Eremane, viscidane and isozizaene diterpenoids from the leaves of Eremophila rigida and their absolute configurations

Chao Liang, Chi Ndi, Susan J. Semple, Bevan Buirchell, Sonia Coriani, Birger Lindberg Møller, Dan Staerk*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

Previously undescribed eremane, viscidane, and isozizaene diterpenoids, eremorigidanes A-F, along with six known O-methylated flavonoids and three known triterpenoids were isolated and identified from the leaves of Eremophila rigida Chinnock by combined use of high-resolution PTP1B inhibition profiling, semipreparative- and analytical-scale HPLC separations, HPLC-PDA-HRMS analysis, and NMR spectroscopy. The absolute configuration of the unreported diterpenoids were determined by comparison of their experimental and calculated ECD spectra as well as by biosynthetic arguments. All isolates were evaluated for their PTP1B inhibitory activities, which revealed the flavonoid penduletin (3) to show inhibition with an IC50 value of 18.3 μM, and the triterpenoids 3,4-seco-olean-12-ene-3,28-dioic acid (15), oleanolic acid (16), and 3-oxo-oleanolic acid (17) to show inhibition with IC50 values of 55.7, 9.9, and 6.3 μM, respectively. The preliminary structure-activity relationship (SAR) of isolated flavonoids and triterpenoids is discussed. Plausible biosynthetic steps involved in eremane and isozizaene metabolism are presented and discussed.

Original languageEnglish
Article number113972
JournalPhytochemistry
Volume219
Number of pages16
ISSN0031-9422
DOIs
Publication statusPublished - 2024

Keywords

  • Eremane diterpenoid
  • Eremophila rigida Chinnock
  • High-resolution inhibition profiling
  • Isozizaene diterpenoid
  • Protein tyrosine phosphatase 1B inhibitors
  • Scrophulariaceae
  • Viscidane diterpenoid

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