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标题：Characterization of cis-9 trans-11 trans-15 C18:3 in milk fat by GC and covalent adduct chemical ionization tandem MS
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作者：Pilar Gómez-Cortés ; Cynthia Tyburczy ; J. Thomas Brenna 等
期刊名称：JLR Papers In Press
印刷版ISSN：0022-2275
电子版ISSN：1539-7262
出版年度：2009
卷号：50
期号：12
页码：2412-2420
DOI：10.1194/jlr.M800662-JLR200
语种：English
出版社：American Society for Biochemistry and Molecular Biology
摘要：Rumen biohydrogenation of dietary α-linolenic acid gives rise in ruminants to accumulation of fatty acid intermediates, some of which may be transferred into milk. Rumelenic acid [ cis -9 trans -11 cis -15 C18:3 (RLnA)] has recently been characterized, but other C18:3 minor isomers are still unknown. The objective of this work was to identify a new isomer of octatridecenoic acid present in milk fat from ewes fed different sources of α-linolenic acid. Structural characterization of this fatty acid was achieved by GC-MS. Analysis of dimethyloxazoline and picolinyl ester derivatives allowed for location of the double bond positions. Covalent adduct chemical ionization tandem mass spectrometry confirmed the positional structure 9-11-15, identical to RLnA, and helped to establish double bond geometry ( cis-trans-trans ). This new C18:3 isomer could be formed by isomerization of cis -15 bond of RLnA and subsequently converted by hydrogenation to trans -11 trans -15 C18:2, an octadecadienoic acid also detected in this study.
关键词：fatty acid ; α-linolenic acid ; conjugated linoleic acid ; ewe ; biohydrogenation intermediate ; vaccenic acid ; gas chromatography ; mass spectrometry