The acid-promoted reaction of ethyl linoleate with nitrite. New insights from 15N-labelling and peculiar reactivity of a model skipped diene

Red cell membrane and plasma linoleic acid nitration products: Synthesis, clinical identification, and quantitation

“…This ''molecular lens'' effect that is induced by solvation in hydrophobic cell compartments accelerates the reaction of • NO with O 2 to yield N 2 O 3 and N 2 O 4 . As a consequence of this diversity of • NO reactions with partially reduced oxygen species, a rich spectrum of products is formed that orchestrates target molecule oxidation, nitrosation, and nitration reactions.Multiple mechanisms account for the nitration of fatty acids by• NO-derived species (15)(16)(17)(18)(19)(20). During both basal cell-signaling and tissue-inflammatory conditions, • NO 2 that is generated by the aforementioned reactions can react with membrane and lipoprotein lipids.…”

“…During the unique oxidationreduction conditions of inflammation or ischemia-reoxygenation, tissue O 2 levels are often suppressed and nitrogen oxide levels are elevated, favoring lipid radical reaction with • NO 2 to yield multiple nitration products, including nitrated nitrohydroxy and dinitro fatty acid derivatives (18,19,21). Polyunsaturated fatty acids can also be nitrated by acidified nitrite (HNO 2 ), generating a complex mixture of products that are similar to those formed by direct reaction with• NO 2 , including singly nitrated species that maintain the bis-allylic bond arrangement (18,19). Acid-catalyzed fatty acid nitration is expected during physiological and pathological conditions in which NO 2 Ϫ is exposed to low pH (e.g., pH Ͻ 4.0), such as in the gastric compartment after endosomal or phagolysosomal acidification or in tissues after postischemic reperfusion.…”

“…• NO-derived species (15)(16)(17)(18)(19)(20). During both basal cell-signaling and tissue-inflammatory conditions, • NO 2 that is generated by the aforementioned reactions can react with membrane and lipoprotein lipids.…”

“…• NO 2 , including singly nitrated species that maintain the bis-allylic bond arrangement (18,19). Acid-catalyzed fatty acid nitration is expected during physiological and pathological conditions in which NO 2 Ϫ is exposed to low pH (e.g., pH Ͻ 4.0), such as in the gastric compartment after endosomal or phagolysosomal acidification or in tissues after postischemic reperfusion.…”

“…This lipid radical species predominantly reacts with molecular oxygen to form a peroxyl radical. During the unique oxidationreduction conditions of inflammation or ischemia-reoxygenation, tissue O 2 levels are often suppressed and nitrogen oxide levels are elevated, favoring lipid radical reaction with • NO 2 to yield multiple nitration products, including nitrated nitrohydroxy and dinitro fatty acid derivatives (18,19,21). Polyunsaturated fatty acids can also be nitrated by acidified nitrite (HNO 2 ), generating a complex mixture of products that are similar to those formed by direct reaction with…”