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Lipids from the guinea pig harderian gland: Use of picolinyl and other pyridine‐containing derivatives to investigate the structures of novel branched‐chain fatty acids and glycerol ethers
Author(s) -
Harvey D. J.
Publication year - 1991
Publication title -
biological mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1052-9306
DOI - 10.1002/bms.1200200204
Subject(s) - chemistry , trimethylsilyl , alkyl , organic chemistry , alkaline hydrolysis , glycerol , branching (polymer chemistry) , hydrolysis , gas chromatography , side chain , stereochemistry , chromatography , polymer
The lipid extracted from guinea pig Harderian glands was hydrolysed and the constituents were examined as trimethylsilyl (TMS), ( 2 H 9 )TMS, methyl ester/TMS, acetonide/TMS, nicotinate/TMS, picolinyl/TMS and nicotinylidene/TMS derivatives by capillary gas‐liquid chromatography and gas chromatography/mass spectrometry. Over 70 compounds amounting to over 93% of the extract were identified. These consisted of 1‐ O ‐alkyl glycerols (glycerol ethers) with alkyl chains containing from 17 to 21 carbon atoms and fatty acids ranging from 14 to 26 carbon atoms. The alkyl chains in the glycerol ethers were straight, mono‐ and dimethyl‐branched with the major site of branching being at C‐14. All straight‐chain acids from C 14 to C 26 were present, with the most abundant being n ‐24:0. Again mono‐ and dimethyl branched structures comprised the bulk of the remaining acids. Methyl groups tended to be towards the middle of the chain rather than in the more usual ω‐1 ( iso ) and ω‐2 ( anteiso ) positions, with C‐14 again being a major site. The shorter‐chain acids tended to have methyl groups closer to the acid group, with several of the short‐chain compounds being substituted at C‐2. Structural information on the acids was provided by the picolinyl derivatives and the sample provided an opportunity to evaluate these derivatives with branched acids other than the iso and anteiso compounds studied previously. They were found to be satisfactory for analysis of both mono‐ and dimethyl branched acids with the possible exception of compounds containing a methyl branch at C‐4. However, in this case, structural information was provided by the methyl ester. Both nicotinate and the new nicotinylidene derivatives were evaluated for analysis of the glycerol ethers. The latter derivatives were superior, giving spectra similar to those given by the picolinyl derivatives of the acids.