Research Database

Author: Osamu Morita and John F. Knapp and Yasushi Tamaki and Donald G. Stump and John S. Moore and Mark D. Nemec

Evidence suggests that the health benefits associated with green tea consumption are related to tea catechins. The objective of this study was to evaluate potential maternal and fetal effects of standardized heat-sterilized green tea catechins (GTC-H). GTC-H was gavage administered to mated female rats from gestation day 6 through 17, at doses of 0, 200, 600, and 2000 mg/kg/day. There were no GTC-H-related deaths or macroscopic findings. During the entire gestation period in the high-dose (2000 mg/kg/day)-treated group and during days 6–9 and 6–18 in the 600 mg/kg/day group, mean body weight gain was lower. Mean feed consumption was lower during gestation days 6–9 in the 600 mg/kg/day group and during gestation days 6–9 and 9–12 in the 2000 mg/kg/day group. Compared to the control group, mean body weights in the 600 and 2000 mg/kg/day groups were up to 5.1% and 7.7% lower during gestation days 9–20. GTC-H administration did not affect mean gravid uterine weights or intrauterine growth and survival. There were no GTC-H-related fetal malformations or developmental variations. Based on the results of this study, the no-observed-adverse-effect level (NOAEL) for GTC-H was 200 mg/kg/day for maternal toxicity, and 2000 mg/kg/day for embryo/fetal development.

 

 

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Author: Frank Thielecke and Michael Boschmann

The metabolic syndrome (MetS) represents an emerging health burden for governments and health care providers. Particularly relevant for prevention and early management of MetS are lifestyle conditions including physical activity and the diet. It has been shown that green tea, when consumed on a daily basis, supports health. Many of the beneficial effects of green tea are related to its catechin, particularly (−)-epigallocatechin-3-gallate (EGCG), content. There is conclusive evidence from in vitro and animal studies which provide the concepts for underlying functional mechanisms of green tea catechins and their biological actions. An increasing number of human studies have explored the effects of green tea catechins on the major MetS conditions such as obesity, type-2 diabetes and cardiovascular risk factors. This article provides a comprehensive overview of the human studies addressing the potential benefits of green tea catechins on the MetS. The number of human studies in this field is still limited. However, the majority of human epidemiological and intervention studies demonstrate beneficial effects of green tea or green tea extracts, rich in EGCG on weight management, glucose control and cardiovascular risk factors. The optimal dose has not yet been established. The current body of evidence in humans warrants further attention. In particular, well-controlled long-term human studies would help to fully understand the protective effects of green tea catechins on parameters related to the MetS.

 

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Author: Joaudimir Castro and Tara Pregibon and Kristina Chumanov and R. Kenneth Marcus

Presented here is the quantitative analysis of green tea NIST standard reference materials (SRMs) via liquid chromatography-particle beam/electron ionization mass spectrometry (LC-PB/EIMS). Three different NIST green tea standard reference materials (SRM 3254 Camellia sinesis Leaves, SRM 3255 C. sinesisExtract and SRM 3256 Green Tea-containing Oral Dosage Form) are characterized for the content of caffeine and a series of catechin species (gallic acid, catechin, epicatechin, epigallocatechin, epicatechin gallate and epigallocatechin gallate (EGCG)). The absolute limits of detection for caffeine and the catechin species were determined to be on the nanogram level. A reversed-phase chromatographic separation of the green tea reference materials was carried out on a commercial C18 column using a gradient of water (containing 0.1% TFA) and 2:1 methanol:acetonitrile (containing 0.1%TFA) at 0.9 mL min−1 and an analysis time of 50 min. Quantification of caffeine and the catechin species was carried out using the standard addition and internal standard methods, with the latter providing appreciable improvements in precision and recovery.

 

 

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Author: Antonios E. Koutelidakis and Mauro Serafini and Michael Komaitis and Maria Kapsokefalou

We tested in mice the hypothesis that iron fortificants may exert oxidative activity on colon tissue homogenates (CTH), depending on the antioxidant capacity of infusions received with their diet. CTH were obtained from mice receiving daily by gavage 0.1 mL of infusion (8 g/100 mL water) from green tea or white tea or Pelargonium purpureum or catechin (0.01 g/100 mL) or water (control) for five days. All CTH had higher total antioxidant capacity than the control and lower susceptibility to oxidation induced by the retentates of in vitro digests of ferrous lactate, ferrous gluconate, ferrous sulfate and NaFeEDTA. Ferrous sulfate and NaFeEDTA exhibited higher oxidative effect on CTH than ferrous gluconate or ferrous lactate. These results are in support of our hypothesis and suggest that infusions received with diet may protect the colon from a potential oxidative effect of non-absorbed iron.

 

 

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Author: Gang Xu and Guijie Ren and Xia Xu and Huiqing Yuan and Zhenzheng Wang and Ludong Kang and Wenguang Yu and Keli Tian

Author: Keon Wook Kang and Soo Jin Oh and Shi Yong Ryu and Gyu Yong Song and Bong-Hee Kim and Jong Seong Kang and Sang Kyum Kim

The antioxidant activity of catechins isolated from green tea against peroxyl radicals, hydroxyl radicals, and peroxynitrite was determined using the total oxy-radical scavenging capacity (TOSC) assay. (−)-Epicatechin, (−)-epigallocatechin, (−)-epicatechin-3-gallate, and (−)-epigallocatechin-3-gallate were isolated and their structures were characterised based on their physical and spectral properties, and by comparison of these results with similar data in the literature. (−)-Epigallocatechin showed the highest TOSC value, and (−)-epicatechin-3-gallate was the least effective among the catechins tested. These results indicated that the presence of a gallate group at the three position plays a critical role in their antioxidant activity. However, additional insertion of a hydroxyl group at the 5′ position in the B ring attenuates the oxy-radical scavenging capacity of catechins. These results suggest that the antioxidant activity of catechins is dependent on the reactivity of both the original catechins and their products generated during reaction with oxy-radicals.

 

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Author: Norleena P. Gullett and A.R.M. Ruhul Amin and Soley Bayraktar and John M. Pezzuto and Dong M. Shin and Fadlo R. Khuri and Bharat B. Aggarwal and Young-Joon Surh and Omer Kucuk

Botanical and nutritional compounds have been used for the treatment of cancer throughout history. These compounds also may be useful in the prevention of cancer. Population studies suggest that a reduced risk of cancer is associated with high consumption of vegetables and fruits. Thus, the cancer chemopreventive potential of naturally occurring phytochemicals is of great interest. There are numerous reports of cancer chemopreventive activity of dietary botanicals, including cruciferous vegetables such as cabbage and broccoli, Allium vegetables such as garlic and onion, green tea, Citrus fruits, soybeans, tomatoes, berries, and ginger, as well as medicinal plants. Several lead compounds, such as genistein (from soybeans), lycopene (from tomatoes), brassinin (from cruciferous vegetables), sulforaphane (from asparagus), indole-3-carbinol (from broccoli), and resveratrol (from grapes and peanuts) are in preclinical or clinical trials for cancer chemoprevention. Phytochemicals have great potential in cancer prevention because of their safety, low cost, and oral bioavailability. In this review, we discuss potential natural cancer preventive compounds and their mechanisms of action.

 

 

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Author: Su-Chen Ho and Szu-Pei Wu and Shyh-Mirn Lin and Ya-Li Tang

Advanced glycation end-products (AGEs) are implicated in the pathogenesis of diabetic microvascular complications and microvascular complications of the aged. Dietary compounds that can reduce glycation may reasonably serve as valuable adjuvants, promoting the health of the aged and diabetics. This work evaluates and compares the anti-glycation activities of different herbal infusions with that of green tea, a well-documented anti-glycation beverage. The anti-glycation activity of herbal infusions were determined based on the ability of an infusion to attenuate the formation of fluorescent AGEs in glucose- and methylglyoxal-mediated protein glycation systems. All of the tested herbs except for lemongrass and rosemary—balm, mint, black tea, sage and common verbena—had potent anti-glycation abilities that exceeded or equalled that of green tea. Additionally, the amounts of phenolics and flavonoid in the herbal infusions were highly correlated with their anti-glycation activity, revealing that the anti-glycation activity of herbal infusions was primarily attributable to phenolics, particularly flavonoids.

 

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Author: Jung-Soo Son and Jae Hee Hong and Kwang-Ok Kim

The objective of this study was to investigate the effects of the interval length between sessions (1-day vs. 3-day), the sweetener level (Optimal (OP) vs. Low (LO)), and the number of stimuli (one vs. two) on long-term acceptability of a novel green tea drink. Two consumer groups (N = 80) rated their liking of two drinks (OP and LO) while another 4 consumer groups (N = 162) rated only one drink over 10 sessions at either 1-day or 3-day intervals. Repeated consumption led to an overall increase in liking of the novel drink even though the patterns of increase were different according to the sweetener level and the interval length. Higher sweetener level and shorter interval length might contribute to increase in liking score during the earlier sessions and stable liking during the later sessions for novel green tea drink.

 

 

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Author: I. Quelhas and C. Petisca and O. Viegas and A. Melo and O. Pinho and I.M.P.L.V.O. Ferreira