Immunosuppressive gentianellane-type sesterterpenoids from the traditional Uighur medicine Gentianella turkestanorum

Phytochemistry. 2021 Jul:187:112780. doi: 10.1016/j.phytochem.2021.112780. Epub 2021 Apr 27.

Abstract

Whole plants of Gentianella turkestanorum are commonly used as a traditional Uighur medicine. A phytochemical investigation led to the isolation of eight undescribed gentianellane-type sesterterpenoids (18-epi-nitidasin, gentianelloids D-F, and 18-epi-gentianelloids C-F), one undescribed 11,12-seco-gentianellane (18-epi-alborosin), and three known analogs (nitidasin, gentianelloid C and alborosin) among which gentianelloid C was found for the first time from a natural source. The structures of these compounds were elucidated by extensive spectroscopic analyses (including 1D and 2D NMR, HRMS, IR, and specific rotation) and in the case of 18-epi-gentianelloid C by the single-crystal X-ray diffraction analysis. A putative biosynthetic route for these sesterterpenoids was proposed. The immunosuppressive activity of the isolated compounds was also evaluated by their ability to inhibit the proliferation of T cells and T cell cytokine IFN-γ production. Nitidasin suppressed IFN-γ production with an IC50 value of 16.50 μM, while gentianelloid F and alborosin inhibited the proliferation of and IFN-γ production in T cells with IC50 values of 12.40-14.66 μM.

Keywords: Gentianaceae; Gentianella turkestanorum; Gentianellane-type; Immunosuppressive activity; Plant sesterterpenoids.

MeSH terms

  • Gentianella*
  • Magnetic Resonance Spectroscopy
  • Medicine, Traditional
  • Molecular Structure
  • Phytochemicals

Substances

  • Phytochemicals