Pharmacological effects of green tea on the gastrointestinal system.

Department of Pharmacology, Faculty of Medicine, The University of Hong Kong, L2-55 Laboratory Block, 21 Sassoon Road, Hong Kong, PR China.
European Journal of Pharmacology (Impact Factor: 2.68). 11/2004; 500(1-3):177-85. DOI: 10.1016/j.ejphar.2004.07.023
Source: PubMed

ABSTRACT Green tea is rich in polyphenolic compounds, with catechins as its major component. Studies have shown that catechins possess diverse pharmacological properties that include anti-oxidative, anti-inflammatory, anti-carcinogenic, anti-arteriosclerotic and anti-bacterial effects. In the gastrointestinal tract, green tea was found to activate intracellular antioxidants, inhibit procarcinogen formation, suppress angiogenesis and cancer cell proliferation. Studies on the preventive effect of green tea in esophageal cancer have produced inconsistent results; however, inverse relationships of tea consumption with cancers of the stomach and colon have been widely reported. Green tea is effective to prevent dental caries and reduce cholesterols and lipids absorption in the gastrointestinal tract, thus benefits subjects with cardiovascular disorders. As tea catechins are well absorbed in the gastrointestinal tract and they interact synergistically in their disease-modifying actions, thus drinking unfractionated green tea is the most simple and beneficial way to prevent gastrointestinal disorders.

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Available from: Marcel Koo, Jul 15, 2015
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    • "Based on these previous studies, it could be asserted that extracts containing polyphenolic antioxidants can reduce the formation of HAAs because of their inhibitory effects on free radical reactions. Among antioxidant compounds, green tea is rich in polyphenolic content due to its catechin as a major component (Koo & Cho, 2004). Several studies have shown that the HAA inhibitory effects of green tea are due to the presence of tea polyphenols and catechins (Mukhtar, Katiyar, & Agarwal, 1994; Stavrıc, Matula, Klassen, & Downie, 1996; Yang & Wang, 1993). "
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    ABSTRACT: Heterocyclic aromatic amines (HAAs) are mutagenic compounds formed naturally in meats after thermal processing and are classified as a probable human carcinogen. Also, mutagenic potency of HAAs is about 100-fold stronger than that of aflatoxin and 2000-fold stronger than that of benzo[a]pyrene. The aims of the present study were to investigate HAA contents and to determine HAA existence in coated chicken drumsticks (CDs) and coated chicken wings (CWs) which are frequently consumed in fast food chains after purchasing from fast food restaurants, and the effects of green tea extract added into the cover material and microwave-precooking for the mitigation and the formation of HAAs in CD and CW samples produced using a laboratory model. HAA (lQx, IQ MeIQx, Men 7,8-DiMeIQx, 4,8-DiMeIQx, PhIP, A alpha C, MeA alpha C) analysis was done by HPLC after solid-phase extraction. MeIQx is the dominant HAA in all CD and CW samples obtained from fast food restaurants, and its level was found to vary between 0.22-33.73 and 11.22-62.83 ng/g, respectively. PhIP was detected in 5 out of 20 samples from fast food restaurants with a maximum level of 3.15 ng/g, and IQx, 7,8-DiMeIQx, AaC, and MetQ were also detected. MeIQx values of CIA! and CD samples produced with the laboratory model varied between not detected and 1.45 and not detected and 232 ng/g, respectively, while IQ MeIQ 7.8 DiMeIQx, 4,8-DiMeIQx, AaC, and MeAaC were not detected in any of the CW or CD samples produced using the laboratory model. HAA contents of CD and CW samples obtained from fast food restaurants were higher than those of samples produced using the laboratory model due to the possible effect of uncontrolled frying conditions in restaurants. In addition, it was determined that the addition of green tea extract (GTE) and microwave pre-cooking (MC) did not present any detectable effect on reducing the formation of HAAs in fried CDs and CWs produced using a laboratory model under controlled frying conditions.
    Food Research International 09/2014; 63:373-381. DOI:10.1016/j.foodres.2014.04.001 · 3.05 Impact Factor
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    • "Teas from C. sinensis are highly consumed worldwide because of their pleasing taste and, moreover, due to their digestive benefit, causing more people to choose this plant (Sharangi, 2009). Also, green-and black-teas have presented anti-ulcer effect (Adhikary, Yadav, Bandyopadhyay, & Chattopadhyay, 2011; Hamaishi, Kojima, & Ito, 2006; Koo & Cho, 2004; Morikawa et al., 2006; Maity, Vedasiromoni, & Ganguly, 1995). Because the major differences in the composition of teas are related to post-harvest processes (oxidation), in order to investigate whether the processing have also altered the gastroprotective activity, hydro-alcoholic extracts from green-and black-teas (GEt and BEt) were examined in an experimental model of gastric lesion induced by ethanol. "
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    ABSTRACT: Hydro-alcoholic extracts from leaves of Camellia sinensis (green-and black-tea leaves) were submitted to a fractionation, promoting the compound separation according to their polarity, and analyzed by ultra-high performance liquid chromatography–mass spectrometry. A wide range of compounds could be identified, such as catechins and their gallate (esters) or oxidation derivatives (theaflavins), glycosylated flavonoids and other phenolics, as well as lipids, saponins and alkaloids. Also have been developed, via bio-guided examination, the gastroprotective property of the compounds identified. The samples were assayed using the model of acute gastric lesions induced in rats by ethanol. Hydro-alcoholic extracts of green-tea and black-tea protected the gastric mucosa with ED 50 = 3.6 and 10.2 mg/kg, respectively, with participation of gas-tric mucus and reduced glutathione (GSH). The ethyl acetate fraction from green-tea and aqueous fraction from black-tea were, respectively, 6 and 10 times more effectiveness than the initial extracts. Moreover, the epigallocatechin gallate (EGCG, 0.204 mg/kg), a main component of ethyl acetate fraction from green tea, reduced the gastric lesion by 56% and restored the mucus levels, however the rutin (0.0133 mg/kg), a flavonoid found in the most active fraction of black-tea, was less significant at the natural concentrations. These results have confirmed that the different compounds present in green-and black-tea hydro-alcoholic extracts and partitioned fractions produce relevant gastroprotection mainly via maintenance of the protective factors, mucus and GSH.
    Food Research International 07/2014; 64. DOI:10.1016/j.foodres.2014.07.043 · 3.05 Impact Factor
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    • "The antioxidant capacity of dietary components has been linked to the prevention of cancer, cardiovascular disease, neurodegenerative disease, and other degenerative diseases [1] [2] [3] [4] [5] [6] [7]. Dietary components, such as fruits, vegetables, spices, and extracts of herbs, particularly tea (Camellia sinensis), have been studied for their antioxidant properties in vitro [8 –10]. "
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    ABSTRACT: Objective: We tested in mice the hypothesis that ingestion of infusions of green tea, white tea, or the aromatic plant Pelargonium purpureum increases total antioxidant capacity (TAC) of plasma and organs. Methods: Twenty-five mice were randomly assigned to five groups, each of which received by gavage 0.1 mL of infusion from green tea, white tea, or P. purpureum (8 g/100 mL of water) or catechin (0.01 g/100 mL) or water for 5 consecutive days. On the fifth day the animals were euthanized. Blood was taken by heart puncture and the heart, lungs, liver, spleen, kidney, and brain were removed. TAC was measured in plasma and in all organ homogenates with the ferric reducing antioxidant power assay and in selected organ homogenates by the total radical-trapping antioxidant parameter assay. Results: Green tea and P. purpureum increased TAC in the plasma and lungs, whereas green tea, white tea, and catechin increased TAC in heart homogenates. No effect was observed on the liver, brain, spleen, and kidney homogenates in comparison with the water control with the ferric reducing antioxidant power assay or the total radical-trapping antioxidant parameter assay. Conclusion: These results suggest that green tea, white tea, and P. purpu
    Nutrition 04/2009; 25(4). DOI:10.1016/j.nut.2008.10.007 · 3.05 Impact Factor
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