Enhancement of Annexin V in response to combination of epigallocatechin gallate and quercetin as a potent arrest the cell cycle of colorectal cancer / Aumento da anexina V em resposta à combinação de galato de epigalocatequina e quercetina como uma potente parada do ciclo celular do câncer colorretal

Abstract Colorectal cancer (CRC) is one of the most common cancers leading to comorbidities and mortalities globally. The rational of current study was to evaluate the combined epigallocatechin gallate and quercetin as a potent antitumor agent as commentary agent for therapeutic protocol. The present study investigated the effect of epigallocatechin Gallate (EGCG) (150mg) and quercetin (200mg) at different proportions on proliferation and induction of apoptosis in human colon cancer cells (HCT-116). Cell growth, colonogenic, Annexin V in addition cell cycle were detected in response to phytomolecules. Data obtained showed that, the colony formation was inhibited significantly in CRC starting from the lowest concentration tested of 10 µg/mL resulting in no colonies as visualized by a phase-contrast microscope. Data showed a significant elevation in the annexin V at 100 µg/mL EGCG(25.85%) and 150 µg/mL quercetin (48.35%). Moreover, cell cycle analysis showed that this combination caused cell cycle arrest at the G1 phase at concentration of 100 µg/mL (72.7%) and 150 µg/mL (75.25%). The combined effect of epigallocatechin Gallate and quercetin exert antiproliferative activity against CRC, it is promising in alternative conventional chemotherapeutic agent.

Resumo O câncer colorretal (CCR) é um dos cânceres mais comuns, levando a comorbidades e mortalidade em todo o mundo. O racional do presente estudo foi avaliar a combinação de galato de epigalocatequina e quercetina como um agente antitumoral potente como agente de comentário para protocolo terapêutico. O presente estudo investigou o efeito de galato de epigalocatequina (EGCG) (150 mg) e quercetina (200 mg) em diferentes proporções na proliferação e indução de apoptose em células de câncer de cólon humano (HCT-116). O crescimento celular, colonogênico, anexina V, além do ciclo celular foram detectados em resposta a fitomoléculas. Os dados obtidos mostraram que a formação de colônias foi inibida significativamente no CRC a partir da concentração mais baixa testada de 10 µg/mL, resultando em nenhuma colônia conforme visualizado por um microscópio de contraste de fase. Os dados mostraram uma elevação significativa na anexina V a 100 µg/mL de EGCG (25,85%) e 150 µg/mL de quercetina (48,35%). Além disso, a análise do ciclo celular mostrou que essa combinação causou parada do ciclo celular na fase G1 na concentração de 100 µg/mL (72,7%) e 150 µg/mL (75,25%). O efeito combinado da epigalocatequina galato e quercetina exerce atividade antiproliferativa contra o CCR, é promissor como agente quimioterápico alternativo convencional.

EGCG and ECG induce apoptosis and decrease autophagy via the AMPK/mTOR and PI3K/AKT/mTOR pathway in human melanoma cells / 中国天然药物

Catechins have been proven to exert antitumor effects in different kinds of cancers. However, the underlying mechanisms have not been completely clarified yet. This study aimed to assess the effects and mechanisms of (-)-epigallocatechin-3-gallate (EGCG) and (-)-epicatechin-3-gallate (ECG) on human melanoma skin A375 cells. Results showed that EGCG and ECG inhibited the proliferation of A375 cells and ECG showed better inhibitory effect. Flow cytometry analysis had shown that EGCG and ECG induced apoptosis and led to cell cycle arrest. EGCG and ECG decreased Bcl-2 expression and upregulated Caspase-3 protein level, indicating the development of apoptosis. Furthermore, EGCG and ECG could decreased mitochondrial membrane potential of A375 cells. In addition, the expression of Beclin-1, LC3 and Sirt3 were downregulated at protein levels, which known to be associated with autophagy. After autophagy was increased by rapamycin, the apoptotic trend was not change, indicating that apoptosis and autophagy are independent. Mechanistically, EGCG and ECG treatments decreased phosphorylated-AMPK (p-AMPK) and increased the ratios of p-PI3K, p-AKT and p-mTOR in melanoma cells. Conclusively, EGCG and ECG induced apoptosis via mitochondrial signaling pathway, downregulated autophagy through modulating the AMPK/mTOR and PI3K/AKT/mTOR signaling pathway. It indicated that EGCG and ECG may be utilized in human melanoma treatment.

Influence of green tea extract with different concentrations of epigallocatechin gallate on calvaria bone repair of ovariectomized rats / Influencia del extracto de té verde con diferentes concentraciones de galato de epigalocatequina sobre la reparación ósea de calvaria de ratas ovariectomizadas

Impairing osteoporosis progression is a challenge, and recently the role of antioxidants has been associated to bone metabolism. Green tea extract is rich in catechins, especially epigallocatechin gallate (EGCG), which may help control osteoporosis damage in bone tissue. This investigation evaluated the efficacy of green tea ingestion containing different concentrations of EGCG in calvaria bone repair of ovariectomized rats. Wistar rats (n=15) were ovariectomized and divided into 3 groups: ovariectomized (OVX), ovariectomized + GTE 15 % EGCG (OVX/GTE15), and ovariectomized + GTE 94 % EGCG (OVX/GTE94). Green tea extract was administered by gavage in the concentration of 50 mg/kg and sham group (n=5) received water. Bone defects were performed in the calvaria 60 days after ovariectomy followed by 4 weeks until euthanasia. Bone samples were collected to perform qualitative and quantitative histological analysis of bone formation. Data obtained were submitted to normality and ANOVA statistical test for p<0.05. The mean values of neoformed bone for Sham, OVX, OVX/GTE15 and OVX/GTE94 were respectively: 21.11 ± 3.91; 19.92 ± 2.20; 33.05 ± 1.26 e 34.75 ± 0.54 (p<0.05). Results show that continuous ingestion of green tea extract immediately after ovariectomy shows positive effects in the prevention of bone loss in osteoporosis, even with low concentrations of EGCG.

La disminución en la progresión de la osteoporosis es un desafío, y recientemente el papel de los antioxidantes se ha asociado al metabolismo óseo. El extracto de té verde es rico en catequinas, especialmente el galato de epigalocatequina (EGCG), lo que puede ayudar a controlar el daño de la osteoporosis en el tejido óseo. Esta investigación evaluó la eficacia de la ingesta de té verde con diferentes concentraciones de EGCG en la reparación ósea de calvaria de ratas ovariectomizadas. Las ratas Wistar (n = 15) fueron ovariectomizadas y divididas en 3 grupos: ovariectomizadas (OVX), ovariectomizadas + GTE 15 % EGCG (OVX / GTE15), y ovariectomizadas + GTE 94 % EGCG (OVX / GTE94). El extracto de té verde se administró por sonda en una concentración de 50 mg/kg y el grupo simulado (n = 5) recibió agua. Los defectos óseos se realizaron en la calvaria 60 días después de la ovariectomía, seguido de 4 semanas hasta la eutanasia. Se obtuvieron muestras de hueso para realizar un análisis histológico cualitativo y cuantitativo de la formación ósea. Los datos obtenidos se sometieron a normalidad y prueba estadística ANOVA (p<0,05). Los valores medios de hueso neoformado para Sham, OVX, OVX / GTE15 y OVX / GTE94 fueron: 21,11 ± 3,91; 19,92 ± 2,20; 33,05 ± 1,26 y 34,75 ± 0,54 (p <0,05), respectivamente. Los resultados muestran que la ingesta continua de extracto de té verde, inmediatamente después de la ovariectomía, muestra efectos positivos en la prevención de la pérdida ósea ocurrida en la osteoporosis, incluso con concentraciones bajas de EGCG.

Epigallocatechin-3-gallate ameliorates lipopolysaccharide-induced acute lung injury by suppression of TLR4/NF-κB signaling activation

Acute lung injury (ALI) is a serious clinical syndrome with a high rate of mortality. The activation of inflammation is well-recognized as a vital factor in the pathogenesis of lipopolysaccharide (LPS)-induced ALI. Therefore, suppression of the inflammatory response could be an ideal strategy to prevent ALI. Epigallocatechin-3-gallate (EGCG), mainly from green tea, has been shown to have an anti-inflammatory effect. The aim of the study was to explore whether EGCG alleviates inflammation in sepsis-related ALI. Male BALB/C mice were treated with EGCG (10 mg/kg) intraperitoneally (ip) 1 h before LPS injection (10 mg/kg, ip). The results showed that EGCG attenuated LPS-induced ALI as it decreased the changes in blood gases and reduced the histological lesions, wet-to-dry weight ratios, and myeloperoxidase (MPO) activity. In addition, EGCG significantly decreased the expression of pro-inflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 in the lung, serum, and bronchoalveolar lavage fluid, and alleviated the expression of TLR-4, MyD88, TRIF, and p-p65 in the lung tissue. In addition, it increased the expression of IκB-α and had no influence on the expression of p65. Collectively, these results demonstrated the protective effects of EGCG against LPS-induced ALI in mice through its anti-inflammatory effect that may be attributed to the suppression of the activation of TLR 4-dependent NF-κB signaling pathways.

Mechanical-physicochemical properties and biocompatibility of catechin-incorporated adhesive resins

Abstract Several anti-proteolytic dentin therapies are being exhaustively studied in an attempt to reduce dentin bond degradation and improve clinical performance and longevity of adhesive restorations. Objectives This study assessed the effect of epigallocatechin-3-gallate (EGCG) on long-term bond strength when incorporated into adhesives. Material and Methods Adhesive systems were formulated with EGCG concentrations of 0 wt%: (no EGCG; control); 0.5 wt% EGCG; 1.0 wt% EGCG, and 1.5 wt% EGCG. Flexural strength (FS), modulus of elasticity (ME), modulus of resilience (MR), compressive strength (CS), degree of conversion (DC), polymerization shrinkage (PS), percentage of water sorption (%WS), percentage of water solubility (%WL) and cytotoxicity properties were tested. Dentin microtensile bond strength (µTBS) was evaluated after 24 h and again after 6 months of water storage. The adhesive interface was analyzed using scanning electron microscopy (SEM). Results No significant differences were found among the groups in terms of FS, ME, MR, CS and PS. EGCG-doped adhesives increased the DC relative to the control group. EGCG concentrations of 1.0 wt% and 0.5 wt% decreased the WS of adhesives. WL decreased in all cases in which EGCG was added to adhesives, regardless of the concentration. EGCG concentrations of 1.0 wt% and 0.5 wt% reduced cytotoxicity. EGCG concentrations of 1.0 wt% and 0.5 wt% preserved µTBS after 6 months of storage, while 1.5 wt% EGCG significantly decreased µTBS. SEM: the integrity of the hybrid layer was maintained in the 0.5 wt% and 1.0 wt% EGCG groups. Conclusion EGCG concentrations of 1.0 wt% and 0.5 wt% showed better biological and mechanical performance, preserved bond strength and adhesive interface, and reduced cytotoxicity.

Active compounds and derivatives of camellia sinensis responding to erosive attacks on dentin

Abstract This research explored the potential of Camellia sinensis-derived teas and active compounds to be used as treatments to prevent dentin wear. Human root dentin slabs were randomly assigned to 5 groups (n = 10) as follows: distilled water (DW, control), epigallocatechin-3-gallate (EGCG), theaflavin gallate derivatives (TF), commercial green tea (GT), and commercial black tea (BT). The samples were submitted to a pellicle formation and an erosive cycling model (5x/day, demineralization using 0.01 M hydrochloric acid/60 s) followed by remineralization (human stimulated saliva/60 min) for three days. The samples were treated for 5 min using the test group solutions between the erosive cycles. Dentin changes were assessed with profilometry analysis and FT-Raman spectroscopy. The data regarding wear were analyzed by ANOVA followed by Tukey's test (p < 0.05). EGCG, TF derivatives, and both regular teas significantly suppressed erosive dentin loss (38-47%, p < 0.05). No obvious changes in the Raman spectra were detected in the specimens; however, the DW group had a minor relationship of 2880/2940 cm−1. The phenolic contents in both green and black tea and the important catechins appear to have protective effects on dentin loss.

Potential benefit of (-)-epigallocatechin-3-gallate for macrovascular complications in diabetes

Vascular problems are the most common complications in diabetes. Substantial evidence from epidemiological and pathophysiological studies show that hyperglycemia is a major risk factor for macrovascular complications in patients with diabetes. (-)-Epigallocatechin-3-gallate (EGCG), the major catechin derived from green tea, is known to exert a variety of cardiovascular beneficial effects. The protective effects of EGCG in diabetes are also evident. However, whether EGCG is beneficial against macrovascular complications that occur in diabetes remains unknown. Our previous studies demonstrated that treatment of EGCG inhibits high glucose-induced vascular smooth muscle cell proliferation and suppresses high glucose-mediated vascular inflammation in human umbilical vein endothelial cells. Therefore, we hypothesize that EGCG might be an effective potential candidate to reduce the macrovascular complications in diabetes.

Anti-melanogenic effects of black, green, and white tea extracts on immortalized melanocytes

Tea contains polyphenols and is one of the most popular beverages consumed worldwide. Because most tyrosinase inhibitors that regulate melanogenesis are phenol/catechol derivatives, this study investigated the inhibitory effects of Camellia sinensis water extracts (CSWEs), including black tea, green tea, and white tea extracts, on melanogenesis using immortalized melanocytes. CSWEs inhibited melanin accumulation and melanin synthesis along with tyrosinase activity in a concentration-dependent manner. These inhibitory effects were superior to those of arbutin, a well-known depigmenting agent. The anti-melanogenic activity of black (fermented) tea was higher than that of a predominant tea catecholamine, epigallocatechin gallate. CSWEs, especially black tea extract, decreased tyrosinase protein levels in a concentration-dependent manner. These results suggest that the anti-melanogenic effect of CSWEs is mediated by a decrease in both tyrosinase activity and protein expression, and may be augmented by fermentation. Thus, CSWEs could be useful skin-whitening agents in the cosmetic industry.

Effect of (+)-catechin hydrate on oxidative stress induced by high sucrose and high fat diet in male Wistar rats.

Increased lipid peroxidation and reduced glutathione levels in liver of rats fed high sucrose high fat (HSHF) diet were normalized by concomitant administration of (+)-catechin hydrate. Plasma non-enzymatic antioxidants viz. α-tocopherol, ascorbic acid and total thiols decrease were also significantly less in rats administered with (+)-catechin hydrate concomitantly with HSHF diet. Thus the present results indicate that (+)-catechin hydrate has antioxidant activity and is effective in reducing oxidative stress. The study is of clinical importance as oxidative stress is known to be the cause of many clinical manifestations viz. cancer, Parkinson’s disease, atherosclerosis, heart failure, myocardial infarction and many other diseases.

Effect of epigallocatechin-3-gallate on inflammatory mediators release in LPS-induced Parkinson's disease in rats.

Degeneration of dopamine (DA)-containing neurons in the substantia nigra of the midbrain causes Parkinson's disease (PD). Although neuroinflammatory response of the brain has long been speculated to play a role in the pathogenesis of this neurological disorder, the mechanism is still poorly understood. The aim of the present study was to examine the effect of epigallocatechin-3-gallate (EGCG) in prevention of inflammatory mediators release and protection of dopaminergic neurons from lipopolysaccharide (LPS)-induced neurotoxicity. A single intraperitoneal injection of LPS (15 mg/kg) in male Sprague Dawley rats resulted in an increase of midbrain content of TNF-α, NO and a decrease of DA level at 4, 24 h, 3 and 7 days compared to the control. In addition, LPS reduced the number and the density of tyrosine hydroxylase-immunoreactive (TH-ir) neurons in the midbrain at 7 days. Pretreatment with EGCG (10 mg/kg) 24 h before LPS for 7 days decreased TNF-α and NO compared to LPS-treated rats. Moreover, it increased DA level and preserved the number and the density of TH-ir neurons compared to LPS group. In conclusion, EGCG was found to have a potential therapeutic effect against LPS-induced neurotoxicity via reducing TNF-α and NO inflammatory mediators and preserving DA level in midbrain.

Catechin-incorporated dental copolymers inhibit growth of Streptococcus mutans

Objective: To test the inhibitory growth activity of green tea catechin incorporated into dental resins compared to resins containing the broad-spectrum antimicrobial compound chlorhexidine against Streptococcus mutans in vitro. Material and Methods: The minimum inhibitory concentrations (MICs) of epigallocatechin-gallate (EGCg) and chlorhexidine (CHX) were determined according to the microdilution method. Resin discs (5 mm × 3 mm) were prepared from Bis-GMA/TEGDMA (R1) and Bis-GMA/CH3Bis-GMA (R2) comonomers (n=9) containing: a) no drug, b) EGCg, c) CHX. Two concentrations of each drug (0.5× MIC and 1× MIC) were incorporated into the resin discs. Samples were individually immersed in a bacterial culture and incubated for 24 h at 37°C under constant agitation. Cell viability was assessed by counting the number of colonies on replica agar plates. Statistical analysis was performed using one-way ANOVA, Tukey and Student t-tests (α=0.05). Results: Both resins containing EGCg and CHX showed a significant inhibition of bacterial growth at both concentrations tested (p<0.05). A significantly higher inhibition was observed in response to resins containing CHX at 0.5× MIC and 1× MIC, and EGCg at 1× MIC when compared to EGCg at 0.5× MIC. Also, EGCg at 0.5× MIC in R1 had a significantly higher growth inhibition than in R2. Conclusions: Both EGCg and CHX retained their antibacterial activity when incorporated into the resin matrix. EGCg at 1× MIC in R1 and R2 resins significantly reduced S. mutans survival at a level similar to CHX. The data generated from this study will provide advances in the field of bioactive dental materials with the potential of improving the lifespan of resin-based restorations.

Epigallocatechin-3-gallate inhibits paracrine and autocrine hepatocyte growth factor/scatter factor-induced tumor cell migration and invasion

Aberrant activation of hepatocyte growth factor/scatter factor (HGF/SF) and its receptor, Met, is involved in the development and progression of many human cancers. In the cell-based screening assay, (-)epigallocatechin-3-gallate (EGCG) inhibited HGF/SF-Met signaling as indicated by its inhibitory activity on HGF/SF-induced cell scattering and uPA activation (IC50 = 15.8 microg/ml). Further analysis revealed that EGCG at low doses specifically inhibited HGF/SF-induced tyrosine phosphorylation of Met but not epidermal growth factor (EGF)-induced phosphorylation of EGF receptor (EGFR). On the other hand, high-dose EGCG decreased both Met and EGFR proteins. We also found that EGCG did not act on the intracellular portion of Met receptor tyrosine kinase, i.e., it inhibited InlB-dependent activation of Met but not NGF-induced activation of Trk-Met hybrid receptor. This inhibition decreased HGF-induced migration and invasion by parental or HGF/SF-transfected B16F10 melanoma cells in vitro in either a paracrine or autocrine manner. Furthermore, EGCG inhibited the invasion/metastasis of HGF/SF-transfected B16F10 melanoma cells in mice. Our data suggest the possible use of EGCG in human cancers associated with dysregulated paracrine or autocrine HGF/SF-Met signaling.

Inhibitory effect of (-)-epigallocatechin gallate on titanium particle-induced TNF-alpha release and in vivo osteolysis

Tumor necrosis factor-alpha (TNF-alpha) and inflammatory cytokines released from activated macrophages in response to particulate debris greatly impact periprosthetic bone loss and consequent implant failure. In the present study, we found that a major polyphenolic component of green tea, (-)-epigallocatechin gallate (EGCG), inhibited Ti particle-induced TNF-alpha release in macrophages in vitro and calvarial osteolysis in vivo. The Ti stimulation of macrophages released TNF-alpha in a dose- and time-dependent manner, and EGCG substantially suppressed Ti particle-induced TNF-alpha release. Analysis of signaling pathway showed that EGCG inhibited the Ti-induced c-Jun N-terminus kinase (JNK) activation and inhibitory kappaB (IkappaB) degradation, and consequently the Ti-induced transcriptional activation of AP-1 and NF-kappaB. In a mouse calvarial osteolysis model, EGCG inhibited Ti particle-induced osteolysis in vivo by suppressing TNF-alpha expression and osteoclast formation. Therefore, EGCG may be a potential candidate compound for osteolysis prevention and treatment as well as aseptic loosening after total replacement arthroplasty.

Anti-inflammatory effect of the epigallocatechin gallate following spinal cord trauma in rat

Spinal cord injury [SCI] stimulates an inflammatory reaction that causes substantial secondary damage inside the injured spinal tissue. The purpose of this study was to determine the anti-inflammatory effects of epigallocatechin gallate [EGCG] on traumatized spinal cord. Methods: Rats were randomly divided into four groups of 12 rats each as follow: sham-operated group, trauma group, and EGCG-treatment groups [50 mg/kg, i.p., immediately and 1 hour after SCI]. Spinal cord samples were taken 24 hours after injury and studied for determination of myeloperoxidase [MPO] activity, histopathological assessment and immunohistochemistry of tumor necrosis factor-a [TNF-alpha], interleukin-1 beta [IL-1beta], Nitrotyrosine, inducible nitric oxide synthase [iNOS], cyclooxygenase-2 [COX-2], and poly [ADP-ribose] polymerase [PARP]. The results showed that MPO activity was significantly decreased in EGCG-treatment groups. Attenuated TNF-alpha, IL-1beta, Nitrotyrosine, iNOS, COX-2, and PARP expression could be detected in the EGCG treated rats. Also, EGCG attenuated myelin degradation. On the basis of these findings, we propose that EGCG may be effective in protecting rat spinal cord from secondary damage by modulating the inflammatory reactions

Cytotoxicity of gamma-ray in rat immature hippocampal neurons

This in vitro study evaluated the detrimental effect of acute gamma (gamma)-irradiation on rat immature hippocampal neurons. Rat immature hippocampal neurons (0.5 day in vitro) were irradiated with 0~4 Gy gamma-rays. Cytotoxicity was analyzed using a lactate dehydrogenase release assay at 24 h after gamma-irradiation. Radiation-induced cytotoxicity in immature hippocampal neurons increased in a dose-dependent manner. Pre-treatments of pro-apoptotic caspase inhibitors and anti-oxidative substances significantly blocked gamma-irradiation-induced cytotoxicity in immature hippocampal neurons. The results suggest that the caspase-dependent cytotoxicity of gamma-rays in immature hippocampal cultured neurons may be caused by oxidative stress.

In Vitro Antifungal Activity of Epigallocatechin 3-O-Gallate against Clinical Isolates of Dermatophytes

Previously, we reported that epigallocatechin 3-O-gallate (EGCg) has growth-inhibitory effect on clinical isolates of Candida species. In this study, we investigated the antifungal activity of EGCg and antifungal agents against thirty-five of dermatophytes clinically isolated by the international guidelines (M38-A2). All isolates exhibited good susceptibility to EGCg (MIC50, 2-4 microg/mL, MIC90, 4-8 microg/mL, and geometric mean (GM) MICs, 3.36-4 microg/mL) than those of fluconazole (MIC50, 2-16 microg/mL, MIC90, 4-32 microg/mL, and GM MICs, 3.45-25.8 microg/mL) and flucytosin (MIC50, MIC90, and GM MICs, >64 microg/mL), although they were less susceptible to other antifungal agents, such as amphotericin B, itraconazole, and miconazole. These activities of EGCg were approximately 4-fold higher than those of fluconazole, and were 4 to 16-fold higher than flucytosin. This result indicates that EGCg can inhibit pathogenic dermatophyte species. Therefore, we suggest that EGCg may be effectively used solely as a possible agent or combined with other antifungal agents for antifungal therapy in dermatophytosis.

Study of neuroprotective effects of green tea antioxidant on spinal cord injury of rat

Recent studies revealed the neuroprotective effects of green tea antioxidant on experimental cerebral ischemia, but these effects on spinal cord injury [SCI] has not yet been studied. Rats were randomly divided into three groups of 18 rats each as follows: sham group [laminectomy], control group [SCI] and experimental group [EGCG]. Spinal cord samples were taken 24 h after injury and studied for determination of lipid peroxidation levels and TUNEL reaction. Behavioral testing was performed weekly upto six weeks post-injury. Then, the rats were euthanized for histopathological assessment. The results showed that lipid peroxidation levels were significantly decreased in experimental group. EGCG significantly reduced TUNEL-positive rate. Also, EGCG reduced significantly lesion area, and improved behavioral function more than the control group. EGCG treatment decreased secondary spinal cord injury

Polyphenol (-)-Epigallocatechin Gallate during Ischemia Limits Infarct Size Via Mitochondrial K(ATP) Channel Activation in Isolated Rat Hearts

Polyphenol (-)-epigallocatechin gallate (EGCG), the most abundant catechin of green tea, appears to attenuate myocardial ischemia/reperfusion injury. We investigated the involvement of ATP-sensitive potassium (K(ATP)) channels in EGCG-induced cardioprotection. Isolated rat hearts were subjected to 30 min of regional ischemia and 2 hr of reperfusion. EGCG was perfused for 40 min, from 10 min before to the end of index ischemia. A nonselective K(ATP) channel blocker glibenclamide (GLI) and a selective mitochondrial K(ATP) (mK(ATP)) channel blocker 5-hydroxydecanoate (HD) were perfused in EGCG-treated hearts. There were no differences in coronary flow and cardiodynamics including heart rate, left ventricular developed pressure, rate-pressure product, +dP/dt(max), and -dP/dt(min) throughout the experiments among groups. EGCG-treatment significantly reduced myocardial infarction (14.5+/-2.5% in EGCG 1 micrometer and 4.0+/-1.7% in EGCG 10 micrometer, P<0.001 vs. control 27.2+/-1.4%). This anti-infarct effect was totally abrogated by 10 micrometer GLI (24.6+/-1.5%, P<0.001 vs. EGCG). Similarly, 100 micrometer HD also aborted the anti-infarct effect of EGCG (24.1+/-1.2%, P<0.001 vs. EGCG ). These data support a role for the K(ATP) channels in EGCG-induced cardioprotection. The mK(ATP) channels play a crucial role in the cardioprotection by EGCG.

Protective Effects of Epigallocatechin Gallate After UV Irradiation of Cultured Human Lens Epithelial Cells

PURPOSE: To evaluate the protective effects of epigallocatechin gallate (EGCG) against UV irradiation of cultured human lens epithelial cells. METHODS: We irradiated cultured human lens epithelial cells with a 30-second pulse from a UV lamp with an irradiance of 0.6 mW/cm2. Five minutes and 1 hour after UV irradiation, we administered 0, 5, 10, 15, 25, 50, or 100 uM EGCG. The cell number was measured with a microscopic counting chamber and cell viability was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. RESULTS: Compared to untreated cells, the total number of cultured human lens epithelial cells was markedly higher after UV irradiation. In a dose-dependent manner, viability was also higher in EGCG-treated cells. CONCLUSIONS: EGCG increased the cell count and cell viability after UV irradiation of cultured human lens epithelial cells, indicating that EGCG can protect lens epithelium against UV damage.

Epigallocatechin-3 gallate prevents cardiac hypertrophy induced by pressure overload in rats

Pressure overload diseases, such as valvular stenosis and systemic hypertension, manifest morphologically in patients as cardiac concentric hypertrophy. Prevention of cardiac remodeling due to increased pressure overload is important to reduce morbidity and mortality. Epigallocatechin-3 gallate (EGCG) is a major bioactive polyphenol present in green tea which has been found to be a nitric oxide-mediated vasorelaxant and to be cardioprotective in myocardial ischemia-reperfusion injury. Therefore, we investigated whether EGCG supplementation could reduce in vivo pressure overloadmediated cardiac hypertrophy. Cardiac hypertrophy was induced by suprarenal transverse abdominal aortic constriction (AC) in rats. Three weeks after AC surgery, heart to body weight ratio increased in the AC group by 34% compared to the sham group. EGCG administration suppressed the load-induced increase in heart weight by 69%. Attenuation of cardiac hypertrophy by EGCG was associated with attenuation of the increase in myocyte cell size and fibrosis induced by aortic constriction. Despite abolition of hypertrophy by EGCG, transstenotic pressure gradients did not change. Echocardiogram revealed that increased left ventricular systolic dimensions and deteriorated systolic function were relieved by EGCG. These results suggest that EGCG prevents the development of left ventricular concentric hypertrophy by pressure overload and may be a useful therapeutic modality to prevent cardiac remodeling in patients with pressure overload myocardial diseases.