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)

• 松尾 洋介

  長崎大院医歯薬総合

• 李 岩

  長崎大院医歯薬総合

• 田中 隆

  長崎大院医歯薬総合

• 河野 功

  長崎大院医歯薬総合

書誌事項

タイトル別名

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

抄録

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.

収録刊行物

• 天然有機化合物討論会講演要旨集

  天然有機化合物討論会講演要旨集 47 (0), 437-442, 2005

  天然有機化合物討論会実行委員会

詳細情報

• CRID: 1390001206078622720
• NII論文ID: 110006682585
• DOI: 10.24496/tennenyuki.47.0_437
• ISSN: 24331856
• 本文言語コード: ja
• データソース種別:
  • JaLC
  • CiNii Articles
• 抄録ライセンスフラグ: 使用不可