Screening of enzyme sources for efficient and specific synthesis of theaflavins, black tea polyphenols.

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K07823
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Food science
• Research Institution: Nippon Veterinary and Life Science University
• Principal Investigator: Narai-Kanayama Asako 日本獣医生命科学大学, 応用生命科学部, 准教授 (00339475)
• Co-Investigator(Kenkyū-buntansha): 中山 勉 東京農業大学, 応用生物科学部, 教授 (50150199)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: テアフラビン / 酵素的合成 / 紅茶 / カテキン

Outline of Final Research Achievements

Theaflavins (TF), characteristic red-orange pigments of black tea infusion, are dimers of selectively combined two catechins. TFs can be synthesized by the polyphenol oxidase (PPO)-catalyzed oxidation of catechins, however, the oxidative conditions cause their further polymerization. The shortage of the purified TF retards the progress of researches on various biological activities of TF and their pharmaceutical applications. Thus, in this study, we conducted the kinetic analyses of enzymatic synthesis of TF using mushroom tyrosinase, which has been often used as a typical model of PPO, to find the reaction conditions required for high-level production of TF. We for the first time indicated that the 1-octanol/buffer biphasic system and the exogenous addition of catalase into the reaction mixture increased TF2A and TF2B, respectively. We also found potential in crude extracts from some plant materials as useful catalysts for the efficient TF synthesis.

Free Research Field

食品科学

Academic Significance and Societal Importance of the Research Achievements

本研究では紅茶テアフラビン類（TF）の酵素的合成反応の速度論的解析から、TFが高収量で得られない反応機構を明らかにするとともに、基質と酵素の疎水性の指標である分配係数に基づいて新たに溶媒－緩衝液二相系という効率的なTF合成法を提案した。また、既往の研究を参考に、酵素を不活化させる副生成物の過酸化水素をカタラーゼ添加によって消去し、TF生成速度と収量を高めるという画期的な反応条件も提案した。また、TF合成に有用な酵素資源を探索し、入手容易な素材と酵素抽出法を見出した。これらの成果は、紅茶の保健機能の研究・応用に必要なTFを安定して供給するシステムの構築に貢献するものである。