9,12,15‐octadecatrien‐6‐ynoic acid, new acetylenic acid from mosses

Abstract Lipids of the moss, Ceratodon purpureus , yield up to 25% of an acetylenic acid which was identified as all cis ‐9,12,15‐octadecatrien‐6‐ynoic acid. The methyl ester of this acid was isolated in 95% purity by gas liquid chromatography. Mass spectroscopy provided the mol wt and confirmed methyl stearate as product of hydrogenation. Ozonization indicated a triple bond in position 6 and a double bond in position 15. UV and IR spectra showed cis ‐double bonds, no conjugation, and no trans ‐double bonds. The Raman spectrum provided direct evidence for the triple bond and confirmed the presence of double bonds and the absence of conjugation. The ratio of intensities indicated 1 triple bond/3 double bonds. 9,12,15‐Octadecatrien‐6‐ynoic acid has not previously been isolated from biological materials. It was found only in the triglycerides of Ceratodon purpureus and several other mosses. In contrast to arachidonic and eicosapentaenoic acids, the acetylenic acid seems to be restricted to few moss genera.