Ellagitannin biosynthesis via non-enzymatic quinone dimerization and redox dismutation

2016 Fiscal Year Final Research Report

• Project/Area Number: 26460125
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Natural medicines
• Research Institution: Nagasaki University
• Principal Investigator: TANAKA Takashi 長崎大学, 医歯薬学総合研究科(薬学系), 教授 (90171769)
• Co-Investigator(Renkei-kenkyūsha): MATSUO Yosuke 長崎大学, 医歯薬学総合研究科(薬学系), 助教 (10432981) ; SAITO Yoshinori 長崎大学, 医歯薬学総合研究科(薬学系), 准教授 (30441588)
• Research Collaborator: KOJIMA Daisetu ; WAKAMATSU Hatsumi ; ERA Manami ; TSUJITA Takaaki ; SHII Takuya
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: エラジタンニン / 生合成 / 酸化還元不均化 / キノン / 紅茶 / ポリフェノール / タンニン

Outline of Final Research Achievements

Ellagitannins have hexahydroxydiphenoyl (HHDP) esters, and biogenesis of which was thought to be simple oxidative couplings between two galloyl esters. However, the HHDP esters in the leaves of Carpinus sp. were generated reductively from dehydrohexahydroxydiphenoyl (DHHDP) esters. Similar reductive metabolism were also observed in the leaves of Sapium sp. and Punica sp. Purified DHHDP esters isolated Carpinus sp. and Sapium sp. were spontaneously decomposed to give HHDP esters in aqueous solution. The reaction is non-enzymatic and probably proceed by the reduction-oxidation dismutation mechanism. The results may propose a new biosynthetic mechanisms of ellagitannins.

Free Research Field

天然物化学