Stereoselectivity in Oxidative Dimerization of Catechins during Tea-fermentation

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K07741
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Food science
• Research Institution: Nagasaki University
• Principal Investigator: MATSUO Yosuke 長崎大学, 医歯薬学総合研究科(薬学系), 助教 (10432981)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 紅茶 / カテキン / DFT計算 / 分子間相互作用

Outline of Final Research Achievements

Detailed mechanism of oxidative dimerization of catechins during black tea manufacturing was investigated. Dimerization of pyrogallol-type catechins affords dehydrotheasinensins stereoselectively. DFT optimization of dehydrotheasinensin C suggested that the selectivity was accounted for intramolecular π-π stacking between two A-rings in aqueous solution.
On the other hand, oxidative coupling between pyrogallol-type and catechol-type catechins affords theaflavins with a benzotropolone chromophore. Plane structure of the chromophore is produced via a bicyclo[3.2.1]octane-type intermediate, and formation of the intermediate was non-stereoselective coupling between catechol quinone and pyrogallol.

Free Research Field

天然物化学、食品化学

Academic Significance and Societal Importance of the Research Achievements

紅茶製造過程におけるポリフェノール成分の化学変化機構が解明されたことは、有機化学的観点からも高い意義があるだけでなく、紅茶の食品としての生理機能性を解明する基盤となる結果であり、大きな意義を持つ。複雑な組成を有するポリフェノール含有食品の生理機能成分解明が今後さらに進むことが期待される。