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Acid‐catalyzed isomerization of fucosterol and Δ 5 ‐avenasterol
Author(s) -
KamalEldin Afaf,
Määttä Kaisu,
Toivo Jari,
Lampi AnnaMaija,
Piironen Vieno
Publication year - 1998
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-998-0307-6
Subject(s) - isomerization , chemistry , hydrolysis , sterol , acid hydrolysis , chromatography , mass spectrometry , catalysis , organic chemistry , biochemistry , cholesterol
This work shows that fucosterol, Δ 5 ‐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 Δ 5 ‐avenasterol two Δ 5,23 ‐stigmastadienols, and Δ 5,24(250) ‐stigmastadienol. When the unsaponifiables fraction from oat oil was subjected to acid hydrolysis, the two Δ 5,23 ‐stigmastadienol isomers and Δ 5,24(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.