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Ascorbic acid EGCG

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https://www.readbyqxmd.com/read/27803872/age-related-changes-in-the-kinetics-of-human-lenses-prevention-of-the-cataract
#1
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
#2
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
#3
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
#4
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
#5
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
#6
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
#7
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
#8
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
#9
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
#10
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
#11
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
https://www.readbyqxmd.com/read/23892041/enhancement-of-epigallocatechin-3-gallate-and-theaflavin-3-3-digallate-induced-apoptosis-by-ascorbic-acid-in-human-lung-adenocarcinoma-spc-a-1-cells-and-esophageal-carcinoma-eca-109-cells-via-mapk-pathways
#12
Ying Gao, Wei Li, Lingyan Jia, Bo Li, Yi Charlie Chen, Youying Tu
Tea polyphenols (-)-epigallocatechin-3-gallate (EGCG) and theaflavin-3-3'-digallate (TF3) are two prospective compounds in cancer prevention and treatment. Ascorbic acid (Vc) is essential to a healthy diet as well as being a highly effective antioxidant. In this work, the effects of the combination of EGCG or TF3 with Vc on the apoptosis and caspases-3/9 activities in human lung adenocarcinoma SPC-A-1 cells and esophageal carcinoma Eca-109 cells were determined. Furthermore, the role of mitogen-activated protein kinases (MAPK) pathways in the apoptosis induced by TF3 or EGCG together with Vc were studied using three MAPK inhibitors (ERK inhibitor PD98059, JNK inhibitor SP600125 and p38 inhibitor SB203580)...
August 23, 2013: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/23298331/degradation-kinetics-of-chlorogenic-acid-at-various-ph-values-and-effects-of-ascorbic-acid-and-epigallocatechin-gallate-on-its-stability-under-alkaline-conditions
#13
Yusaku Narita, Kuniyo Inouye
5-Caffeoylquinic acid (5-CQA) is generally referred to as chlorogenic acid and exhibits various biological activities such as antioxidant activity and porcine pancreas α-amylase inhibitory activities. 5-CQA may be useful as an antioxidant for food and to prevent diabetes and obesity. The degradation of 5-CQA and caffeic acid (CA) in an aqueous solution at 37 °C and pH 5.0-9.0 was studied. The degradation of 5-CQA and CA, demonstrating time and pH dependence (i.e., the rate constant, k, was higher at higher pH), was satisfactorily described by the Weibull equation...
January 30, 2013: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/23292326/comparative-evaluation-of-different-co-antioxidants-on-the-photochemical-and-functional-stability-of-epigallocatechin-3-gallate-in-topical-creams-exposed-to-simulated-sunlight
#14
COMPARATIVE STUDY
Santo Scalia, Nicola Marchetti, Anna Bianchi
The catechin (-)-epigallocatechin-3-gallate (EGCG) exhibits high antioxidant activity and it has been reported to provide protection of the skin against damage induced by solar UV radiation. However, EGCG is highly unstable under sunlight. The present study aimed to compare the effectiveness of the co-antioxidant agents vitamin E, butylated hydroxytoluene, vitamin C and a-lipoic acid for their potential to protect the catechin from photochemical degradation. Model creams (oil-in-water emulsions) containing EGCG (1%, w/w) alone or combined with equimolar concentrations of co-antioxidant were exposed to a solar simulator at an irradiance corresponding to natural sunlight...
January 4, 2013: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/22417433/bioactive-dietary-polyphenols-inhibit-heme-iron-absorption-in-a-dose-dependent-manner-in-human-intestinal-caco-2-cells
#15
Qianyi Ma, Eun-Young Kim, Elizabeth Ann Lindsay, Okhee Han
UNLABELLED: Although heme iron is an important form of dietary iron, its intestinal absorption mechanism remains elusive. Our previous study revealed that (-)-epigallocatechin-3-gallate (EGCG) and grape seed extract (GSE) markedly inhibited intestinal heme iron absorption by reducing the basolateral iron export in Caco-2 cells. The aim of this study was to examine whether small amounts of EGCG, GSE, and green tea extract (GT) could inhibit heme iron absorption, and to test whether the inhibitory action of polyphenols could be offset by ascorbic acid...
June 2011: Journal of Food Science
https://www.readbyqxmd.com/read/21645609/in-vitro-screening-of-synergistic-ascorbate-drug-combinations-for-the-treatment-of-malignant-mesothelioma
#16
Simona Martinotti, Elia Ranzato, Bruno Burlando
Malignant mesothelioma (MMe) is a lethal tumor arising from the mesothelium of serous cavities as a result of exposure to asbestos. Current clinical standards consist of combined treatments, but an effective therapy has not been established yet and there is an urgent need for new curative approaches. Ascorbate is a nutrient that is also known as a remedy in the treatment of cancer. In the present study, we have tested the cytotoxicity of ascorbate to MMe cells in combination with drugs used in MMe therapy, such as cisplatin, etoposide, gemcitabine, imatinib, paclitaxel, and raltitrexed, as well as with promising antitumor compounds like taurolidine, α-tocopherol succinate, and epigallocatechin-3-gallate (EGCG)...
December 2011: Toxicology in Vitro: An International Journal Published in Association with BIBRA
https://www.readbyqxmd.com/read/21430251/ascorbic-acid-offsets-the-inhibitory-effect-of-bioactive-dietary-polyphenolic-compounds-on-transepithelial-iron-transport-in-caco-2-intestinal-cells
#17
Eun-Young Kim, Soo-Kyung Ham, Daniel Bradke, Qianyi Ma, Okhee Han
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...
May 2011: Journal of Nutrition
https://www.readbyqxmd.com/read/21400028/preclinical-evaluation-of-the-antitumor-activity-of-bortezomib-in-combination-with-vitamin-c-or-with-epigallocatechin-gallate-a-component-of-green-tea
#18
Bret Bannerman, Ling Xu, Matthew Jones, Christopher Tsu, Jie Yu, Paul Hales, Johan Monbaliu, Paul Fleming, Lawrence Dick, Mark Manfredi, Christopher Claiborne, Joseph Bolen, Erik Kupperman, Allison Berger
PURPOSE: To investigate whether clinically relevant levels of epigallocatechin gallate (EGCG, a component of green tea) or vitamin C (ascorbic acid) could antagonize bortezomib antitumor activity in CWR22 human prostate xenograft tumors. METHODS: The pharmacokinetics (PK) of EGCG and ascorbic acid were determined in immunocompromised mice and compared with concentrations measured in human PK studies of dietary supplements. Antitumor activity of bortezomib in combination with EGCG or ascorbic acid was determined using several dosing regimens to evaluate different target plasma concentrations of EGCG and ascorbic acid...
November 2011: Cancer Chemotherapy and Pharmacology
https://www.readbyqxmd.com/read/21211509/green-tea-polyphenol-epigallocatechin-3-gallate-egcg-induced-intermolecular-cross-linking-of-membrane-proteins
#19
Rong Chen, Jian-Bo Wang, Xian-Qing Zhang, Jing Ren, Cheng-Ming Zeng
Increasing evidence has demonstrated that EGCG possesses prooxidant potential in biological systems, including modifying proteins, breaking DNA strands and inducing the generation of reactive oxygen species. In the present study, the prooxidant effect of EGCG on erythrocyte membranes was investigated. SDS-PAGE and NBT-staining assay were utilized to detect the catechol-protein adducts that generated upon treating the membranes with EGCG. The results indicated that EGCG was able to bind covalently to sulfhydryl groups of membrane proteins, leading to the formation of protein aggregates with intermolecular cross-linking...
March 15, 2011: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/20730621/metals-oxidative-stress-and-neurodegenerative-disorders
#20
REVIEW
Klaudia Jomova, Dagmar Vondrakova, Michael Lawson, Marian Valko
The neurodegenerative diseases, Alzheimer's disease (AD) and Parkinson's disease (PD), are age-related disorders characterized by the deposition of abnormal forms of specific proteins in the brain. AD is characterized by the presence of extracellular amyloid plaques and intraneuronal neurofibrillary tangles in the brain. Biochemical analysis of amyloid plaques revealed that the main constituent is fibrillar aggregates of a 39-42 residue peptide referred to as the amyloid-β protein (Aβ). PD is associated with the degeneration of dopaminergic neurons in the substantia nigra pars compacta...
December 2010: Molecular and Cellular Biochemistry
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