A novel synthetic pathway for tropolone ring formation via the olefin monoterpene intermediate terpinolene in cultured Cupressus lusitanica cells

Koki Fujita, Yasufumi Bunyu, Ken'ich Kuroda, Tatsuya Ashitani, Jun Shigeto, Yuji Tsutsumi

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

β-Thujaplicin is a wood monoterpene and tropolone compound with a unique conjugated 7-membered ring. Because of its strong antifungal and antitumor activities, β-thujaplicin is used in several fields. The biosynthesis pathway of β-thujaplicin has not yet been elucidated. Using Cupressus lusitanica cell cultures in a radioisotope feeding experiment, our group previously demonstrated that geranyl pyrophosphate (GPP) is the starting material of β-thujaplicin biosynthesis. The results of our previous terpene synthase assay suggested that terpinolene is the first olefin terpenoid intermediate from GPP to β-thujaplicin, although there was no experimental evidence of this at that time. In the present study, we fed deuterium-labeled terpinolene to cultured C. lusitanica cells to determine whether terpinolene is an intermediate metabolite of β-thujaplicin biosynthesis. A gas chromatography-mass spectroscopy analysis of the cell extracts from labeled terpinolene cultures revealed a peak of labeled β-thujaplicin that was not observed after treatment with non-labeled terpinolene. The identification of labeled β-thujaplicin was also performed by mass spectrum assignment. The outcome indicated that terpinolene is indeed an intermediate metabolite of β-thujaplicin biosynthesis. To the best of our knowledge, there has been no prior report that tropolone compounds are biosynthesized via a terpene biosynthesis system, and our results thus suggest the existence of a novel biosynthetic pathway that produces the conjugated 7-membered ring.

Original languageEnglish
Pages (from-to)610-614
Number of pages5
JournalJournal of Plant Physiology
Volume171
Issue number8
DOIs
Publication statusPublished - May 1 2014

All Science Journal Classification (ASJC) codes

  • Physiology
  • Agronomy and Crop Science
  • Plant Science

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