title: Neuroprotective effects of green and black teas and their catechin gallate esters against beta-amyloid-induced toxicity.
abstract: Teas represent a large family of plants containing high amounts of polyphenols that may confer health benefits in various diseases. Recently, it has been hypothesized that tea consumption may also reduce the risk of age-related neurodegenerative pathologies. Considering the deleterious role of beta-amyloid (Abeta) in the aetiology of Alzheimer's disease (AD), we investigated green and black tea extracts and flavan-3-ols (present as monomers and dimers in green and black forms, respectively) against toxicity induced by Abeta-derived peptides using primary cultures of rat hippocampal cells as model. Both green and black tea extracts (5-25 microg/mL) displayed neuroprotective action against Abeta toxicity. These effects were shared by gallic acid (1-20 microm), epicatechin gallate (ECG; 1-20 microM) and epigallocatechin gallate (EGCG; 1-10 microM), the former being the most potent flavan-3-ol. In contrast, epicatechin and epigallocatechin were ineffective in the same range of concentrations. Moreover, only tea flavan-3-ol gallate esters (i.e. ECG, EGCG) and gallic acid inhibited apoptotic events induced by Abeta(25-35). Interestingly, EGCG and gallic acid inhibited Abeta aggregation and/or the formation of Abeta-derived diffusible neurotoxin ligands. Taken together, these results indicate that the catechin gallates (through the galloyl moiety) contribute to the neuroprotective effects of both green and black teas. Moreover, the protective effect of EGCG is likely to be associated, at least in part, with its inhibitory action on Abeta fibrils/oligomers formation. These data also support the hypothesis that not only green but also black teas may reduce age-related neurodegenerative diseases, such as AD.
authors.affiliation: Douglas Hospital Research Centre, Department of Psychiatry, McGill University, 6875 Blvd LaSalle, Verdun, Québec, Canada H4H 1R3.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Bastianetto
authors.forename: Zhi-Xing
authors.initials: ZX
authors.lastname: Yao
authors.forename: Vassilios
authors.initials: V
authors.lastname: Papadopoulos
authors.forename: Rémi
authors.initials: R
authors.lastname: Quirion
mesh_terms: D016229:Amyloid beta-Peptides / Q000037:antagonists & inhibitors / Q000633:toxicity*; D000704:Analysis of Variance; D000818:Animals; D001562:Benzimidazoles; D002148:Calmodulin-Binding Proteins / Q000378:metabolism; D002392:Catechin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004622:Embryo, Mammalian; D005419:Flavonoids / Q000494:pharmacology*; D015200:Fluoroimmunoassay / Q000379:methods; D006624:Hippocampus / Q000166:cytology; D009474:Neurons / Q000187:drug effects*; D018696:Neuroprotective Agents / Q000737:chemistry / Q000494:pharmacology*; D010446:Peptide Fragments / Q000037:antagonists & inhibitors / Q000633:toxicity; D010936:Plant Extracts / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D013778:Tetrazolium Salts; D013844:Thiazoles; D000099291:Adducins
chemical_list: D016229:Amyloid beta-Peptides; D001562:Benzimidazoles; D002148:Calmodulin-Binding Proteins; D002392:Catechin; D005419:Flavonoids; D018696:Neuroprotective Agents; D010446:Peptide Fragments; D010936:Plant Extracts; D017382:Reactive Oxygen Species; D013778:Tetrazolium Salts; D013844:Thiazoles; C102021:ADD3 protein, human; D000099291:Adducins; C075222:amyloid beta-protein (1-42); C074636:amyloid beta-protein (25-35); C404987:flavan-3-ol; C417939:catechin gallate; C022616:thiazolyl blue; C017807:bisbenzimide ethoxide trihydrochloride