Evaluation of epigallocatechin gallate and epicatechin gallate effects on acrylamide-induced neurotoxicity in rats and cytotoxicity in PC 12 cells

The neurotoxicity of acrylamide (ACR) monomer occurs through different mechanisms such as oxidative stress. Epigallocatechin gallate (EGCG) and epicatechin gallate (ECG) are green tea catechins which are known as powerful antioxidants. In this study, we examined the possible protective effects of ECG and EGCG on ACR neurotoxicity in both in-vitro and in-vivo models. PC12 cells were exposed to different concentrations of ECG and EGCG. After 24 and 48?hours, ACR was added to the cells (IC₅₀?=?4.85?mM) and cell viability was measured through MTT assay after 24?hours. Male Wistar rats were pretreated with ECG, EGCG (10, 20 and 40?mg/kg, i.p) and vitamin E (200?IU/kg i.p.) for 3?days. Afterwards they were treated with ACR (50?mg/kg, i.p.) for 11?days. After the treatment period, gait score examination was performed and molondialdehyde (MDA) and reduced glutathione (GSH) were measured in cerebral cortex. ACR reduced the cell viability in a concentration-dependent manner. Both ECG and EGCG (20?μM) showed inhibitory effects on ACR cytotoxicity. ACR significantly induced gait abnormalities, decreased GSH level and increased lipid peroxidation in cerebral cortex. ECG and EGCG (20?mg/kg) improved all ACR toxic effects. Although the food intake was increased in pretreated groups compared to the ACR-treated group, intensive weight loss was observed due to the green tea’s different weight loss mechanisms. ECG and EGCG inhibited the cytotoxicity of ACR in PC12 cells and increased GSH level and decreased lipid peroxidation in rat cerebral cortex.     

Cyclin D1在EGCG抗鼻咽癌中表达的变化及意义

目的：探讨Cyclin D1基因在表没食子儿茶素没食子酸酯（EGCG）抗鼻咽癌中表达的变化及意义,揭示EGCG的抗鼻咽癌作用机制。方法：体外培养低分化鼻咽癌细胞株CNE-2并以不同浓度EGCG处理,倒置显微镜下观察不同浓度EGCG作用48h后CNE-2细胞的形态变化,采用MTT比色法检测细胞增殖抑制率,流式细胞仪检测细胞周期,半定量逆转录PCR检测细胞中Cyclin D1mRNA的表达变化。结果：EGCG处理后,CNE-2细胞的数量及密度逐渐降低,分裂象减少,贴壁差,部分细胞变圆且体积变小,漂浮及凋亡细胞不断增多;细胞增殖明显受到抑制,CNE-2细胞被阻滞在G0/G1期,呈时间和剂量依赖性（P〈0.05）;Cyclin D1mRNA表达明显下调,且EGCG作用浓度与时间依赖性（P〈0.05）。结论：EGCG抑制CNE-2细胞的增殖,可能与其呈浓度与时间依赖性下调Cyclin D1mRNA的表达相关。     

Acute EGCG Supplementation Reverses Endothelial Dysfunction in Patients with Coronary Artery Disease

Background: Epidemiological studies demonstrate an inverse relation between dietary flavonoid intake and cardiovascular risk. Recent studies with flavonoid-containing beverages suggest that the benefits of these nutrients may relate, in part, to improved endothelial function.

Objective: We hypothesized that dietary supplementation with epigallocatechin gallate (EGCG), a major catechin in tea, would improve endothelial function in humans.

Design: We examined the effects of EGCG on endothelial function in a double blind, placebo-controlled, crossover design study. We measured brachial artery flow-mediated dilation by vascular ultrasound at six time points: prior to treatment with EGCG or placebo, two hours after an initial dose of EGCG (300 mg) or placebo, and after two weeks of treatment with EGCG (150 mg twice daily) or placebo. The order of treatments (EGCG or placebo) was randomized and there was a one-week washout period between treatments.

Results: A total of 42 subjects completed the study, and brachial artery flow-mediated dilation improved from 7.1 ± 4.1 to 8.6 ± 4.7% two hours after the first dose of 300 mg of EGCG (P = 0.01), but was similar to baseline (7.8 ± 4.2%, P = 0.12) after two weeks of treatment with the final measurements made approximately 14 hours after the last dose. Placebo treatment had no significant effect, and there were no changes in reactive hyperemia or the response to sublingual nitroglycerin. The changes in vascular function paralleled plasma EGCG concentrations, which increased from 2.6 ± 10.9 to 92.8 ± 78.7 ng/ml after acute EGCG (P < 0.001), but were unchanged from baseline after two weeks of treatment (3.4 ± 13.1 ng/ml).

Conclusion: EGCG acutely improves endothelial function in humans with coronary artery disease, and may account for a portion of the beneficial effects of flavonoid-rich food on endothelial function.     

Roles for Epigallocatechin Gallate in Cardiovascular Disease and Obesity: An Introduction

After water, tea from Camellia sinensis is the most consumed beverage worldwide. Tea is rich in catechin flavonoids that possess an array of bioactivity including antioxidant, anti-inflammatory, apoptotic, and probiotic mechanisms of action that may contribute to some of the putative health benefits associated with tea intake. A substantial body of evidence indicates that tea and its principal catechin, epigallocatechin gallate (EGCG) may contribute to a reduction in the risk of cardiovascular disease. Recent studies suggest EGCG may also have a positive impact on glucose tolerance and thermogenesis with implications for an effect on the pathogenesis of type 2 diabetes mellitus and obesity, respectively. This introduction to a symposium on EGCG’s role in cardiovascular disease and obesity presented at the 2006 annual meeting of the American College of Nutrition provides a background on tea and tea flavonoids and their possible relationship to health promotion and disease prevention.     

PLAGL1 Gene Demethylation Induced by Epigallocatechin Gallate Promotes Pheochromocytoma Cell Apoptosis Via Wnt/β-catenin Signaling Pathway

Objective: The aim of this study was to investigate the expression and the promoter methylation level of PLAGL1 gene and the mechanism of epigallocatechin gallate (EGCG) that induces PLAGL1 gene demethylation and promotes the apoptosis of pheochromocytoma (PCC) in PC12 cell line. Methods: The PC12 cells were treated with 25, 50, 75, 100, and 150 μg/mL EGCG for 48 hours. MSP was used to examine PLAGL1 gene methylation and an MTT assay was performed to detect the cell proliferation. The cell apoptosis was detected using flow cytometry. The mRNA and protein expressions of DNMT1, PLAGL1, Wnt, and β-catenin were detected using RT-quantitative PCR and Western blot. Results: EGCG dose-dependently reduced the cell viability and reversed PLAGL1 gene hypermethylation in PC12 cells (P<0.05). The cell apoptosis was significantly increased in PC12 cells treated with EGCG. The EGCG treatment restored the expressions of PLAGL1 and downregulated the expression of DNMT1, Wnt, and β-catenin in PC12 cells (P<0.05). Conclusion: The EGCG induces the demethylation process of PLAGL1 gene through down-regulating DNMT1 and restores the PLAGL1 mRNA and protein expression. The Wnt/β-catenin signaling pathway is involved in the regulation of PCC cell apoptosis promoted by EGCG inducing PLAGL1 gene demethylation.     

紫外线对皮肤角质形成细胞和成纤维细胞产生MMP-1和MMP-3的影响

目的:研究中波紫外线辐射对体外培养的表皮角质形成细胞和真皮成纤维细胞产生基质金属蛋白酶-1(MMP-1)和MMP-3的直接和间接影响,研究绿茶中的主要活性成分表没食子儿茶酚没食子酸酯(EGCG)对此影响的保护作用。方法:体外培养角质形成细胞株HaCaT和真皮成纤维细胞,中波紫外线辐射、不同浓度IL-6刺激及EGCG处理后,ELISA方法测定上清液中Pro-MMP-1和MMP-3蛋白含量,半定量RT-PCR方法测细胞中mRNA含量。结果:UVB30mJ/cm2辐射后角质形成细胞分泌的pro-MMP-1和MMP-3并未增加(P>0.05),真皮成纤维细胞合成和分泌MMP-1和MMP-3mRNA含量和蛋白水平均显著增加(P<0.05),IL-6(8、16、24pg/mL)可显著增加成纤维细胞产生MMP-1和MMP-3(P<0.05)。EGCG(0.15、0.3mM)能够显著抑制紫外线诱导成纤维细胞产生MMP含量的增加(P<0.05),但IL-6刺激成纤维细胞所产生的MMP-1和MMP-3的增加不受EGCG的影响(P>0.05)。结论:中波紫外线辐射并不能直接导致角质形成细胞分泌MMP-1和MMP-3增加,但紫外线辐射后角质形成细胞分泌的IL-6可促进成纤维细胞产生MMP。EGCG对IL-6刺激成纤维细胞产生MMP增加没有影响,但它可以显著抑制紫外线辐射直接导致的成纤维细胞产生MMP-1和MMP-3的增加,对防治皮肤光老化可能有一定作用。     

负载表没食子儿茶素没食子酸酯对血小板功能与凋亡等影响

本研究探讨表没食子儿茶素没食子酸酯(epigallocatechin gallate,EGCG)负载后对血小板生理生化功能的影响.将血小板用不同浓度EGCG(浓度分别为:0、2.5、5、7.5、10、12.5、15、20、30 mmol/L)的负载液处理,通过比对回收率和聚集活性,将实验分为2.5、5、10 mmo1/...     

表没食子儿茶素没食子酸酯对心血管疾病防治作用的研究进展

中国在公元前3 000年以前就有饮用绿茶的记载。现代技术发现绿茶含有大量的茶多酚,儿茶素是茶多酚的主要成分,包括4种单体物质,即表没食子儿茶素没食子酸酯[(-)-epigallocatechin gallate, EGCG]、表儿茶素没食子酸酯(epicatechin gallate,ECG)、表没食子儿茶素(epigallocatechin,EGC)和表儿茶素(epicatechin,EC),其中最主要的活性成分EGCG被认为具有抗癌、减肥、抗糖尿病、抗菌、抗病毒、预防龋齿等作用^[1]。大量研究发现饮茶也会减少心血管疾病的发生风险,对心脏具有明确的保护作用,本文就EGCG对心血管疾病的预防作用研究进展进行综述。