heart-health

Author: Marco Assunção and Maria J. Santos-Marques and Félix Carvalho and José P. Andrade

Author: Yan Xu and Jun-jian Zhang and Li Xiong and Lei Zhang and Dong Sun and Hui Liu

Responses to oxidative stress contribute to damage caused by chronic cerebral hypoperfusion, which is characteristic of certain neurodegenerative diseases. We used a rat model of chronic cerebral hypoperfusion to determine whether green tea polyphenols, which are potent antioxidants and free radical scavengers, can reduce vascular cognitive impairment and to investigate their underlying mechanisms of action. Different doses of green tea polyphenols were administered orally to model rats from 4 to 8 weeks after experimentally induced cerebral hypoperfusion, and spatial learning and memory were assessed using the Morris water maze. Following behavioral testing, oxygen free radical levels and antioxidative capability in the cortex and hippocampus were measured biochemically. The levels of lipid peroxidation and oxidative DNA damage were assessed by immunohistochemical staining for 4-hydroxynonenal and 8-hydroxy-2′-deoxyguanosine, respectively. Rats that received green tea polyphenols 400 mg/kg per day had better spatial learning and memory than saline-treated rats. Green tea polyphenols 400 mg/kg per day were found to scavenge oxygen free radicals, enhance antioxidant potential, decrease lipid peroxide production and reduce oxidative DNA damage. However, green tea polyphenols 100 mg/kg per day had no significant effects, particularly in the cortex. This study suggests that green tea polyphenols 400 mg/kg per day improve spatial cognitive abilities following chronic cerebral hypoperfusion and that these effects may be related to the antioxidant effects of these compounds.

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Author: Lei Li and C.-Y. Oliver Chen and Giancarlo Aldini and Elizabeth J. Johnson and Helen Rasmussen and Yasukazu Yoshida and Etsuo Niki and Jeffrey B. Blumberg and Robert M. Russell and Kyung-Jin Yeum

Epigallocatechin gallate, a major component of green tea polyphenols, protects against the oxidation of fat-soluble antioxidants including lutein. The current study determined the effect of a relatively high but a dietary achievable dose of lutein or lutein plus green tea extract on antioxidant status. Healthy subjects (50–70 years) were randomly assigned to one of two groups (n=20 in each group): (1) a lutein (12 mg/day) supplemented group or (2) a lutein (12 mg/day) plus green tea extract (200 mg/day) supplemented group. After 2 weeks of run-in period consuming less than two servings of lightly colored fruits and vegetables in their diet, each group was treated for 112 days while on their customary regular diets. Plasma carotenoids including lutein, tocopherols, flavanols and ascorbic acid were analyzed by HPLC-UVD and HPLC-electrochemical detector systems; total antioxidant capacity by fluorometry; lipid peroxidation by malondialdehyde using a HPLC system with a fluorescent detector and by total hydroxyoctadecadienoic acids using a GC/MS. Plasma lutein, total carotenoids and ascorbic acid concentrations of subjects in either the lutein group or the lutein plus green tea extract group were significantly increased (P<.05) at 4 weeks and throughout the 16-week study period. However, no significant changes from baseline in any biomarker of overall antioxidant activity or lipid peroxidation of the subjects were seen in either group. Our results indicate that an increase of antioxidant concentrations within a range that could readily be achieved in a healthful diet does not affect in vivo antioxidant status in normal healthy subjects when sufficient amounts of antioxidants already exist.

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Author: Anais Gondoin and Dominic Grussu and Derek Stewart and Gordon J. McDougall

Green, white and black teas were assayed for inhibition of pancreatic lipase activity in vitro. White tea proved to be more effective than green tea with black tea showing little inhibition even at 200 μg GAE/ml. The EC50 values for inhibition were 22 μg/ml for white tea and 35 μg/ml for green tea; both easily achievable from normal infusions of tea. Liquid chromatography-mass spectroscopy analysis showed that white and green teas had essentially equal amounts of flavan-3-ols but green tea had higher levels of flavonols. White tea had higher levels of 5-galloyl quinic acid, digalloyl glucose, trigalloyl glucose and the tannin, strictinin. After chromatography on Sephadex LH-20, the main inhibitory fraction was enriched in strictinin and fractions enriched in other components were ineffective. This suggests that strictinin content may be crucial for inhibition of pancreatic lipase. However, the possibility of synergies between the polyphenols cannot be disregarded.

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Author: Shigeki Yanagi and Kazuaki Matsumura and Akira Marui and Manabu Morishima and Suong-Hyu Hyon and Tadashi Ikeda and Ryuzo Sakata

Objective Ischemia–reperfusion injury is among the most serious problems in cardiac surgery. Epigallocatechin-3-gallate, a major polyphenolic component of green tea, is thought to be cardioprotective through its antioxidant activities. We investigated cardioprotective effects of oral epigallocatechin-3-gallate pretreatment against ischemia–reperfusion injury in isolated rat hearts and considered possible underlying mechanisms. Methods Rats were given epigallocatechin-3-gallate solution orally at 0.1, 1, or 10 mmol/L (n = 12 per group) for 2 weeks; controls (n = 12) received tap water alone for 2 weeks. Subsequently, Langendorff-perfused hearts were subjected to global ischemia for 30 minutes, followed by 60 minutes of reperfusion. Results Recoveries at 60 minutes after reperfusion of left ventricular developed pressure and maximum positive and minimum negative first derivatives of left ventricular pressure were significantly higher in 1-mmol/L group than in 0.1-mmol/L (P < .0001), 10-mmol/L (P < .05), and control (P < .0001) groups. Oxidative stress after reperfusion, as reflected by 8-hydroxy-2′-deoxyguanosine index, was lower in 1-mmol/L group than in control (P < .01) and 0.1-mmol/L (P < .05) groups. Western blot analysis after reperfusion showed p38 activation and active caspase-3 expression to be lower in 1-mmol/L group than in control group (P < .05). Conclusions Oral pretreatment with epigallocatechin-3-gallate preserved cardiac function after ischemia–reperfusion, an effect that may involve its antioxidative, antiapoptotic properties, although a high dose did not lead to dramatic improvement in cardiac function. Oral epigallocatechin-3-gallate pretreatment may be a novel and simple cardioprotective method for preventing perioperative cardiac dysfunction in cardiac surgery.

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Author: Karl J. Siebert and Atsushi A. Maekawa and P.Y. Lynn

Samples of dilute HCl intended to result in mixtures with saliva with pH levels below, near and above the level of maximum protein–polyphenol interaction were presented to panelists. Significant differences in astringency were seen, but no evidence of a decline in astringency with stronger acid. Panelists abstained from tea drinking for some time, then drank two or more cups of green tea per day for some days, and finally omitted tea drinking for a period. Salivary polyphenol levels were determined throughout the experiment. Drinking green tea resulted in a highly significant (p < 0.01) increase in salivary polyphenol levels that persisted for some days. Very dilute HCl solutions (0, 0.005, 0.006 and 0.007 N) were presented to panelists before, during and after the period of tea drinking and rated for astringency and sourness. Astringency and sourness intensity ratings increased significantly (p < 0.01) during the period of tea drinking. It appears that there is a metabolic pool of polyphenol that is influenced by dietary habits. It appears likely that the salivary polyphenol level influences perception of astringency caused by acids.

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Author: Chung S. Yang and Hong Wang and Guang Xun Li and Zhihong Yang and Fei Guan and Huanyu Jin

The cancer preventive activities of tea (Camellia sinensis Theaceae) have been studied extensively. Inhibition of tumorigenesis by green tea extracts and tea polyphenols has been demonstrated in different animal models, including those for cancers of the skin, lung, oral cavity, esophagus, stomach, small intestine, colon, bladder, liver, pancreas, prostate, and mammary glands. Many studies in cell lines have demonstrated the modulation of signal transduction and metabolic pathways by (−)-epigallocatechin-3-gallate (EGCG), the most abundant and active polyphenol in green tea. These molecular events can result in cellular changes, such as enhancement of apoptosis, suppression of cell proliferation, and inhibition of angiogenesis. Nevertheless, the molecular mechanisms of inhibition of carcinogenesis in animals and humans remain to be further investigated. Future research directions in this area are discussed.

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Author: Jonathan W. Betts and Stuart P. Kitney and Yiton Fu and Wei-Min Peng and Stephen M. Kelly and Stephen J. Haswell

Green tea catechins have been reported to have multiple health benefits. To understand their metabolic and toxicological interactions in the human body studies need to be undertaken using stable isotope labelled compounds, but they can be time consuming and expensive. Using microreactor technology labelling catechins could be produced more quickly and at a reduced cost. This research reports on a 2-step synthesis of deuterium labelled epicatechin developed using microreactor technology for the production.

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Author: S.M. Abdeen and T.C. Mathew and H.M. Dashti and S. Asfar

Author: David Banji and Otilia J.F. Banji and Saidulu Abbagoni and Md. Sikinder Hayath and Srilatha Kambam and Vijaya Lakshmi Chiluka

Exposure to toxicants prenatally and postnatally could have deleterious consequences on the offspring. Postnatal exposure to valproate in mice pups is capable of inducing experimental autism resulting in neurobehavioral aberrations. Consumption of green tea has been associated with neuronal protection against the impact of toxicants. We investigated the role of green tea extract in reversing cardinal behavioral changes and aberrations in oxidative stress induced by valproate exposure. Young mice of both genders received a single dose of valproate (400 mg/kg subcutaneously) on postnatal day 14 followed by a daily dose of green tea extract (75 and 300 mg/kg) orally up to postnatal day 40. Mice pups were subjected to behavioral testing to assess motor co-ordination, nociceptive response, locomotion, anxiety, exploratory activity and cognition on various postnatal days up to postnatal day 40. At the end of behavioral testing, blood was withdrawn from the retro orbital plexus for the estimation of lipid peroxides. Animals were sacrificed on postnatal day 41 and whole brain was subjected to histopathological examination. Our studies revealed a significant improvement in behavioral assessments particularly with 300 mg/kg of green tea extract. Formation of markers of oxidative stress was reduced at both dose levels. Histological findings confirm the neuroprotective effect of green tea at a dose of 300 mg/kg. In conclusion it can be stated that green tea exerts neuronal cytoprotective action possibly due to anti-oxidant action and could be efficacious in the management of autism.

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