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Cited by 114Edible Oils Quality and AnalysisFatty Acid Research and HealthPhytochemicals and Antioxidant Activities

Olives and olive oil are sources of electrophilic fatty acid nitroalkenes

Open access
Fazzari, Marco, Trostchansky, Andrés, Schopfer, Francisco J., Salvatore, Sonia R., Sánchez-Calvo, Beatriz, Vitturi, Dario, Valderrama, Raquel, Barroso, Juan B. +3 more·2014·PLoS ONE
DOI 10.1371/journal.pone.0084884PMC PMC3891761
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Abstract

Extra virgin olive oil (EVOO) and olives, key sources of unsaturated fatty acids in the Mediterranean diet, provide health benefits to humans. Nitric oxide (•NO) and nitrite (NO2 (-))-dependent reactions of unsaturated fatty acids yield electrophilic nitroalkene derivatives (NO2-FA) that manifest salutary pleiotropic cell signaling responses in mammals. Herein, the endogenous presence of NO2-FA in both EVOO and fresh olives was demonstrated by mass spectrometry. The electrophilic nature of these species was affirmed by the detection of significant levels of protein cysteine adducts of nitro-oleic acid (NO2-OA-cysteine) in fresh olives, especially in the peel. Further nitration of EVOO by NO2 (-) under acidic gastric digestive conditions revealed that human consumption of olive lipids will produce additional nitro-conjugated linoleic acid (NO2-cLA) and nitro-oleic acid (NO2-OA). The presence of free and protein-adducted NO2-FA in both mammalian and plant lipids further affirm a role for these species as signaling mediators. Since NO2-FA instigate adaptive anti-inflammatory gene expression and metabolic responses, these redox-derived metabolites may contribute to the cardiovascular benefits associated with the Mediterranean diet.

AI snapshot

Written from the paper’s full text.

TL;DR

This study reports that extra virgin olive oil (EVOO) and fresh olives contain endogenous electrophilic fatty acid nitroalkenes (NO2-FA), including NO2-cLA and protein-adducted NO2-OA-cysteine, and that EVOO can generate additional NO2-FA under simulated gastric nitrite conditions. The authors propose these redox-derived lipids may contribute to the cardiovascular benefits associated with the Mediterranean diet.

Key findings

  • Endogenous NO2-cLA was detected in EVOO by HPLC-MS/MS using MRM transition 324.2/46; it co-eluted with [15N]O2-cLA but not with NO2-[13C18]LA. NO2-LA and NO2-OA were not detected basally in EVOO, and nitrite was undetectable in EVOO, lipase preparations, and solvents.
  • Fresh olives contained NO2-OA-cysteine adducts (MRM 447/120), with the peel having the greatest content, up to ∼50 pmol NO2-OA-cysteine/g; levels varied between cultivars. Artifactual formation was controlled by adding 1 μM Na[15N]O2 during hydrolysis, and [15N]O2-OA-cysteine was undetectable.
  • In vitro gastric digestion of EVOO with 5 mM Na[15N]O2 produced seven principal NO2-FA ions and generated [15N]O2-LA, [15N]O2-cLA, and [15N]O2-OA; 9-NO2-cLA and 12-NO2-cLA were the most prevalent. cLA in EVOO was predominantly octadecadi-(9,11)-enoic acid, confirmed by PTAD derivatization and HPLC-MS/MS.

Methods

  • EVOO and fresh olives came from Jaen, Spain, from three cultivars: Arbequina, Frantoio, and Picual. EVOO storage was controlled by measuring α-tocopherol stability.
  • Lipid extracts were analyzed by HPLC-ESI-MS/MS with a triple quadrupole mass spectrometer and LTQ Orbitrap Velos in negative ion mode, using MRM transitions and high-resolution MS. cLA was detected via PTAD Diels-Alder derivatization; NO2-FA-cysteine adducts were analyzed after protein extraction, acid hydrolysis, and SPE.
  • In vitro digestion: EVOO was incubated for 1 h at 37°C in artificial gastric juice with 5 mM Na[15N]O2, then with pancreatic lipase for 3 h. Olive adduct data were analyzed by one-way ANOVA with Bonferroni post hoc comparisons.

Limitations

  • The paper does not state a limitations section. Evident from the text: the gastric nitration findings rely on an in vitro digestion model, not human consumption or clinical outcomes.
  • Evident from the text: samples were limited to EVOO and olives from three cultivars from Jaen, Spain, so broader geographic and cultivar variation is not addressed.
  • Evident from the text: basal NO2-cLA in EVOO was detected qualitatively, while NO2-OA and NO2-LA were not detected basally; NO2-cLA concentrations in EVOO are not quantified in the reported results.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1371/journal.pone.0084884

Cites

Statistics

Nothing to recompute.

Claims the paper makes

0 of 50 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    Octadecadi-(9,11)-enoic acid is the predominant conjugated linoleic acid (cLA) regioisomer in extra virgin olive oil (EVOO).

    “The MRM transitions, elution profiles and MS/MS analysis revealed that octadecadi-(9,11)-enoic acid (m/z 454.4/335.2, m/z 454.4/224.2, m/z 454.4/191.2 and m/z 454.4/168.2) was the predominant cLA regioisomer (Figure S2).”
    Quote in the paperNot a substantial claim
  • Findingown data

    Conjugated linoleic acid (cLA) is present in extra virgin olive oil (EVOO).

    “The presence of cLA in EVOO [39], [40] was determined by selective derivatization with 4-phenyl-1,2,4- triazoline-3,5-dione (PTAD) and product analysis by HPLC-MS/MS (Figure S2) (30).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [39] SF Chin, 1992, Dietary Sources of Conjugated Dienoic Isomers of Linoleic Acid, a Newly Recognized Class of Anticarcinogens, Journal of Food Composition and Analysis source

      Not checked in the free run.

    • cites [40] ME Evans, 2002, Isomer-specific effects of conjugated linoleic acid (CLA) on adiposity and lipid metabolism, Journal of Nutritional Biochemistry source

      Not checked in the free run.

  • Findingown data

    Endogenous nitro-conjugated linoleic acid (NO2-cLA) is present in extra virgin olive oil (EVOO).

    “Endogenous nitro-conjugated linoleic acid (NO2-cLA) was detected by multiple reaction monitoring (MRM) transition 324.2/46 (Figure 1A).”
    • Also stated in: § Endogenous NO2-cLA and cLA in olive oil · boosted
      “Analysis by high resolution mass spectrometry and the electrophilic reactivity of this species, determined by thiol reactivity according to [32], [38], further confirmed the endogenous presence of NO2-cLA (Figure S1).”
    • Also stated in: § Abstract · boosted
      “Herein, the endogenous presence of NO2-FA in both EVOO and fresh olives was demonstrated by mass spectrometry.”
    Quote in the paperSubstantial claim
  • Findingown data

    Incubating extra virgin olive oil (EVOO) in artificial gastric juice with 5 mM Na[15N]O2 generates [15N]O2-OA.

    “Under these conditions nitro-oleic acid (NO2-OA) was also detected (Figure 3). Specifically, [15N]O2-OA formation was revealed by the MRM transition 327.2/47.”
    • Also stated in: § NO2-FA generation from olive oil by modeling digestion ex vivo · plain
      “High resolution MS analysis at the 3 ppm level confirmed the elemental composition of [15N]O2-OA and MS2 analysis showed the presence of both 9- and 10-NO2 regio-isomers of NO2-OA (Figure 3; ref. [37]).”
    Quote in the paperSubstantial claim
  • Findingown data

    Nitroalkene derivatives of fatty acids (NO2-FA) are endogenously present in fresh olives.

    “Herein, the endogenous presence of NO2-FA in both EVOO and fresh olives was demonstrated by mass spectrometry.”
    Quote in the paperSubstantial claim
  • May combine two claims. 19
  • Classified as probably not a substantial claim. 22
  • The quote only partly states this claim. 1

  • May combine two claims.

    Findingown data

    NO2-LA and NO2-OA were not detected in extra virgin olive oil (EVOO).

    “Neither NO2-LA nor NO2-OA (MRM 326/46) was detected.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    These species displayed retention times and fragmentation characteristics corresponding to the [15N]O2-cLA standard and not the bis-allylic NO2-[13C18]LA standard.

    “These species displayed retention times and fragmentation characteristics corresponding to the [15N]O2-cLA standard (Figure 1A,B) and not the bis-allylic NO2-[13C18]LA standard (Figure 1C).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Under these conditions, there was significant NO2-OA, NO2-LA and NO2-cLA generation, with 9-NO2-cLA and 12-NO2-cLA the most prevalent.

    “Under these conditions, there was significant NO2-OA, NO2-LA and NO2-cLA generation, with 9-NO2-cLA and 12-NO2-cLA the most prevalent (Figure 2B).”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The in vitro gastric fluid digestion model with Na[15N]O2 reflects the nitration conditions of the human stomach sufficiently to support conclusions about EVOO in the gastric milieu.

  • May combine two claims.

    Findingown data

    NO2-OA-cysteine adducts were endogenously present in olives, with a stable pool of protein-adducted nitroalkene derivatives in the peel and mesocarp of different olive cultivars.

    “Notably, NO2-OA-cysteine adducts were endogenously present in olives, where there was a stable pool of protein-adducted nitroalkene derivatives in the peel and mesocarp of different olive cultivars (Figure 5).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Olive oil is the principal source of lipids in the Mediterranean diet.

    “Olive oil is the principal source of lipids in the Mediterranean diet, with “extra virgin” olive oil (EVOO) referring to an oil fraction produced via mechanical rather than chemical extraction of olives at temperatures that limit effects on intrinsic properties of the oil [1], [2].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [1] EN Frankel, 2011, Nutritional and biological properties of extra virgin olive oil, J Agric Food Chem source

      Not checked in the free run.

    • cites [2] A Romani, 2007, Evolution of minor polar compounds and antioxidant capacity during storage of bottled extra virgin olive oil, J Agric Food Chem source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The reported data are representative of at least 3 independent experiments.

    “Data is representative of at least 3 independent experiments.”
    • Also stated in: § NO2-FA generation from olive oil by modeling digestion ex vivo · plain
      “Data shown are representative of at least 3 independent experiments.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Commensal bacteria of the enterosalivary system reduce dietary nitrate (NO3−) to physiologically-significant levels of nitrite (NO2−), nitric oxide (NO) and secondary species.

    “In the case of NO3 −, the commensal bacteria of the enterosalivary system reduce dietary NO3 − to physiologically-significant levels of NO2 −, NO and secondary species [12].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [12] EA Jansson, 2008, A mammalian functional nitrate reductase that regulates nitrite and nitric oxide homeostasis, Nat Chem Biol source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Fatty acid nitroalkenes are detectable clinically and in rodent models as free, esterified and protein-adducted species.

    “Fatty acid nitroalkenes are detectable clinically and in rodent models as free, esterified and protein-adducted species [14], but have not been reported in plants.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [14] H Rubbo, 2009, Peroxynitrite-mediated lipid oxidation and nitration: mechanisms and consequences, Arch Biochem Biophys source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation

    Nitroalkene derivatives of fatty acids (NO2-FA) are electrophilic if the nitro group is adducted to alkenyl carbons.

    “Biochemical studies and cell models revealed that NO2-FA are electrophilic, if the nitro group is adducted to alkenyl carbons.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [16] LM Baker, 2007, Nitro-fatty acid reaction with glutathione and cysteine. Kinetic analysis of thiol alkylation by a Michael addition reaction, J Biol Chem source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The endogenous generation of nitrogen dioxide (NO2) occurs via multiple acid-catalyzed and oxidative inflammatory reactions involving nitric oxide (NO) and nitrite (NO2−).

    “The endogenous generation of NO2 occurs via multiple acid-catalyzed and oxidative inflammatory reactions involving NO and NO2 − [15].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [15] F Schopfer, 2011, Formation and signaling actions of electrophilic lipids, Chem Rev source

      Not checked in the free run.

  • May combine two claims.

    Study design and conductown data

    Nitrite was undetectable in EVOO, purified lipase preparations and all solvents used for extractions and chromatography, discounting the possibility of artifactual fatty acid nitration during sample preparation.

    “Nitrite was undetectable in EVOO, purified lipase preparations and all solvents used for extractions and chromatography, discounting the possibility of artifactual fatty acid nitration during sample preparation.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Nitroalkene derivatives of fatty acids (NO2-FA) are partial agonists of peroxisome proliferator-activated receptor-γ (PPARγ), which they activate via hydrogen bonding interactions and covalent adduction of the ligand binding domain Cys285.

    “NO2-FA are also partial agonists of peroxisome proliferator-activated receptor-γ (PPARγ), which NO2-FA activate via hydrogen bonding interactions and covalent adduction of the ligand binding domain Cys285 [19].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [19] Y Li, 2008, Molecular recognition of nitrated fatty acids by PPAR gamma, Nat Struct Mol Biol source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductown data

    α-Tocopherol (α-TOH) levels in EVOO were stable for at least two weeks at -20°C, in contrast to storage at room temperature.

    “α-TOH levels were stable for at least two weeks at -20°C in contrast to storage at room temperature.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    There is an emerging body of evidence from higher plants that nitric oxide (NO) and other reactive species mediate nitro-oxidative reactions that regulate plant stress perception, signal transduction and senescence responses.

    “There is also an emerging body of evidence from higher plants that NO and other reactive species mediate nitro-oxidative reactions that regulate plant stress perception, signal transduction and senescence responses.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [13] FJ Corpas, 2013, Nitro-oxidative stress vs oxidative or nitrosative stress in higher plants, New Phytol source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    Because NO2-FA instigate adaptive anti-inflammatory gene expression and metabolic responses, these redox-derived metabolites may contribute to the cardiovascular benefits associated with the Mediterranean diet.

    “Since NO2-FA instigate adaptive anti-inflammatory gene expression and metabolic responses, these redox-derived metabolites may contribute to the cardiovascular benefits associated with the Mediterranean diet.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    The acidic milieu of the gastric compartment and the presence of nitrite (NO2−) in food promotes a nitrative environment due to HNO2 formation that can mediate biomolecule nitration.

    “The acidic milieu of the gastric compartment and the presence of NO2 − in food promotes a nitrative environment due to HNO2 formation (NO2 − pKa, 3.4) that in turn can mediate biomolecule nitration [41], [42].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [41] BS Rocha, 2012, Intragastric nitration by dietary nitrite: implications for modulation of protein and lipid signaling, Free Radic Biol Med source

      Not checked in the free run.

    • cites [42] JO Lundberg, 2012, Biology of nitrogen oxides in the gastrointestinal tract, Gut source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation

    Nitroalkene derivatives of fatty acids (NO2-FA) rapidly react via Michael addition with thiols and to a lesser extent primary and secondary amines.

    “These species rapidly react via Michael addition with thiols and to a lesser extent primary and secondary amines [16].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [16] LM Baker, 2007, Nitro-fatty acid reaction with glutathione and cysteine. Kinetic analysis of thiol alkylation by a Michael addition reaction, J Biol Chem source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The Mediterranean diet is linked with the consumption of fruits and vegetables that are rich in the inorganic anions nitrite (NO2−) and nitrate (NO3−).

    “Notably, the Mediterranean diet is also linked with the consumption of fruits and vegetables that are rich in the inorganic anions nitrite (NO2 −) and nitrate (NO3 −) [9], [10].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [9] JO Lundberg, 2009, NO generation from inorganic nitrate and nitrite: Role in physiology, nutrition and therapeutics, Arch Pharm Res source

      Not checked in the free run.

    • cites [10] JO Lundberg, 2008, The nitrate-nitrite-nitric oxide pathway in physiology and therapeutics, Nat Rev Drug Discov source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Multiple health benefits are linked with diets rich in olive oil and the Mediterranean diet, including anti-inflammatory and anti-hypertensive effects that lead to a reduced risk of cardiovascular morbidity and mortality.

    “Multiple health benefits are linked with diets rich in olive oil and the Mediterranean diet in general, including anti-inflammatory and anti-hypertensive effects that lead to a reduced risk of cardiovascular morbidity and mortality [6]–[8].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [6]–[8]

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Nitroalkene derivatives of fatty acids (NO2-FA) limit inflammatory responses by non-cGMP-dependent inhibition of platelet and neutrophil function and by inhibiting the catalytic activity and gene expression of cyclooxygenase-2 and xanthine oxidoreductase.

    “Finally, NO2-FA limit inflammatory responses by non-cGMP-dependent inhibition of platelet and neutrophil function [20], [21] and by inhibiting the catalytic activity and gene expression of the pro-inflammatory proteins cyclooxygenase-2 and xanthine oxidoreductase [22], [23].”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [20] B Coles, 2002, Nitrolinoleate Inhibits Superoxide Generation, Degranulation, and Integrin Expression by Human Neutrophils: Novel Antiinflammatory Properties of Nitric Oxide-Derived Reactive Species in Vascular Cells, Circ Res source

      Not checked in the free run.

    • cites [21] B Coles, 2002, Nitrolinoleate inhibits platelet activation by attenuating calcium mobilization and inducing phosphorylation of vasodilator-stimulated phosphoprotein through elevation of cAMP, J Biol Chem source

      Not checked in the free run.

    • cites [22] EE Kelley, 2008, Nitro-oleic Acid, a Novel and Irreversible Inhibitor of Xanthine Oxidoreductase, J Biol Chem source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    The principal components of extra virgin olive oil (EVOO) are triglycerides (98-99%) predominantly esterified with monounsaturated oleic acid, and to a lesser extent palmitic, linoleic and linolenic acids.

    “The principal components of EVOO are triglycerides (TG, 98–99%) predominantly esterified with monounsaturated oleic acid (OA), and to a lesser extent palmitic, linoleic (LA) and linolenic acids [3]–[5].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [3]–[5]

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    EVOO and olives are both a source and metabolic reserve of NO2-FA.

    “These results confirm that EVOO and olives are both a source and metabolic reserve of NO2-FA.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The in vitro gastric fluid digestion model with Na[15N]O2 reflects the nitration conditions of the human stomach sufficiently to support conclusions about EVOO in the gastric milieu.
    • Rests on an assumption: The three olive cultivars studied are representative of olives generally.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Plant lipids have cLA levels of up to ∼1.0 mg cLA/g fat, and reported levels of cLA in olive oils are up to 0.2 mg/g fat, predominantly cis9-, trans11- and trans10-, cis12- isomers.

    “Plant lipids have cLA levels of up to ∼1.0 mg cLA/g fat [39], with reported levels of cLA in olive oils of up to 0.2 mg/g fat [39], predominantly the cis9-, trans11- and trans10-, cis12- isomers [39].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [39] SF Chin, 1992, Dietary Sources of Conjugated Dienoic Isomers of Linoleic Acid, a Newly Recognized Class of Anticarcinogens, Journal of Food Composition and Analysis source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    cLA consists of positional isomers of linoleic acid having conjugated dienes in the cis and trans configurations.

    “cLA consists of positional isomers of linoleic acid having conjugated dienes in the cis and trans configurations [39], [51], [52].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [39] SF Chin, 1992, Dietary Sources of Conjugated Dienoic Isomers of Linoleic Acid, a Newly Recognized Class of Anticarcinogens, Journal of Food Composition and Analysis source

      Not checked in the free run.

    • cites [51] CM Reynolds, 2010, Conjugated linoleic acid and inflammatory cell signalling, Prostaglandins Leukot Essent Fatty Acids source

      Not checked in the free run.

    • cites [52] WL Cheng, 2004, Contribution of conjugated linoleic acid to the suppression of inflammatory responses through the regulation of the NF-kappaB pathway, J Agric Food Chem source

      Not checked in the free run.

  • May combine two claims.

    Study design and conductown data

    Artifactual nitration reactions induced by the hydrolysis procedure were controlled for by adding 1 μM Na[15N]O2 and monitoring potential formation of [15N]O2-OA-cysteine, which was undetectable.

    “Artifactual nitration reactions induced by the hydrolysis procedure was controlled for by adding 1 μM Na[15N]O2 and monitoring the potential formation of [15N]O2-OA- cysteine, which was undetectable.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Both mammalian and enterosalivary microbiome enzymes can synthesize conjugated diene fatty acids in humans both de novo and by desaturation of monoenoic fatty acid substrates.

    “In addition, both mammalian and enterosalivary microbiome enzymes can synthesize conjugated diene fatty acids in humans both de novo and by desaturation of monoenoic fatty acid substrates [39], [40].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [39] SF Chin, 1992, Dietary Sources of Conjugated Dienoic Isomers of Linoleic Acid, a Newly Recognized Class of Anticarcinogens, Journal of Food Composition and Analysis source

      Not checked in the free run.

    • cites [40] ME Evans, 2002, Isomer-specific effects of conjugated linoleic acid (CLA) on adiposity and lipid metabolism, Journal of Nutritional Biochemistry source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Redox-mediated formation of heme and protein thiol nitrosyl adducts and protein 3-nitrotyrosine adducts is integral to nitro-oxidative reactions in higher plants.

    “Integral to these events is the redox-mediated formation of heme and protein thiol nitrosyl adducts and protein 3-nitrotyrosine adducts [13].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [13] FJ Corpas, 2013, Nitro-oxidative stress vs oxidative or nitrosative stress in higher plants, New Phytol source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    NO2-FA activate Nrf2-regulated anti-inflammatory gene expression and heat shock factor-regulated heat shock protein expression.

    “Additionally, NO2-FA activate Nrf2-regulated anti-inflammatory gene expression and heat shock factor-regulated heat shock protein expression [17], [46], [55].”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [17] E Kansanen, 2011, Electrophilic Nitro-fatty Acids Activate NRF2 by a KEAP1 Cysteine 151–independent Mechanism, J Biol Chem source

      Not checked in the free run.

    • cites [46] L Villacorta, 2007, Nitro-linoleic acid inhibits vascular smooth muscle cell proliferation via the Keap1/Nrf2 signaling pathway, Am J Physiol Heart Circ Physiol source

      Not checked in the free run.

    • cites [55] E Kansanen, 2009, Nrf2-dependent and -independent responses to nitro-fatty acids in human endothelial cells: identification of heat shock response as the major pathway activated by nitro-oleic acid, J Biol Chem source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Conjugated linoleic acid displays immune-modulatory and anti-inflammatory effects, with proposed mechanisms including reduction of pro-inflammatory cytokine levels via inhibition of NF-κB-dependent gene expression and activation of PPAR-regulated gene expression.

    “Conjugated linoleic acid displays immune-modulatory and anti-inflammatory effects [51], [52], with the mechanisms accounting for these actions proposed to include the reduction of pro-inflammatory cytokine levels via inhibition of NF-κB-dependent gene expression and activation of PPAR-regulated gene expression [51], [52].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [51] CM Reynolds, 2010, Conjugated linoleic acid and inflammatory cell signalling, Prostaglandins Leukot Essent Fatty Acids source

      Not checked in the free run.

    • cites [52] WL Cheng, 2004, Contribution of conjugated linoleic acid to the suppression of inflammatory responses through the regulation of the NF-kappaB pathway, J Agric Food Chem source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    Data shown in Figure 4 is representative of at least 3 independent experiments.

    “Data shown is representative of at least 3 independent experiments.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductown data

    Data plotted in Figure 5 correspond to the mean ± SD (n = 3) and is representative of at least 3 independent experiments.

    “Data plotted correspond to the mean ± SD (n = 3) and is representative of at least 3 independent experiments.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    Data shown in Figure 3 is representative of at least 3 independent experiments.

    “Data shown is representative of at least 3 independent experiments.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). The quote only partly states this claim.

    Study design and conductown data

    Statistical analysis in Figure 5 was performed by one-way ANOVA with Bonferroni post hoc comparisons.

    “Statistical analysis was performed by one-way ANOVA with Bonferroni post hoc comparisons.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    In Figure 5, a indicates p < 0.01.

    “a, p <0.01.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationnone given

    Olives and EVOO serve as both a direct source of and precursors for NO2-FA generation.

    “In this regard, olives and EVOO serve as both a direct source of and precursors for NO2-FA generation.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The in vitro gastric fluid digestion model with Na[15N]O2 reflects the nitration conditions of the human stomach sufficiently to support conclusions about EVOO in the gastric milieu.
    • Rests on an assumption: The three olive cultivars studied are representative of olives generally.
35 of 35

  • The paper relies on this without support.

    The in vitro gastric digestion conditions (artificial gastric juice with 5 mM Na[15N]O2, 1 h, 37°C, followed by pancreatic lipase) adequately mimic human gastric pH and nitrite concentrations during digestion.

    “Herein, we report the endogenous presence of NO2-FA in plants, specifically in olives and EVOO and show the additional formation of NO2-FA from EVOO under conditions which mimic gastric pH and NO2 − concentrations during digestion.”
    “Olive oil (10 µl) was incubated for 1 h at 37°C in 1 ml of gastric juice artificial with 5 mM Na[15N]O2, under continuous agitation [32], [35].”

  • The paper relies on this without support.

    Plants in general, and fresh olives in particular, are abundant in readily-nitrated unsaturated fatty acids.

    “fresh olives in particular, are abundant in readily-nitrated unsaturated fatty acids, the present study evaluated whether electrophilic fatty acid nitroalkene derivatives (NO2-FA) are a) endogenously present in olives, b) extractable into the EVOO fraction and c) generated after consumption of olive lipids by the acidic conditions of digestion.”

  • The paper relies on this without support.

    The three EVOO cultivars from Jaen, Spain (Arbequina, Frantoio, Picual) are representative of extra virgin olive oil generally.

    “Extra virgin olive oils and fresh olives were from Jaen, Spain, and came from three different types of cultivars: Arbequina, Frantoio and Picual [33].”

  • The paper relies on this without support.

    Pancreatic lipase digestion releases free fatty acids from EVOO in a manner representative of human digestion.

    “The lipid fraction was extracted by hexane, dried under a stream of nitrogen and 1 ml pancreatic lipase (0.4 mg protein/ml) in 0.5 M phosphate buffer, pH 7.4 was added and the reaction mixture incubated at 37°C for 3 h, under agitation.”

  • The paper relies on this without support.

    The presence of free and protein-adducted NO2-FA in plant lipids is sufficient to infer that these species act as signaling mediators in plants.

    “The presence of free and protein-adducted NO2-FA in both mammalian and plant lipids further affirm a role for these species as signaling mediators.”

  • The paper relies on this without support.

    The in vitro gastric fluid digestion model with Na[15N]O2 reflects the nitration conditions of the human stomach sufficiently to support conclusions about EVOO in the gastric milieu.

    “Olive oil was nitrated, extracted and treated with Na[15N]O2 as in Figure 2.”
    “Herein, the formation of electrophilic NO2-FA species in EVOO exposed to Na[15N]O2 in gastric fluid was detected with HPLC-MS/MS (Figures 2 and 3).”

  • The paper relies on this without support.

    The three olive cultivars studied are representative of olives generally.

    “NO2-OA-cysteine levels varied between different cultivars (Figure 5A).”
    “The presence of cLA in the oils from the three olive cultivars studied herein was confirmed by HPLC-MS/MS detection of a Diels Alder reaction of conjugated dienes with 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD, m/z 454) (Figure S2 [32]).”
7 of 7

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Fatty acid nitroalkene derivatives (NO2-FA) are detected in species as diverse as plants, insects and humans.

    “Fatty acid nitroalkene derivatives (NO2-FA) are detected in species as diverse as plants, insects and humans [1–3], but little is known of how NO2-FA are endogenously generated.”

    From Nitrite and nitrate-dependent generation of anti-inflammatory fatty acid nitroalkenes (2015) · cites this paper as [2]

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Conflicting protein-hydrolysis conditions

    Minor

    The Figure 4 caption says the olive proteins were hydrolyzed "for 6°C," whereas the methods specify hydrolysis for 6 hours at 110°C. The caption gives a different temperature and no valid duration.

1 of 1

The citation lists haven’t been fetched yet

References 57 · Cited by 114

Authors
Fazzari, M., Trostchansky, A., Schopfer, F. J., Salvatore, S. R., Sánchez-Calvo, B., Vitturi, D., Valderrama, R., Barroso, J. B., Radi, R., Freeman, B. A., & Rubbo, H.
Affiliations
  • University of Pittsburgh (US)
  • Universidad de la República de Uruguay (UY)
  • Universidad de Jaén (ES)
Corresponding author
Rubbo, Homero
ORCID
Venue
PLoS ONE
Publisher
Public Library of Science (PLoS)
Published
2014-01-14
Volume
9
Issue
1
Pages
e84884
ISSN
1932-6203 (ISSN-L)
DOI
10.1371/journal.pone.0084884
PMC
PMC3891761
OpenAlex
W2007442813
Semantic Scholar
3ac5aedddfe95ec70e9920e37d859d65ac23a453
Cited by
114
References
57
Citations by year
2026: 3 · 2025: 4 · 2024: 8 · 2023: 10 · 2022: 8 · 2021: 7 · 2020: 10 · 2019: 14 · 2018: 14 · 2017: 8 · 2016: 17 · 2015: 7 · 2014: 4
FWCI
5.28
Type
journal article
Language
en
Open access
Licence
Locations
  • PLoS ONE (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • D-Scholarship@Pitt (University of Pittsburgh) (acceptedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • Figshare (submittedVersion, cc-by)
Funders
  • Agencia Nacional de Investigación e Innovación (P01-HL103455)
  • National Institutes of Health (R01-HL-058115, DK072506)
  • European Regional Development Fund (BIO286)
  • National Heart, Lung, and Blood Institute (R01HL64937, R01HL064937, R37HL058115, R01HL058115, P01HL103455, R01HL132550)
  • National Institute of Diabetes and Digestive and Kidney Diseases (P30DK072506)
  • National Center for Complementary and Integrative Health (R01AT006822)
Topics
  • Physical Sciences › Chemistry › Organic Chemistry › Edible Oils Quality and Analysis
  • Health Sciences › Nursing › Nutrition and Dietetics › Fatty Acid Research and Health
  • Health Sciences › Medicine › Biochemistry › Phytochemicals and Antioxidant Activities
Keywords
nitroalkenes, nitro-oleic acid, nitric oxide, nitrite, unsaturated fatty acids, extra virgin olive oil, olive, cysteine adducts, electrophilic metabolites, redox signaling, anti-inflammatory gene expression, Mediterranean diet, cardiovascular health, gastric digestion
MeSH terms
Olive Oil, Alkenes, Anti-Inflammatory Agents, Dietary Fats, Digestion, Electrons, Fatty Acids, Hydrogen-Ion Concentration, Nitro Compounds, Plant Oils, Plant Proteins, Stomach, Olea, Biomimetics

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