| Abstract
| - Because a great deal of attention has been focused on the metabolism of (−)-epigallocatechin gallate(EGCg), quantitative analysis of this compound is required. For this purpose we developed a methodof chemical synthesis of [4-3H]EGCg. Synthesized [4-3H]EGCg showed 99.5% radiochemical purityand a specific activity of 13 Ci/mmol. To clarify the excretion route of EGCg, the radioactivity levelsof bile and urine were quantified after intravenous administration of [4-3H]EGCg to bile-duct-cannulated rats. Results showed that the radioactivity of the bile sample excreted within 48 haccounted for 77.0% of the dose, whereas only 2.0% of the dose was recovered in the urine. Theexcretion ratio of bile to urine was calculated to be about 97:3. These results clearly showed thatbile was the major excretion route of EGCg. Time-course analysis of the radioactivity in blood wasalso performed to estimate the pharmacokinetic parameters following intravenous administrationof [4-3H]EGCg. In addition, EGCg metabolites excreted in the bile within 4 h after the intravenousdose of [4-3H]EGCg were analyzed by HPLC. The results showed that 4‘,4‘ ‘-di-O-methyl-EGCg waspresent in the conjugated form and made up about 14.7% of the administered radioactivity. Keywords: (−)-Epigallocatechin gallate; (−)-[4-3H]epigallocatechin gallate; catechin; tea; biliaryexcretion
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