Acid-catalyzed isomerization of fucosterol and delta5-avenasterol.
This work shows that fucosterol, delta5-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 delta5-avenasterol, two delta5,23-stigmastadienols, and delta5,24(25)-stigmastadienol. When the unsaponifiables fraction from oat oil was subjected to acid hydrolysis, the two delta5,23-stigmastadienol isomers and delta5,24(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.
Kamal-Eldin
A
A
Department of Food Science, Swedish University of Agricultural Sciences (SLU), Uppsala. Afaf.Kamal-Eldin@Imv.slu.se
Määttä
K
K
Toivo
J
J
Lampi
A M
AM
Piironen
V
V
D000924:Anticholesteremic Agents / Q000737:chemistry; D018554:Avena / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry; D006868:Hydrolysis; D007536:Isomerism; D012639:Seeds / Q000737:chemistry; D013265:Stigmasterol / Q000031:analogs & derivatives* / Q000737:chemistry
D000924:Anticholesteremic Agents; C015896:fucosterol; D013265:Stigmasterol