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EGCG amyloid beta

Syed Haris Omar, Christopher J Scott, Adam S Hamlin, Hassan K Obied
The focus of this study was on inhibition of enzymes involved in the pathogenesis Alzheimer's disease (AD) including prime amyloid beta (Aβ) producing enzyme (β-secretase: BACE-1) and disease progression enzymes including acetylcholinesterase (AChE), butyrylcholinesterase (BChE), histone deacetylase (HDAC), and tyrosinase along with the catecholamine L-DOPA, by using olive biophenols. Here we report the strongest inhibition of BACE-1 from rutin (IC50 : 3.8 nM) followed by verbascoside (IC50 : 6.3 nM) and olive fruit extract (IC50 : 18 ng), respectively...
May 14, 2018: Fitoterapia
Rashik Ahmed, Giuseppe Melacini
The self-association of the amyloid beta (Aβ) peptide into toxic oligomers is implicated in the early events leading to Alzheimer's disease (AD). Blocking the formation of Aβ oligomers and their interactions with the extracellular and cellular environment through small molecules and biopharmaceuticals is therefore a promising preventive strategy for AD. However, given the heterogeneity and transient nature of the Aβ oligomeric species, detailed structural and kinetic characterizations of such oligomers and oligomer:inhibitor complexes have proven to be challenging...
April 16, 2018: Chemical Communications: Chem Comm
Kolla Rajasekhar, Kapilkumar Mehta, Thimmaiah Govindaraju
Amyloid beta (Aβ) aggregation is the key trait responsible for the pathological devastation caused by Alzheimer's disease (AD). Among the various pathways of multifaceted toxicity exhibited by Aβ aggregates in neuronal cells, generation of reactive oxygen species (ROS) by Aβ-CuII complex and mitochondrial damage are prominent. Aβ interferes with mitochondrial transport channels, causing mitochondrial dysfunction. Herein, we present nontoxic hybrid multifunctional modulators (HMMs, TGR86-88) developed by integrating the structural and functional features of the metal chelating aggregation modulator, clioquinol (Clq) and the antioxidant epigallocatechin gallate (EGCG)...
March 20, 2018: ACS Chemical Neuroscience
Sureshbabu Nagarajan, Lisa J Lapidus
The aggregation of intrinsically disordered and misfolded proteins in the form of oligomers and fibrils plays a crucial role in a number of neurological and neurodegenerative diseases. Currently, most probes and biophysical techniques that detect and characterize fibrils at high resolution fail to show sensitivity and binding for oligomers. Here, we show that 9-(dicyano-vinyl)julolidine (DCVJ), a class of molecular rotor, binds amyloid beta (Aβ) early aggregates, and we report the kinetics as well as packing of the oligomer formation...
November 16, 2017: Chembiochem: a European Journal of Chemical Biology
Son Tung Ngo, Duc Toan Truong, Nguyen Minh Tam, Minh Tho Nguyen
An extensive replica exchange molecular dynamics (REMD) simulation was performed to investigate the progress patterns of the inhibition of (-)-epigallocatechin-3-gallate (EGCG) on the Aβ16-22 hexamer. Structural variations of the oligomers without and with EGCG were monitored and analyzed in detail. It has been found that EGCG prevents the formation of Aβ oligomer through two different ways by either accelerating the Aβ oligomerization or reducing the β-content of the hexamer. It also decreases the potential "highly toxic" conformations of Aβ oligomer, which is related to the conformations having high order β-sheet sizes...
June 21, 2017: Journal of Molecular Graphics & Modelling
Srinivas Kantham, Stephen Chan, Gawain McColl, Jared A Miles, Suresh Kumar Veliyath, Girdhar Singh Deora, Satish N Dighe, Samira Khabbazi, Marie-Odile Parat, Benjamin P Ross
The biphenyl neolignan honokiol is a neuroprotectant which has been proposed as a treatment for central nervous system disorders such as Alzheimer's disease (AD). The death of cholinergic neurons in AD is attributed to multiple factors, including accumulation and fibrillation of amyloid beta peptide (Aβ) within the brain; metal ion toxicity; and oxidative stress. In this study, we used a transgenic Caenorhabditis elegans model expressing full length Aβ42 as a convenient in vivo system for examining the effect of honokiol against Aβ-induced toxicity...
July 19, 2017: ACS Chemical Neuroscience
Koushik Debnath, Shashi Shekhar, Vipendra Kumar, Nihar R Jana, Nikhil R Jana
Green tea polyphenol epigallocatechin-3-gallate (EGCG) is known for its antiamyloidogenic property, and it is observed that molecular EGCG binds with amyloid structure, redirects fibrillation kinetics, remodels mature fibril, and lowers the amyloid-derived toxicity. However, this unique property of EGCG is difficult to utilize because of their poor chemical stability and substandard bioavailability. Here we report a nanoparticle form of EGCG of 25 nm size (nano-EGCG) which is 10-100 times more efficient than molecular EGCG in inhibiting protein aggregation, disintegrating mature protein aggregates, and lowering amyloidogenic cytotoxicity...
August 10, 2016: ACS Applied Materials & Interfaces
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
Amit Pithadia, Jeffrey R Brender, Carol A Fierke, Ayyalusamy Ramamoorthy
Fibrillar aggregates of human islet amyloid polypeptide, hIAPP, a pathological feature seen in some diabetes patients, are a likely causative agent for pancreatic beta-cell toxicity, leading to a transition from a state of insulin resistance to type II diabetes through the loss of insulin producing beta-cells by hIAPP induced toxicity. Because of the probable link between hIAPP and the development of type II diabetes, there has been strong interest in developing reagents to study the aggregation of hIAPP and possible therapeutics to block its toxic effects...
2016: Journal of Diabetes Research
Tomas Šneideris, Lina Baranauskienė, Jonathan G Cannon, Rasa Rutkienė, Rolandas Meškys, Vytautas Smirnovas
A range of diseases is associated with amyloid fibril formation. Despite different proteins being responsible for each disease, all of them share similar features including beta-sheet-rich secondary structure and fibril-like protein aggregates. A number of proteins can form amyloid-like fibrils in vitro, resembling structural features of disease-related amyloids. Given these generic structural properties of amyloid and amyloid-like fibrils, generic inhibitors of fibril formation would be of interest for treatment of amyloid diseases...
2015: PeerJ
Kathrin Andrich, Jan Bieschke
Studies on the interaction of the green tea polyphenol (-)-Epigallocatechin-3-gallate (EGCG) with fourteen disease-related amyloid polypeptides and prions Huntingtin, Amyloid-beta, alpha-Synuclein, islet amyloid polypeptide (IAPP), Sup35, NM25 and NM4, tau, MSP2, semen-derived enhancer of virus infection (SEVI), immunoglobulin light chains, beta-microglobulin, prion protein (PrP) and Insulin, have yielded a variety of experimental observations. Here, we analyze whether these observations could be explained by a common mechanism and give a broad overview of the published experimental data on the actions of EGCG...
2015: Advances in Experimental Medicine and Biology
Qin Zhao, Guo-Dong Chen, Xiao-Lin Feng, Yang Yu, Rong-Rong He, Xiao-Xia Li, Yan Huang, Wen-Xia Zhou, Liang-Dong Guo, Yi-Zhi Zheng, Xin-Sheng Yao, Hao Gao
Eight new viridins, nodulisporiviridins A-H (1-8), were isolated from the extract of an endolichenic fungal strain Nodulisporium sp. (No. 65-17-2-1) that was fermented with potato-dextrose broth. The structures were determined using spectroscopic and X-ray crystallographic analysis. Nodulisporiviridins A-D (1-4) are unique viridins with an opened ring A. The Aβ42 aggregation inhibitory activities of 1-8 were evaluated using a thioflavin T (ThT) assay with epigallocatechin gallate (EGCG) as the positive control (EGCG IC50 of 0...
June 26, 2015: Journal of Natural Products
Heike J Wobst, Apurwa Sharma, Marc I Diamond, Erich E Wanker, Jan Bieschke
The accumulation of amyloid-beta (Aβ) and tau aggregates is a pathological hallmark of Alzheimer's disease. Both polypeptides form fibrillar deposits, but several lines of evidence indicate that Aβ and tau form toxic oligomeric aggregation intermediates. Depleting such structures could thus be a powerful therapeutic strategy. We generated a fragment of tau (His-K18ΔK280) that forms stable, toxic, oligomeric tau aggregates in vitro. We show that (-)-epigallocatechin gallate (EGCG), a green tea polyphenol that was previously found to reduce Aβ aggregation, inhibits the aggregation of tau K18ΔK280 into toxic oligomers at ten- to hundred-fold substoichiometric concentrations, thereby rescuing toxicity in neuronal model cells...
January 2, 2015: FEBS Letters
Kim Kennedy, Michelle A Tucci, Hamed A Benghuzzi
Alzheimer’s disease (AD) is the only cause of death among the top 10 diseases that cannot be prevented, cured, or slowed with the current treatments available. Amyloid beta is thought to be the main initiator of AD cognitive decline, activating internal pathways which lead to inflammation, oxidation, and cell death. The objective of this study was to determine if pretreatment of human SH-SY5Y neuroblastoma cells, a model for AD, with antioxidants thymoquinone (TQ), epigallocatechin-3-gallate (EGCG), or dilinoleoylphosphatidylcholine (DLPC) 30 minutes prior to a challenge with tumor necrosis factor a (TNFa), an inflammatory mediator, can prevent oxidation of amyloid beta (Aß)...
2014: Biomedical Sciences Instrumentation
Hong-Feng Gu, Ya-Xiong Nie, Qiao-Zhen Tong, Ya-Ling Tang, Yang Zeng, Kai-Quan Jing, Xi-Long Zheng, Duan-Fang Liao
Epigallocatechin gallate (EGCG) is a major polyphenol in green tea with beneficial effects on the impairment in learning and memory. Autophagy is a cellular process that protects neurons from stressful conditions. The present study was designed to investigate whether EGCG can rescue chronic unpredictable mild stress (CUMS)-induced cognitive impairment in rats and whether its protective effect involves improvement of autophagic flux. As expected, our results showed that CUMS significantly impaired memory performance and inhibited autophagic flux as indicated by elevated LC3-II and p62 protein levels...
2014: PloS One
Jennifer M Walker, Diana Klakotskaia, Deepa Ajit, Gary A Weisman, W Gibson Wood, Grace Y Sun, Peter Serfozo, Agnes Simonyi, Todd R Schachtman
Alzheimer's disease (AD) is a progressive, age-dependent neurodegenerative disorder affecting specific brain regions that control memory and cognitive functions. Epidemiological studies suggest that exercise and dietary antioxidants are beneficial in reducing AD risk. To date, botanical flavonoids are consistently associated with the prevention of age-related diseases. The present study investigated the effects of 4 months of wheel-running exercise, initiated at 2-months of age, in conjunction with the effects of the green tea catechin (-)-epigallocatechin-3-gallate (EGCG) administered orally in the drinking water (50 mg/kg daily) on: (1) behavioral measures: learning and memory performance in the Barnes maze, nest building, open-field, anxiety in the light-dark box; and (2) soluble amyloid-β (Aβ) levels in the cortex and hippocampus in TgCRND8 (Tg) mice...
2015: Journal of Alzheimer's Disease: JAD
Huan Zhao, Gao-Qian Wang, Xu-Peng Tong, Guo-Dong Chen, Yuan-Fan Huang, Jia-Yu Cui, Ming-Zhu Kong, Liang-Dong Guo, Yi-Zhi Zheng, Xin-Sheng Yao, Hao Gao
Two new compounds with the character of diphenyl ether structure, oxisterigmatocystin D (1) and 9-acetyldiorcinol B (6), were isolated from the endolichenic fungal strain Aspergillus sp. (No. 16-20-8-1), along with six known compounds, oxisterigmatocystin A (2), oxisterigmatocystin C (3), sterigmatocystin (4), diorcinol B (5), violaceol-I (7), and violaceol-II (8). The structures of the new compounds were determined by extensive NMR spectroscopic data, and the absolute configuration of 1 was established by single-crystal X-ray diffraction analysis...
October 2014: Fitoterapia
Jingnan Zhang, Xianbo Zhou, Qianqian Yu, Licong Yang, Dongdong Sun, Yanhui Zhou, Jie Liu
Alzheimer's disease (AD), the most common neurodegenerative disease, is caused by an accumulation of amyloid-β (Aβ) plaque deposits in the brains. Evidence is increasingly showing that epigallocatechin-3-gallate (EGCG) can partly protect cells from Aβ-mediated neurotoxicity by inhibiting Aβ aggregation. In order to better understand the process of Aβ aggregation and amyloid fibril disaggregation and reduce the cytotoxicity of EGCG at high doses, we attached EGCG onto the surface of selenium nanoparticles (EGCG@Se)...
June 11, 2014: ACS Applied Materials & Interfaces
José Antonio Vázquez
BACKGROUNDS: The process of amyloid proteins aggregation causes several human neuropathologies. In some cases, e.g. fibrillar deposits of insulin, the problems are generated in the processes of production and purification of protein and in the pump devices or injectable preparations for diabetics. Experimental kinetics and adequate modelling of chemical inhibition from amyloid aggregation are of practical importance in order to study the viable processing, formulation and storage as well as to predict and optimize the best conditions to reduce the effect of protein nucleation...
2014: BMC Pharmacology & Toxicology
Caroline Menard, Stéphane Bastianetto, Rémi Quirion
Polyphenols such as epigallocatechin gallate (EGCG) and resveratrol have received a great deal of attention because they may contribute to the purported neuroprotective action of the regular consumption of green tea and red wine. Many studies, including those published by our group, suggest that this protective action includes their abilities to prevent the neurotoxic effects of beta-amyloid, a protein whose accumulation likely plays a pivotal role in Alzheimer's disease. Moreover, the scavenging activities of polyphenols on reactive oxygen species and their inhibitory action of cyclooxygenase likely explain, at least in part, their antioxidant and anti-inflammatory activities...
2013: Frontiers in Cellular Neuroscience
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