Short Communication Formation and Identification of 4*-O-Methyl-(2)-Epigallocatechin in Humans
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چکیده
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 (2)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-(2)-epigallocatechin (4*-O-MeEGC) by H and C 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 6 0.07 and 4.39 6 1.14 h, respectively. The amount of 4*-OMeEGC 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 activ-
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تاریخ انتشار 2001