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: 2.53). 11/2004; 500(1-3):177-85. DOI: 10.1016/j.ejphar.2004.07.023
Source: PubMed


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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    • "Epigallocatechin- 3-gallate is the main catechin found in green tea; it accounts for about 50–60% of total catechins and is a considerably active compound in biological terms (Koo & Cho 2004; Uuganbayar et al. 2006; Zhong et al. 2009; Ariana et al. 2011). The herb or its extract, which has abundant ingredient catechins, was determined to have antioxidant, antimicrobial, antifungal, anti-carcinogenic, hypoallergic, and hypoglycemic effects by previous studies (Biswas et al. 2000; Kocyigit et al. 2000; Koo & Cho 2004; Ariana et al. 2011; Kara & Guclu 2012). "
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    • "Güçlü bir antioksidan olan yeşil çay polifenolleri glutatyon redüktaz gibi hücre içinde bulunan antioksidan enzimlerin sentezini tetikleyerek dolaylı olarak antioksidan aktivite gösterir. Bu etkileriyle yeşil çay, lipid peroksidasyonunu ve DNA yapısında oluşabilecek hasarları engeller (Koo ve Cho, 2004). "
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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.
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