similar increases in urinary excretion of hippuric acid and 1,3-dihydroxyphenyl-2-O-sulfate, both of which are end products of tea flavonoid degradation by colonic bacteria. Several unidentified aromatic metabolites were detected in urine specifically after green tea intake. Interestingly, green and black tea intake also had a different impact on endogenous metabolites in urine and plasma. Green tea intake caused a stronger increase in urinary excretion of several citric acid cycle intermediates, which suggests an effect of green tea flavanols on human oxidative energy metabolism and/or biosynthetic pathways.
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Affiliation(s)
- Ferdi A Van Dorsten
- Unilever Food and Health Research Institute, Olivier van Noortlaan 120, P.O. Box 114, 3130 AC Vlaardingen, The Netherlands.
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342
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Neilson AP, Green RJ, Wood KV, Ferruzzi MG. High-throughput analysis of catechins and theaflavins by high performance liquid chromatography with diode array detection. J Chromatogr A 2006; 1132:132-40. [PMID: 16919286 DOI: 10.1016/j.chroma.2006.07.059] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2006] [Revised: 07/20/2006] [Accepted: 07/25/2006] [Indexed: 10/24/2022]
Abstract
Increased interest in potential health-protective activities of flavonoid-rich tea has created the need to take advantage of HPLC column and system advances in order to optimize methodologies for flavonoid analysis. Two new RP-C18 methods for HPLC-DAD analysis of tea flavonoids were developed to facilitate separation of catechins within 5 min and separation of catechins and theaflavins within 10 min total analysis time. Calibration results indicate that these methods have on-column limits of detection on the order of 1-10 pmol for most tea catechins, and method replication generally resulted in intraday and interday peak area variation of <5% for catechins and <9% for theaflavins in green and black tea infusions. These new methods are therefore sensitive, reproducible, and represent a 2-4-fold reduction in HPLC analysis time from existing analytical methods. These improvements are readily achievable with commonly used HPLC equipment, thus facilitating increased sample throughput and efficiency across a broad range of experimental applications.
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Affiliation(s)
- Andrew P Neilson
- Department of Food Science, Purdue University, 745 Agriculture Mall Dr. West Lafayette, IN 47907, United States
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343
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Babu PVA, Sabitha KE, Shyamaladevi CS. Green tea impedes dyslipidemia, lipid peroxidation, protein glycation and ameliorates Ca2+-ATPase and Na+/K+-ATPase activity in the heart of streptozotocin-diabetic rats. Chem Biol Interact 2006; 162:157-64. [PMID: 16846594 DOI: 10.1016/j.cbi.2006.05.020] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2006] [Revised: 05/30/2006] [Accepted: 05/31/2006] [Indexed: 11/25/2022]
Abstract
Diabetes-induced hyperlipidemia, oxidative stress and protein glycation impair cellular calcium and sodium homeostasis associated with abnormal membrane-bound enzyme activities resulting in cardiac dysfunction in diabetes. To explore the cardioprotective mechanism of green tea in diabetes, we measured the changes in the levels of calcium, sodium, potassium and the activities of Na+/K+ -ATPase and Ca2+ -ATPase in green tea treated diabetic rat hearts. The effect of green tea on triglycerides, lipid peroxidation and protein glycation in diabetic heart were also measured to elucidate the underlying mechanisms. Diabetes was induced by streptozotocin (STZ, 60 mg/kg i.p.). Six weeks after the induction of diabetes, some of the diabetic rats were treated orally with green tea extract (GTE) (300 mg/kg/day) for 4 weeks. GTE produced reduction in blood glucose and lowered the levels of lipid peroxides, triglycerides and extent of protein glycation in the heart of diabetic rats. GTE blunted the rise in cardiac [Ca2+] and [Na+] whereas increased the activities of Ca2+ -ATPase and Na+/K+ -ATPase in diabetic rats. In conclusion, the data provide support to the therapeutic effect of GTE and suggest that a possible mechanism of action may be associated with the attenuation of the rise in [Ca2+] and [Na+] by ameliorating Ca2+ -ATPase and Na+/K+ -ATPase activities.
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344
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Lee AH, Fraser ML, Meng X, Binns CW. Protective effects of green tea against prostate cancer. Expert Rev Anticancer Ther 2006; 6:507-13. [PMID: 16613539 DOI: 10.1586/14737140.6.4.507] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Prostate cancer has the third highest incidence of all cancers in men worldwide with incidence and mortality being particularly high in affluent, developed countries. Tea, especially green tea, has demonstrated promise in the prevention of several cancers. Green tea contains several components including catechins, a category of polyphenols that have chemopreventive properties. Although evidence from epidemiological studies is not comprehensive, it is strengthened by animal and in vitro evidence suggesting that consumption of tea is associated with decreased risk or progression of prostate cancer. Emerging evidence and potential biological mechanisms for the role of green tea in prostate cancer prevention are presented in this review.
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Affiliation(s)
- Andy H Lee
- School of Public Health, Curtin University of Technology, GPO Box U 1987, Perth, WA 6845, Australia.
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345
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Spinella F, Rosanò L, Di Castro V, Decandia S, Albini A, Nicotra MR, Natali PG, Bagnato A. Green tea polyphenol epigallocatechin-3-gallate inhibits the endothelin axis and downstream signaling pathways in ovarian carcinoma. Mol Cancer Ther 2006; 5:1483-92. [PMID: 16818507 DOI: 10.1158/1535-7163.mct-06-0053] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The polyphenol epigallocatechin-3-gallate (EGCG), the principal mediator of the green tea, has been known to possess antitumor effect. The endothelin A receptor (ET(A)R)/endothelin-1 (ET-1) axis is overexpressed in ovarian carcinoma representing a novel therapeutic target. In this study, we examined the green tea and EGCG effects on two ovarian carcinoma cell lines, HEY and OVCA 433. EGCG inhibited ovarian cancer cell growth and induced apoptosis that was associated with a decrease in Bcl-X(L) expression and activation of caspase-3. Treatment with green tea or EGCG inhibited ET(A)R and ET-1 expression and reduced the basal and ET-1-induced cell proliferation and invasion. The EGCG-induced inhibitory effects were associated with a decrease of ET(A)R-dependent activation of the p42/p44 and p38 mitogen-activated protein kinases and phosphatidylinositol 3-kinase pathway. Remarkably, EGCG treatment resulted in a lowering of basal and ET-1-induced angiogenesis and invasiveness mediators, such as vascular endothelial growth factor and tumor proteinase activation. Finally, in HEY ovarian carcinoma xenografts, tumor growth was significantly inhibited by oral administration of green tea. This effect was associated with a reduction in ET-1, ET(A)R, and vascular endothelial growth factor expression, microvessel density, and proliferation index. These results provide a novel insight into the mechanism by which EGCG, affecting multiple ET(A)R-dependent pathways, may inhibit ovarian carcinoma growth, suggesting that EGCG may be useful in preventing and treating ovarian carcinoma in which ET(A)R activation by ET-1 plays a critical role in tumor growth and progression.
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Affiliation(s)
- Francesca Spinella
- Laboratory of Molecular Pathology and Ultrastructure, Regina Elena Cancer Institute, Via delle Messi d'Oro, 156, 00158 Rome, Italy
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346
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Kirkland J. Phytochemicals, Xenobiotic Metabolism, and Carcinogenesis. NUTRIENT-DRUG INTERACTIONS 2006. [DOI: 10.1201/9781420019131.ch3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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347
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Coimbra S, Castro E, Rocha-Pereira P, Rebelo I, Rocha S, Santos-Silva A. The effect of green tea in oxidative stress. Clin Nutr 2006; 25:790-6. [PMID: 16698148 DOI: 10.1016/j.clnu.2006.01.022] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2005] [Revised: 12/02/2005] [Accepted: 01/22/2006] [Indexed: 11/27/2022]
Abstract
BACKGROUND & AIMS Green tea, an infusion prepared with the leaves of Camellia sinensis is particularly rich in flavonoids, which are strong antioxidants. Tea drinking, by providing antioxidants, may become valuable in several oxidative stress conditions. Our aim was to evaluate the effect of green tea drinking on some factors reflecting the development of oxidative stress in plasma and in erythrocytes. METHODS The study was performed in 34 Portuguese subjects. We evaluated the total antioxidant status (TAS), the lipid peroxidation products-malonyldialdehyde (MDA) and malonyldialdehyde+4-hydroxy-2(E)-nonenal (MDA+4-HNE)-and the oxidative changes in erythrocyte membrane, namely membrane bound haemoglobin (MBH) and the band 3 profile. Analytical evaluations were performed after 3 weeks drinking 1l of water daily, and after 4 weeks drinking 1l of green tea daily. Tea was prepared daily at the same conditions of temperature, time of infusion and concentration. RESULTS After green tea drinking, we found a significant reduction in serum levels of MDA and MDA+4-HNE and in the oxidative stress within the erythrocyte, as suggested by a significantly lower value of MBH and by changes in band 3 profile towards a normal mean profile, namely an increase in the band 3 monomer. A rise in the antioxidant capacity was also observed. CONCLUSIONS Our data suggest for green tea drinking a beneficial effect, by reducing the development or the enhancement of oxidative stress and, therefore, protecting the individual for oxidative stress diseases. Moreover, we propose further studies about the value of band 3 profile and of MBH in providing a cumulative measurement of the effect of green tea drinking upon the oxidative stress in cells. Moreover, further studies are also needed, to clarify the effect of green tea consumption, the value of regular green tea consumption and the way it should be prepared to reach a healthy effect.
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Affiliation(s)
- Susana Coimbra
- Faculdade Farmácia, Serviço Bioquímica, Universidade Porto, Portugal
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348
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Bigelow RLH, Cardelli JA. The green tea catechins, (-)-Epigallocatechin-3-gallate (EGCG) and (-)-Epicatechin-3-gallate (ECG), inhibit HGF/Met signaling in immortalized and tumorigenic breast epithelial cells. Oncogene 2006; 25:1922-30. [PMID: 16449979 DOI: 10.1038/sj.onc.1209227] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The hepatocyte growth factor (HGF) receptor, Met, is a strong prognostic indicator of breast cancer patient outcome and survival, suggesting that therapies targeting Met may have beneficial outcomes in the clinic. (-)-Epigallocatechin-3-gallate (EGCG), a catechin found in green tea, has been recognized as a potential therapeutic agent. We assessed the ability of EGCG to inhibit HGF signaling in the immortalized, nontumorigenic breast cell line, MCF10A, and the invasive breast carcinoma cell line, MDA-MB-231. HGF treatment in both cell lines induced rapid, sustained activation of Met, ERK and AKT. Pretreatment of cells with concentrations of EGCG as low as 0.3 microM inhibited HGF-induced Met phosphorylation and downstream activation of AKT and ERK. Treatment with 5.0 microM EGCG blocked the ability of HGF to induce cell motility and invasion. We assessed the ability of alternative green tea catechins to inhibit HGF-induced signaling and motility. (-)-Epicatechin-3-gallate (ECG) functioned similar to EGCG by completely blocking HGF-induced signaling as low as 0.6 microM and motility at 5 microM in MCF10A cells; whereas, (-)-epicatechin (EC) was unable to inhibit HGF-induced events at any concentration tested. (-)-Epigallocatechin (EGC), however, completely repressed HGF-induced AKT and ERK phosphorylation at concentrations of 10 and 20 microM, but was incapable of blocking Met activation. Despite these observations, EGC did inhibit HGF-induced motility in MCF10A cells at 10 microM. These observations suggest that the R1 galloyl and the R2 hydroxyl groups are important in mediating the green tea catechins' inhibitory effect towards HGF/Met signaling. These combined in vitro studies reveal the possible benefits of green tea polyphenols as cancer therapeutic agents to inhibit Met signaling and potentially block invasive cancer growth.
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Affiliation(s)
- R L H Bigelow
- Department of Microbiology and Immunology, Feist-Weiller Cancer Center, Louisiana State University-Health Sciences Center, Shreveport, LA 71130, USA
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349
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Babu PVA, Sabitha KE, Shyamaladevi CS. Therapeutic effect of green tea extract on oxidative stress in aorta and heart of streptozotocin diabetic rats. Chem Biol Interact 2006; 162:114-20. [PMID: 16860299 DOI: 10.1016/j.cbi.2006.04.009] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2006] [Revised: 04/10/2006] [Accepted: 04/21/2006] [Indexed: 10/24/2022]
Abstract
Hyperglycemia induced oxidative stress has been proposed as a cause of many complications of diabetes including cardiac dysfunction. The present study depicts the therapeutic effect of green tea extract on oxidative stress in aorta as well as heart of streptozotocin diabetic rats. Six weeks after diabetes induction, green tea was administered orally for 4 weeks [300 mg (kg body weight)(-1) day (-1)]. In aorta and heart of diabetic rats there was a significant increase in the activity of superoxide dismutase, catalase and glutathione peroxidase with an increase in lipid peroxides. Diabetic rats showed a significant decrease in the levels of serum and cardiac glutathione. Green tea administration to diabetic rats reduced lipid peroxides and activity of antioxidant enzymes whereas increased glutathione content. The results demonstrate that the induction of antioxidant enzymes in diabetic rats is not efficient and sufficient to reduce the oxidative stress. But green tea by providing a competent antioxidative mechanism ameliorates the oxidative stress in the aorta and heart of diabetic rats. The study suggests that green tea may provide a useful therapeutic option in the reversal of oxidative stress induced cardiac dysfunction in diabetes mellitus.
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350
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Abstract
Tea has been found to possess widespread biological functions based on a variety of laboratory data. The effects of tea on obesity and diabetes have received increasing attention. This paper reviews the evidence for the connections among tea catechins, and obesity and diabetes. Tea catechins, especially (-)-epigallocatechin gallate (EGCG), appear to have antiobesity and antidiabetic effects. While few epidemiological and clinical studies show the health benefits of EGCG on obesity and diabetes, the mechanisms of its actions are emerging based on the various laboratory data. These mechanisms may be related to certain pathways, such as through the modulations of energy balance, endocrine systems, food intake, lipid and carbohydrate metabolism, the redox status, and activities of different types of cells (i. e., fat, liver, muscle, and beta-pancreatic cells). Because the EGCG receptor, the so-called 67-kDa laminin receptor (LR), has been discovered with colocalization of other types of LR and cytoskeleton in both cancer cells and normal cells, this may explain that EGCG possesses numerous actions. The mechanistic results of this review may possibly be utilized in the treatment of obesity, diabetes, and other related diseases using tea- and EGCG-based folk medicines.
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Affiliation(s)
- Yung-Hsi Kao
- Department of Life Science, College of Science, National Central University, Chung-Li City, Taoyuan, Taiwan.
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