Component

Ambient cellular hydroperoxide concentration

Ambient cellular hydroperoxide concentration. Species, exposure and limitations are retained in each linked claim.

5 recorded relationships. Experimental role, claim status and evidence remain attached to each record.

Read recorded mechanisms Open recursive mind map

How nutrients influence it

Every nutrient with a recorded effect on this component, credited to the nutrient that acted rather than the chapter that recorded it. Open a nutrient to see the findings and the conditions they were measured under.

How nutrients reach it in more than one step

Chains of two or more recorded steps that end here, grouped by the nutrient they start from. Each step is a separate finding, so a chain is a route a mechanism could take, not proof that it does.

Tracing routes…

What it does

Every recorded relationship this component is part of, grouped by its role. Plain wording comes first; the technical statement follows.

Recorded relationships

What it acts on

  1. Paracetamol and salicylate are weak inhibitors of both isolated cyclooxygenase-1 and -2 but potent inhibitors of prostaglandin synthesis in intact cells if low concentrations of arachidonic acid are available, the effects of both being overcome by increased hydroperoxide levels; at low arachidonic acid concentrations cyclooxygenase-2 is the major isoenzyme involved when both are present, so these drugs may selectively inhibit synthesis involving cyclooxygenase-2 because the lower flux through that pathway produces less prostaglandin G2 than the pathway involving cyclooxygenase-1, and the authors propose the class name peroxide sensitive analgesic and antipyretic drugs.

    Ambient cellular hydroperoxide concentration → The ratio of cyclooxygenase-1 to cyclooxygenase-2 inhibitory potency source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/paracetamol-research/15035793.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "f72415969de66bea6c0588049cbe1fd1a4b23195c0e2f5a60293eaf99a0f641e", "start_char": 0, "end_char": 1279, "text_sha256": "f72415969de66bea6c0588049cbe1fd1a4b23195c0e2f5a60293eaf99a0f641e"}
    experimental_model
    Review of the mechanism of paracetamol and salicylate as peroxide-sensitive inhibitors
    exposure
    Paracetamol and salicylate at low arachidonic acid concentrations
    limitations
    A review proposing a drug class rather than a new measurement. Its argument that apparent cyclooxygenase-2 selectivity arises from flux rather than binding is the useful part.
    nutrient_topic
    Paracetamol research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from the metabolites NAPQI and AM404. · Paracetamol
    organism
    Human and enzyme
    plain_language
    The apparent preference for the second enzyme may be nothing to do with binding it, and everything to do with how much peroxide each pathway makes.
    primary_references
    [apap-p15035793] Mechanisms of action of paracetamol and related analgesics. (2003). https://pubmed.ncbi.nlm.nih.gov/15035793/ DOI: 10.1163/156856003322699573
    tissue_or_cell_type
    Cyclooxygenase

    Paracetamol: the enzyme it reduces rather than blocks, the isoform that turned out not to exist, the metabolite that carries the analgesia, and the metabolite that destroys the liver (2026-09-22) · lines 181–192

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Review of the mechanism of paracetamol and salicylate as peroxide-sensitive inhibitors · source_derived_draft · unverified_draft

    ### apap-apparent-selectivity-from-flux Paracetamol and salicylate are weak inhibitors of both isolated cyclooxygenase-1 and -2 but potent inhibitors of prostaglandin synthesis in intact cells if low concentrations of arachidonic acid are available, the effects of both being overcome by increased hydroperoxide levels; at low arachidonic acid concentrations cyclooxygenase-2 is the major isoenzyme involved when both are present, so these drugs may selectively inhibit synthesis involving cyclooxygenase-2 because the lower flux through that pathway produces less prostaglandin G2 than the pathway involving cyclooxygenase-1, and the authors propose the class name peroxide sensitive analgesic and antipyretic drugs. Condition category: normal nutrient_topic: Paracetamol research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from the metabolites NAPQI and AM404. plain_language: The apparent preference for the second enzyme may be nothing to do with binding it, and everything to do with how much peroxide each pathway makes. organism: Human and enzyme tissue_or_cell_type: Cyclooxygenase experimental_model: Review of the mechanism of paracetamol and salicylate as peroxide-sensitive inhibitors limitations: A review proposing a drug class rather than a new measurement. Its argument that apparent cyclooxygenase-2 selectivity arises from flux rather than binding is the useful part. exposure: Paracetamol and salicylate at low arachidonic acid concentrations evidence_span: {"source_cache": "artifacts/paracetamol-research/15035793.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "f72415969de66bea6c0588049cbe1fd1a4b23195c0e2f5a60293eaf99a0f641e", "start_char": 0, "end_char": 1279, "text_sha256": "f72415969de66bea6c0588049cbe1fd1a4b23195c0e2f5a60293eaf99a0f641e"} [apap-p15035793] Mechanisms of action of paracetamol and related analgesics. (2003). https://pubmed.ncbi.nlm.nih.gov/15035793/ DOI: 10.1163/156856003322699573
    Complete structured claim and evidence

  2. Increasing the peroxide product of the cyclooxygenase, prostaglandin G2, by elevating the concentration of either enzyme or substrate reverses the inhibitory action of acetaminophen, as does adding prostaglandin G2 itself, 0.3 micromolar 12-hydroperoxyeicosatetraenoic acid which is a major product of the platelet completely reverses the action on synthase-1, and inhibition in endothelial cells is abrogated by tert-butyl hydroperoxide, supporting the hypothesis that hydroperoxide concentration contributes to the cellular selectivity.

    Ambient cellular hydroperoxide concentration → Paracetamol source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    biomarker_context Imported condition classification; unverified.
    evidence_span
    {"source_cache": "artifacts/paracetamol-research/12011469.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "7e599890f658a63c52471fbc7e6853d7db6a5ecbe892241a39c8a633b3ab2d0d", "start_char": 0, "end_char": 1561, "text_sha256": "7e599890f658a63c52471fbc7e6853d7db6a5ecbe892241a39c8a633b3ab2d0d"}
    experimental_model
    Interleukin-1-alpha-stimulated human endothelial cells and human platelets compared, with hydroperoxide addition
    exposure
    Acetaminophen with 2 micromolar arachidonic acid, and with prostaglandin G2, 12-hydroperoxyeicosatetraenoic acid or tert-butyl hydroperoxide added back
    limitations
    The decisive record of the chapter: it measures a 435-fold difference between two human cell types, shows it is not isoform selectivity, and reverses it by adding the peroxide back.
    nutrient_topic
    Paracetamol research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from the metabolites NAPQI and AM404. · Paracetamol
    organism
    Human
    plain_language
    Put the peroxide back and the drug stops working, which is why the platelet is untouched.
    primary_references
    [apap-p12011469] Determinants of the cellular specificity of acetaminophen as an inhibitor of prostaglandin H(2) synthases. (2002). https://pubmed.ncbi.nlm.nih.gov/12011469/ DOI: 10.1073/pnas.102588199
    tissue_or_cell_type
    Endothelium and platelets
    trigger_kind
    biomarker_context Imported condition classification; unverified.

    Paracetamol: the enzyme it reduces rather than blocks, the isoform that turned out not to exist, the metabolite that carries the analgesia, and the metabolite that destroys the liver (2026-09-22) · lines 103–114

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Interleukin-1-alpha-stimulated human endothelial cells and human platelets compared, with hydroperoxide addition · source_derived_draft · unverified_draft

    ### apap-peroxide-reverses-it Increasing the peroxide product of the cyclooxygenase, prostaglandin G2, by elevating the concentration of either enzyme or substrate reverses the inhibitory action of acetaminophen, as does adding prostaglandin G2 itself, 0.3 micromolar 12-hydroperoxyeicosatetraenoic acid which is a major product of the platelet completely reverses the action on synthase-1, and inhibition in endothelial cells is abrogated by tert-butyl hydroperoxide, supporting the hypothesis that hydroperoxide concentration contributes to the cellular selectivity. Condition category: biomarker_context nutrient_topic: Paracetamol research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from the metabolites NAPQI and AM404. plain_language: Put the peroxide back and the drug stops working, which is why the platelet is untouched. organism: Human tissue_or_cell_type: Endothelium and platelets experimental_model: Interleukin-1-alpha-stimulated human endothelial cells and human platelets compared, with hydroperoxide addition limitations: The decisive record of the chapter: it measures a 435-fold difference between two human cell types, shows it is not isoform selectivity, and reverses it by adding the peroxide back. exposure: Acetaminophen with 2 micromolar arachidonic acid, and with prostaglandin G2, 12-hydroperoxyeicosatetraenoic acid or tert-butyl hydroperoxide added back evidence_span: {"source_cache": "artifacts/paracetamol-research/12011469.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "7e599890f658a63c52471fbc7e6853d7db6a5ecbe892241a39c8a633b3ab2d0d", "start_char": 0, "end_char": 1561, "text_sha256": "7e599890f658a63c52471fbc7e6853d7db6a5ecbe892241a39c8a633b3ab2d0d"} [apap-p12011469] Determinants of the cellular specificity of acetaminophen as an inhibitor of prostaglandin H(2) synthases. (2002). https://pubmed.ncbi.nlm.nih.gov/12011469/ DOI: 10.1073/pnas.102588199
    Complete structured claim and evidence

Where it participates (unsigned role)

  1. Higher concentrations of eugenol were required to inhibit iron-reconstituted prostaglandin H synthase than the manganese-reconstituted enzyme which retains cyclooxygenase but not peroxidase activity, inhibition was highly dependent on arachidonic acid concentration, adding 10 micromolar prostaglandin G2 did not prevent the inhibitory effects, and other phenolic compounds including guaiacol, butylated hydroxyanisole and acetaminophen inhibited the manganese enzyme similarly, demonstrating that these compounds specifically inhibit the cyclooxygenase component in addition to or independent of their effect on peroxide tone, which the authors suggest is due to competition with arachidonic acid for the active site.

    Paracetamol → Prostaglandin H synthase reconstituted with manganese protoporphyrin, retaining cyclooxygenase but little peroxidase activity source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/paracetamol-research/2511429.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "8dbe8c6f23fc857be6bba07e2a518c59f8dc76c9f8625c25ba84030c43f6e636", "start_char": 0, "end_char": 1593, "text_sha256": "8dbe8c6f23fc857be6bba07e2a518c59f8dc76c9f8625c25ba84030c43f6e636"}
    experimental_model
    Prostaglandin H synthase apoenzyme reconstituted with manganese or iron protoporphyrin
    exposure
    Eugenol, guaiacol, butylated hydroxyanisole and acetaminophen against both reconstituted forms, with prostaglandin G2 added
    limitations
    The manganese-reconstituted enzyme retains cyclooxygenase but little peroxidase activity, which is what lets this study separate the two proposed sites. Its conclusion is the opposite of the peroxide-tone account.
    nutrient_topic
    Paracetamol research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from the metabolites NAPQI and AM404. · Paracetamol
    organism
    Enzyme
    plain_language
    In an enzyme stripped of its peroxidase the drug still works, which argues it also competes at the other site.
    primary_references
    [apap-p2511429] Mechanism of inhibition of prostaglandin H synthase by eugenol and other phenolic peroxidase substrates. (1989). https://pubmed.ncbi.nlm.nih.gov/2511429/ DOI: 10.1016/s0026-895x(25)09658-0
    tissue_or_cell_type
    Reconstituted prostaglandin H synthase

    Paracetamol: the enzyme it reduces rather than blocks, the isoform that turned out not to exist, the metabolite that carries the analgesia, and the metabolite that destroys the liver (2026-09-22) · lines 155–166

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Prostaglandin H synthase apoenzyme reconstituted with manganese or iron protoporphyrin · source_derived_draft · unverified_draft

    ### apap-maybe-the-cox-site-instead Higher concentrations of eugenol were required to inhibit iron-reconstituted prostaglandin H synthase than the manganese-reconstituted enzyme which retains cyclooxygenase but not peroxidase activity, inhibition was highly dependent on arachidonic acid concentration, adding 10 micromolar prostaglandin G2 did not prevent the inhibitory effects, and other phenolic compounds including guaiacol, butylated hydroxyanisole and acetaminophen inhibited the manganese enzyme similarly, demonstrating that these compounds specifically inhibit the cyclooxygenase component in addition to or independent of their effect on peroxide tone, which the authors suggest is due to competition with arachidonic acid for the active site. Condition category: normal nutrient_topic: Paracetamol research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from the metabolites NAPQI and AM404. plain_language: In an enzyme stripped of its peroxidase the drug still works, which argues it also competes at the other site. organism: Enzyme tissue_or_cell_type: Reconstituted prostaglandin H synthase experimental_model: Prostaglandin H synthase apoenzyme reconstituted with manganese or iron protoporphyrin limitations: The manganese-reconstituted enzyme retains cyclooxygenase but little peroxidase activity, which is what lets this study separate the two proposed sites. Its conclusion is the opposite of the peroxide-tone account. exposure: Eugenol, guaiacol, butylated hydroxyanisole and acetaminophen against both reconstituted forms, with prostaglandin G2 added evidence_span: {"source_cache": "artifacts/paracetamol-research/2511429.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "8dbe8c6f23fc857be6bba07e2a518c59f8dc76c9f8625c25ba84030c43f6e636", "start_char": 0, "end_char": 1593, "text_sha256": "8dbe8c6f23fc857be6bba07e2a518c59f8dc76c9f8625c25ba84030c43f6e636"} [apap-p2511429] Mechanism of inhibition of prostaglandin H synthase by eugenol and other phenolic peroxidase substrates. (1989). https://pubmed.ncbi.nlm.nih.gov/2511429/ DOI: 10.1016/s0026-895x(25)09658-0
    Complete structured claim and evidence

  2. The potency of acetaminophen against both purified ovine cyclooxygenase-1 and human cyclooxygenase-2 was increased approximately 30-fold by the presence of glutathione peroxidase and glutathione, giving half-maximal inhibitory concentrations of 33 and 980 micromolar respectively, acetaminophen was found to be a good reducing agent of both enzymes, and the results are consistent with a mechanism in which it reduces the active oxidized form of the enzyme to the resting form, so that inhibition would be more effective under conditions of low peroxide concentration, consistent with the known tissue selectivity.

    Paracetamol → Cyclooxygenase-1 (PTGS1) source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/paracetamol-research/11370851.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "4eeda4b163828f2cc2a4341c4810df6bf6c683d6165eeb09479104f185e52ca4", "start_char": 0, "end_char": 1086, "text_sha256": "4eeda4b163828f2cc2a4341c4810df6bf6c683d6165eeb09479104f185e52ca4"}
    experimental_model
    Purified ovine cyclooxygenase-1 and human cyclooxygenase-2 assayed with and without a peroxide-removing system
    exposure
    Acetaminophen with and without glutathione peroxidase and glutathione
    limitations
    Adding a peroxide-removing system is the manipulation that reveals the mechanism, because it changes potency thirtyfold without changing the drug. Purified enzyme, so the concentrations are not tissue concentrations.
    nutrient_topic
    Paracetamol research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from the metabolites NAPQI and AM404. · Paracetamol
    organism
    Sheep and human enzyme
    plain_language
    Take the peroxide away and the same drug becomes thirty times stronger, which is the whole mechanism in one experiment.
    primary_references
    [apap-p11370851] Mechanism of acetaminophen inhibition of cyclooxygenase isoforms. (2001). https://pubmed.ncbi.nlm.nih.gov/11370851/ DOI: 10.1006/abbi.2000.2232
    tissue_or_cell_type
    Purified cyclooxygenase

    Paracetamol: the enzyme it reduces rather than blocks, the isoform that turned out not to exist, the metabolite that carries the analgesia, and the metabolite that destroys the liver (2026-09-22) · lines 77–88

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified ovine cyclooxygenase-1 and human cyclooxygenase-2 assayed with and without a peroxide-removing system · source_derived_draft · unverified_draft

    ### apap-potency-depends-on-peroxide The potency of acetaminophen against both purified ovine cyclooxygenase-1 and human cyclooxygenase-2 was increased approximately 30-fold by the presence of glutathione peroxidase and glutathione, giving half-maximal inhibitory concentrations of 33 and 980 micromolar respectively, acetaminophen was found to be a good reducing agent of both enzymes, and the results are consistent with a mechanism in which it reduces the active oxidized form of the enzyme to the resting form, so that inhibition would be more effective under conditions of low peroxide concentration, consistent with the known tissue selectivity. Condition category: normal nutrient_topic: Paracetamol research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from the metabolites NAPQI and AM404. plain_language: Take the peroxide away and the same drug becomes thirty times stronger, which is the whole mechanism in one experiment. organism: Sheep and human enzyme tissue_or_cell_type: Purified cyclooxygenase experimental_model: Purified ovine cyclooxygenase-1 and human cyclooxygenase-2 assayed with and without a peroxide-removing system limitations: Adding a peroxide-removing system is the manipulation that reveals the mechanism, because it changes potency thirtyfold without changing the drug. Purified enzyme, so the concentrations are not tissue concentrations. exposure: Acetaminophen with and without glutathione peroxidase and glutathione evidence_span: {"source_cache": "artifacts/paracetamol-research/11370851.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "4eeda4b163828f2cc2a4341c4810df6bf6c683d6165eeb09479104f185e52ca4", "start_char": 0, "end_char": 1086, "text_sha256": "4eeda4b163828f2cc2a4341c4810df6bf6c683d6165eeb09479104f185e52ca4"} [apap-p11370851] Mechanism of acetaminophen inhibition of cyclooxygenase isoforms. (2001). https://pubmed.ncbi.nlm.nih.gov/11370851/ DOI: 10.1006/abbi.2000.2232
    Complete structured claim and evidence

  3. Salicylate inhibits prostaglandin H synthase-1 and -2 with a potency inversely related to ambient hydroperoxide concentrations and its inhibition of synthase-1 was prevented by 12-hydroperoxyeicosatetraenoic acid, but unlike typical phenolic inhibitors such as acetaminophen, salicylate was ineffective as a reducing cosubstrate for the peroxidase activity, implicating the cyclooxygenase site as its target; 12-HPETE does not prevent inhibition of the manganese-reconstituted enzyme by salicylate, indicating that reversal by hydroperoxides depends on electron transfer between the cyclooxygenase and peroxidase active sites.

    Salicylate / salicylic acid → Paracetamol source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/paracetamol-research/12538810.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "23bbb8a6c280cfcae85e304695c2a93f2c748c804befc1e006f415f4f8dfaed0", "start_char": 0, "end_char": 1592, "text_sha256": "23bbb8a6c280cfcae85e304695c2a93f2c748c804befc1e006f415f4f8dfaed0"}
    experimental_model
    Prostaglandin H synthase inhibition by salicylate compared with phenolic inhibitors, using manganese-reconstituted enzyme
    exposure
    Salicylate and benzoic acid analogues, with 12-hydroperoxyeicosatetraenoic acid and prostaglandin G2
    limitations
    Recorded here because it separates paracetamol from salicylate mechanistically while showing both are peroxide-sensitive. The work is on salicylate, which is stated on the claim.
    nutrient_topic
    Paracetamol research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from the metabolites NAPQI and AM404. · Paracetamol
    organism
    Enzyme
    plain_language
    Two drugs that both stop working when peroxide is high, reaching that point by different routes.
    primary_references
    [apap-p12538810] Inhibition of prostaglandin H2 synthases by salicylate is dependent on the oxidative state of the enzymes. (2003). https://pubmed.ncbi.nlm.nih.gov/12538810/ DOI: 10.1124/jpet.102.042853
    tissue_or_cell_type
    Prostaglandin H synthase

    Paracetamol: the enzyme it reduces rather than blocks, the isoform that turned out not to exist, the metabolite that carries the analgesia, and the metabolite that destroys the liver (2026-09-22) · lines 168–179

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Prostaglandin H synthase inhibition by salicylate compared with phenolic inhibitors, using manganese-reconstituted enzyme · source_derived_draft · unverified_draft

    ### apap-salicylate-is-not-a-cosubstrate Salicylate inhibits prostaglandin H synthase-1 and -2 with a potency inversely related to ambient hydroperoxide concentrations and its inhibition of synthase-1 was prevented by 12-hydroperoxyeicosatetraenoic acid, but unlike typical phenolic inhibitors such as acetaminophen, salicylate was ineffective as a reducing cosubstrate for the peroxidase activity, implicating the cyclooxygenase site as its target; 12-HPETE does not prevent inhibition of the manganese-reconstituted enzyme by salicylate, indicating that reversal by hydroperoxides depends on electron transfer between the cyclooxygenase and peroxidase active sites. Condition category: normal nutrient_topic: Paracetamol research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from the metabolites NAPQI and AM404. plain_language: Two drugs that both stop working when peroxide is high, reaching that point by different routes. organism: Enzyme tissue_or_cell_type: Prostaglandin H synthase experimental_model: Prostaglandin H synthase inhibition by salicylate compared with phenolic inhibitors, using manganese-reconstituted enzyme limitations: Recorded here because it separates paracetamol from salicylate mechanistically while showing both are peroxide-sensitive. The work is on salicylate, which is stated on the claim. exposure: Salicylate and benzoic acid analogues, with 12-hydroperoxyeicosatetraenoic acid and prostaglandin G2 evidence_span: {"source_cache": "artifacts/paracetamol-research/12538810.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "23bbb8a6c280cfcae85e304695c2a93f2c748c804befc1e006f415f4f8dfaed0", "start_char": 0, "end_char": 1592, "text_sha256": "23bbb8a6c280cfcae85e304695c2a93f2c748c804befc1e006f415f4f8dfaed0"} [apap-p12538810] Inhibition of prostaglandin H2 synthases by salicylate is dependent on the oxidative state of the enzymes. (2003). https://pubmed.ncbi.nlm.nih.gov/12538810/ DOI: 10.1124/jpet.102.042853
    Complete structured claim and evidence

In the sources

Preserved passages that mention this component, quoted exactly. Open one to read it in context.

    This is a research prototype built from draft material. It is not medical advice, and its statements still await verification against the original studies.

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