4-hydroxy-2-nonenal and epigallocatechin-gallate

Lipid peroxidation-derived reactive carbonyl species (RCS) such as acrolein and 4-hydroxynonenal pose health risks. We characterized the RCS-scavenging reactions of tea catechins in an aqueous solution and in baked cake. Acrolein's reaction with each of the major tea catechins (epicatechin, epigallocatechin, epicatechin gallate, and epigallocatechin gallate) resulted in the formation of mono-, di-, and tri-acrolein conjugates of each catechin as revealed by our LC-linear ion trap MS analysis. The formation of the acrolein-conjugates of the four catechins was confirmed in the reaction of acrolein with green tea powder (matcha) extract. The addition of matcha tea powder to cake dough significantly suppressed the accumulation of RCS during cake baking. The mono-acrolein conjugates of the four major catechins were detected in the baked cake. The RCS-scavenging capability of tea catechins offers a new functionality of matcha tea powder, and its heat stability demonstrates the usefulness of matcha as a food additive.

Topics: Acrolein; Aldehydes; Catechin; Chromatography, High Pressure Liquid; Cooking; Free Radical Scavengers; Hot Temperature; Mass Spectrometry; Plant Extracts; Powders; Tea

Despite advances in bone regenerative medicine, the relationship between stress-induced premature senescence (SIPS) in cells and bone regeneration remains largely unknown. Herein, we demonstrated that the implantation of a lipopolysaccharide (LPS) sustained-release gelatin sponge (LS-G) increases the number of SIPS cells and that the elimination of these cells promotes bone formation in critical-sized bone defects in the rat calvaria. Histological (hematoxylin-eosin and SA-β-gal) and immunohistological (p16 and p21 for analyzing cellular senescence and 4-HNE for oxidation) staining was used to identify SIPS cells and elucidate the underlying mechanism. Bone formation in defects were analyzed using microcomputed tomography, one and four weeks after surgery. Parallel to LS-G implantation, local epigallocatechin gallate (EGCG) administration, and systemic senolytic (dasatinib and quercetin: D+Q) administration were used to eliminate SIPS cells. After LS-G implantation, SA-β-gal-, p16-, and p21-positive cells (SIPS cells) accumulated in the defects. However, treatment with LS-G+EGCG and LS-G+D+Q resulted in lower numbers of SIPS cells than that with LS-G in the defects, resulting in an augmentation of newly formed bone. We demonstrated that SIPS cells induced by sustained stimulation by LPS may play a deleterious role in bone formation. Controlling these cell numbers is a promising strategy to increase bone regeneration.

Topics: Aldehydes; Animals; Bone Regeneration; Bone Substitutes; Catechin; Cell Line; Cellular Senescence; Dasatinib; Delayed-Action Preparations; Lipopolysaccharides; Osteoblasts; Quercetin; Rats; Skull; X-Ray Microtomography

Cigarette smoke (CS), the major risk factor of chronic obstructive pulmonary disease (COPD), contains numerous free radicals that can cause oxidative stress and exaggerated inflammatory responses in the respiratory system. Lipid peroxidation which is oxidative degradation of polyunsaturated fatty acids and results in cell damage has also been associated with COPD pathogenesis. Increased levels of lipid peroxidation as well as its end product 4-hydroxynonenal have indeed been detected in COPD patients. Additionally, reactive oxygen species such as those contained in CS can activate nuclear factor-κB signaling pathway, initiating cascades of proinflammatory mediator expression. As emerging evidence attests to the antioxidative and anti-inflammatory properties of tea catechins, we sought to determine whether epigallocatechin gallate, the most abundant tea catechin, can provide protection against oxidative stress, lipid peroxidation, and inflammatory responses caused by CS. We found that EGCG treatment blocked cigarette smoke extract (CSE)-induced oxidative stress as indicated by decreased production and accumulation of reactive oxygen species in airway epithelial cells (AECs). Likewise, lipid peroxidation in CSE-stimulated AECs was suppressed by EGCG. Our findings further suggest that EGCG sequestered 4-hydroxynonenal and interfered with its protein adduct formation. Lastly, we show that EGCG inhibited nuclear factor-κB activation and the downstream expression of proinflammatory mediators. In summary, our study describing the antioxidative and anti-inflammatory effects of EGCG in CSE-exposed AECs provide valuable information about the therapeutic potential of this tea catechin for COPD.

Topics: Aldehydes; Alveolar Epithelial Cells; Anti-Inflammatory Agents; Antioxidants; Bronchi; Catechin; Cell Line; Cigarette Smoking; Epithelial Cells; Humans; Inflammation; Lipid Peroxidation; NF-kappa B; Oxidation-Reduction; Oxidative Stress; Pulmonary Alveoli; Pulmonary Disease, Chronic Obstructive; Reactive Oxygen Species; Signal Transduction; Smoke; Smoking

Matrix metalloproteinase (MMP)-2 and MMP-9 are well-known gelatinases that disrupt the extracellular matrix, including gelatin. However, the advantages of modulating MMP expression in gelatin-based materials for applications in bone regenerative medicine have not been fully clarified. In this study, we examined the effects of epigallocatechin gallate (EGCG), a major polyphenol catechin isolated from green tea, on MMP expression in gelatin sponges and its association with bone formation. Four gelatin sponges with or without EGCG were prepared and implanted into bone defects for up to 4 weeks. Histological and immunohistological staining were performed. Micro-computed tomography was used to estimate the bone-forming capacity of each sponge. Our results showed that EGCG integration attenuated MMP-2 (70.6%) and -9 expression (69.1%) in the 1 week group, increased residual gelatin (118.7%), and augmented bone formation (101.8%) in the 4 weeks group in critical-sized bone defects of rat calvaria compared with vacuum-heated gelatin sponges without EGCG. Moreover, vacuum-heated gelatin sponges with EGCG showed superior bone formation compared with other sponges. The results indicated that integration of EGCG in gelatin-based materials modulated the production and activity of MMP-2 and -9 in vivo, thereby enhancing bone-forming capacity.

Topics: Absorbable Implants; Aldehydes; Animals; Biocompatible Materials; Bone Regeneration; Bone Resorption; Catechin; Cell Line; Cell Proliferation; Gelatin; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Matrix Metalloproteinase Inhibitors; Osteoblasts; Rats; Rats, Sprague-Dawley; Skull; Tissue Engineering; Tissue Scaffolds; X-Ray Microtomography

The in vivo mechanism of tea polyphenol-mediated prevention of many chronic diseases is still largely unknown. Studies have shown that accumulation of toxic reactive cellular metabolites, such as ammonia and reactive carbonyl species (RCS), is one of the causing factors to the development of many chronic diseases. In this study, we investigated the in vivo interaction between (-)-epigallocatechin-3-gallate (EGCG), the most abundant polyphenol in tea leaves, and ammonia and RCS. We found that EGCG could be oxidized to EGCG quinone in mice, and then rapidly react with ammonia to generate the aminated EGCG metabolite, 4'-NH

Topics: Aldehydes; Amination; Ammonia; Animals; Catechin; Free Radical Scavengers; Gastrointestinal Microbiome; Germ-Free Life; HCT116 Cells; HT29 Cells; Humans; Malondialdehyde; Mice; Oxidation-Reduction; Pyruvaldehyde; Quinones; Sorption Detoxification; Tea

α-Syntrophin is a component of the dystrophin-glycoprotein complex that interacts with various intracellular signaling proteins in muscle cells. The α-syntrophin knock-down C2 cell line (SNKD), established by infecting lentivirus particles with α-syntrophin shRNA, is characterized by a defect in terminal differentiation and increase in cell death. Since myoblast differentiation is accompanied by intensive mitochondrial biogenesis, the generation of intracellular reactive oxygen species (ROS) is also increased during myogenesis. Two-photon microscopy imaging showed that excessive intracellular ROS accumulated during the differentiation of SNKD cells as compared with control cells. The formation of 4-hydroxynonenal adduct, a byproduct of lipid peroxidation during oxidative stress, significantly increased in differentiated SNKD myotubes and was dramatically reduced by epigallocatechin-3-gallate, a well-known ROS scavenger. Among antioxidant enzymes, catalase was significantly decreased during differentiation of SNKD cells without changes at the mRNA level. Of interest was the finding that the degradation of catalase was rescued by MG132, a proteasome inhibitor, in the SNKD cells. This study demonstrates a novel function of α-syntrophin. This protein plays an important role in the regulation of oxidative stress from endogenously generated ROS during myoblast differentiation by modulating the protein stability of catalase.

Topics: Aldehydes; Animals; Antioxidants; Blotting, Western; Calcium-Binding Proteins; Catalase; Catechin; Cell Differentiation; Cell Line; Cysteine Proteinase Inhibitors; Leupeptins; Membrane Proteins; Mice; Microscopy, Fluorescence, Multiphoton; Muscle Development; Muscle Proteins; Myoblasts; Oxidative Stress; Protein Stability; Reactive Oxygen Species; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference

(-)-Epigallocatechin-3-gallate (EGCG), a constituent of green tea, has been suggested to have numerous health-promoting effects. On the other hand, high-dose EGCG is able to evoke hepatotoxicity. In the present study, we elucidated the responses of hepatic major antioxidant enzymes and nuclear factor erythroid 2-related factor 2 (Nrf2) rescue pathway to high-dose levels of EGCG in Kunming mice. At a non-lethal toxic dose (75mg/kg, i.p.), repeated EGCG treatments markedly decreased the levels of superoxide dismutase, catalase, and glutathione peroxidase. As a rescue response, the nuclear distribution of Nrf2 was significantly increased; a battery of Nrf2-target genes, including heme oxygenase 1 (HO1), NAD(P)H:quinone oxidoreductase 1 (NQO1), glutathione S-transferase (GST), and those involved in glutathione and thioredoxin systems, were all up-regulated. At the maximum tolerated dose (45mg/kg, i.p.), repeated EGCG treatments did not disturb the major antioxidant defense. Among the above-mentioned genes, only HO1, NQO1, and GST genes were significantly but modestly up-regulated, suggesting a comprehensive and extensive activation of Nrf2-target genes principally occurs at toxic levels of EGCG. At a lethal dose (200mg/kg, i.p.), a single EGCG treatment dramatically decreased not only the major antioxidant defense but also the Nrf2-target genes, demonstrating that toxic levels of EGCG are able to cause a biphasic response of Nrf2. Overall, the mechanism of EGCG-triggered hepatotoxicity involves suppression of major antioxidant enzymes, and the Nrf2 rescue pathway plays a vital role for counteracting EGCG toxicity.

Topics: Alanine Transaminase; Aldehydes; Animals; Aspartate Aminotransferases; Catalase; Catechin; Chemical and Drug Induced Liver Injury; Glutathione Peroxidase; Histones; Interleukin-6; Liver; Male; Maximum Tolerated Dose; Mice; NF-E2-Related Factor 2; Superoxide Dismutase; Tea; Thioredoxin Reductase 1; Thioredoxins

Our previous study indicated that consuming (-)-epigallocatechin gallate (EGCG) before or after traumatic brain injury (TBI) eliminated free radical generation in rats, resulting in inhibition of neuronal degeneration and apoptotic death, and improvement of cognitive impairment. Here we investigated the effects of administering EGCG at various times pre- and post-TBI on cerebral function and morphology. Wistar rats were divided into five groups and were allowed access to (1) normal drinking water, (2) EGCG pre-TBI, (3) EGCG pre- and post-TBI, (4) EGCG post-TBI, and (5) sham-operated group with access to normal drinking water. TBI was induced with a pneumatic controlled injury device at 10 weeks of age. Immunohistochemistry and lipid peroxidation studies revealed that at 1, 3, and 7 days post-TBI, the number of 8-Hydroxy-2'-deoxyguanosine-, 4-Hydroxy-2-nonenal- and single-stranded DNA (ssDNA)-positive cells, and levels of malondialdehyde around the damaged area were significantly decreased in all EGCG treatment groups compared with the water group (P < 0.05). Although there was a significant increase in the number of surviving neurons after TBI in each EGCG treatment group compared with the water group (P < 0.05), significant improvement of cognitive impairment after TBI was only observed in the groups with continuous and post-TBI access to EGCG (P < 0.05). These results indicate that EGCG inhibits free radical-induced neuronal degeneration and apoptotic death around the area damaged by TBI. Importantly, continuous and post-TBI access to EGCG improved cerebral function following TBI. In summary, consumption of green tea may be an effective therapy for TBI patients.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aldehydes; Animals; Brain Edema; Brain Injuries; Catechin; Deoxyguanosine; Disease Models, Animal; DNA, Single-Stranded; Drug Administration Schedule; Glial Fibrillary Acidic Protein; Lipid Peroxidation; Male; Maze Learning; Neurons; Neuroprotective Agents; Phosphopyruvate Hydratase; Proto-Oncogene Proteins c-bcl-2; Rats; Rats, Wistar; Time Factors

There is a need for a nontoxic antioxidant agent to be identified which will prevent alcoholic liver disease (ALD) in alcoholic patients. We tested 4 candidate agents: quercetin, EGCG, catechin and betaine, all of which occur naturally in food. HepG2 cells overexpressing CYP2E1 were subjected to arachidonic acid, iron and 100mM ethanol with or without the antioxidant agent. All the agents prevented oxidative stress and MDA/4HNE formation induced by ethanol, except for EGCG. Catechin prevented CYP2E1 induction by ethanol. All the agents tended to down-regulate the ethanol-induced increased expression of glutathionine peroxidase 4 (GPX4). All the agents, except catechin, tended to reduce the expression of SOD2 induced by ethanol. Heat shock protein 70 was up-regulated by ethanol alone and betaine tended to prevent this. All 4 agents down-regulated the expression of Gadd45b in the presence of ethanol, which could explain the mechanism of DNA demethylation associated with the up-regulation of the gene expression observed in experimental ALD. In conclusion, the in vitro model of oxidative stress induced by ethanol provided evidence that all 4 agents tested prevented some aspect of liver cell injury caused by ethanol.

Topics: Aldehydes; Anti-Infective Agents, Local; Antioxidants; Betaine; Blotting, Western; Carcinoma, Hepatocellular; Catechin; Cells, Cultured; Cytochrome P-450 CYP2E1; Ethanol; Gastrointestinal Agents; Hepatocytes; Humans; In Vitro Techniques; Liver Neoplasms; Malondialdehyde; Oxidative Stress; Quercetin; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger

The tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) has been studied for chronic disease preventive effects, and is marketed as part of many dietary supplements. However, case-reports have associated the use of green tea-based supplements with liver toxicity. We studied the hepatotoxic effects of high dose EGCG in male CF-1 mice. A single dose of EGCG (1500 mg/kg, i.g.) increased plasma alanine aminotransferase (ALT) by 138-fold and reduced survival by 85%. Once-daily dosing with EGCG increased hepatotoxic response. Plasma ALT levels were increased 184-fold following two once-daily doses of 750 mg/kg, i.g. EGCG. Moderate to severe hepatic necrosis was observed following treatment with EGCG. EGCG hepatotoxicity was associated with oxidative stress including increased hepatic lipid peroxidation (5-fold increase), plasma 8-isoprostane (9.5-fold increase) and increased hepatic metallothionein and gamma-histone 2AX protein expression. EGCG also increased plasma interleukin-6 and monocyte chemoattractant protein-1. Our results indicate that higher bolus doses of EGCG are hepatotoxic to mice. Further studies on the dose-dependent hepatotoxic effects of EGCG and the underlying mechanisms are important given the increasing use of green tea dietary supplements, which may deliver much higher plasma and tissue concentrations of EGCG than tea beverages.

Topics: Aldehydes; Animals; Antioxidants; Biomarkers; Catechin; Chemical and Drug Induced Liver Injury; Chromatography, High Pressure Liquid; Cysteine; Cytokines; Dose-Response Relationship, Drug; Immunohistochemistry; Lipid Peroxidation; Liver Function Tests; Male; Metallothionein; Mice; Oxidants; Oxidative Stress; Spectrometry, Mass, Electrospray Ionization; Survival Analysis

Cisplatin-induced nephrotoxicity is associated with increased oxidative stress and inflammatory cytokines in the kidney. Epigallocatechin-3-gallate (EGCG) has anti-oxidant, anti-inflammatory, and anti-tumorigenic properties. In this study, we investigated the effects of EGCG on cisplatin-induced nephrotoxicity and potential mechanisms by which it enhances antioxidant activities and resolves inflammation after EGCG treatment during cisplatin-induced nephrotoxicity.. Twenty-eight rats were divided into four groups as control (group 1; no treatment; n=7), EGCG (group 2; n=7), cisplatin (group 3; n=7) or cisplatin and EGCG (group 4; n=7). After 2 days of EGCG treatment at a dose of l00 mg/kg BW, rats were treated with a single i.p. injection of cisplatin (7 mg/kg BW). On day 12 (10days after the cisplatin treatment), all rats were sacrificed by cervical dislocation. The level of protein was examined by Western blotting.. Cisplatin caused a significant decrease in the expression nuclear levels of NF-E2-related factor-2 (Nrf2), heme oxygenase-1(HO-1), and an increase in the levels of nuclear factor-kappa B (NF-kappaB p65) and 4-hydroxynonenal (HNE) an oxidative stress marker. EGCG supplementation significantly improved the changes associated with cisplatin nephrotoxicity by increasing levels of Nrf-2 and HO-1, and decreasing levels of NF-kappaB and HNE. Renal activities of antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase) and glutathione were significantly lower in cisplatin-treated rats compared with control rats, and EGCG treatment significantly increased the activities of antioxidant enzymes and glutathione (P<0.001).. The results suggest that Nrf2/HO-1 signaling pathway may be the primary target for prevention of cisplatin-induced nephrotoxicity by EGCG, and that reduces it inflammation by inhibiting NF-kappaB.

Topics: Aldehydes; Animals; Antineoplastic Agents; Antioxidants; Catalase; Catechin; Cisplatin; Glutathione; Glutathione Peroxidase; Heme Oxygenase-1; Kidney; Male; Neoplasms; NF-E2-Related Factor 2; NF-kappa B; Rats; Rats, Wistar; Signal Transduction; Superoxide Dismutase; Tea

Oxidative stress has been implicated in the pathogenesis of cancer and prominent neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Apoptosis and cell cycle deregulation appear to be the mode of cell death in these disorders. Green tea polyphenol, epigallocatechin-3-gallate (EGCG) has been shown to be a potent antiinflammatory, apoptotic and cancer chemopreventive agent. 4-Hydroxynonenal (HNE), a by-product of lipid peroxidation (LPO), has been reported to induce apoptosis and inhibit growth in many cell systems including neuroglial cultures. We have studied both the dose and time dependent effects of HNE and EGCG on the viability of primary astrocyte cell cultures prepared from neonatal rats. HNE was found to be cytotoxic at a higher dose (0.1 mM) and markedly reduced (up to 80%) the astrocyte viability while EGCG did not appear to be cytotoxic under similar conditions. In addition, we have also studied the alterations in glutathione (GSH) and LPO levels and the activities of GSH metabolizing enzymes after treatment with HNE and EGCG. A 40% decrease in GSH level and a moderate increase in LPO were observed in HNE treated cells suggesting an increase in oxidative stress. HNE treatment caused a 50% decrease in GSH reductase and a 35% increase in GSH peroxidase activities. Although HNE treatment did not lead to any significant alterations in GSH-S-transferase (GST) activity, an increased expression of GST isoenzymes was seen following the exposure to HNE. EGCG treatment caused a significant increase in LPO even in the presence of elevated GSH content. In contrast to HNE, EGCG treatment resulted in a significant decrease (50%) in the activity and expression of GSTs. Treatment of astrocyte cultures with HNE, resulted in a severe impairment in mitochondrial respiration as measured by MTT exclusion assay, while treatment with EGCG had no effect on mitochondrial respiratory activity. Both HNE and EGCG were found to initiate apoptosis in astrocytes as measured by DNA fragmentation assay. However, HNE seems to be a stronger apoptotic and cytotoxic agent than EGCG. These results suggest that HNE and EGCG differentially modulate oxidative stress and regulate the growth and survival of astrocytes.

Topics: Aldehydes; Animals; Apoptosis; Astrocytes; Blotting, Western; Catechin; Flavonoids; Glutathione; Glutathione Transferase; Immunohistochemistry; Isoenzymes; Lipid Peroxidation; Mitochondria; Oxidative Stress; Phenols; Polymers; Rats; Rats, Wistar; Tea; Tetrazolium Salts; Thiazoles