105(P-44) エピガロカテキンの新しい酵素酸化機構(ポスター発表の部)

概要

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Enzymatic oxidation of epigallocatechin yielded dehydrotheasinensin C and a highly oxidized epigallocatechin dimer (TQ). Dehydrotheasinensin C yielded theasinensins C and E and desgalloyloolongtheanin by oxidation-reduction dismutation under neutral conditions; therefore, dehydrotheasinensin C is a precursor of the black tea polyphenols. The spectroscopic analysis of the other epigallocatechin dimer TQ revealed that it has a bicyclo[5.4.0]undecane skeleton with four ketone carbon equivalents and a carboxyl carbon. After enzymatic oxidation of epigallocatechin, treatment of the reaction mixture with o-phenylenediamine yielded seven phenazine derivatives derived from TQ and its decarboxyl analog. Structures of the derivatives confirmed that TQ and its decarboxyl analog exist as equilibrium mixtures of several isomers. The results indicated presence of a new oxidation route of epigallocatechin, which was related to the mechanism of theaflavin synthesis from epicatechin and epigallocatechin.
天然有機化合物討論会の論文
2004-10-01