cancer-prevention
Recent Research Papers on
cancer-prevention
Author: Saad M. Bin Dajem and Ali A. Shati and Mohamed A. Adly and Osama M. Ahmed and Essam H. Ibrahim and Osama M.S. Mostafa
This study was designed to assess the effect of green tea, an aqueous extract of Camellia sinensis, on the oxidative stress, antioxidant defense system and liver pathology of Schistosoma mansoni-infected mice. Green tea at concentration of 3% (w/v) was given orally to treated mice as sole source of drinking water from the end of the 4th week to the end of 10th week post-infection; untreated mice were allowed to drink normal water. The data of the studied S. mansoni-infected mice exhibited a suppression of hepatic total antioxidant capacity, superoxide dismutase (SOD), catalase (CAT) activity and glutathione content. The liver lipid peroxidation was deleteriously elevated in S. mansoni-infected mice. The hepatic total protein content, AST and ALT activities were profoundly decreased in the S. mansoni-infected mice. Most hepatocytes were damaged and showed abnormal microscopic appearance with aggressive necrosis. Both total protein and glycogen levels have been greatly reduced as indicated by histochemical examination. The treatment of S. mansoni-infected mice with green tea succeeded to suppress oxidative stress by decreasing the lipid peroxides but failed to significantly enhance the antioxidant defense system and deteriorated changes owing to liver damage and necrosis. In consistence with biochemical data, histopathological and histochemical data indicated that treatment of S. mansoni-infected mice with green tea could ameliorate hepatocytes thus reduce cellular necrosis and partially restore both total protein and glycogen levels. Thus, the study concluded that the green tea suppresses the oxidative stress through its constituent with free radicals scavenging properties rather than through the endogenous antioxidant defense system.
Author: Yanli Li and Shen-Chih Chang and Binh Y. Goldstein and William L. Scheider and Lin Cai and Nai-Chieh Y. You and Heather P. Tarleton and Baoguo Ding and Jinkou Zhao and Ming Wu and Qingwu Jiang and Shunzhang Yu and Jianyu Rao and Qing-Yi Lu and Zuo-Feng Zhang and Lina Mu
Objective: Green tea has been found to possess anti-inflammatory, anti-oxidative and anti-carcinogenic properties. The present study examines the association between green tea drinking and hepatocellular carcinoma (HCC) and its interactions with other risk or protective factors and single nucleotide polymorphisms (SNP) of inflammation and oxidative stress related genes. Methods: A population-based case-control study with 204 primary HCC cases and 415 healthy controls was conducted in Taixing, China. Epidemiological data were collected using a standard questionnaire. SNPs of genes of the inflammation and metabolic pathways were genotyped at the UCLA Molecular Epidemiology Laboratory. Logistic regression was performed to estimate adjusted odds ratios and 95% confidence intervals. Results: Longer duration and larger quantities of green tea consumption were inversely associated with primary HCC. Individuals who drank green tea longer than 30 years were at lowest risk (adjusted OR = 0.44, 95% CI: 0.19–0.96) compared with non-drinkers. A strong interaction was observed between green tea drinking and alcohol consumption (adjusted OR for interaction = 3.40, 95% CI: 1.26–9.16). Green tea drinking was also observed to have a potential effect modification on HBV/HCV infection, smoking and polymorphisms of inflammation related cytokines, especially for IL-10. Conclusion: Green tea consumption may protect against development of primary HCC. Potential effect modifications of green tea on associations between primary HCC and alcohol drinking, HBV/HCV infection, and inflammation-related SNPs were suggested.
Author: Tia M. Rains and Sanjiv Agarwal and Kevin C. Maki
Green tea catechins (GTC) are polyphenolic compounds present in the unfermented dried leaves of the plant, Camellia sinensis. Results from a number of randomized, controlled intervention trials have shown that consumption of GTC (270 mg to 1200 mg/day) may reduce body weight and fat. There are several proposed mechanisms whereby GTC may influence body weight and composition. The predominating hypothesis is that GTC influences sympathetic nervous system (SNS) activity, increasing energy expenditure and promoting the oxidation of fat. Caffeine, naturally present in green tea, also influences SNS activity, and may act synergistically with GTC to increase energy expenditure and fat oxidation. Other potential mechanisms include modifications in appetite, up-regulation of enzymes involved in hepatic fat oxidation, and decreased nutrient absorption. This article reviews the evidence for each of these purported mechanisms, with particular reference to studies in humans.
Author: Jinping Qiao and Chenxin Gu and Weihu Shang and Jinglei Du and Wei Yin and Meilin Zhu and Wei Wang and Mei Han and Weidong Lu
Tea drinking is widely practiced in the world and has recently increased among cancer patients. However, the effects of concurrent consumption of tea on the bioavailability and the net therapeutic potential of co-administered chemical drugs are not clear. In this study, the effects of green tea on the pharmacokinetics of 5-fluorouracil (5-FU) in rats and the pharmacodynamics in human cell lines in vitro were studied. The pharmacokinetic experiment indicated that there was an approximately 151% increase in the maximum plasma concentration (Cmax) and an approximately 425% increase in the area under the plasma concentration curve (AUC) of 5-FU in the green tea-treated group compared with the control group. Green tea consumption increased the plasma concentration of 5-FU. In addition, the pharmacodynamics experiment showed that at the moderate dose level (equivalent to 6 cups daily in human), neither fresh green tea extract nor (−)-epigallocatechin-3-gallate (EGCG) showed significant additive effects on the cytotoxicity of 5-FU in human cell lines. The results showed that it is crucial to perform therapeutic drug monitoring (TDM) when the cancer patients have a habit of drinking green tea.
Author: Yu-Wen Hsu and Chia-Fang Tsai and Wen-Kang Chen and Chun-Fa Huang and Cheng-Chieh Yen
Green tea is believed to be beneficial to health because it possesses antioxidant, antiviral and anticancer properties. The potential toxicity of green tea when administered at high doses via concentrated extracts, however, has not been completely investigated. The objective of the present study was to evaluate the safety of green tea extract in ICR mice using a subacute exposure paradigm. In this study, mice were orally administered (gavage) green tea extract at doses of 0 (as normal group), 625, 1250 and 2500 mg/kg body weight/day for 28 days. The results showed that oral administration of green tea extract did not cause adverse effects on body weight, organ weights, hematology, serum biochemistry, urinalysis or histopathology. Additionally, administering green tea extract via gavage significantly reduced triglyceride and cholesterol levels. These observed effects could be attributed to the high levels of catechins present in green tea as these compounds have been reported to have beneficial health effects. The no-observed-adverse-effect level for green tea extract derived from the results of the present study was 2500 mg/kg body weight/day.
Author: Vera Lavelli and Mark Corey and William Kerr and Claudia Vantaggi
Intermediate moisture products made from blanched apple flesh and green tea extract (about 6 mg of monomeric flavan 3-ols added per g of dry apple) or blanched apple flesh (control) were produced, and their quality attributes were investigated over storage for two months at water activity (aw) levels of 0.55 and 0.75, at 30 °C. Products were evaluated for colour (L∗, a∗, and b∗ Hunter’s parameters), phytochemical contents (flavan 3-ols, chlorogenic acid, dihydrochalcones, ascorbic acid and total polyphenols), ferric reducing antioxidant potential, 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl radical-scavenging activity and ability to inhibit formation of fructose-induced advanced glycation end-products. During storage of the fortified and unfortified intermediate moisture apples, water availability was sufficient to support various chemical reactions involving phytochemicals, which degraded at different rates: ascorbic acid > flavan 3-ols > dihydrochalcones and chlorogenic acid. Colour variations occurred at slightly slower rates after green tea addition. In the intermediate moisture apple, antioxidant and anti-glycoxidative properties decreased at similar rates (half-life was about 80 d at aw of 0.75, 30 °C). In the green tea-fortified intermediate moisture apple, the antioxidant activity decreased at a slow rate (half-life was 165 d at aw of 0.75, 30 °C) and the anti-glycoxidative properties did not change, indicating that flavan 3-ol degradation involved the formation of derivatives that retained the properties of their parent compounds. Since these properties are linked to oxidative- and advanced glycation end-product-related diseases, these results suggest that green tea fortification of intermediate moisture apple products could be a valuable means of product innovation, to address consumers’ nutritional needs.
Author: Carol López-de-Dicastillo and Joaquin Gómez-Estaca and Ramón Catalá and Rafael Gavara and Pilar Hernández-Muñoz
Active antioxidant food packaging films were produced by the incorporation of ascorbic acid, ferulic acid, quercetin, and green tea extract into an ethylene vinyl alcohol copolymer (EVOH) matrix. The characterisation of the thermal and barrier properties of the developed film showed that the addition of these bioactive compounds did not greatly modify their properties. However, the presence of ascorbic and ferulic acids resulted in a significant decrease in water vapour permeability, possibly due to the high affinity for water of these substances. Exposure of the films to various food simulants showed that the release from the films was dependent on the type of food simulant and the antioxidant incorporated: in the aqueous food simulant, materials containing ascorbic acid produced the largest release; in the fatty food simulant, quercetin and green tea extract presented the best performance. The efficiency of the films developed was determined by real packaging applications of brined sardines. The evolution of the peroxide index and the malondialdehyde content showed that, in general, the films improved sardine stability. Films with green tea extract offered the best protection against lipid oxidation.
Author: A.S.G. Costa and M.A. Nunes and I.M.C. Almeida and M.R. Carvalho and M.F. Barroso and R.C. Alves and M.B.P.P. Oliveira
Nowadays, new emerging products claiming antioxidant properties are becoming more frequent. However, information about this topic in their labels is usually scarce. In this paper, we analyzed total phenolics, total flavonoids and ascorbic acid contents, as well as DPPH scavenging activity of several commercial samples, namely green tea and other herbal infusions, dietary supplements, and fruit juices, available in the Portuguese market. In general, beverages containing green tea and hibiscus showed higher phenolics contents (including flavonoids) and antioxidant activity than those without these ingredients. A borututu infusion presented the lowest concentrations of bioactive compounds and scavenging activity, due to the low recommended amount of plant to prepare the beverage. Some juices without antioxidant claims in the label presented similar values to those with it.
Author: Jaqueline Minatti and Elisabeth Wazlawik and Mariana A. Hort and Fernanda L. Zaleski and Rosa M. Ribeiro-do-Valle and Marcelo Maraschin and Edson L. da Silva
The aim of this study was to evaluate the effects of green tea extract (GTE) administration on vascular reactivity and atherosclerosis progression in low-density lipoprotein receptor knockout mice. We hypothesized that GTE intake may ameliorate atherosclerosis by improving endothelial dysfunction. Animals (n = 12 per group) were fed a hypercholesterolemic diet and received either water or GTE at a dose of 50, 100, or 300 mg/kg once a day by gavage (100 μL/10 g weight). After 4 weeks, atherosclerosis extension and vascular reactivity were evaluated in the aorta, and the levels of lipids, monocyte chemotactic protein-1(MCP-1), and tumor necrosis factor α were measured in the plasma. Administration of GTE at a dose of 50 mg/kg significantly decreased the area of atherosclerotic lesions by 35%, improved the vascular reactivity in the isolated thoracic aorta, and lowered the plasma levels of both MCP-1 and triglycerides. Delivery of 100 mg/kg of GTE only promoted vasocontraction and vasorelaxation (P < .05), whereas a dose of 300 mg/kg was ineffective. Maximum contraction and relaxation negatively correlated with the lesion area (r = −0.755 and −0.767, respectively), whereas the plasma levels of MCP-1 and triglycerides positively correlated with plaque size (r = 0.549 and 0.421, respectively). In summary, our results supported the hypothesis that administration of GTE at low doses may contribute to a decrease in atherosclerosis progression by reversing endothelial dysfunction.
Author: Ubonrat Siripatrawan and Suparat Noipha
Chitosan film incorporating green tea extract (CGT-film) was used as active packaging for shelf life extension of pork sausages. The physical, chemical, microbiological, and sensory qualities of pork sausages wrapped with CGT-film were compared with those wrapped with chitosan-alone film (C-film) and those without chitosan film wrapping (control). Changes in the qualities of pork sausages including color, texture, lipid oxidation with respect to thiobarbituric value (TBA), and microbiological qualities including total plate counts, yeasts and molds, and lactic acid bacteria were determined throughout the storage at 4 °C. The sensory qualities including odor, color, slime formation, and overall acceptability were evaluated using Quantitative Descriptive Analysis. It was found that samples wrapped with CGT-film showed lower changes in color, texture, TBA value, microbial growth, and sensory characteristics than those wrapped with C-film and control, respectively. Successful inhibition of lipid oxidation and microbial growth in the refrigerated pork sausages was possible with chitosan film incorporating green tea extract. The results suggested that incorporation of green tea extract into chitosan film could enhance the antioxidant and antimicrobial properties of the film and thus maintained the qualities and prolonged the shelf life of the sausages.