P-69 Production Mechanism of Black Tea Polyphenols : Catechin Oxidation Cascade

Matsuo Yosuke, Li Yan, Tanaka Takashi, Kouno Isao

doi:10.24496/tennenyuki.47.0_437

Bibliographic Information

Other Title

P-69 紅茶ポリフェノールの生成機構 : カテキン酸化カスケード(ポスター発表の部)

Abstract

Enzymatic oxidation of epigallocatechin and its gallate, as a model of fermentation process of black tea production, provided valuable information on catechin oxidation. Coupling of B-ring o-quinones afforded dehydrotheasinensin A, a quinone dimer having hydrated triketone structure, which undergo oxidation-reduction dismutation to yield theasinensins and oolongtheanins. We have now succeeded to show production of analogous catechin trimers having two hydrated triketone moieties produced by oxidative coupling between a galloyl group of dehydrotheasinensin A and epigallocatechin B-ring. It is presumed that dismutation reaction of the trimers affords complex mixtures of dismutation products and it may explain the complexity of black tea polyphenols. In addition, new formation mechanism of benzotropolone pigments was disclosed. In the mechanism, oxidative condensation between two pyrogallol B-rings gave an unstable compound having hydrated bicyclo[5,4,0]undeca-1,2,7,8,9-pentaoxo-3-ene moiety. On heating, the compound converted to epitheaflagallin and hydroxytheaflavin, which are known and new benzotropolone pigments, respectively. Furthermore, a novel quinone dimer of epigallocatechin-3-O-gallate was isolated, which have a caged structure formed by successive aldol-type C-C bond formation between two B-ring o-quinones.

Journal

Symposium on the Chemistry of Natural Products, symposium papers

Symposium on the Chemistry of Natural Products, symposium papers 47 (0), 437-442, 2005

Symposium on the Chemistry of Natural Products Steering Committee

Details 詳細情報について

CRID: 1390001206078622720

NII Article ID: 110006682585

DOI: 10.24496/tennenyuki.47.0_437

ISSN: 24331856

Text Lang: ja

Data Source

JaLC
CiNii Articles

Abstract License Flag: Disallowed

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