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Ascorbic acid EGCG

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https://www.readbyqxmd.com/read/29739590/quantification-of-ascorbyl-adducts-of-epigallocatechin-gallate-and-gallocatechin-gallate-in-bottled-tea-beverages
#1
Wei-Lun Hung, Siyu Wang, Shengmin Sang, Xiaochun Wan, Yu Wang, Chi-Tang Ho
Catechins are the major bioactive compounds existing in tea leaves (Camellia sinensis). Dehydroascorbic acid is (DHAA) a reactive dicarbonyl species and previous studies have demonstrated that catechins could effectively trap DHAA to form ascorbyl adducts of catechins, especially epigallocatechin gallate (EGCG). Since catechins in the aqueous solution are unstable due to their structural features, ascorbic acid (AA) is usually added to bottled tea beverages to protect catechins. However, whether ascorbyl adducts of catechins are formed in bottled tea beverages remains unclear...
September 30, 2018: Food Chemistry
https://www.readbyqxmd.com/read/29667503/effects-of-noble-metal-nanoparticles-on-the-hydroxyl-radical-scavenging-ability-of-dietary-antioxidants
#2
Hui Zhang, Xiumei Jiang, Gaojuan Cao, Xiaowei Zhang, Timothy R Croley, Xiaochun Wu, Jun-Jie Yin
Noble metal nanoparticles (NPs) have been widely used in many consumer products. Their effects on the antioxidant activity of commercial dietary supplements have not been well evaluated. In this study, we examined the effects of gold (Au NPs), silver (Ag NPs), platinum (Pt NPs), and palladium (Pd NPs) on the hydroxyl radical (·OH) scavenging ability of three dietary supplements vitamin C (L-ascorbic acid, AA), (-)-epigallocatechin gallate (EGCG), and gallic acid (GA). By electron spin resonance (ESR) spin-trapping measurement, the results show that these noble metal NPs can inhibit the hydroxyl radical scavenging ability of these dietary supplements...
April 3, 2018: Journal of Environmental Science and Health. Part C, Environmental Carcinogenesis & Ecotoxicology Reviews
https://www.readbyqxmd.com/read/29339972/evaluation-of-green-tea-extract-as-a-safe-personal-hygiene-against-viral-infections
#3
Yun Ha Lee, Yo Han Jang, Young-Seok Kim, Jinku Kim, Baik Lin Seong
Background: Viral infections often pose tremendous public health concerns as well as economic burdens. Despite the availability of vaccines or antiviral drugs, personal hygiene is considered as effective means as the first-hand measure against viral infections. The green tea catechins, in particular, epigallocatechin-3-gallate (EGCG), are known to exert potent antiviral activity. In this study, we evaluated the green tea extract as a safe personal hygiene against viral infections. Results: Using the influenza virus A/Puerto Rico/8/34 (H1N1) as a model, we examined the duration of the viral inactivating activity of green tea extract (GTE) under prolonged storage at various temperature conditions...
2018: Journal of Biological Engineering
https://www.readbyqxmd.com/read/28930270/protective-effects-of-six-selected-dietary-compounds-against-leptin-induced-proliferation-of-oestrogen-receptor-positive-mcf-7-breast-cancer-cells
#4
Meran Keshawa Ediriweera, Kamani Hemamala Tennekoon, Sameera Ranganath Samarakoon, Ira Thabrew, E Dilip de Silva
BACKGROUND: Obesity is considered as one of the risk factors for breast cancer. Leptin has been found to be involved in breast cancer progression. Therefore, novel approaches to antagonize biological effects of leptin are much needed. The objective of this study was to evaluate the protective effects of six dietary compounds (quercetin, curcumin, gallic acid, epigallocatechin gallate (EGCG), ascorbic acid and catechin) and assess the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) in leptin-stimulated MCF-7 breast cancer cells in vitro...
July 26, 2017: Medicines (Basel, Switzerland)
https://www.readbyqxmd.com/read/28544013/-epigallocatechin-3-gallate-inhibits-human-angiotensin-converting-enzyme-activity-through-an-autoxidation-dependent-mechanism
#5
Zhe Liu, Sayaka Nakashima, Toshiyuki Nakamura, Shintaro Munemasa, Yoshiyuki Murata, Yoshimasa Nakamura
We investigated the molecular mechanisms involved in the angiotensin-converting enzyme (ACE) inhibition by (-)-epigallocatechin-3-gallate (EGCg), a major tea catechin. EGCg inhibited both the ACE activity in the lysate of human colorectal cancer cells and human recombinant ACE (rh-ACE) in a dose-dependent manner. Co-incubation with zinc sulfate showed no influence on the rh-ACE inhibition by EGCg, whereas it completely counteracted the inhibitory effect of ethylenediaminetetraacetic acid, a chelating-type ACE inhibitor...
September 2017: Journal of Biochemical and Molecular Toxicology
https://www.readbyqxmd.com/read/28440509/modulation-of-mmp-2-and-9-secretion-by-cytokines-inducers-and-inhibitors-in-human-melanoma-a-2058-cells
#6
M Waheed Roomi, Tatiana Kalinovsky, Aleksandra Niedzwiecki, Matthias Rath
Melanoma, an extremely aggressive cancer, causes the most skin cancer-related deaths, due to metastasis to other areas of the body, such as lymph nodes, lungs, liver, brain or bone. It is characterized by high levels of matrix metalloproteinase (MMP)-2 and -9 secretions that degrade the extracellular matrix and basement membrane, allowing cancer cells to spread to distal organs. Various cytokines, mitogens, growth factors, inducers and inhibitors control MMP activities. We investigated the roles of these in regulation of MMP-2 and -9 in human melanoma A-2058 cells...
June 2017: Oncology Reports
https://www.readbyqxmd.com/read/28166649/evaluation-of-plasma-antioxidant-activity-in-rats-given-excess-egcg-with-reference-to-endogenous-antioxidants-concentrations-and-assay-methods
#7
Kaori Yokotani, Keizo Umegaki
The contribution of (-)-epigallocatechin gallate (EGCg) intake to in vivo antioxidant activity is unclear, even with respect to plasma. In this study, we examined how administration of EGCg contributes to plasma antioxidant activity, relative to its concentration, endogenous antioxidants, and assay methods, namely oxygen radical absorbance capacity (ORAC) and ferric reducing/antioxidant power (FRAP). Administration of EGCg (500 mg/kg) to rats increased plasma EGCg (4μmol/L as free form) and ascorbic acid (1...
February 2017: Free Radical Research
https://www.readbyqxmd.com/read/28112361/modulation-of-mmp-2-and-mmp-9-secretion-by-cytokines-inducers-and-inhibitors-in-human-glioblastoma-t-98g-cells
#8
M Waheed Roomi, Tatiana Kalinovsky, Matthias Rath, Aleksandra Niedzwiecki
Brain tumors are highly aggressive, characterized by the secretion of high levels of matrix metalloproteinase (MMP)-2 and MMP-9 that degrade the extracellular matrix and basement membrane, allowing cancer cells to spread to distal organs. Various cytokines, mitogens, growth factors, inducers and inhibitors control MMP activity. We investigated the roles of these in the regulation of MMP-2 and MMP-9 in human glioblastoma T-98G cells. Human T-98G cells were grown in DME supplemented with 15% fetal bovine serum and antibiotics in 24-well tissue culture plates...
March 2017: Oncology Reports
https://www.readbyqxmd.com/read/28038426/oxidized-epigallocatechin-gallate-inhibited-lysozyme-fibrillation-more-strongly-than-the-native-form
#9
Ting-Ting An, Shuang Feng, Cheng-Ming Zeng
Epigallocatechin gallate (EGCG), the most abundant flavanoid in green tea, is currently being evaluated in the clinic due to its benefits in the treatment of amyloid disorders. Its anti-amyloidogenic effect has been attributed to direct interaction of the intact molecule with misfolded polypeptides. In addition, antioxidant activity is also involved in the anti-amyloidogenic role. The detailed molecular mechanism is still unclear and requires further investigation. In the present study, the kinetics of EGCG oxidation and the anti-amyloidogenic effect of the resultant oxidation substances have been examined...
April 2017: Redox Biology
https://www.readbyqxmd.com/read/27803872/age-related-changes-in-the-kinetics-of-human-lenses-prevention-of-the-cataract
#10
REVIEW
Nicola Pescosolido, Andrea Barbato, Rossella Giannotti, Chiara Komaiha, Fiammetta Lenarduzzi
The crystalline lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina and, by changing shape, it adjusts focal distance (accommodation). The three classes of structural proteins found in the lens are α, β, and γ crystallins. These proteins make up more than 90% of the total dry mass of the eye lens. Other components which can be found are sugars, lipids, water, several antioxidants and low weight molecules. When ageing changes occur in the lens, it causes a gradual reduction in transparency, presbyopia and an increase in the scattering and aberration of light waves as well as a degradation of the optical quality of the eye...
2016: International Journal of Ophthalmology
https://www.readbyqxmd.com/read/27702495/functionalization-of-chitosan-by-a-free-radical-reaction-characterization-antioxidant-and-antibacterial-potential
#11
María Jesús Moreno-Vásquez, Emma Lucía Valenzuela-Buitimea, Maribel Plascencia-Jatomea, José Carmelo Encinas-Encinas, Francisco Rodríguez-Félix, Saúl Sánchez-Valdes, Ema Carina Rosas-Burgos, Víctor Manuel Ocaño-Higuera, Abril Zoraida Graciano-Verdugo
Chitosan was functionalized with epigallocatechin gallate (EGCG) by a free radical-induced grafting procedure, which was carried out by a redox pair (ascorbic acid/hydrogen peroxide) as the radical initiator. The successful preparation of EGCG grafted-chitosan was verified by spectroscopic (UV, FTIR and XPS) and thermal (DSC and TGA) analyses. The degree of grafting of phenolic compounds onto the chitosan was determined by the Folin-Ciocalteu procedure. Additionally, the biological activities (antioxidant and antibacterial) of pure EGCG, blank chitosan and EGCG grafted-chitosan were evaluated...
January 2, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/26775960/metal-chelation-radical-scavenging-and-inhibition-of-a%C3%AE-%C3%A2-%C3%A2-fibrillation-by-food-constituents-in-relation-to-alzheimer-s-disease
#12
Stephen Chan, Srinivas Kantham, Venkatesan M Rao, Manoj Kumar Palanivelu, Hoang L Pham, P Nicholas Shaw, Ross P McGeary, Benjamin P Ross
Various food constituents have been proposed as disease-modifying agents for Alzheimer's disease (AD), due to epidemiological evidence of their beneficial effects, and for their ability to ameliorate factors linked to AD pathogenesis, namely by: chelating iron, copper and zinc; scavenging reactive oxygen species; and suppressing the fibrillation of amyloid-beta peptide (Aβ). In this study, nine different food constituents (l-ascorbic acid, caffeic acid, caffeine, curcumin, (-)-epigallocatechin gallate (EGCG), gallic acid, propyl gallate, resveratrol, and α-tocopherol) were investigated for their effects on the above factors, using metal chelation assays, antioxidant assays, and assays of Aβ42 fibrillation...
May 15, 2016: Food Chemistry
https://www.readbyqxmd.com/read/25437149/tea-flavanols-block-advanced-glycation-of-lens-crystallins-induced-by-dehydroascorbic-acid
#13
Yingdong Zhu, Yantao Zhao, Pei Wang, Mohamed Ahmedna, Chi-Tang Ho, Shengmin Sang
Growing evidence has shown that ascorbic acid (ASA) can contribute to protein glycation and the formation of advanced glycation end products (AGEs), especially in the lens. The mechanism by which ascorbic acid can cause protein glycation probably originates from its oxidized form, dehydroascorbic acid (DASA), which is a reactive dicarbonyl species. In the present study, we demonstrated for the first time that four tea flavanols, (-)-epigallocatechin 3-O-gallate (EGCG), (-)-epigallocatechin (EGC), (-)-epicatechin 3-O-gallate (ECG), and (-)-epicatechin (EC), could significantly trap DASA and consequently form 6C- or 8C-ascorbyl conjugates...
January 20, 2015: Chemical Research in Toxicology
https://www.readbyqxmd.com/read/25229015/effects-of-flavonoid-compounds-on-%C3%AE-amyloid-peptide-induced-neuronal-death-in-cultured-mouse-cortical-neurons
#14
Seong-Min Choi, Byeong C Kim, Yeun-Hee Cho, Kang-Ho Choi, Jane Chang, Man-Seok Park, Myeong-Kyu Kim, Ki-Hyun Cho, Jong-Keun Kim
Excessive accumulation of β-amyloid peptide (Aβ) is one of the major mechanisms responsible for neuronal death in Alzheimer's disease. Flavonoids, primarily antioxidants, are a group of polyphenolic compounds synthesized in plant cells. The present study aimed to identify flavonoid compounds that could inhibit Aβ-induced neuronal death by examining the effects of various flavonoids on the neurotoxicity of Aβ fragment 25-35 (Aβ25-35) in mouse cortical cultures. Aβ25-35 induced concentration- and exposure-time-dependent neuronal death...
August 2014: Chonnam Medical Journal
https://www.readbyqxmd.com/read/25214322/assessment-of-plasma-concentrations-of-epigallocatechin-gallate-in-mice-following-administration-of-a-dose-reflecting-consumption-of-a-standard-green-tea-beverage
#15
Admire Dube, Joseph A Nicolazzo, Ian Larson
The plasma exposure of (-)-epigallocatechin gallate (EGCg) is typically assessed following administration of EGCg at doses equivalent to the consumption of at least 10 cups of green tea in one sitting. This study determines the plasma concentrations of EGCg in mice following administration of a dose reflecting typical consumption of one standard green tea beverage. Swiss Outbred mice were orally administered 0.76mg/kg EGCg, and using a validated HPLC method, the Cmax of un-conjugated and total EGCg was determined to be 31...
September 1, 2011: Food Chemistry
https://www.readbyqxmd.com/read/25189759/effects-of-nutrients-on-matrix-metalloproteinases-in-human-t-lymphotropic-virus-type-1-positive-and-negative-malignant-t-lymphocytes
#16
Steve Harakeh, Raefa Abou-Khouzam, Ghazi A Damanhouri, Ahmed Al-Hejin, Taha Kumosani, Aleksandra Niedzwiecki, Mathias Rath, Elie Barbour, Mona Diab-Assaf, Rania Azar
Experimental and clinical studies have revealed the effectiveness of a specific nutrient synergy (SNS) mixture composed of ascorbic acid (AA), lysine, proline, arginine, epigallocatechin gallate (EGCG) and other micronutrients in targeting crucial physiological mechanisms involved in cancer progression and metastasis. HTLV-1 causes adult T-cell leukemia (ATL). The spread and metastases of ATL as well as other tumors has been associated with matrix metalloproteinases, especially the gelatinases MMP-2 and MMP-9...
November 2014: International Journal of Oncology
https://www.readbyqxmd.com/read/25175728/validation-of-a-high-performance-liquid-chromatography-method-for-the-stabilization-of-epigallocatechin-gallate
#17
Joana F Fangueiro, Alexander Parra, Amélia M Silva, Maria A Egea, Eliana B Souto, Maria L Garcia, Ana C Calpena
Epigallocatechin gallate (EGCG) is a green tea catechin with potential health benefits, such as anti-oxidant, anti-carcinogenic and anti-inflammatory effects. In general, EGCG is highly susceptible to degradation, therefore presenting stability problems. The present paper was focused on the study of EGCG stability in HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid) medium regarding the pH dependency, storage temperature and in the presence of ascorbic acid a reducing agent. The evaluation of EGCG in HEPES buffer has demonstrated that this molecule is not able of maintaining its physicochemical properties and potential beneficial effects, since it is partially or completely degraded, depending on the EGCG concentration...
November 20, 2014: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/24611903/chemopreventive-and-hepatoprotective-effects-of-epigallocatechin-gallate-against-hepatocellular-carcinoma-role-of-heparan-sulfate-proteoglycans-pathway
#18
Mohamed M Darweish, Ahmed Abbas, Mohamed A Ebrahim, Mohammed M H Al-Gayyar
OBJECTIVE: Epigallocatechin-gallate (EGCG) claims a plethora of health benefits including protection against neoplastic diseases. Meanwhile, heparan-sulfate proteoglycans (HSPGs) have defensive role against tumour cell invasion. Therefore, the chemopreventive and hepatoprotective effects of EGCG were studied in hepatocellular carcinoma (HCC) in vivo and in vitro and compared with strong water soluble antioxidant, sodium ascorbate. METHODS: HCC was induced in SD rats by thioacetamide (200 mg/Kg)...
July 2014: Journal of Pharmacy and Pharmacology
https://www.readbyqxmd.com/read/24256565/impact-of-antioxidants-on-the-ability-of-phenolic-phytochemicals-to-kill-hct116-colon-cancer-cells
#19
A Murphy, K Testa, J Berkelhammer, S Hopkins, G Loo
Certain phenolic phytochemicals can kill cancer cells. Possible interference from antioxidants is a concern, and this issue has not been studied appreciably. Therefore, the effect of ascorbate and N-acetylcysteine on the ability of epigallocatechin gallate (EGCG) and curcumin to kill HCT116 colon cancer cells was examined. EGCG and curcumin each caused DNA damage in the cells. The DNA-damaging ability of EGCG, but not curcumin, was hindered by either ascorbate or NAC, which was also shown in HT29 and SW480 colon cancer cells...
March 2014: Free Radical Research
https://www.readbyqxmd.com/read/23973768/ascorbic-acid-and-dietary-polyphenol-combinations-protect-against-genotoxic-damage-induced-in-mice-by-endogenous-nitrosation
#20
Suresh K Abraham, Nidhi Khandelwal
We investigated whether combinations of ascorbic acid (AA) plus dietary polyphenols can protect in vivo against genotoxic damage induced by endogenous nitrosation. A nitrosation reaction mixture consisting of methylurea (MU) plus sodium nitrite (SN), which can react to form N-nitroso-N-methylurea in the stomach, was administered orally to mice, together with AA and one of the dietary polyphenols ferulic acid (FA), gallic acid (GA), chlorogenic acid (CA), or epigallocatechin gallate (EGCG). Genotoxic damage in bone marrow cells was assessed by measuring micronucleated polychromatic erythrocytes (Mn PCEs) and metaphase chromosome aberrations...
October 9, 2013: Mutation Research
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