Details

Autor(en) / Beteiligte

• Rubin, David
• Sansom, Catherine E.
• Richards, David J.
• Lucas, Nigel T.
• Garden, Anna L.
• Saldivia Pérez, Patricio R.
• Lord, Janice M.
• Perry, Nigel B.

Titel

Halimane Diterpenes in the Alpine Daisy Celmisia viscosa: Absolute Configuration, 2,6-Dideoxyhexopyran-3-ulosides, Conformational Flexibility, and Intraspecific Variation

Ist Teil von

• Journal of natural products (Washington, D.C.), 2022-08, Vol.85 (8), p.1893-1903

Ort / Verlag

American Chemical Society and American Society of Pharmacognosy

Erscheinungsjahr

2022

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The methyl-migrated bicyclic skeleton of the halimane diterpenes has been found in a wide range of organisms, including flowering plants, liverworts, marine animals, and bacteria. The discovery of halima-1(10),14-dien-13-ol (3) from the Aotearoa New Zealand endemic alpine daisy Celmisia viscosa is now reported. The full configuration was assigned for the first time by X-ray crystallography, enantiomeric to that of a liverwort isolate. The absolute configuration at C-5 of the halimane is opposite to that at C-5 of the labdane epimanool (1) found in some C. viscosa specimens. Two new 2,6-dideoxyhexopyran-3-uloside halimane derivatives (4 and 5) were also found, and the absolute configuration of 5 was determined by 1H NMR analysis of the Mosher esters. Line broadening in the 13C NMR spectra of these halim-1(10)-enes was due to conformational exchange in the decalin ring A, as shown by molecular modeling and DFT calculations. 1H NMR and GC analyses of leaf extracts of individual plants from across the full geographic range of C. viscosa revealed intraspecific variation of diterpenes: 37 samples had halimadienol as the main diterpene in large amounts and 2 specimens had predominantly epimanool, again in large amounts. Three other viscid (sticky leaved) Celmisia species also contained diterpenes, but none was detectable in four nonviscid Celmisia species.