title: The mechanism of oleic acid nitration by *NO(2).
abstract: Fatty acid nitration is a recently discovered process that generates biologically active nitro lipids; however, its mechanism has not been fully characterized. For example, some structural details such as vinyl and allyl isomers of the nitro fatty acids have not been established. To characterize lipids that originated from a biomimetic reaction of *NO(2) with oleic acid, we synthesized several isomers of nitro oleic acids and studied their chromatography and mass spectra by various techniques of mass spectrometry. LC/MS analysis performed on a high resolution micro column detected molecular carboxylic anions of various oleic acid nitro isomers (NO(2)OA). Esterification of NO(2)OA with pentafluorobenzyl bromide and diisopropylethylamine as a catalyst produced a unique isoxazole ester derivative exclusively from allyl NO(2)OA isomers via dehydration of the nitro group at ambient temperatures. This new analytical procedure revealed that *NO(2) generated two vinyl and two allyl isomers of NO(2)OA. The vinyl isomers showed high regioselectivity with the 1.8:1 preference for the 10-NO(2)OA isomer that was absent among allylic isomers. The nitration also generated elaidic acid via cis-trans isomerization and diatereoisomers of vicinal nitro hydroxy, nitro keto and alpha-nitro epoxy stearic acids with high stereo and regioselectivity. Nitration of small unilamelar phospholipid vesicles resulted in several phospholipids containing nitro lipids and elaidic acid amenable to hydrolysis by phospholipase A(2).
authors.affiliation: New York Medical College, Valhalla, NY 10595, USA.
authors.forename: Kavita
authors.initials: K
authors.lastname: Jain
authors.forename: Anjaiah
authors.initials: A
authors.lastname: Siddam
authors.forename: Archana
authors.initials: A
authors.lastname: Marathi
authors.forename: Uzzal
authors.initials: U
authors.lastname: Roy
authors.forename: J R
authors.initials: JR
authors.lastname: Falck
authors.forename: Michael
authors.initials: M
authors.lastname: Balazy
mesh_terms: D002851:Chromatography, High Pressure Liquid; D005609:Free Radicals; D008401:Gas Chromatography-Mass Spectrometry; D007536:Isomerism; D009585:Nitrogen Dioxide / Q000737:chemistry* / Q000378:metabolism; D019301:Oleic Acid / Q000737:chemistry* / Q000378:metabolism
chemical_list: D005609:Free Radicals; D019301:Oleic Acid; D009585:Nitrogen Dioxide