Tropolone Ring Construction in the Biosynthesis of Rubrolone B, a Cationic Tropolone Alkaloid from Endophytic Streptomyces

  • Org Lett. 2016 Mar 18;18(6):1254-7. doi: 10.1021/acs.orglett.6b00074.
Yijun Yan  1 ,  Ya-Tuan Ma  1 ,  Jing Yang  1 ,  Geoff P Horsman  2 ,  Dan Luo  1 ,  Xu Ji  1 ,  Sheng-Xiong Huang  1
Affiliations
  • 1. State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences , Kunming 650201, China.
  • 2. Department of Chemistry & Biochemistry, Wilfrid Laurier University , Waterloo, ON N2L 3C5, Canada.
PMID: 26926531 DOI: 10.1021/acs.orglett.6b00074
Abstract

Rubrolones are tropolonoid natural products with a unique carbon skeleton. Extensive secondary metabolite analysis of the endophytic Streptomyces sp. KIB-H033 revealed a new class of rubrolone analogue possessing a rare benzoic acid-pyridine inner salt moiety. Precursor feeding with [(13)C]-acetate revealed a labeling pattern consistent with tropolone moiety construction via type-II PKS chemistry followed by complex oxidative rearrangements. This Bacterial biosynthetic route represents a surprising departure from Fungal tropolone assembly during stipitatic acid biosynthesis.

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