PT - JOURNAL ARTICLE AU - Xiaofeng Meng AU - Mao-Jung Lee AU - Chuan Li AU - Shuqun Sheng AU - Nanqun Zhu AU - Shengmin Sang AU - Chi-Tang Ho AU - Chung S. Yang TI - Formation and Identification of 4′-<em>O</em>-Methyl-(−)-Epigallocatechin in Humans DP - 2001 Jun 01 TA - Drug Metabolism and Disposition PG - 789--793 VI - 29 IP - 6 4099 - http://dmd.aspetjournals.org/content/29/6/789.short 4100 - http://dmd.aspetjournals.org/content/29/6/789.full SO - Drug Metab Dispos2001 Jun 01; 29 AB - The possible beneficial effects of tea consumption have attracted a great deal of attention. Many of the biological effects have been attributed to tea catechins, but the metabolic fate of these compounds is not clear. In the present study, a major metabolite observed in human blood and urine samples after green tea administration was identified as a O-methylated derivative of (−)-epigallocatechin (EGC) by comparison with products from chemical and enzymatic O-methylation of EGC. The structure of this metabolite was elucidated as 4′-O-methyl-(−)-epigallocatechin (4′-O-MeEGC) by 1H and 13C NMR and heteronuclear multiple bond connectivity experiment. The human plasma level of 4′-O-MeEGC reached its peak value within the first 2 h following tea ingestion. Its maximum concentration was 4 to 6 times higher than that of EGC. The half-lives of EGC and 4′-O-MeEGC in the blood were 1.02 ± 0.07 and 4.39 ± 1.14 h, respectively. The amount of 4′-O-MeEGC excreted in urine was about 3 times higher than that of EGC, and 88% of 4′-O-MeEGC was excreted in urine within 8 h. The present structural information and concentration-time profile of this metabolite provide the basis for understanding the biotransformation of EGC and for future elucidation of its biological activities. The American Society for Pharmacology and Experimental Therapeutics