Helenynolic acid

Helenynolic acid is a hydroxylated and conjugated unsaturated fatty acid containing both a double and a triple bond. The acid belongs to the class of alkyne and alkenoic acids, as well as to the enynes. It is optically active with a negative rotation, i.e., levorotatory.
The delta notation is S-9-OH-18:2Δ10t,12a.

Discovery

The acid was initially isolated in 1965 from the glycerides of the seed oil of Helichrysum bracteatum of the Asteraceae family, by R. G. Powell and others.
Helenynolic acid occurs in enantiomerically pure form in Xerochrysum bracteatum. In some seeds, heleninolic acid is formed by oxidation during storage, e.g., in those of Crepis vesicaria from the genus Crepis.
The acid's presence has also been confirmed among the lipids of Helichrysum italicum.

Synthesis

Racemic heleninolic acid can be synthesized starting from methyl oleate. Ozonolysis of this methyl oleate yields methyl 9-oxononanoate. Its carbon chain is extended by acetylene and 1-bromohept-1-yne, thereby forming a compound with two triple bonds. One of the triple bonds is reduced using lithium aluminum hydride.

Uses

Studies on helenynolic acid and related compounds frequently explore their possible therapeutic uses. Fatty acids containing distinct functional groups, such as hydroxy and alkyne groups, have been shown to possess anti-inflammatory, antimicrobial, and anticancer properties. These characteristics position them as promising options for creating novel medications or dietary supplements.