Discovery of bioactive nitrated lipids and nitro-lipid-protein adducts using mass spectrometry-based approaches

Figures

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  Fig. 1. Schematic representation of nitrated lipids pathways: from their generation to their biological effect.

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  Fig. 2. Representative mechanisms of nitro-fatty acid (NO2-FA) formation. Radical-induced nitration of unsaturated fatty acids by nitrogen dioxide (•NO2) yields a β-nitroalkyl radical that can further react with other •NO2 generating the nitronitrite intermediates. Further loss of nitrous acid (HNO2) leads to the generation of the nitroalkene derivatives also called NO2-FA. Electrophilic substitution at the double bond mediated by nitronium cation (NO2+) also yields NO2-FA.

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  Fig. 3. Proposed structures for nitro-oleic (NO2-OA) and nitro-linoleic acids (NO2-LA), with assignment of their different positional isomers, which were previously detected in in vitro studies and/or biological samples.

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  Fig. 4. Proposed structures for nitro arachidonic acid (NO2-AA), with assignment of its different positional isomers, which were previously detected in in vitro studies and/or biological samples.

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  Fig. 5. Proposed structures for nitro-docosahexaenoic acid (NO2-DHA), with assignment of its different positional isomers, which were previously detected in in vitro studies and/or biological samples.

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  Fig. 6. ESI-MS spectra of mono charged [M+H]+ (A) and double charged [M+ 2H]2+ ions (B) of NO2POPC-GSH adducts, acquired in Q-Exactive Orbitrap, with identification of major fragmentation pathways. (Reprinted with permission from [49], copyright 2018 [John Wiley & Sons]).