Bioactivity guided and random isolation of polyacetylenic compounds from Seseli praecox

• Published in: Planta Medica
• Main Authors: Leonti, M, Gertsch, J, Casu, L, Cottiglia, F, Solinas, MN, Bonsignore, L, Raduner, S, Altmann, KH
• Format: Conference Proceeding
• Language: English
• Published: 21.07.2009
• ISSN: 0032-0943; 1439-0221
• DOI: 10.1055/s-0029-1234333

Seseli praecox (Gramisans) Gramisans, (Apiacaee) is an endemic chamaephyte species from Sardinia. The lipophilic extract of S. praecox stems was subjected to a bioactivity guided fractionation and isolation process with the binding affinity towards human CB receptors as a lead. The activity guided isolation process afforded (R)-falcarinol (panaxynol), which accounted for 12–15% of total crude lipophilic extract. Random isolation afforded the new polyacetylenic compound heptadeca-1-ene-4,6-diyne-3,10-diol (dihydroseselidiol) (fig). With respect to seseldiol reported by [1] dihydroseselidiol differs by the missing double bond between C-8 and C-9. Falcarinol is known for its notorious instability. In order to identify the main degradation products sunlight exposed and freezer stored falcarinol was subjected to HPLC isolation. Falcarinone and E -Heptadeca-1,8-diene-4,6-diyne-3,10-diol were found to be the main oxidation products of sunlight exposed falcarinol, while 4,5-dihydrofalcarinol was found in freezer stored falcarinol. It was shown that only falcarinol elicits allergic contact dermatitis in patch tests, while the degradation products have no allergenic potential [2]. We found that only freshly isolated falcarinol showed CB receptor affinity and that this might be the mechanism of action for its pro-allergenicity. References: [1] Hu, C.Q. et al. (1990)J. Nat. Prod. 53:932–935. [2] Hansen, L. et al. (1986) Phytochemistry 25:285–293.