title: Monoepoxy octadecadienoates and monoepoxy octadecatrienoates 2: mass spectral characterization.
abstract: Methyl esters of C18 polyunsaturated fatty acids, including gamma-linolenic acid, alpha-linolenic acid and stearidonic acid, were epoxidised using m-chloroperbenzoic acid. Nine monoepoxides were obtained by normal-phase HPLC, identified using LC-MS and NMR, and characterized by NMR spectroscopy and mass spectrometry. This study is focused on structural characterization using LC-MS and LC/APCI/MS/MS. The elution profiles of these monoepoxides in RP-HPLC are determined as 12,13->9,10->6,7-epoxy, 9,10->15,16->12,13-epoxy and 15,16->12,13->9,10-epoxy derivatives of gamma-linolenic, alpha-linolenic and stearidonic acid methyl esters, respectively. The major diagnostic fragmentations in MS/MS identified are postulated to be induced by cleavages of the epoxide ring and alpha-bond cleavage to the epoxy group from [M+H]+ and/or [M+H-MeOH]+.
authors.affiliation: Pharmacogenomics, Faculty of Pharmacy, University of Sydney, NSW 2006, Australia.
authors.forename: Pei H
authors.initials: PH
authors.lastname: Cui
authors.forename: Rujee K
authors.initials: RK
authors.lastname: Duke
authors.forename: Bruce N
authors.initials: BN
authors.lastname: Tattam
authors.forename: Colin C
authors.initials: CC
authors.lastname: Duke
mesh_terms: D001671:Biochemistry / Q000379:methods*; D001703:Biophysics / Q000379:methods*; D002723:Chlorobenzoates / Q000737:chemistry; D002853:Chromatography, Liquid / Q000379:methods; D004852:Epoxy Compounds / Q000737:chemistry*; D005227:Fatty Acids / Q000737:chemistry*; D007477:Ions; D013058:Mass Spectrometry / Q000379:methods*; D008956:Models, Chemical; D008968:Molecular Conformation; D008970:Molecular Weight; D010100:Oxygen / Q000737:chemistry; D013997:Time Factors
chemical_list: D002723:Chlorobenzoates; D004852:Epoxy Compounds; D005227:Fatty Acids; D007477:Ions; C000433:3-chloroperbenzoic acid; D010100:Oxygen