Acid‐catalyzed isomerization of fucosterol and Δ5‐avenasterol

Publisher Website
Google Scholar
Abstract
This work shows that fucosterol, Δ5‐avenasterol, and similar ethylidene‐side chain sterols can undergo acid‐catalyzed isomerization to give a mixture of five isomers. Four isomers formed from fucosterol were analyzed, using gas chromatography‐mass spectrometry, and were characterized as Δ5‐avenasterol two Δ5,23‐stigmastadienols, and Δ5,24(250)‐stigmastadienol. When the unsaponifiables fraction from oat oil was subjected to acid hydrolysis, the two Δ5,23‐stigmastadienol isomers and Δ5,24(25)‐stigmastadienol were detected while fucosterol coeluted with sitosterol. Interisomerization of ethylidene‐side chain sterols represents a limitation to the use of the acid hydrolysis method in the determination of sterols in food and other plant materials rich in these sterols, e.g., oat lipids.