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Author Zhu, Yingdong
Author Zhao, Yantao
Author Wang, Pei
Author Ahmedna, Mohamed
Author Ho, Chi-Tang
Author Sang, Shengmin
Available date 2017-02-23T07:30:27Z
Publication Date 2015-01
Publication Name Chemical Research in Toxicologyen_US
Citation Tea Flavanols Block Advanced Glycation of Lens Crystallins Induced by Dehydroascorbic Acid Yingdong Zhu, Yantao Zhao, Pei Wang, Mohamed Ahmedna, Chi-Tang Ho, and Shengmin Sang Chemical Research in Toxicology 2015 28 (1), 135-143en_US
ISSN 0893-228X
Abstract 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. Among these four flavanols, EGCG exerted the strongest trapping efficacy by capturing approximate 80% of DASA within 60 min. We successfully purified and identified seven 6C- or 8C-ascorbyl conjugates of flavanols from the chemical reaction between tea flavanols and DASA under slightly basic conditions. Of which, five ascorbyl conjugates, EGCGDASA-2, EGCDASA-2, ECGDASA-1, ECGDASA-2 and ECDASA-1, were recognized as novel compounds. The NMR data showed that positions 6 and 8 of the ring A of flavanols were the major active sites for trapping DASA. We further demonstrated that tea flavanols could effectively inhibit the formation of DASA-induced AGEs via trapping DASA in the bovine lens crystallin-DASA assay. In this assay, 8C-ascorbyl conjugates of flavanols were detected as the major adducts using LCMS. This study suggests that daily consumption of beverages containing tea flavanols may prevent protein glycation in the lens induced by ascorbic acid and its oxidized products.en_US
Sponsor Qatar National Research Fund NPRP no. 5-220-3-063en_US
Language enen_US
Publisher American Chemical Societyen_US
Subject Teaen_US
Subject Glycationen_US
Subject Falvanoidsen_US
Title Tea flavanols block advanced glycation of lens crystallins induced by dehydroascorbic aciden_US
Type Articleen_US
Pagination 135–143
Issue Number 1
Volume Number 28

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