Tea Polyphenol (−)-Epigallocatechin-3-Gallate: A New Trapping Agent of Reactive Dicarbonyl Species

作者：Shengmin Sang, Xi Shao, Naisheng Bai, Chih‐Yu Lo, Chung Shu Yang, Chi‐Tang Ho · 发表于：Chemical Research in Toxicology · 年份：2007 · DOI：10.1021/tx700190s · 被引用次数：214 · 研究领域：Advanced Glycation End Products research、Tea Polyphenols and Effects、Biochemical effects in animals

Previous studies have demonstrated that reactive dicarbonyl compounds [e.g., methylglyoxal (MGO) and glyoxal (GO)] irreversibly and progressively modify proteins over time and yield advanced glycation end products (AGEs), which are thought to contribute to the development of diabetes mellitus and its subsequent complications. Thus, decreasing the levels of MGO and GO will be an effective approach to reduce the formation of AGEs and the development of diabetic complications. In our studies to find nontoxic trapping agents of reactive dicarbonyl species from dietary sources, we found that (-)-epigallocatechin-3-gallate (EGCG), the major bioactive green tea polyphenol, could efficiently trap reactive dicarbonyl compounds (MGO or GO) to form mono- and di-MGO or GO adducts under physiological conditions (pH 7.4, 37 degrees C). The products formed from EGCG and MGO (or GO), combined at different ratios, were analyzed using LC/MS. We also developed a method to purify the two major mono-MGO adducts of EGCG without derivatization, and their structures were identified as stereoisomers of mono-MGO adducts of EGCG based on their 1D and 2D NMR spectra. Our LC/MS and NMR data showed that positions 6 and 8 of the EGCG A-ring were the major active sites for trapping reactive dicarbonyl compounds. We also found that EGCG lost its trapping efficacy under acidic conditions (pH