immunity

Author: Christian H. Coyle and Brian J. Philips and Shelby N. Morrisroe and Michael B. Chancellor and Naoki Yoshimura

Genitourinary tract inflammation/ailments affect the quality of life and health of a large segment of society. In recent years, studies have demonstrated strong antioxidant effects of green tea and its associated polyphenols in inflammatory states. This in vitro study examined the antioxidant capabilities (and putative mechanisms of action) of green tea extract (GTE), polyphenon-60 (PP-60, 60% pure polyphenols), (−)-epicatechin-3-gallate (ECG) and (−)-epigallocatechin-3-gallate (EGCG) in normal/malignant human bladder cells following catechin treatment ± 1 mM H2O2 (oxidative agent). Cell viability, apoptosis and reactive oxygen species (ROS) formation were evaluated. Our results showed that H2O2exposure significantly reduced normal (UROtsa) and high-grade (TCCSUP, T24) bladder cancer (BlCa) cell viability compared with control-treated cells (p < 0.001). No affect on low-grade RT4 and SW780 BlCa cell viability was observed with exposure to H2O2. Compared to H2O2-treated UROtsa, treatment with PP-60, ECG and EGCG in the presence of H2O2 significantly improved UROtsa viability (p < 0.01), with strongest effects evoked by ECG. Additionally, though not as effective as in UROtsa cells, viability of both high-grade TCCSUP and T24 BlCa cells, in comparison to H2O2-treated cells, was significantly improved (p < 0.01) by treatment with PP-60, ECG, and EGCG in the presence of H2O2. Overall, our findings demonstrate that urothelium cell death via H2O2-induced oxidative stress is mediated, in part, through superoxide (O2−">;), and potentially, direct H2O2 mechanisms, suggesting that green tea polyphenols can protect against oxidative stress/damage and bladder cell death.

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Antioxidant synergism of green tea polyphenols with α-tocopherol and l-ascorbic acid in SDS micelles

Author: Fang Dai and Wei-Feng Chen and Bo Zhou

The synergistic antioxidant effect of polyphenols extracted from green tea, i.e. (−)-epicatechin (EC), (−)-epigallocatechin (EGC), (−)-epicatechin gallate (ECG), (−)-epigallocatechin gallate (EGCG) and gallic acid (GA), with α-tocopherol (vitamin E) and l-ascorbic acid (vitamin C) against the peroxidation of linoleic acid has been studied in sodium dodecyl sulfate (SDS) micelles. The peroxidation was initiated thermally by a water-soluble azo initiator 2,2′-azobis(2-amidinopropane) hydrochloride (AAPH), and the reaction kinetics were studied by monitoring the formation of linoleic acid hydroperoxides and consumption of the antioxidants. It was found that the mixture of the green tea polyphenol, vitamin E and vitamin C could act synergistically to protect lipid peroxidation. Kinetic and mechanistic studies on the antioxidation process revealed that this antioxidant synergism was due to the regeneration of vitamin E by the green tea polyphenol and the regeneration of the latter by vitamin C.

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Author: Elvira Gonzalez de Mejia and Marco Vinicio Ramirez-Mares and Sirima Puangpraphant

Tea is one of the most widely consumed beverages worldwide. Several studies have suggested that catechins and theaflavins found in tea may reduce the risk of various types of cancers. Major advances have been made to understand the molecular events leading to cancer prevention; however, the evidence is not conclusive. Evidence from pre-clinical and clinical studies also suggests that persistent inflammation can progress to cancer. Several possible mechanisms of action may explain the cancer preventive aspects of tea components specifically anti-inflammatory effects. In regards to brain health, green tea catechins have been recognized as multifunctional compounds for neuroprotection with beneficial effects on vascular function and mental performance. Theanine, a unique amino acid in tea, enhances cognition in humans and has neuroprotective effects. Human interventional studies with well characterized tea products are needed.

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Author: A.B. Sharangi

The medicinal effects of tea have a history dating back almost 5000 years. The chemical components of green tea chiefly include polyphenols, caffeine and amino acids. Tea also contains flavonoids, compounds reported to have anti-oxidant properties having many beneficial effects. Tea flavonoids reduce inflammation, have antimicrobial effects and prevent tooth decay. Consumption of tea may have diuretic effects due to the caffeine. A related compound found in tea is theophylline, a licensed medicine for the treatment of respiratory diseases such as asthma. Today’s computer-driven world can generate complicated lifestyle-related disorders and consumption of certain natural product like tea may very well replace the ill-effects of chemical drugs leading to a safer world with happier life. The paper is an overview of revealing all such ethno medicinal research efforts throughout the world over the times.

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Author: Haim Shapiro and Shaul Lev and Jonathan Cohen and Pierre Singer

Sepsis is the overwhelming systemic response to infection of a normally sterile body compartment. Despite advances in elucidating its pathophysiology, severe sepsis remains a leading cause of death in the critically ill. Polyphenols are a family of chemicals found in food and beverages derived from plants, such as cocoa, green tea, turmeric, and soya, as well as in medicinal herbs. These phytochemicals exhibit anti-inflammatory and vasculoprotective properties in clinical and preclinical studies. The oral or systemic administration of polyphenols protects rodents from endotoxinemia and microbial sepsis. Under these circumstances, polyphenols reproducibly attenuate microvascular hyperpermeability, tissue infiltration by leukocytes, oxidative and nitrosative stress, tissue injury, organ dysfunction, shock and vasoplegia, lactate production, and mortality. Importantly, efficacy is maintained in some cases even when treatment is initiated hours after the onset of sepsis. The inhibition of nuclear factor–κB activation and subsequent expression of inducible nitric oxide synthase, adhesion molecules, and tumor necrosis factor–α by polyphenols is operative in ameliorating the sequelae of sepsis. Enhancement of the endogenous antioxidant capacity probably also contributes to the effectiveness of the polyphenols. Because several of the polyphenols reviewed in this article appear to be safe and to exert anti-inflammatory effects in humans, clinical trials assessing their efficacy in the critically ill are indicated. Whether delivered alone or in combination with nutritional formulas, polyphenols may help to prevent and treat sepsis.

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Author: Soichiro Kori and Hideo Namiki and Kingo Suzuki

Green tea polyphenols have been reported to have anti-inflammatory activities, although the molecular mechanisms responsible for this effect remain unclear. In the present study, we examined the effect of green tea extract and a variety of polyphenolic compounds on spreading of peripheral blood polymorphonuclear leukocytes (PMNs) over fibrinogen-coated surfaces. Green tea extract exerted a biphasic effect on PMN spreading; it induced or suppressed spreading at low and high concentrations, respectively. We also found that pyrogallol-bearing compounds have spreading induction activity. Among the compounds tested, tannic acid (TA) had the strongest activity; the concentrations required for induction of maximal spreading were 2 µM for TA, 200 µM for (−)-epigallocatechin gallate, and 2000 µM for the other active compounds. Furthermore, TA was the only compound showing a biphasic effect similar to that of green tea extract; TA at 20 or 200 µM suppressed spreading. The spreading-stimulatory signal was still latent during PMN exposure to TA at concentrations that inhibited spreading, because the pre-exposed PMNs underwent spreading when plated after removal of free TA by centrifugation. The spreading-inhibitory effect of TA at high concentrations overcame the induction of spreading by other stimuli, including phorbol 12-myristate 13-acetate, hydrogen peroxide, denatured fibrinogen surfaces, and naked plastic surfaces. These results suggest that TA as well as green tea extract is bi-functional, having pro-inflammatory and anti-inflammatory effects at low and high concentrations, respectively. Pharmacological use of TA may thus provide new strategies aimed at regulation of PMN spreading for control of inflammation.

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Author: Sara A. Khan and Shubha Priyamvada and Neelam Farooq and Sheeba Khan and Md Wasim Khan and Ahad N.K. Yusufi

Gentamicin (GM) is an effective aminoglycoside antibiotic against severe infections but nephrotoxicity and oxidative damage limits its long term clinical use. Various strategies were attempted to ameliorate GM nephropathy but were not found suitable for clinical practice. Green tea (GT) polyphenols have shown strong chemopreventive and chemotherapeutic effects against various pathologies. We hypothesized that GT prevents GM nephrotoxicity by virtue of its antioxidative properties. A nephrotoxic dose of GM was co-administered to control and GT-fed male Wistar rats. Serum parameters and enzymes of oxidative stress, brush border membrane (BBM), and carbohydrate metabolism were analyzed. GM increased serum creatinine, cholesterol, blood urea nitrogen (BUN), lipid peroxidation (LPO) and suppressed superoxide dismutase (SOD) and catalase activities in renal tissues. Activity of hexokinase, lactate dehydrogenase increased whereas malate dehydrogenase decreased. Gluconeogenic enzymes and glucose-6-phosphate dehydrogenase were differentially altered in the cortex and medulla. However, GT given to GM rats reduced nephrotoxicity parameters, enhanced antioxidant defense and energy metabolism. The activity of BBM enzymes and transport of Pi declined by GM whereas GT enhanced BBM enzymes and Pi transport. In conclusion, green tea ameliorates GM elicited nephrotoxicity and oxidative damage by improving antioxidant defense, tissue integrity and energy metabolism.

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Author: Dong Wook Shin and Su Nam Kim and Sang Min Lee and Woojung Lee and Min Jeong Song and Sun Mi Park and Tae Ryong Lee and Joo-Hyun Baik and Han Kon Kim and Jeong-Ho Hong and Minsoo Noh

Green tea intake has been shown to confer various health benefits to patients suffering from metabolic disorders. Here, we studied the effect of several major green tea polyphenols on adipocyte differentiation in human bone marrow mesenchymal stem cells (hBM-MSCs) and compared it to the effect of representative antidiabetic drugs. (−)-Catechin was the most potent of the eight green tea polyphenols evaluated in promoting adipocyte differentiation in hBM-MSCs, and this effect was dose-dependent. (−)-Catechin increased the mRNA levels of various adipogenic markers, such as adiponectin, peroxisome proliferator-activated receptor gamma (PPARγ), FABP4, and LPL, as measured during adipocyte differentiation in hBM-MSCs. In addition, (−)-catechin upregulated the secretion of adiponectin in hBM-MSC culture. Using a reporter gene assay and a competitive ligand binding study, (−)-catechin also significantly activated PPARγ in a dose-dependent fashion; however, (+)-catechin, the enantiomer of (−)-catechin, was not effective as a PPARγ agonist, which seems to imply that the effect of (−)-catechin on PPARγ is stereospecific. In conclusion, our data suggest that (−)-catechin promotes adipocyte differentiation and increased sensitivity to insulin in part by direct activation of PPARγ, which could be at the basis of the observed pharmacological benefits of green tea intake in reducing the risk of type 2 diabetes.

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Author: Calin Stoicov and Reza Saffari and JeanMarie Houghton

Helicobacter infection, one of the most common bacterial infections in man worldwide, is a type 1 carcinogen and the most important risk factor for gastric cancer. Helicobacter pylori bacterial factors, components of the host genetics and immune response, dietary cofactors and decreased acid secretion resulting in bacterial overgrowth are all considered important factors for induction of gastric cancer. Components found in green tea have been shown to inhibit bacterial growth, including the growth of Helicobacter spp. In this study, we assessed the bactericidal and/or bacteriostatic effect of green tea against Helicobacter felis and H. pylori in vitro and evaluated the effects of green tea on the development of Helicobacter-induced gastritis in an animal model. Our data clearly demonstrate profound growth effects of green tea against Helicobacter and, importantly, demonstrate that green tea consumption can prevent gastric mucosal inflammation if ingested prior to exposure to Helicobacter infection. Research in the area of natural food compounds and their effects on various disease states has gained increased acceptance in the past several years. Components within natural remedies such as green tea could be further used for prevention and treatment of Helicobacter-induced gastritis in humans.

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Author: Janice Snider

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