Tea polyphenols for health promotion

Dietary agents in the prevention of alcohol-induced hepatotoxicty: preclinical observations

Long term alcohol consumption is one of the important causes for liver failure and death. To complicate the existing problem there are no dependable hepatoprotective drugs and a large number of patients prefer using complementary and alternative medicines for treating and managing hepatic complications. Almost 25 centuries ago, Hippocrates, the father of medicine, proclaimed "Let food be thy medicine and medicine be thy food." Exploring the association between diet and health continues even today. Preclinical studies carried out in the recent past have shown that the commonly used dietary agents like Allium sativum (garlic), Camellia sinensis (tea), Curcuma longa (turmeric), Emblica officinalis (Indian gooseberry), Ferula asafoetida (asafoetida), Garcinia cambogia (Malabar tamarind), Glycine max (soyabean), Murraya koenigii (curry leaves), Piper betle (beetle leaf), Prunus armeniaca (apricot), Ocimum gratissimum (wild basil), Theobroma cacao (cocoa), Trigonella foenum-graecum (fenugreek) and Vitis vinifera (grapes) protect against ethanol-induced hepatotoxicity. Mechanistic studies have shown that the beneficial effects of these phytochemicals in preventing the ethanol-induced hepatotoxicity are mediated by the antioxidant, free radical scavenging, anti-inflammatory and anti-fibrotic effects. The present review for the first time collates the hepatoprotective effects of these agents and also emphasizes on aspects that need future research to establish their utility in humans.

Selective removal of caffeine from tea extracts using macroporous crosslinked polyvinyl alcohol adsorbents

The hydrolysis reaction of ester groups in vinyl acetate (VAc) was used to introduce hydroxyl groups into the matrix of a macroporous adsorbent, which was itself prepared by free radical suspension copolymerization of triallyl isocyanurate (TAIC) and VAc. Therefore, the copolymerization incompatibility between the hydrophilic and the hydrophobic monomer was overcome successfully and the hydrophobic matrix of the polymeric adsorbent containing a polyvinyl alcohol (PVA) segment was obtained. Introduction of the PVA segment decreased the hydrophobic adsorption affinity of the adsorbent while producing the hydrogen-bonding interaction. When isolating the two active components, polyphenols (TPh) and caffeine (CAF), from green tea extracts, this polymeric adsorbent, namely poly(TAIC-co-VA), exhibited good adsorption selectivity towards TPh over CAF. The adsorption mechanism leading to this selectivity involved a hydrophobic interaction mechanism for CAF and multiple weak hydrophobic and hydrogen-bonding interactions for TPh. The adsorption thermodynamics for TPh on poly(TAIC-co-VA) were studied. The effects of adsorbent structure and gradient desorption conditions on isolation were investigated. The result showed that adsorbent, with 20% TAIC content, was able to efficiently remove CAF from different tea extracts with different ratios of TPh and CAF. Finally, almost no CAF was detected in the TPh fraction and the recovery of TPh was greater than 95%.

New insights into the mechanisms of green tea catechins in the chemoprevention of prostate cancer

Prostate cancer is the most commonly diagnosed cancer and second most common cause of cancer deaths in American men. Its long latency, slow progression, and high incidence rate make prostate cancer ideal for targeted chemopreventative therapies. Therefore, chemoprevention studies and clinical trials are essential for reducing the burden of prostate cancer on society. Epidemiological studies suggest that tea consumption has protective effects against a variety of human cancers, including that of the prostate. Laboratory and clinical studies have demonstrated that green tea components, specifically the green tea catechin (GTC) epigallocatechin gallate, can induce apoptosis, suppress progression, and inhibit invasion and metastasis of prostate cancer. Multiple mechanisms are involved in the chemoprevention of prostate cancer with GTCs; understanding and refining models of fundamental molecular pathways by which GTCs modulate prostate carcinogenesis is essential to apply the utilization of green tea for the chemoprevention of prostate cancer in clinical settings. The objective of this article is to review and summarize the most current literature focusing on the major mechanisms of GTC chemopreventative action on prostate cancer from laboratory, in vitro, and in vivo studies, and clinical chemoprevention trials.

Transport mechanisms of flavanone aglycones across Caco-2 cell monolayers and artificial PAMPA membranes

Objectives

We recently reported that flavanone aglycones (hesperetin, naringenin and eriodictyol) are efficiently absorbed via proton-coupled active transport, in addition to transcellular passive diffusion, in Caco-2 cells. Here, we aimed to evaluate in detail the absorption mechanisms of these flavanones, as well as homoeriodictyol and sakuranetin.

Methods

We evaluated the absorption mechanisms of the above compounds by means of in vitro studies in Caco-2 cells in parallel with an artificial membrane permeation assay (PAMPA) under pH-gradient and iso-pH conditions.

Key findings

Comparison of the permeability characteristics of flavanones in Caco-2 cells and in PAMPA under these conditions, as well as a consideration of the physicochemical properties, indicated that hesperetin, naringenin, eriodictyol and homoeriodictyol were efficiently transported by passive diffusion according to the pH-partition hypothesis, except in the case of sakuranetin. However, transport of all flavanones were remarkably temperature-dependent, and was significantly reduced when Caco-2 cells were treated with amino acid-modifying reagents.

Conclusions

Our data confirm that both passive diffusion and an active transport mechanism contribute to flavanone absorption through human intestinal epithelium.

Fatty acid composition and antioxidant activity of tea (Camellia sinensis L.) seed oil extracted by optimized supercritical carbon dioxide

Seeds are another product in addition to leaves (raw materials for teas) of tea (Camellia sinensis L.) plant. The great increase of tea consumption in recent years raises the challenge of finding commercial applications for tea seeds. In the present study, supercritical carbon dioxide (SC-CO(2)) extraction edible oil from tea seed was carried out, response surface methodology (RSM) was used to optimize processing parameters including time (20-90 min), temperature (35-45 °C) and pressure (50-90 MPa). The fatty acid composition and antioxidant activity of the extracted oil was also investigated. The highest yield of oil (29.2 ± 0.6%) was obtained under optimal SC-CO(2) extraction conditions (45 °C, 89.7 min and 32 MPa, respectively), which was significantly higher (p < 0.05) than that (25.3 ± 1.0%) given by Soxhlet extraction. Meanwhile, tea seed oil extracted by SC-CO(2) contained approximately 80% unsaturated fatty acids and showed a much stronger scavenging ability on the DPPH radical than that extracted by Soxhlet. SC-CO(2) is a promising alternative for efficient extraction of edible oil from tea seed. Moreover, tea seed oil extracted by SC-CO(2) is highly edible and has good antioxidant activity, and therefore may play a potential role as a health-promoting food resource in human diets.

Preparation, preliminary characterization, antioxidant, hepatoprotective and antitumor activities of polysaccharides from the flower of tea plant (Camellia sinensis)

In the present study, the crude polysaccharides from the flowers of tea plant (Camellia sinensis) (TFPS) were prepared with hot water and further fractionated on a DEAE-52 cellulose chromatography to afford three purified fractions of TFPS-1, TFPS-2 and TFPS-3. Then, their preliminary structures, antioxidant and antitumor activities in vitro and hepatoprotective activity in vivo were investigated. Compared with TFPS-2 and TFPS-3, TFPS-1 had relative higher content of sulfate and relative complicated monosaccharide composition. In addition, TFPS-1 and TFPS-3 showed relative stronger antioxidant activity and inhibitory activity on the growth of human gastric cancer BGC-823 cells. For hepatoprotective activity in vivo, we demonstrated that crude TFPS significantly prevented the increase of serum alanine aminotransferase and aspartate aminotransferase levels, reduced the formation of malondialdehyde and enhanced the activities of superoxide dismutase and glutathione peroxidase in carbon tetrachloride-induced liver injury mice. The results suggested that TFPS should be a potent natural polymer with antioxidant, hepatoprotective and antitumor activities.

Black tea extract prevents lipopolysaccharide-induced NF-κB signaling and attenuates dextran sulfate sodium-induced experimental colitis

Background

Black tea has been shown to elicit anti-oxidant, anti-carcinogenic, anti-inflammatory and anti-mutagenic properties. In this study, we investigated the impact of black tea extract (BTE) on lipopolysaccharide (LPS)-induced NF-κB signaling in bone marrow derived-macrophages (BMM) and determined the therapeutic efficacy of this extract on colon inflammation.

Methods

The effect of BTE on LPS-induced NF-κB signaling and pro-inflammatory gene expression was evaluated by RT-PCR, Western blotting, immunofluorescence and electrophoretic mobility shift assay (EMSA). The in vivo efficacy of BTE was assessed in mice with 3% dextran sulfate sodium (DSS)-induced colitis. The severity of colitis was measured by weight loss, colon length and histologic scores.

Results

LPS-induced IL-12p40, IL-23p19, IL-6 and IL-1β mRNA expressions were inhibited by BTE. LPS-induced IκBα phosphorylation/degradation and nuclear translocation of NF-κB/p65 were blocked by BTE. BTE treatment blocked LPS-induced DNA-binding activity of NF-κB. BTE-fed, DSS-exposed mice showed the less weight loss, longer colon length and lower histologic score compared to control diet-fed, DSS-exposed mice. DSS-induced IκBα phosphorylation/degradation and phosphorylation of NF-κB/p65 were blocked by BTE. An increase of cleaved caspase-3 and poly (ADP-ribose) polymerase (PARP) in DSS-exposed mice was blocked by BTE.

Conclusions

These results indicate that BTE attenuates colon inflammation through the blockage of NF-κB signaling and apoptosis in DSS-induced experimental colitis model.

Modulation of Nrf2/ARE pathway by food polyphenols: a nutritional neuroprotective strategy for cognitive and neurodegenerative disorders

In recent years, there has been a growing interest, supported by a large number of experimental and epidemiological studies, for the beneficial effects of some phenolic substances, contained in commonly used spices and herbs, in preventing various age-related pathologic conditions, ranging from cancer to neurodegenerative diseases. Although the exact mechanisms by which polyphenols promote these effects remain to be elucidated, several reports have shown their ability to stimulate a general xenobiotic response in the target cells, activating multiple defense genes. Data from our and other laboratories have previously demonstrated that curcumin, the yellow pigment of curry, strongly induces heme-oxygenase-1 (HO-1) expression and activity in different brain cells via the activation of heterodimers of NF-E2-related factors 2 (Nrf2)/antioxidant responsive element (ARE) pathway. Many studies clearly demonstrate that activation ofNrf2 target genes, and particularly HO-1, in astrocytes and neurons is strongly protective against inflammation, oxidative damage, and cell death. In the central nervous system, the HO system has been reported to be very active, and its modulation seems to play a crucial role in the pathogenesis of neurodegenerative disorders. Recent and unpublished data from our group revealed that low concentrations of epigallocatechin-3-gallate, the major green tea catechin, induces HO-1 by ARE/Nrf2 pathway in hippocampal neurons, and by this induction, it is able to protect neurons against different models of oxidative damages. Furthermore, we have demonstrated that other phenolics, such as caffeic acid phenethyl ester and ethyl ferulate, are also able to protect neurons via HO-1 induction. These studies identify a novel class of compounds that could be used for therapeutic purposes as preventive agents against cognitive decline.

(-)-Epigallocatechin-3-gallate blocks 3T3-L1 adipose conversion by inhibition of cell proliferation and suppression of adipose phenotype expression

AIMS

A major objective in the treatment of obese individuals is the development of agents that reduce body fat and improve metabolic homeostasis. Among a variety of biological effects, green tea exerts an anti-obesity effect; however, the mechanisms behind its activity on adipose tissue are uncertain. Tea contains high levels of (-)-epigallocatechin-3-gallate (EGCG), which is one of its main bioactive substances. Therefore, we studied the effects of EGCG on mouse embryonic fibroblast-adipose like cell line (3T3-L1) preadipocyte proliferation and differentiation.

MAIN METHODS

3T3-L1 cells were incubated with physiologically attainable (0.1-1 μM) and pharmacological (5μM, 10μM) concentrations of EGCG for various lengths of time. Cell proliferation was assessed by cell counting and cell cycle analysis. Adipose conversion was evaluated by lipid accumulation and expression of CCAAT/enhancer binding protein alpha (C/EBPα) and peroxisome proliferator-activated receptor gamma (PPARγ) transcription factors.

KEY FINDINGS

A dose dependent suppressive effect on preadipocyte proliferation was observed, with the highest reduction in cell number at 10μM EGCG. On the other hand, adipose conversion was fully inhibited with 10μM EGCG. Flow-cytometric analysis showed that 3T3-L1 cells treated with EGCG underwent an arrest of cell cycle at G2/M. The inhibition of the expression of C/EBPα and PPARγ was accompanied by the inhibitory effect of EGCG. Microscopic observation showed that 3T3-L1 cells treated with EGCG maintained the fibroblastic shape and failed to accumulate cytoplasmic fat droplets even after the induction of differentiation.

SIGNIFICANCE

Our results suggest that EGCG reduces adipogenesis through an arrest of cell cycle and a blockage of adipose phenotype expression. These results also suggest that the anti-obesity activity of green tea may be partially attributed to its suppressive effects in adipogenesis.

Theaflavins inhibit the ATP synthase and the respiratory chain without increasing superoxide production

Four dietary polyphenols, theaflavin, theaflavin-3-gallate, theaflavin-3'-gallate and theaflavin-3,3'-digallate (TF3), have been isolated from black tea, and their effects on oxidative phosphorylation and superoxide production in a model system (Escherichia coli) have been examined. The esterified theaflavins were all potent inhibitors of the membrane-bound adenosine triphosphate (ATP) synthase, inhibiting at least 90% of the activity, with IC(50) values in the range of 10-20 μM. ATP-driven proton translocation was inhibited in a similar fashion, as was the purified F(1)-ATPase, indicating that the primary site of inhibition was in the F(1) sector. Computer modeling studies supported this interpretation. All four theaflavins were also inhibitory towards the electron transport chain, whether through complex I (NDH-1) or the alternative NADH dehydrogenase (NDH-2). Inhibition of NDH-1 by TF3 appeared to be competitive with respect to NADH, and this was supported by computer modeling studies. Rates of superoxide production during NADH oxidation by each dehydrogenase were measured. Superoxide production was completely eliminated in the presence of about 15 μM TF3, suggesting that inhibition of the respiratory chain by theaflavins does not contribute to superoxide production.

Optimizing conditions for the extraction of catechins from green tea using hot water

Six different factors involved in the extraction of catechins from green tea using water were examined for their impact on the yield of catechins and on the efficiency of water use. The best temperature and time combination for catechin extraction was at 80°C for 30 min. The yield of catechins was also optimal with a tea particle size of 1 mm, a brewing solution pH <6 and a tea-to-water ratio at 50:1 (mL/g). In terms of efficient use of water in a single extraction, a water-to-tea ratio of 20:1 (mL/g) gave the best results; 2.5 times less water was used per gram of green tea. At the water-to-tea ratio of 20:1 mL/g, the highest yield of catechins per gram of green tea was achieved by extracting the same sample of green tea twice. However, for the most efficient use of water, the best extraction was found to be once at a water-to-tea ratio of 12:1 (mL/g) and once at a water-to-tea ratio of 8:1 (mL/g). Therefore, all six of the factors investigated had an impact on the yield of catechins extracted from green tea using water and two had an impact on the efficiency of water use.

Theaflavin Inhibits LPS-Induced IL-6, MCP-1, and ICAM-1 Expression in Bone Marrow-Derived Macrophages Through the Blockade of NF-κB and MAPK Signaling Pathways

Theaflavin, the main polyphenol in black tea, has anti-inflammatory, antioxidative, anti-mutagenic, and anti-carcinogenic properties. The aim of this study was to evaluate the effects of theaflavin on lipopolysaccharide (LPS)-induced innate signaling and expression of pro-inflammatory mediators in bone marrow-derived macrophages isolated from ICR mice. The effects of theaflavin on the expression of proinflammatory mediators, LPS-induced nuclear factor-kappa B (NF-κB), and mitogen-activated protein kinase (MAPK) signaling pathways were examined by reverse transcriptase-polymerase chain reaction (RT-PCR), Western blotting, and immunofluorescence. LPS-induced interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and intercellular adhesion molecule-1 (ICAM-1) expression was inhibited by theaflavin. LPS-induced inhibitor kappa B alpha (IκBα) degradation and nuclear translocation of RelA were blocked by theaflavin. LPS-induced phosphorylation of extracellular signal-regulated kinase1/2 (ERK1/2), c-Jun-N-terminal kinase (JNK), and p38 MAPK was inhibited by theaflavin. The inhibitory effect of theaflavin on IL-6, MCP-1, and ICAM-1 expression was completely inhibited by Bay11-7082 (NF-κB inhibitor). The inhibitory effect of theaflavin on IL-6 and ICAM-1 expression was inhibited by SB203580 (p38 MAPK inhibitor). The inhibitory effect of theaflavin on MCP-1 expression was inhibited by SP600125 (JNK inhibitor). These results indicate that theaflavin prevents LPS-induced IL-6, MCP-1, and ICAM-1 expression through blockade of NF-κB and MAPK signaling pathways in bone marrow-derived macrophages.

Effect of milk and brewing method on black tea catechin bioaccessibility

The aim of this study was to investigate whether milk reduces the bioaccessibility of tea catechins, which would compromise tea beneficial effects ascribed to polyphenols. Adding milk to black tea has been shown to lead to polyphenol-protein complexes. So far, data on the intestinal stability of polyphenol-protein complexes are scarce. English black tea (0.93 ± 0.06 mol/L total catechins) and Indian black tea (1.83 ± 0.08 mol/L catechins) were prepared with skimmed or full-fat milk and subjected to simulated gastric, small intestinal, and brush border digestion. Adding milk (5.6-40%) to tea results in a decrease of total catechin (TCAT) recovery. However, the bioaccessibilities of TCAT of tea with milk versus tea controls were comparable (p > 0.05). The type of milk did not influence TCAT recovery during all digestive stages (p > 0.05). Polyphenol-protein complexes are degraded during digestion. It is very unlikely that consumption of tea with or without milk will result in differences in catechin plasma concentration.

Acute effects of epigallocatechin gallate from green tea on oxidation and tissue incorporation of dietary lipids in mice fed a high-fat diet

OBJECTIVE

To examine in mice the acute effects of epigallocatechin gallate (EGCG), a green tea bioactive polyphenol on substrate metabolism with focus on the fate of dietary lipids.

METHODS

Male C57BL/6 mice were fed high-fat diets supplemented with EGCG extracted from green tea (TEAVIGO, DSM Nutritional Products Ltd, Basel, Switzerland) at different dosages up to 1% (w/w). Effects of EGCG on body composition (quantitative magnetic resonance), food intake and digestibility, oxidation and incorporation of exogenous lipids (stable isotope techniques: (13)C-labeled palmitate and diet supplemented with corn oil as a natural source of (13)C-enriched lipids) as well as gene expression (quantitative real-time PCR) in liver and intestinal mucosa were investigated.

RESULTS

Short-term supplementation (4-7 days) of dietary EGCG increased energy excretion, while food and energy intake were not affected. Fecal energy loss was accompanied by increased fat and nitrogen excretion. EGCG decreased post-prandial triglyceride and glycogen content in liver, increased oxidation of dietary lipids and decreased incorporation of dietary 13C-enriched lipids into fat tissues, liver and skeletal muscle. EGCG dose dependently reversed high-fat diet-induced effects on intestinal substrate transporters (CD36, FATP4 and SGLT1) and downregulated lipogenesis-related genes (ACC, FAS and SCD1) in liver in the post-prandial state.

CONCLUSIONS

Anti-obesity effects of EGCG can be explained by a decreased food digestibility affecting substrate metabolism of intestinal mucosa and liver, leading to increased post-prandial fat oxidation and reduced incorporation of dietary lipids into tissues.

Effect of tea polyphenols on microbiological and biochemical quality of Collichthys fish ball

BACKGROUND

Tea polyphenols (TP), as the most active constituents of tea, are considered natural food additives. This study examined the preservative properties of TP for Collichthys fish ball in well storage. Vacuum-packed Collichthys fish balls were treated with 0, 0.1, 0.15, 0.20, 0.25, and 0.30 g kg(-1) TP and stored at 0 °C for 17 days.

RESULTS

Microbiological results were obtained using a biochemical test, API system kit, and 16S rDNA sequence analysis. Results confirmed that the dominant bacteria in Collichthys fish balls are the genera Serratia and Pseudomonas. Total viable counts dropped two orders of magnitude in Collichthys fish balls with 0.25 g kg(-1) TP compared with the control. The advantages of total volatile basic nitrogen value, 2-thiobarbituric acid value and texture value were clearly observed, whereas pH and whiteness value exhibited no significant decrease for the group treated with 0.25 g kg(-1) TP. More than 0.25 g kg(-1) TP added could retain excellent fish ball characteristics in terms of sensory assessment after 17 days.

CONCLUSION

The shelf life of Collichthys fish balls supplemented with tea polyphenols can be prolonged for an additional 6 days in good condition at 0 °C storage.

EGCG-meditated cyto- and genotoxicity in HaCat keratinocytes is impaired by cell-mediated clearance of auto-oxidation-derived H2O2: an algorithm for experimental setting correction

Several lines of evidence suggest that besides antioxidant also prooxidant properties are crucially involved in cytotoxic and protective activities of the major green tea catechin epigallocatechin-3-gallate (EGCG) in vitro (Elbling et al., 2011). Furthermore recent data suggest that EGCG induces oxidative stress also in vivo (Li et al., 2010). Here we set out to identify factors modulating cellular effects of EGCG in vitro. Using the HaCat keratinocytes model, we demonstrate that the cytotoxic, genotoxic and signal-activating effects of EGCG are significantly dependent on the ratio of cell number to working volume. Treatment with identical EGCG concentrations at altered experimental settings resulted in IC(50) values differing up to orders of magnitude and could even exert contradictory effects. This effect was based on cell-mediated clearance of autooxidation-derived H(2)O(2) from the supernatant. In order to estimate EGCG/H(2)O(2) concentrations equally effective under different settings, we have rationally derived and experimentally verified a simple algorithm relating concentration, working volume, cell number and - indirectly - exposure time. Algorithm application resulted in similar H(2)O(2) clearance curves from cell supernatants as well as comparable EGCG/H(2)O(2) effects at different settings. Our results demonstrate the importance of standardized experimental settings when investigating cytotoxic and/or beneficial effects of autooxidizing compounds.

Genotoxic Effects of Green Tea Extract on Human Laryngeal Carcinoma Cells In Vitro

Green tea (Camellia sinensis) contains several bioactive compounds which protect the cell and prevent tumour development. Phytochemicals in green tea extract (mostly flavonoids) scavenge free radicals, but also induce pro-oxidative reactions in the cell. In this study, we evaluated the potential cytotoxic and prooxidative effects of green tea extract and its two main flavonoid constituents epigallocatechin gallate (EGCG) and epicatechin gallate (ECG) on human laryngeal carcinoma cell line (HEp2) and its cross-resistant cell line CK2. The aim was to see if the extract and its two flavonoids could increase the sensitivity of the cisplatin-resistant cell line CK2 in comparison to the parental cell line. The results show that EGCG and green tea extract increased the DNA damage in the CK2 cell line during short exposure. The cytotoxicity of EGCG and ECG increased with the time of incubation. Green tea extract induced lipid peroxidation in the CK2 cell line. The pro-oxidant effect of green tea was determined at concentrations higher than those found in traditionally prepared green tea infusions.

Punica granatum protects against oxidative stress in PC12 cells and oxidative stress-induced Alzheimer's symptoms in mice

Alzheimer's disease (AD) is a progressive degenerative brain disorder that is characterized by neuronal loss, neurofibrillary tangles, and the abnormal deposition of senile plaque and amyloid β peptide (Aβ). The brains of AD patients are under intense oxidative stress. The overproduction of Aβ leads to Aβ-associated free radical oxidative stress. In this study, the antioxidative and neuronal protective effects of Punica granatum extract were investigated against oxidative stress-induced cytotoxicity in PC12 cells. The ethanol extracts of P. granatum protected PC12 cells from hydrogen peroxide (H₂O₂-induced oxidative stress. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assays revealed a significant increase in cell viability when oxidatively stressed PC12 cells were treated with the P. granatum extract. To examine the effects of P. granatum on Aβ₁₋₄₂-induced learning and memory impairment in mice, in vivo behavioral tests were performed. Treatment with the extract of P. granatum increased step-through latency in mice injected with Aβ₁₋₄₂. The results of this study suggest that the ethanol extract of P. granatum mitigated H₂O₂-induced oxidative stress in PC12 cells. In addition, the extract inhibited neuronal cell death caused by Aβ-induced oxidative stress and Aβ-induced learning and memory deficiency.

Antihypertensive and cardiovascular effects of catechin-rich oil palm (Elaeis guineensis) leaf extract in nitric oxide-deficient rats

Oil palm (Elaeis guineensis) leaf extract (OPLE) possesses good ex vivo vasodilation and antioxidant properties. This study evaluated the catechin-rich OPLE antioxidant, antihypertensive, and cardiovascular effects in normal and nitric oxide (NO)-deficient hypertensive rats. OPLE was administered orally (500 mg/kg of body weight/day) to normotensive Wistar rats and N(ω)-nitro-L-arginine methyl ester (L-NAME)-induced NO-deficient hypertensive rats. OPLE significantly (P<.05) attenuated blood pressure increases, increased serum NO, reduced lipid peroxidation, and showed antioxidant effects in NO-deficient hypertensive rats. OPLE decreased the coronary arteriole wall-to-lumen ratio to near normal values under NO deficiency. Although OPLE showed good antihypertensive and antioxidant effects under NO deficiency, it was not hypotensive to normal rats and produced no chronic cardiovascular toxicity in any of the rats throughout the 12-week study. This is the first report on the in vivo antihypertensive properties of green tea catechins extracted from an alternative source, namely, oil palm leaf, for use as a medicinal food for hypertension and cardiovascular ailments.

(-)-Epigallocatechin-3-gallate suppresses growth of AZ521 human gastric cancer cells by targeting the DEAD-box RNA helicase p68

(-)-Epigallocatechin-3-gallate (EGCG), the most abundant and biologically active polyphenol in green tea, induces apoptosis and suppresses proliferation of cancer cells by modulating multiple signal transduction pathways. However, the fundamental mechanisms responsible for these cancer-preventive effects have not been clearly elucidated. Recently, we found that EGCG can covalently bind to cysteine residues in proteins through autoxidation and subsequently modulate protein function. In this study, we demonstrate the direct binding of EGCG to cellular proteins in AZ521 human gastric cancer cells by redox-cycle staining. We comprehensively explored the binding targets of EGCG from EGCG-treated AZ521 cells by proteomics techniques combined with the boronate-affinity pull-down method. The DEAD-box RNA helicase p68, which is overexpressed in a variety of tumor cells and plays an important role in cancer development and progression, was identified as a novel EGCG-binding target. Exposure of AZ521 cells to EGCG lowered the p68 level dose dependently. The present findings show that EGCG inhibits AZ521 cell proliferation by preventing β-catenin oncogenic signaling through proteasomal degradation of p68 and provide a new perspective on the molecular mechanism of EGCG action.

Ascorbic acid offsets the inhibitory effect of bioactive dietary polyphenolic compounds on transepithelial iron transport in Caco-2 intestinal cells

We previously reported that (-)-epigallocatechin-3-gallate (EGCG) and grape seed extract (GSE) at high concentration nearly blocked intestinal iron transport across the enterocyte. In this study, we aimed to determine whether small amounts of EGCG, GSE, and green tea extract (GT) are capable of inhibiting iron absorption, to examine if ascorbic acid counteracts the inhibitory action of polyphenols on iron absorption, and to explore the mechanisms of polyphenol-mediated apical iron uptake and basolateral iron release. An(55)Fe absorption study was conducted by adding various concentrations of EGCG, GSE, and GT using Caco-2 intestinal cells. Polyphenols were found to inhibit the transepithelial (55)Fe transport in a dose-dependent manner. The addition of ascorbic acid offset the inhibitory effects of polyphenols on iron transport. Ascorbic acid modulated the transepithelial iron transport without changing the apical iron uptake and the expression of ferroportin-1 protein in the presence of EGCG. The polyphenol-mediated apical iron uptake was inhibited by membrane impermeable Fe(2+) chelators (P < 0.001), but at a low temperature (4°C), the apical iron uptake was still higher than the control values at 37°C (P < 0.001). These results suggest that polyphenols enhance the apical iron uptake partially by reducing the conversion of ferric to ferrous ions and possibly by increasing the uptake of polyphenol-iron complexes via the energy-independent pathway. The present results indicate that the inhibitory effects of dietary polyphenols on iron absorption can be offset by ascorbic acid. Further studies are needed to confirm the current findings in vivo.

Catechin stimulates osteogenesis by enhancing PP2A activity in human mesenchymal stem cells

SUMMARY

Using human mesenchymal stem cells, we identified catechin from a panel of herbal ingredients and Chinese traditional compounds with the strongest osteogenic effects. Catechin increased alkaline phosphatase activity, calcium deposition, and mRNA expression of Runx2 and osteocalcin. We further clarified the signaling pathway that catechin mediated to stimulate osteogenesis.

INTRODUCTION

Human mesenchymal stem cells (hMSCs), useful as a species specific cell culture system for studying cell lineage differentiation, were examined as a tool to identify novel herbal ingredients and Chinese traditional compounds for enhancing osteogenesis.

METHODS

Immortalized and primary hMSCs were induced in osteogenic induction medium in the presence of a variety of herbal ingredients and Chinese traditional compounds and osteogenic differentiation was evaluated by histochemical assays and quantitative RT-PCR.

RESULTS

Using immortalized hMSCs, we first identified catechin, 18β-glycyrrhetinic acid, baishao, and danggui with osteogenic properties, which enhanced calcium deposition at the dose without significant cytotoxic effects. Primary hMSCs were then applied for confirming the osteogenic effects of catechin, which increased alkaline phosphatase activity, calcium deposition, and mRNA expression of Runx2 and osteocalcin. We further found the extracellular signal-regulated kinase (ERK) pathway was downregulated upon stimulation with catechin. Catechin increased the level and activity of protein phosphatases 2A (PP2A) that dephosphorylates ERK kinase (MEK) and ERK. Further, PP2A inhibitor, okadaic acid, abolished the effect of catechin-mediated inactivation of ERK and stimulation of osteogenesis. The blocking effect of okadaic acid on osteogenesis was further reversed by PD98059, a specific inhibitor of MEK. Co-immunoprecipitation revealed the association of PP2A to both MEK and ERK.

CONCLUSIONS

These studies propose catechin enhanced osteogenesis by increasing the PP2A level that inhibits the MEK and ERK signaling in hMSCs. These results prove the concept of using hMSCs as a convenient tool for rapid and consistent screening of the osteogenic herbal ingredients and traditional Chinese compounds.

Adsorption behavior of the catechins and caffeine onto polyvinylpolypyrrolidone

Adsorbent is one of the most important factors for separation efficiency in fixed-bed purification techniques. The adsorption behavior of catechins and caffeine onto polyvinylpolypyrrolidone (PVPP) was investigated by static adsorption tests. The results showed that catechins rather than caffeine were preferred to adsorb onto PVPP since the adsorption selectivity coefficient of total catechins vs caffeine was around 22.5, and that adsorption of catechins could be described by the pseudo-second-order model. Adsorption amount of caffeine onto PVPP in green tea extracts solution was much higher than that in purified caffeine solution although the initial concentration of caffeine was similar in the two solutions, indicating the caffeine might be attached with catechins which were adsorbed by PVPP instead of being adsorbed by PVPP directly. The results also showed that the adsorption capacity of catechins and caffeine decreased with an increase in temperature, and that Freundlich and Langmuir models were both suitable for describing the isothermal adsorption of catechins, but not suitable for caffeine. The predicted maximum monolayer adsorption capacity of total catechins by PVPP was 671.77 mg g(-1) at 20 °C, which was significantly higher than that by other reported adsorbents. The thermodynamics analyses indicated that the adsorption of catechins onto PVPP was a spontaneous and exothermic physisorption process, revealing lower temperature was favorable for the adsorption of catechins. Elution tests showed that the desorption rates of catechins and caffeine were higher than 91% and 99% after two elution stages; in detail, almost all of the caffeine could be washed down at the water eluting stage, while catechins could be recovered at the dimethyl sulfoxide/ethanol solution eluting stage. Thus, the PVPP could be used as an excellent alternative adsorbent candidate for separating catechins from crude tea extracts, although some investigations, such as exploring the new eluants with low boiling point and high desorption efficiency, should be conducted furthermore.

Alternate day fasting impacts the brain insulin-signaling pathway of young adult male C57BL/6 mice

Dietary restriction (DR) has recognized health benefits that may extend to brain. We examined how DR affects bioenergetics-relevant enzymes and signaling pathways in the brains of C57BL/6 mice. Five-month-old male mice were placed in ad libitum or one of two repeated fasting and refeeding (RFR) groups, an alternate day (intermittent fed; IF) or alternate day plus antioxidants (blueberry, pomegranate, and green tea extracts) (IF + AO) fed group. During the 24-h fast blood glucose levels initially fell but stabilized within 6 h of starting the fast, thus avoiding frank hypoglycemia. DR in general appeared to enhance insulin sensitivity. After six weeks brain AKT and glycogen synthase kinase 3 beta phosphorylation were lower in the RFR mice, suggesting RFR reduced brain insulin-signaling pathway activity. Pathways that mediate mitochondrial biogenesis were not activated; AMP kinase phosphorylation, silent information regulator 2 phosphorylation, peroxisomal proliferator-activated receptor-gamma coactivator 1 alpha levels, and cytochrome oxidase subunit 4 levels did not change. ATP levels also did not decline, which suggests the RFR protocols did not directly impact brain bioenergetics. Antioxidant supplementation did not affect the brain parameters we evaluated. Our data indicate in young adult male C57BL/6 mice, RFR primarily affects brain energy metabolism by reducing brain insulin signaling, which potentially results indirectly as a consequence of reduced peripheral insulin production.

Tea contains potent inhibitors of tyrosine phosphatase PTP1B

Tea is widely consumed all over the world. Studies have demonstrated the role of tea in prevention and treatment of various chronic diseases including diabetes and obesity, but the underlying mechanism is unclear. PTP1B is a widely expressed tyrosine phosphatase which has been defined as a target for therapeutic drug development to treat diabetes and obesity. In screening for inhibitors of PTP1B, we found that aqueous extracts of teas exhibited potent PTP1B inhibitory effects with an IC50 value of 0.4-4 g dry tea leaves per liter of water. Black tea shows the strongest inhibition activities, followed by oolong and then by green tea. Biochemical fractionations demonstrated that the major effective components in tea corresponded to oxidized polyphenolic compounds. This was further verified by the fact that tea catechins became potent inhibitors of PTP1B upon oxidation catalyzed by tyrosinases. When applied to cultured cells, tea extracts induced tyrosine phosphorylation of cellular proteins. Our study suggests that some beneficial effects of tea may be attributed to the inhibition of PTP1B.

Effects of catechin-rich oil palm leaf extract on normal and hypertensive rats' kidney and liver

Catechin-rich oil palm (Elaeis guineensis) leaf extract (OPLE) possesses good ex vivo vasodilation, antioxidant and cardiovascular properties. This study evaluated the beneficial or toxic effects of OPLE on the liver and kidneys of normal and hypertensive rats. The OPLE (500mg/kg body weight) were administered orally to normal Wistar Kyoto rats, spontaneously hypertensive rats (SHR) and N-ω-nitro-l-arginine methyl ester (l-NAME)-induced NO-deficient hypertensive rats. The OPLE reduced hypertension in NO-deficient rats, but not in SHR. Hepatocytes or glomeruli injury and oxidative markers were high in hypertensive rats compared to normal rats, and they were reduced (p<0.05) by OPLE supplementation, even when there was no blood pressure reduction. Unlike the hypertensive drug captopril, the OPLE showed no toxicity to normal rats. The dose reported is equivalent 0.5g of catechins/day for humans or 2.5cups of tea. The catechins are from an abundant alternative source for potential use as functional food.

Changes of constituents and activity to apoptosis and cell cycle during fermentation of tea

Tea is believed to be beneficial for health, and the effects of the fermentation process on its contributions to apoptosis and cell cycle arrest of gastric cancer cells have not been completely investigated. In this study, the chemical components in green tea, black tea and pu-erh tea aqueous extracts were analyzed and compared. The polysaccharide and caffeine levels were substantially higher in the fermented black tea and pu-erh tea, while the polyphenol level was higher in the unfermented green tea. Hence, a treatment of tea aqueous extract and the components, which are emerging as promising anticancer agents, were pursued to determine whether this treatment could lead to enhance apoptosis and cell cycle arrest. In the human gastric cancer cell line SGC-7901, the cell viability and flow cytometry analysis for apoptotic cells indicated effects in a dose-dependent inhibition manner for the three tea treatment groups. The apoptosis rates were found to be elevated after 48 h of treatment with 31.2, 125, and 500 μg/mL of green tea extract, the higher catechins content may be involved in the mechanism. Cell cycle was arrested in S phase in the fermented black tea and pu-erh tea, and the populations were significantly decreased in G2/M phases, possibly due to the oxidation of tea polyphenols, which causes an increase of theabrownins. CCC-HEL-1 normal cells were not sensitive to tea extract. These findings suggest that the fermentation process causes changes of the compounds which might be involved in the changes of cell proliferation inhibition, apoptosis induction and cell cycle arrest.

Evaluation of the antioxidant properties of fruit and flavoured black teas

OBJECTIVE

Antioxidant properties of the water extracts of the commercial bagged fruit and flavoured black teas were evaluated and compared with typical black teas of C. sinensis.

METHODS

Folin-Ciocalteu (FC) assay, cupric ion reducing antioxidant capacity (CUPRAC) and DPPH radical method were used for these purposes. The content of selected flavonoids and phenolic acids was also determined by high-performance liquid chromatography with tandem mass spectrometry in the negative electrospray ionization mode.

RESULTS

Flavoured black teas contain significantly higher level of catechins, quercetin, and rutin, while the content of chlorogenic and caffeic acids as well as naringin and hesperidin was higher in fruit teas. Supplementation with these flavonoids could reduce blood glucose. In FC and DPPH assays, the antioxidant properties of studied tea infusion increases in the order: fruit tea < flavoured black tea > premium black tea, while in CUPRAC method, some aromatized teas exhibit the highest antioxidant properties. Tea infusions with nice smell of fruits would also support the human diet with some source of antioxidants.

Deep sequencing of the Camellia sinensis transcriptome revealed candidate genes for major metabolic pathways of tea-specific compounds

BACKGROUND

Tea is one of the most popular non-alcoholic beverages worldwide. However, the tea plant, Camellia sinensis, is difficult to culture in vitro, to transform, and has a large genome, rendering little genomic information available. Recent advances in large-scale RNA sequencing (RNA-seq) provide a fast, cost-effective, and reliable approach to generate large expression datasets for functional genomic analysis, which is especially suitable for non-model species with un-sequenced genomes.

RESULTS

Using high-throughput Illumina RNA-seq, the transcriptome from poly (A)+ RNA of C. sinensis was analyzed at an unprecedented depth (2.59 gigabase pairs). Approximate 34.5 million reads were obtained, trimmed, and assembled into 127,094 unigenes, with an average length of 355 bp and an N50 of 506 bp, which consisted of 788 contig clusters and 126,306 singletons. This number of unigenes was 10-fold higher than existing C. sinensis sequences deposited in GenBank (as of August 2010). Sequence similarity analyses against six public databases (Uniprot, NR and COGs at NCBI, Pfam, InterPro and KEGG) found 55,088 unigenes that could be annotated with gene descriptions, conserved protein domains, or gene ontology terms. Some of the unigenes were assigned to putative metabolic pathways. Targeted searches using these annotations identified the majority of genes associated with several primary metabolic pathways and natural product pathways that are important to tea quality, such as flavonoid, theanine and caffeine biosynthesis pathways. Novel candidate genes of these secondary pathways were discovered. Comparisons with four previously prepared cDNA libraries revealed that this transcriptome dataset has both a high degree of consistency with previous EST data and an approximate 20 times increase in coverage. Thirteen unigenes related to theanine and flavonoid synthesis were validated. Their expression patterns in different organs of the tea plant were analyzed by RT-PCR and quantitative real time PCR (qRT-PCR).

CONCLUSIONS

An extensive transcriptome dataset has been obtained from the deep sequencing of tea plant. The coverage of the transcriptome is comprehensive enough to discover all known genes of several major metabolic pathways. This transcriptome dataset can serve as an important public information platform for gene expression, genomics, and functional genomic studies in C. sinensis.

Deep sequencing of the Camellia sinensis transcriptome revealed candidate genes for major metabolic pathways of tea-specific compounds

Background

Tea is one of the most popular non-alcoholic beverages worldwide. However, the tea plant, Camellia sinensis, is difficult to culture in vitro, to transform, and has a large genome, rendering little genomic information available. Recent advances in large-scale RNA sequencing (RNA-seq) provide a fast, cost-effective, and reliable approach to generate large expression datasets for functional genomic analysis, which is especially suitable for non-model species with un-sequenced genomes.

Results

Using high-throughput Illumina RNA-seq, the transcriptome from poly (A)⁺ RNA of C. sinensis was analyzed at an unprecedented depth (2.59 gigabase pairs). Approximate 34.5 million reads were obtained, trimmed, and assembled into 127,094 unigenes, with an average length of 355 bp and an N50 of 506 bp, which consisted of 788 contig clusters and 126,306 singletons. This number of unigenes was 10-fold higher than existing C. sinensis sequences deposited in GenBank (as of August 2010). Sequence similarity analyses against six public databases (Uniprot, NR and COGs at NCBI, Pfam, InterPro and KEGG) found 55,088 unigenes that could be annotated with gene descriptions, conserved protein domains, or gene ontology terms. Some of the unigenes were assigned to putative metabolic pathways. Targeted searches using these annotations identified the majority of genes associated with several primary metabolic pathways and natural product pathways that are important to tea quality, such as flavonoid, theanine and caffeine biosynthesis pathways. Novel candidate genes of these secondary pathways were discovered. Comparisons with four previously prepared cDNA libraries revealed that this transcriptome dataset has both a high degree of consistency with previous EST data and an approximate 20 times increase in coverage. Thirteen unigenes related to theanine and flavonoid synthesis were validated. Their expression patterns in different organs of the tea plant were analyzed by RT-PCR and quantitative real time PCR (qRT-PCR).

Conclusions

An extensive transcriptome dataset has been obtained from the deep sequencing of tea plant. The coverage of the transcriptome is comprehensive enough to discover all known genes of several major metabolic pathways. This transcriptome dataset can serve as an important public information platform for gene expression, genomics, and functional genomic studies in C. sinensis.

Safety evaluation of tea (Camellia sinensis (L.) O. Kuntze) flower extract: assessment of mutagenicity, and acute and subchronic toxicity in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Tea (Camellia sinensis (L.) O. Kuntze, Theaceae) flowers possess many physiological functions and have been used in traditional medicines for deodorization, skin care, cough suppressant and expectorant in China. However, there is a little information about its possible toxicity.

AIM OF THE STUDY

The present investigation was carried out to evaluate the safety of tea flower extract by mutagenicity and acute and subchronic toxicity studies.

MATERIALS AND METHODS

Mutagenicity of tea flower extract was evaluated by the Ames test in Salmonella typhimurium strains TA97, TA98, TA100 and TA102 at concentrations of 0.008, 0.04, 0.2, 1.0, 5.0 mg/plate. In the acute toxicity study, Sprague-Dawley rats were administered a single dose of 12.0 g/kg of body weight by gavage, and were monitored for 14 days. In the subchronic toxicity study, tea flower extract was administered by gavage at doses of 1.0, 2.0 and 4.0 g/kg body weight daily for 13 weeks to Sprague-Dawley rats.

RESULTS

In the Ames test, there was no mutagenic effect of tea flower extract (up to 5.0 mg/plate) towards four tested strains (TA97, TA98, TA100, TA102), with or without metabolic activation (S9). In the acute toxicity study, all animals gained weight and appeared active and normal, so the LD(50) value must be >12.0 g/kg body weight. In the subchronic toxicity study, no dose-related effects on survival, growth, hematology, blood chemistry, organ weights, or pathologic lesions were observed.

CONCLUSION

These results indicate that tea flower extract does not possess mutagenic potential, and that both acute and subchronic toxicity towards animals is very low. A no-observed adverse-effect level (NOAEL) for tea flower extract is 4.0 g/kg bw/day for rats under the conditions of this study.

Optimization of adsorption of tea polyphenols into oat β-glucan using response surface methodology

Information on interactions between oat β-glucan and tea polyphenols (TP) is not available in the published literatures. Equilibrium dialysis was applied to determine the adsorption of TP into β-glucan, and response surface methodology (RSM) was employed to optimize the absorbing variables (pH, temperature, and phosphate buffered saline (PBS) buffer concentration). The equilibrium data at constant temperature were fitted with the Langmuir, Freundlich, and Redlich-Peterson models. The results showed that the Freundlich model was the best method to describe the experimental data. Parabolic curves were obtained for pH and temperature. In terms of adsorption capacity, factors including temperature, pH/temperature, and buffer concentration/temperature had the greatest influence on the response. The highest adsorption capacity of TP into β-glucan was 134.55 μg mg(-1) at the following optimized conditions: pH 5.56, PBS buffer concentration 0.13 M, and temperature 40 °C. No significant differences (p > 0.05) between the experimental and predicted values confirmed the adequacy of the response surface equations.

Outcomes of 3% green tea emulsion on skin sebum production in male volunteers

This study was aimed to depict potential effects of stable formulation (water in oil emulsion), containing 3% green tea (Camellia sinensis L) extract on skin sebum production in healthy human volunteers. For this purpose formulation was designed using 3% ethanolic green tea extract and Abil®EM90 was used as an emulsifier. Formulation was applied to the cheeks of healthy human volunteers (n=10) for a period of 8 weeks. Measurements for skin sebum production were considered using Sebumeter MPA 5. Results were compiled and any effect produced by the formulation was justified statistically. It was observable that statistically significant (p < 0.5%) results were found for skin sebum production after long term application of the formulation. 3% formulation of green tea extract was ideal in all aspects and can be experienced in skin disorders like acne to further investigate its effects in unhealthy volunteers.

Chemoselective C-4 aerobic oxidation of catechin derivatives catalyzed by the Trametes villosa laccase/1-hydroxybenzotriazole system: synthetic and mechanistic aspects

Catechin derivatives were oxidized in air in the presence of the Trametes villosa laccase/1-hydroxybenzotriazole (HBT) system in buffered water/1,4-dioxane as reaction medium. The oxidation products, flavan-3,4-diols and the corresponding C-4 ketones, are bioactive compounds and useful intermediates for the hemisynthesis of proanthocyanidins, plant polyphenols which provide beneficial health properties for humans. Determinations of oxidation potentials excluded that catechin derivatives could be directly oxidized by laccase Cu(II), while it resulted in the H-abstraction from benzylic positions being promptly promoted by the enzyme in the presence of the mediator HBT, the parent species producing in situ the reactive intermediate benzotriazole-N-oxyl (BTNO) radical. A remarkable and unexpected result for the laccase/HBT oxidative system has been the chemoselective insertion of the oxygen atom into the C-4-H bond of catechin derivatives. Mechanistic aspects of the oxidation reaction have been investigated in detail for the first time in order to corroborate these results. Since the collected experimental findings could not alone provide information useful to clarify the origin of the observed chemoselectivity, these data were expressly supplemented with information derived by suitable molecular modeling investigations. The integrated evaluation of the dissociation energies of the C-H bonds calculated both by semiempirical and DFT methods and the differential activation energies of the process estimated by a molecular modeling approach suggested that the observed selective oxidation at the C-4 carbon has a kinetic origin.

Green tea polyphenol sensing

Green tea polyphenols have emerged over the past two decades as an important dietary factor for health promotion. There is considerable evidence that tea polyphenols, in particular (-)-epigallocatechin-3-gallate (EGCG) inhibit carcinogenesis. However, the mechanisms for the cancer-preventive activity of EGCG are not completely characterized and many features remain to be elucidated. Recently we have identified a cell-surface EGCG receptor and the relating molecules that confer EGCG responsiveness to many cancer cells at physiological concentrations. Here, we review some of the reported mechanisms for the cancer chemopreventive action of EGCG and provide an overview of several molecules that sense and manage the physiological functions of EGCG.

Black tea polyphenol theaflavin suppresses LPS-induced ICAM-1 and VCAM-1 expression via blockage of NF-κB and JNK activation in intestinal epithelial cells

OBJECTIVE

The aim of this study was to determine the impact of the black tea polyphenol, theaflavin, on the expression of adhesion molecules and activation of lipopolysaccharide (LPS)-induced innate signaling in rat intestinal epithelial (RIE) cells.

METHODS

The effect of theaflavin on neutrophil adhesion, expression of intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1, LPS-induced nuclear factor-kappa B (NF-κB), and mitogen-activated protein kinase (MAPK) signaling was examined by neutrophil adhesion assay, RT-PCR, Western blotting, immunofluorescence, and electrophoretic mobility shift assay (EMSA).

RESULTS

Theaflavin suppressed adhesion of neutrophils to LPS-stimulated RIE cells. LPS-induced ICAM-1 and VCAM-1 expressions were inhibited by theaflavin. LPS-induced IκBα phosphorylation/degradation and nuclear translocation of NF-κB/p65 were blocked by theaflavin. Also, theaflavin blocked NF-κB DNA-binding activity in EMSA. LPS-induced phosphorylation of JNK was inhibited by theaflavin. Bay11-7082 (a NF-κB inhibitor) and SP600125 (a JNK inhibitor) suppressed the LPS-induced ICAM-1 and VCAM-1 mRNA accumulations.

CONCLUSIONS

These results indicate that black tea polyphenol theaflavin suppresses LPS-induced ICAM-1 and VCAM-1 expressions through blockage of NF-κB and JNK activation in intestinal epithelial cells.