Cyclooxygenase-2 (PTGS2)

evidence_span

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experimental_model

Chinese hamster ovary cell lines stably expressing each human cyclooxygenase isoform, with cell-free comparison

exposure

Ibuprofen, indomethacin, NS-398 and DuP-697 across intact cells and microsomal preparations

limitations

Shows that the selectivity numbers depend on the assay, which bears on every potency ratio quoted for this drug class. A heterologous expression system.

nutrient_topic

Ibuprofen research collection; topical membership is not evidence of a direct clinical effect, and the racemate is recorded separately from each of its two enantiomers. · Ibuprofen

organism

Human enzyme in hamster cells

plain_language

Against both enzymes it is a reversible blocker, and the numbers you get depend on which assay you use.

primary_references

[ibu-p8831731] Mechanism of selective inhibition of human prostaglandin G/H synthase-1 and -2 in intact cells. (1996). https://pubmed.ncbi.nlm.nih.gov/8831731/ DOI: 10.1016/0006-2952(96)00462-5

tissue_or_cell_type

Intact cells and cell-free preparations

Ibuprofen: the enantiomer that works, the one that was called inactive, the one-way chemistry that turns one into the other, and the targets that are not cyclooxygenase (2026-09-22) · lines 292–303

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Chinese hamster ovary cell lines stably expressing each human cyclooxygenase isoform, with cell-free comparison · source_derived_draft · unverified_draft

### ibu-reversible-against-both-isoforms Reversible inhibition of both cellular cyclooxygenase-1 and cyclooxygenase-2 was observed with the nonselective drugs ibuprofen and indomethacin, whereas the selective inhibitor DuP-697 was reversible against cyclooxygenase-1 but irreversible against cyclooxygenase-2, and indomethacin displayed time-dependent inhibition of both cellular isoforms; the selectivities and potencies of inhibitors determined using intact cells are affected by substrate concentration and differ from those determined in cell-free microsomal or purified enzyme preparations. Condition category: normal nutrient_topic: Ibuprofen research collection; topical membership is not evidence of a direct clinical effect, and the racemate is recorded separately from each of its two enantiomers. plain_language: Against both enzymes it is a reversible blocker, and the numbers you get depend on which assay you use. organism: Human enzyme in hamster cells tissue_or_cell_type: Intact cells and cell-free preparations experimental_model: Chinese hamster ovary cell lines stably expressing each human cyclooxygenase isoform, with cell-free comparison limitations: Shows that the selectivity numbers depend on the assay, which bears on every potency ratio quoted for this drug class. A heterologous expression system. exposure: Ibuprofen, indomethacin, NS-398 and DuP-697 across intact cells and microsomal preparations evidence_span: {"source_cache": "artifacts/ibuprofen-research/8831731.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "d3161aac692f44c874cafb498e9606f0382b380662ccb58cd1683139f1c1df99", "start_char": 0, "end_char": 1993, "text_sha256": "d3161aac692f44c874cafb498e9606f0382b380662ccb58cd1683139f1c1df99"} [ibu-p8831731] Mechanism of selective inhibition of human prostaglandin G/H synthase-1 and -2 in intact cells. (1996). https://pubmed.ncbi.nlm.nih.gov/8831731/ DOI: 10.1016/0006-2952(96)00462-5

evidence_access

Primary full text

experimental_model

Human primary monocytes and U937 cells; Esther 20% stock diluted to 0.5-10 micrograms/mL, 4-hour pretreatment; homocysteine stimulation.

limitations

Cell exposure does not establish oral exposure, homocysteine removal or cardiovascular benefit. Results text reports homocysteine 200 micromolar, while figure captions say 200 micrograms/mL; dose units are unresolved. Inhibitor concentrations also need original-record clarification.

nutrient_topic

Fulvic acid collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · Fulvic acid (heterogeneous humic fraction)

plain_language

Less inflammatory-enzyme message was produced.

primary_references

Fulvic acid attenuates homocysteine-induced cyclooxygenase-2 expression in human monocytes. · 2015 · https://pubmed.ncbi.nlm.nih.gov/25888188/ · DOI 10.1186/s12906-015-0583-x

Fulvic acid: mixture identity, mineral chemistry, signaling and cross-nutrient mechanisms (2026-09-19) · lines 60–66

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Human primary monocytes and U937 cells; Esther 20% stock diluted to 0.5-10 micrograms/mL, 4-hour pretreatment; homocysteine stimulation. · source_derived_draft · unverified_draft

## fulvic-acid-cox-expression Less inflammatory-enzyme message was produced. Fulvic pretreatment reduced homocysteine-induced COX-2 mRNA in primary monocytes and U937 cells. Model: Human primary monocytes and U937 cells; Esther 20% stock diluted to 0.5-10 micrograms/mL, 4-hour pretreatment; homocysteine stimulation. Limitations: Cell exposure does not establish oral exposure, homocysteine removal or cardiovascular benefit. Results text reports homocysteine 200 micromolar, while figure captions say 200 micrograms/mL; dose units are unresolved. Inhibitor concentrations also need original-record clarification. Evidence access: Primary full text Fulvic acid attenuates homocysteine-induced cyclooxygenase-2 expression in human monocytes. · 2015 · https://pubmed.ncbi.nlm.nih.gov/25888188/ · DOI 10.1186/s12906-015-0583-x

evidence_span

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experimental_model

Ex vivo and in vitro human whole blood cyclooxygenase assays in five volunteers given a single oral dose

exposure

1000 milligrams oral acetaminophen, with coagulation-induced thromboxane B2 and lipopolysaccharide-induced prostaglandin E2 as isoform indices

limitations

Measures both isoform indices in dosed people and relates them to plasma concentration. Five volunteers and a single dose.

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

In people it blocks the second enzyme as hard as a proper anti-inflammatory does, and never blocks the first enough to touch platelets.

primary_references

[apap-p17884974] Acetaminophen (paracetamol) is a selective cyclooxygenase-2 inhibitor in man. (2008). https://pubmed.ncbi.nlm.nih.gov/17884974/ DOI: 10.1096/fj.07-8506com

tissue_or_cell_type

Whole blood

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 259–270

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Ex vivo and in vitro human whole blood cyclooxygenase assays in five volunteers given a single oral dose · source_derived_draft · unverified_draft

### apap-four-fold-cox2-selective-in-man In vitro acetaminophen elicited a 4.4-fold selectivity toward cyclooxygenase-2 inhibition with half-maximal inhibitory concentrations of 113.7 micromolar for cyclooxygenase-1 and 25.8 micromolar for cyclooxygenase-2, following a single oral 1000 milligram dose maximal ex vivo inhibitions were 56% for cyclooxygenase-1 and 83% for cyclooxygenase-2, plasma concentrations remained above the in vitro cyclooxygenase-2 value for at least 5 hours, and ex vivo values compared favourably with in vitro ones; acetaminophen inhibited cyclooxygenase-2 by more than 80%, comparable to non-steroidal anti-inflammatory drugs and selective inhibitors, but the greater than 95% cyclooxygenase-1 blockade relevant for suppression of platelet function was not achieved, and in view of its substantial cyclooxygenase-2 inhibition the cardiovascular warnings defined for selective inhibitors should also be considered. 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 people it blocks the second enzyme as hard as a proper anti-inflammatory does, and never blocks the first enough to touch platelets. organism: Human tissue_or_cell_type: Whole blood experimental_model: Ex vivo and in vitro human whole blood cyclooxygenase assays in five volunteers given a single oral dose limitations: Measures both isoform indices in dosed people and relates them to plasma concentration. Five volunteers and a single dose. exposure: 1000 milligrams oral acetaminophen, with coagulation-induced thromboxane B2 and lipopolysaccharide-induced prostaglandin E2 as isoform indices evidence_span: {"source_cache": "artifacts/paracetamol-research/17884974.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "e2856e9fc1c319219fd3d3cb145f70bb1157f7ca0baa0221594c9583cf7ddc23", "start_char": 0, "end_char": 1857, "text_sha256": "e2856e9fc1c319219fd3d3cb145f70bb1157f7ca0baa0221594c9583cf7ddc23"} [apap-p17884974] Acetaminophen (paracetamol) is a selective cyclooxygenase-2 inhibitor in man. (2008). https://pubmed.ncbi.nlm.nih.gov/17884974/ DOI: 10.1096/fj.07-8506com

dose

Indicaxanthin 5-25 micromolar with IL-1beta 25 ng/mL

duration

24 h for mediator release and permeability; earlier signaling assays

evidence_access

Primary PubMed abstract; detailed exposure for PMID 23931157 additionally checked in publisher results. No uninspected full text is claimed.

evidence_scope

literature_reviewed; source-derived curation, not universally established human effects

experimental_model

Differentiated human Caco-2 intestinal epithelial monolayers

limitations

No clinical IBD treatment effect or molecular binding site was established. Total thiols must not be relabeled as a specific glutathione measurement.

nutrient_topic

Betalains collection; each molecular form, species, exposure and preparation remains explicit. · Betalains

organism

Differentiated human Caco-2 intestinal epithelial monolayers

plain_language

Indicaxanthin reduced induced COX-2 expression in IL-1beta-exposed Caco-2 cells.

primary_references

Indicaxanthin inhibits NADPH oxidase (NOX)-1 activation and NF-κB-dependent release of inflammatory mediators and prevents the increase of epithelial permeability in IL-1β-exposed Caco-2 cells. (2014). https://pubmed.ncbi.nlm.nih.gov/23931157/ DOI: 10.1017/S0007114513002663

route

In vitro co-incubation

tissue

Intestinal epithelial model

Betalains: mechanisms, molecular forms and cross-actor connections (2026-09-20) · lines 277–285

Original AI-assisted curation of twelve primary research papers; study-specific PubMed/DOI links and limitations retained. Not publisher full text. · supports · Differentiated human Caco-2 intestinal epithelial monolayers · source_derived_draft · unverified_draft

## betalains-caco2-cox2 Indicaxanthin reduced induced COX-2 expression in IL-1beta-exposed Caco-2 cells. Model/species: Differentiated human Caco-2 intestinal epithelial monolayers Tissue: Intestinal epithelial model Exposure: Indicaxanthin 5-25 micromolar with IL-1beta 25 ng/mL Route: In vitro co-incubation Duration: 24 h for mediator release and permeability; earlier signaling assays Limits: No clinical IBD treatment effect or molecular binding site was established. Total thiols must not be relabeled as a specific glutathione measurement. Primary reference: Indicaxanthin inhibits NADPH oxidase (NOX)-1 activation and NF-κB-dependent release of inflammatory mediators and prevents the increase of epithelial permeability in IL-1β-exposed Caco-2 cells. (2014). https://pubmed.ncbi.nlm.nih.gov/23931157/ DOI: 10.1017/S0007114513002663

cross_nutrient

false

experimental_model

Purified-enzyme oxygen-electrode kinetics

exposure

13′-COOH 0, 7.5, 15 or 25 µM; arachidonic acid 6–200 µM in Tris pH 8 with 1 µM hematin, phenol and EDTA.

limitations

Purified enzyme kinetics do not establish human anti-inflammatory benefit. Cyclooxygenase and peroxidase activities must not be conflated.

nutrient_topic

Vitamin E research collection; topical membership is not evidence of a direct dietary effect. · Vitamin E

organism

Homo sapiens

plain_language

The long-chain delta-tocopherol metabolite interfered with this purified enzyme’s use of arachidonic acid.

primary_references

[jiang2008] Long-chain carboxychromanols, metabolites of vitamin E, are potent inhibitors of cyclooxygenases. (2008). https://pubmed.ncbi.nlm.nih.gov/19074288/ DOI: 10.1073/pnas.0810962106

tissue_or_cell_type

Cell-free enzyme

Vitamin E: transport, membrane protection and nutrient interactions (2026-09-17) · lines 868–879

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified-enzyme oxygen-electrode kinetics · source_derived_draft · unverified_draft

### e-sig-delta-acid-cox2 Delta-tocopherol-13′-carboxychromanol competitively inhibited purified human COX-2 cyclooxygenase activity with a reported Ki of 10.7 µM, measured by initial oxygen consumption while varying arachidonic acid. Condition category: normal nutrient_topic: Vitamin E research collection; topical membership is not evidence of a direct dietary effect. plain_language: The long-chain delta-tocopherol metabolite interfered with this purified enzyme’s use of arachidonic acid. organism: Homo sapiens tissue_or_cell_type: Cell-free enzyme experimental_model: Purified-enzyme oxygen-electrode kinetics limitations: Purified enzyme kinetics do not establish human anti-inflammatory benefit. Cyclooxygenase and peroxidase activities must not be conflated. exposure: 13′-COOH 0, 7.5, 15 or 25 µM; arachidonic acid 6–200 µM in Tris pH 8 with 1 µM hematin, phenol and EDTA. cross_nutrient: false [jiang2008] Long-chain carboxychromanols, metabolites of vitamin E, are potent inhibitors of cyclooxygenases. (2008). https://pubmed.ncbi.nlm.nih.gov/19074288/ DOI: 10.1073/pnas.0810962106

evidence_span

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experimental_model

Volunteers given celecoxib at three doses or ibuprofen, with platelet, serum and urinary indices

exposure

800 milligrams ibuprofen against 100, 400 or 800 milligrams celecoxib

limitations

Measures both isoform-specific indices in the same people, which is what allows the prostacyclin source to be assigned. Acute dosing in healthy volunteers.

nutrient_topic

Ibuprofen research collection; topical membership is not evidence of a direct clinical effect, and the racemate is recorded separately from each of its two enantiomers. · Ibuprofen

organism

Human

plain_language

The enzyme these drugs are meant to spare the stomach by blocking is the one that makes the body’s main anticlotting prostaglandin.

primary_references

[ibu-p9874808] Systemic biosynthesis of prostacyclin by cyclooxygenase (COX)-2: the human pharmacology of a selective inhibitor of COX-2. (1999). https://pubmed.ncbi.nlm.nih.gov/9874808/ DOI: 10.1073/pnas.96.1.272

tissue_or_cell_type

Platelets and whole body

Ibuprofen: the enantiomer that works, the one that was called inactive, the one-way chemistry that turns one into the other, and the targets that are not cyclooxygenase (2026-09-22) · lines 526–537

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Volunteers given celecoxib at three doses or ibuprofen, with platelet, serum and urinary indices · source_derived_draft · unverified_draft

### ibu-cox2-makes-the-prostacyclin Ibuprofen but not celecoxib significantly inhibited thromboxane-dependent platelet aggregation induced ex vivo by arachidonic acid, 83% against 11.9%, and reduced serum thromboxane B2 by 95% and urinary 11-dehydro thromboxane B2 by 70%, while both ibuprofen and celecoxib suppressed an index of cyclooxygenase-2 activity to a comparable degree and both suppressed urinary excretion of the prostacyclin metabolite 2,3-dinor-6-keto-prostaglandin F1 alpha, data suggesting that cyclooxygenase-2 is a major source of systemic prostacyclin biosynthesis in healthy humans. Condition category: normal nutrient_topic: Ibuprofen research collection; topical membership is not evidence of a direct clinical effect, and the racemate is recorded separately from each of its two enantiomers. plain_language: The enzyme these drugs are meant to spare the stomach by blocking is the one that makes the body’s main anticlotting prostaglandin. organism: Human tissue_or_cell_type: Platelets and whole body experimental_model: Volunteers given celecoxib at three doses or ibuprofen, with platelet, serum and urinary indices limitations: Measures both isoform-specific indices in the same people, which is what allows the prostacyclin source to be assigned. Acute dosing in healthy volunteers. exposure: 800 milligrams ibuprofen against 100, 400 or 800 milligrams celecoxib evidence_span: {"source_cache": "artifacts/ibuprofen-research/9874808.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "a643d03df8bc925866696516e7040644634dca29b4f98d39df38ea9c9ab295f4", "start_char": 0, "end_char": 1789, "text_sha256": "a643d03df8bc925866696516e7040644634dca29b4f98d39df38ea9c9ab295f4"} [ibu-p9874808] Systemic biosynthesis of prostacyclin by cyclooxygenase (COX)-2: the human pharmacology of a selective inhibitor of COX-2. (1999). https://pubmed.ncbi.nlm.nih.gov/9874808/ DOI: 10.1073/pnas.96.1.272

evidence_span

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experimental_model

Cultured cells of several types and mutant amyloid precursor protein transgenic mice

exposure

Ibuprofen, indomethacin and sulindac sulphide, with short-term ibuprofen administration in vivo

limitations

The cyclooxygenase-independence is inferred from the fact that the effect is not shared by all inhibitors of the enzyme, rather than shown by a genetic control. Short-term dosing in a transgenic model.

nutrient_topic

Ibuprofen research collection; topical membership is not evidence of a direct clinical effect, and the racemate is recorded separately from each of its two enantiomers. · Ibuprofen

organism

Human cells and mouse

plain_language

The drug shifts where an enzyme cuts rather than stopping it, and the sticky fragment is replaced by a shorter harmless one.

primary_references

[ibu-p11700559] A subset of NSAIDs lower amyloidogenic Abeta42 independently of cyclooxygenase activity. (2001). https://pubmed.ncbi.nlm.nih.gov/11700559/ DOI: 10.1038/35102591

tissue_or_cell_type

Cultured cells and brain

Ibuprofen: the enantiomer that works, the one that was called inactive, the one-way chemistry that turns one into the other, and the targets that are not cyclooxygenase (2026-09-22) · lines 383–394

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Cultured cells of several types and mutant amyloid precursor protein transgenic mice · source_derived_draft · unverified_draft

### ibu-lowers-abeta42-not-via-cox Ibuprofen, indomethacin and sulindac sulphide preferentially decreased the highly amyloidogenic amyloid-beta 42 peptide produced by a variety of cultured cells by as much as 80%, an effect not seen with all non-steroidal anti-inflammatory drugs and seemingly not mediated by inhibition of cyclooxygenase activity, and short-term administration of ibuprofen to mice producing mutant amyloid precursor protein lowered brain amyloid-beta 42; in cultured cells the decrease was accompanied by an increase in the amyloid-beta 1-38 isoform, indicating that these drugs subtly alter gamma-secretase activity without significantly perturbing other processing pathways or Notch cleavage. Condition category: normal nutrient_topic: Ibuprofen research collection; topical membership is not evidence of a direct clinical effect, and the racemate is recorded separately from each of its two enantiomers. plain_language: The drug shifts where an enzyme cuts rather than stopping it, and the sticky fragment is replaced by a shorter harmless one. organism: Human cells and mouse tissue_or_cell_type: Cultured cells and brain experimental_model: Cultured cells of several types and mutant amyloid precursor protein transgenic mice limitations: The cyclooxygenase-independence is inferred from the fact that the effect is not shared by all inhibitors of the enzyme, rather than shown by a genetic control. Short-term dosing in a transgenic model. exposure: Ibuprofen, indomethacin and sulindac sulphide, with short-term ibuprofen administration in vivo evidence_span: {"source_cache": "artifacts/ibuprofen-research/11700559.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "eb9be6e821c04b48c65a999ac5852996bcb4f0249b8bd78b4454a256435e8267", "start_char": 0, "end_char": 1411, "text_sha256": "eb9be6e821c04b48c65a999ac5852996bcb4f0249b8bd78b4454a256435e8267"} [ibu-p11700559] A subset of NSAIDs lower amyloidogenic Abeta42 independently of cyclooxygenase activity. (2001). https://pubmed.ncbi.nlm.nih.gov/11700559/ DOI: 10.1038/35102591

evidence_span

{"source_cache": "artifacts/ibuprofen-research/8907587.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "99f3a26e6399b5f81c18859b9f62eafcd7aa6fc4e483d97a39e8c35c060a9d75", "start_char": 0, "end_char": 1101, "text_sha256": "99f3a26e6399b5f81c18859b9f62eafcd7aa6fc4e483d97a39e8c35c060a9d75"}

experimental_model

Lipopolysaccharide-challenged human whole blood with prostaglandin E2 and thromboxane B2 as isoform indices

exposure

Lipopolysaccharide induction of cyclooxygenase-2 with a single oral indomethacin dose ex vivo

limitations

Establishes the assay the other records rely on. Indomethacin rather than ibuprofen is the drug dosed here.

nutrient_topic

Ibuprofen research collection; topical membership is not evidence of a direct clinical effect, and the racemate is recorded separately from each of its two enantiomers. · Ibuprofen

organism

Human

plain_language

The first enzyme is always there and the second one appears when tissue is provoked; most of these drugs hit the first harder.

primary_references

[ibu-p8907587] A human whole blood assay for clinical evaluation of biochemical efficacy of cyclooxygenase inhibitors. (1996). https://pubmed.ncbi.nlm.nih.gov/8907587/ DOI: 10.1007/bf02265118

tissue_or_cell_type

Whole blood and mononuclear cells

Ibuprofen: the enantiomer that works, the one that was called inactive, the one-way chemistry that turns one into the other, and the targets that are not cyclooxygenase (2026-09-22) · lines 357–368

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Lipopolysaccharide-challenged human whole blood with prostaglandin E2 and thromboxane B2 as isoform indices · source_derived_draft · unverified_draft

### ibu-most-nsaids-favour-cox1 Incubation of human mononuclear cells with lipopolysaccharide induced a time-dependent increase in cyclooxygenase-2 protein of more than a hundredfold at 24 hours with increased prostaglandin E2 production, while cyclooxygenase-1 protein was present at time zero and not induced, and most non-steroidal anti-inflammatory drugs are more potent at inhibiting cyclooxygenase-1 than cyclooxygenase-2, with five experimental compounds showing greater selectivity for cyclooxygenase-2. Condition category: normal nutrient_topic: Ibuprofen research collection; topical membership is not evidence of a direct clinical effect, and the racemate is recorded separately from each of its two enantiomers. plain_language: The first enzyme is always there and the second one appears when tissue is provoked; most of these drugs hit the first harder. organism: Human tissue_or_cell_type: Whole blood and mononuclear cells experimental_model: Lipopolysaccharide-challenged human whole blood with prostaglandin E2 and thromboxane B2 as isoform indices limitations: Establishes the assay the other records rely on. Indomethacin rather than ibuprofen is the drug dosed here. exposure: Lipopolysaccharide induction of cyclooxygenase-2 with a single oral indomethacin dose ex vivo evidence_span: {"source_cache": "artifacts/ibuprofen-research/8907587.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "99f3a26e6399b5f81c18859b9f62eafcd7aa6fc4e483d97a39e8c35c060a9d75", "start_char": 0, "end_char": 1101, "text_sha256": "99f3a26e6399b5f81c18859b9f62eafcd7aa6fc4e483d97a39e8c35c060a9d75"} [ibu-p8907587] A human whole blood assay for clinical evaluation of biochemical efficacy of cyclooxygenase inhibitors. (1996). https://pubmed.ncbi.nlm.nih.gov/8907587/ DOI: 10.1007/bf02265118

evidence_span

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experimental_model

Reporter and enzyme assays comparing ibuprofen isomers against naproxen and indomethacin across four readouts

exposure

S(+)- and R(-)-ibuprofen compared directly on cyclooxygenase-1 and -2, platelet function and nuclear receptor activation

limitations

The only record here that measures both enantiomers on the same panel, which is what makes the fold-differences meaningful. Several different assay systems are combined.

nutrient_topic

Ibuprofen research collection; topical membership is not evidence of a direct clinical effect, and the racemate is recorded separately from each of its two enantiomers. · Ibuprofen

organism

Rat, human and sheep systems

plain_language

At the first enzyme one hand is thirty to ninety times stronger; at the second enzyme the two hands are indistinguishable.

primary_references

[ibu-p11755111] Activation of peroxisome proliferator-activated receptor isoforms and inhibition of prostaglandin H(2) synthases by ibuprofen, naproxen, and indomethacin. (2001). https://pubmed.ncbi.nlm.nih.gov/11755111/ DOI: 10.1016/s0006-2952(01)00822-x

tissue_or_cell_type

Transfected cells, hepatoma cells, platelets and purified enzyme

Ibuprofen: the enantiomer that works, the one that was called inactive, the one-way chemistry that turns one into the other, and the targets that are not cyclooxygenase (2026-09-22) · lines 318–329

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Reporter and enzyme assays comparing ibuprofen isomers against naproxen and indomethacin across four readouts · source_derived_draft · unverified_draft

### ibu-thirty-two-fold-at-cox1 The S(+) isomer of ibuprofen was 32-, 41- and 96-fold more potent than the R(-) isomer for inhibition of prostaglandin endoperoxide H synthase-1 activity, human platelet aggregation and serotonin secretion respectively, while on prostaglandin endoperoxide H synthase-2 the ibuprofen isomers showed no selectivity, and indomethacin, S(+)-ibuprofen and S(+)-naproxen were 6-, 27- and 5-fold more potent as inhibitors of synthase-1 than of synthase-2. Condition category: normal nutrient_topic: Ibuprofen research collection; topical membership is not evidence of a direct clinical effect, and the racemate is recorded separately from each of its two enantiomers. plain_language: At the first enzyme one hand is thirty to ninety times stronger; at the second enzyme the two hands are indistinguishable. organism: Rat, human and sheep systems tissue_or_cell_type: Transfected cells, hepatoma cells, platelets and purified enzyme experimental_model: Reporter and enzyme assays comparing ibuprofen isomers against naproxen and indomethacin across four readouts limitations: The only record here that measures both enantiomers on the same panel, which is what makes the fold-differences meaningful. Several different assay systems are combined. exposure: S(+)- and R(-)-ibuprofen compared directly on cyclooxygenase-1 and -2, platelet function and nuclear receptor activation evidence_span: {"source_cache": "artifacts/ibuprofen-research/11755111.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "1dd77f4a1eebd7777285c424b1731f4744d0fa593e62cfbde0a92dbb6242b239", "start_char": 0, "end_char": 2074, "text_sha256": "1dd77f4a1eebd7777285c424b1731f4744d0fa593e62cfbde0a92dbb6242b239"} [ibu-p11755111] Activation of peroxisome proliferator-activated receptor isoforms and inhibition of prostaglandin H(2) synthases by ibuprofen, naproxen, and indomethacin. (2001). https://pubmed.ncbi.nlm.nih.gov/11755111/ DOI: 10.1016/s0006-2952(01)00822-x

evidence_access

Primary full text

experimental_model

Human primary monocytes and U937 cells; Esther 20% stock diluted to 0.5-10 micrograms/mL, 4-hour pretreatment; homocysteine stimulation.

limitations

Cell exposure does not establish oral exposure, homocysteine removal or cardiovascular benefit. Results text reports homocysteine 200 micromolar, while figure captions say 200 micrograms/mL; dose units are unresolved. Inhibitor concentrations also need original-record clarification. ChIP is a cultured-cell result; the paper uses in vivo to mean within cells.

nutrient_topic

Fulvic acid collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · Fulvic acid (heterogeneous humic fraction)

plain_language

The inflammatory transcription factor occupied the promoter less.

primary_references

Fulvic acid attenuates homocysteine-induced cyclooxygenase-2 expression in human monocytes. · 2015 · https://pubmed.ncbi.nlm.nih.gov/25888188/ · DOI 10.1186/s12906-015-0583-x

Fulvic acid: mixture identity, mineral chemistry, signaling and cross-nutrient mechanisms (2026-09-19) · lines 52–58

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Human primary monocytes and U937 cells; Esther 20% stock diluted to 0.5-10 micrograms/mL, 4-hour pretreatment; homocysteine stimulation. · source_derived_draft · unverified_draft

## fulvic-acid-p65-binding The inflammatory transcription factor occupied the promoter less. Fulvic pretreatment reduced p65 binding at the COX-2 promoter in stimulated U937 cells. Model: Human primary monocytes and U937 cells; Esther 20% stock diluted to 0.5-10 micrograms/mL, 4-hour pretreatment; homocysteine stimulation. Limitations: Cell exposure does not establish oral exposure, homocysteine removal or cardiovascular benefit. Results text reports homocysteine 200 micromolar, while figure captions say 200 micrograms/mL; dose units are unresolved. Inhibitor concentrations also need original-record clarification. ChIP is a cultured-cell result; the paper uses in vivo to mean within cells. Evidence access: Primary full text Fulvic acid attenuates homocysteine-induced cyclooxygenase-2 expression in human monocytes. · 2015 · https://pubmed.ncbi.nlm.nih.gov/25888188/ · DOI 10.1186/s12906-015-0583-x

evidence_access

Primary full text

experimental_model

Human primary monocytes and U937 cells; Esther 20% stock diluted to 0.5-10 micrograms/mL, 4-hour pretreatment; homocysteine stimulation.

limitations

Cell exposure does not establish oral exposure, homocysteine removal or cardiovascular benefit. Results text reports homocysteine 200 micromolar, while figure captions say 200 micrograms/mL; dose units are unresolved. Inhibitor concentrations also need original-record clarification. This is not a demonstrated direct COX-2 catalytic inhibitor.

nutrient_topic

Fulvic acid collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · Fulvic acid (heterogeneous humic fraction)

plain_language

The downstream prostaglandin output also fell.

primary_references

Fulvic acid attenuates homocysteine-induced cyclooxygenase-2 expression in human monocytes. · 2015 · https://pubmed.ncbi.nlm.nih.gov/25888188/ · DOI 10.1186/s12906-015-0583-x

Fulvic acid: mixture identity, mineral chemistry, signaling and cross-nutrient mechanisms (2026-09-19) · lines 68–74

AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Human primary monocytes and U937 cells; Esther 20% stock diluted to 0.5-10 micrograms/mL, 4-hour pretreatment; homocysteine stimulation. · source_derived_draft · unverified_draft

## fulvic-acid-pge-output The downstream prostaglandin output also fell. Fulvic pretreatment reduced PGE2 release after homocysteine stimulation. Model: Human primary monocytes and U937 cells; Esther 20% stock diluted to 0.5-10 micrograms/mL, 4-hour pretreatment; homocysteine stimulation. Limitations: Cell exposure does not establish oral exposure, homocysteine removal or cardiovascular benefit. Results text reports homocysteine 200 micromolar, while figure captions say 200 micrograms/mL; dose units are unresolved. Inhibitor concentrations also need original-record clarification. This is not a demonstrated direct COX-2 catalytic inhibitor. Evidence access: Primary full text Fulvic acid attenuates homocysteine-induced cyclooxygenase-2 expression in human monocytes. · 2015 · https://pubmed.ncbi.nlm.nih.gov/25888188/ · DOI 10.1186/s12906-015-0583-x

evidence_span

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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

availability_state

biomarker_context Imported condition classification; unverified.

evidence_span

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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

The same drug is four hundred times weaker in a platelet than in an inflamed blood vessel, and it is not because the enzymes differ.

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 90–101

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-four-hundred-fold-cell-difference Acetaminophen inhibited prostaglandin H synthase activity with a half-maximal inhibitory concentration of 4.3 micromolar in interleukin-1-alpha-stimulated human umbilical vein endothelial cells against 1,870 micromolar in the platelet with 2 micromolar arachidonic acid as substrate, and this difference is not caused by isoform selectivity because acetaminophen inhibits purified ovine prostaglandin H synthase-1 and murine recombinant synthase-2 equally. 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: The same drug is four hundred times weaker in a platelet than in an inflamed blood vessel, and it is not because the enzymes differ. 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

evidence_span

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experimental_model

Comparison of acetaminophen, rofecoxib, naproxen and SC560 across rat aorta, heart, lung, brain, cerebellum and whole blood

exposure

Four drugs of differing isoform selectivity, with transcript and protein detection including an anti-canine-COX-3 antibody

limitations

Tests the proposal functionally across tissues and looks for the protein directly. A rat study, and a negative Western blot is weaker evidence than a positive one.

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

Rat

plain_language

Nobody could find the protein, and in brain the drug showed no special selectivity at all.

primary_references

[apap-p15148345] Cyclooxygenases 1, 2, and 3 and the production of prostaglandin I2: investigating the activities of acetaminophen and cyclooxygenase-2-selective inhibitors in rat tissues. (2004). https://pubmed.ncbi.nlm.nih.gov/15148345/ DOI: 10.1124/jpet.103.063875

tissue_or_cell_type

Multiple tissues

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 233–244

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Comparison of acetaminophen, rofecoxib, naproxen and SC560 across rat aorta, heart, lung, brain, cerebellum and whole blood · source_derived_draft · unverified_draft

### apap-no-cox3-protein-found Prostanoid production by rat aorta, heart, lung and whole blood was inhibited by all drugs tested with the order of potency SC560 greater than naproxen greater than acetaminophen greater than or equal to rofecoxib while in brain and cerebellum no differences among drug potencies were found, Western blotting using a commercially available antibody raised against canine COX-3 failed to detect any immunoreactive proteins, and the authors conclude that cyclooxygenase-1 and -2 are the functional forms present in the rat tissues tested, that acetaminophen is not a selective inhibitor of cyclooxygenase activities in the central nervous system, and that expression of an active cyclooxygenase protein from COX-3 messenger RNA in the rat is apparently impossible. 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: Nobody could find the protein, and in brain the drug showed no special selectivity at all. organism: Rat tissue_or_cell_type: Multiple tissues experimental_model: Comparison of acetaminophen, rofecoxib, naproxen and SC560 across rat aorta, heart, lung, brain, cerebellum and whole blood limitations: Tests the proposal functionally across tissues and looks for the protein directly. A rat study, and a negative Western blot is weaker evidence than a positive one. exposure: Four drugs of differing isoform selectivity, with transcript and protein detection including an anti-canine-COX-3 antibody evidence_span: {"source_cache": "artifacts/paracetamol-research/15148345.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "6ca43f39a9bb4cbc398f4f7f6e3401854f6c100b72fb7fdf952ee49486438d3c", "start_char": 0, "end_char": 1940, "text_sha256": "6ca43f39a9bb4cbc398f4f7f6e3401854f6c100b72fb7fdf952ee49486438d3c"} [apap-p15148345] Cyclooxygenases 1, 2, and 3 and the production of prostaglandin I2: investigating the activities of acetaminophen and cyclooxygenase-2-selective inhibitors in rat tissues. (2004). https://pubmed.ncbi.nlm.nih.gov/15148345/ DOI: 10.1124/jpet.103.063875

evidence_span

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experimental_model

Human whole blood and isolated monocytes and platelets with parallel prostaglandin E2 and thromboxane B2 measurement

exposure

Acetaminophen at therapeutic plasma concentrations of 100 and 300 micromolar, in whole blood and in isolated cells

limitations

The whole blood against isolated cell comparison shows plasma components matter, and measuring two prostanoids in parallel separates the synthase from the downstream synthase. Ex vivo only.

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

In whole blood it nearly abolishes the inflammatory prostaglandin; in isolated cells it manages only sixty per cent.

primary_references

[apap-p12598417] Effects of acetaminophen on constitutive and inducible prostanoid biosynthesis in human blood cells. (2003). https://pubmed.ncbi.nlm.nih.gov/12598417/ DOI: 10.1038/sj.bjp.0705078

tissue_or_cell_type

Monocytes and platelets

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 272–283

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human whole blood and isolated monocytes and platelets with parallel prostaglandin E2 and thromboxane B2 measurement · source_derived_draft · unverified_draft

### apap-plasma-changes-the-answer Acetaminophen inhibited lipopolysaccharide-induced whole blood prostaglandin E2 and thromboxane B2 production with half-maximal inhibitory concentrations of 44 and 94 micromolar, at therapeutic concentrations of 100 and 300 micromolar it reduced prostaglandin E2 more than thromboxane B2, but in isolated monocytes both were maximally reduced by only 60%, and at the same concentrations it caused a similar and incomplete inhibition of platelet prostaglandin E2 and thromboxane B2 during whole blood clotting, so that in the presence of plasma the drug almost completely suppressed inducible prostaglandin E2 biosynthesis through effects on both cyclooxygenase-2 and inducible prostaglandin E synthase. 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 whole blood it nearly abolishes the inflammatory prostaglandin; in isolated cells it manages only sixty per cent. organism: Human tissue_or_cell_type: Monocytes and platelets experimental_model: Human whole blood and isolated monocytes and platelets with parallel prostaglandin E2 and thromboxane B2 measurement limitations: The whole blood against isolated cell comparison shows plasma components matter, and measuring two prostanoids in parallel separates the synthase from the downstream synthase. Ex vivo only. exposure: Acetaminophen at therapeutic plasma concentrations of 100 and 300 micromolar, in whole blood and in isolated cells evidence_span: {"source_cache": "artifacts/paracetamol-research/12598417.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "e5796a25a03c77d12e8376a60aa094e481bd0c2ab58b29ddcb70027ab477b267", "start_char": 0, "end_char": 1894, "text_sha256": "e5796a25a03c77d12e8376a60aa094e481bd0c2ab58b29ddcb70027ab477b267"} [apap-p12598417] Effects of acetaminophen on constitutive and inducible prostanoid biosynthesis in human blood cells. (2003). https://pubmed.ncbi.nlm.nih.gov/12598417/ DOI: 10.1038/sj.bjp.0705078

evidence_span

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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

evidence_span

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experimental_model

Review of the evidence for an unidentified cyclooxygenase form, written before COX-3 was cloned

exposure

Acetaminophen compared against its effects on urinary prostaglandin metabolites and on platelet and gastric prostaglandin synthesis

limitations

A review that states the puzzle precisely before an answer existed. The human observations it collects are the clinical signature any mechanism has to explain.

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 animal

plain_language

It lowers prostaglandins measured in urine while leaving the platelet and the stomach alone, and that is the puzzle every account has to solve.

primary_references

[apap-p11113024] Mechanism of action of acetaminophen: is there a cyclooxygenase 3? (2000). https://pubmed.ncbi.nlm.nih.gov/11113024/ DOI: 10.1086/317520

tissue_or_cell_type

Platelets, gastric mucosa and tissue homogenates

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 207–218

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Review of the evidence for an unidentified cyclooxygenase form, written before COX-3 was cloned · source_derived_draft · unverified_draft

### apap-the-puzzle-stated Acetaminophen has potent antipyretic and analgesic actions but very weak anti-inflammatory activity, and when administered to humans it reduces levels of prostaglandin metabolites in urine but does not reduce synthesis of prostaglandins by blood platelets or by the stomach mucosa; because it is a weak inhibitor in vitro of both cyclooxygenase-1 and -2 the possibility exists that it inhibits a so far unidentified form, and in animal studies cyclooxygenase in homogenates of different tissues varies in sensitivity to its inhibitory action, which may be evidence that there are more than two isoforms. 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: It lowers prostaglandins measured in urine while leaving the platelet and the stomach alone, and that is the puzzle every account has to solve. organism: Human and animal tissue_or_cell_type: Platelets, gastric mucosa and tissue homogenates experimental_model: Review of the evidence for an unidentified cyclooxygenase form, written before COX-3 was cloned limitations: A review that states the puzzle precisely before an answer existed. The human observations it collects are the clinical signature any mechanism has to explain. exposure: Acetaminophen compared against its effects on urinary prostaglandin metabolites and on platelet and gastric prostaglandin synthesis evidence_span: {"source_cache": "artifacts/paracetamol-research/11113024.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "f3d9785240d2bc30e79775035576d3b017471500c110d627653e6fd80e820eee", "start_char": 0, "end_char": 1012, "text_sha256": "f3d9785240d2bc30e79775035576d3b017471500c110d627653e6fd80e820eee"} [apap-p11113024] Mechanism of action of acetaminophen: is there a cyclooxygenase 3? (2000). https://pubmed.ncbi.nlm.nih.gov/11113024/ DOI: 10.1086/317520

cross_nutrient

false

experimental_model

A549 culture and preinduced cellular COX assay

exposure

IL-1β 10 ng/mL for 24 h; postinduction gamma-CEHC 1 h, then 5 or 15 µM arachidonic acid for 10 min at 37°C.

limitations

Cancer-derived culture, not treatment evidence. Intact-cell IC50 and purified COX inhibition are distinct measurements; increasing substrate weakened inhibition.

nutrient_topic

Vitamin E research collection; topical membership is not evidence of a direct dietary effect. · Vitamin E

organism

Homo sapiens

plain_language

A breakdown product of gamma-tocopherol reduced prostaglandin production in a human lung cell model, including after brief exposure.

primary_references

[jiang2000] gamma-tocopherol and its major metabolite, in contrast to alpha-tocopherol, inhibit cyclooxygenase activity in macrophages and epithelial cells. (2000). https://pubmed.ncbi.nlm.nih.gov/11005841/ DOI: 10.1073/pnas.200357097

tissue_or_cell_type

Lung epithelial carcinoma cell line

Vitamin E: transport, membrane protection and nutrient interactions (2026-09-17) · lines 842–853

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · A549 culture and preinduced cellular COX assay · source_derived_draft · unverified_draft

### e-sig-cehc-a549-pge2 Gamma-CEHC suppressed cytokine-stimulated PGE2 in A549 cells, with an apparent IC50 near 30 µM. It also inhibited PGE2 after only 1 h exposure of COX-2-preinduced cells before arachidonic acid addition. Condition category: normal nutrient_topic: Vitamin E research collection; topical membership is not evidence of a direct dietary effect. plain_language: A breakdown product of gamma-tocopherol reduced prostaglandin production in a human lung cell model, including after brief exposure. organism: Homo sapiens tissue_or_cell_type: Lung epithelial carcinoma cell line experimental_model: A549 culture and preinduced cellular COX assay limitations: Cancer-derived culture, not treatment evidence. Intact-cell IC50 and purified COX inhibition are distinct measurements; increasing substrate weakened inhibition. exposure: IL-1β 10 ng/mL for 24 h; postinduction gamma-CEHC 1 h, then 5 or 15 µM arachidonic acid for 10 min at 37°C. cross_nutrient: false [jiang2000] gamma-tocopherol and its major metabolite, in contrast to alpha-tocopherol, inhibit cyclooxygenase activity in macrophages and epithelial cells. (2000). https://pubmed.ncbi.nlm.nih.gov/11005841/ DOI: 10.1073/pnas.200357097

availability_state

biomarker_context Imported condition classification; unverified.

evidence_span

{"source_cache": "artifacts/aspirin-research/23094721.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "0fab66fe6fa87b7288d31cfbda54b13b3a1d81fd32302054aa4c791b9d6ede43", "start_char": 0, "end_char": 2456, "text_sha256": "0fab66fe6fa87b7288d31cfbda54b13b3a1d81fd32302054aa4c791b9d6ede43"}

experimental_model

Molecular pathological epidemiology in 964 colorectal cancer patients from the Nurses’ Health Study and the Health Professionals Follow-up Study

exposure

Regular aspirin use after diagnosis, stratified by tumour PIK3CA mutation status

limitations

Observational cohorts with tumour genotyping, not a randomised trial, so aspirin use after diagnosis is chosen rather than assigned and may travel with other differences between patients.

nutrient_topic

Aspirin research collection; topical membership is not evidence of a direct clinical effect, and aspirin is recorded separately from salicylate, the metabolite it becomes. · Aspirin / acetylsalicylic acid

organism

Human

plain_language

Aspirin after diagnosis tracked with much better survival, but only in tumours carrying one particular mutation.

primary_references

[asa-p23094721] Aspirin use, tumor PIK3CA mutation, and colorectal-cancer survival. (2012). https://pubmed.ncbi.nlm.nih.gov/23094721/ DOI: 10.1056/nejmoa1207756

tissue_or_cell_type

Colorectal tumour

trigger_kind

biomarker_context Imported condition classification; unverified.

Aspirin: the serine it acetylates, the enzyme that acetylation creates, the dose that separates platelet from vessel wall, and the metabolite that is a different drug (2026-09-22) · lines 598–609

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Molecular pathological epidemiology in 964 colorectal cancer patients from the Nurses’ Health Study and the Health Professionals Follow-up Study · source_derived_draft · unverified_draft

### asa-benefit-tracks-pik3ca Among 964 colorectal cancer patients, regular aspirin use after diagnosis was associated with superior colorectal-cancer-specific survival in those with mutated-PIK3CA cancers, multivariate hazard ratio for cancer-related death 0.18 with 95% confidence interval 0.06 to 0.61, and superior overall survival at hazard ratio 0.54, whereas among patients with wild-type PIK3CA there was no association with cancer-specific survival at hazard ratio 0.96 or overall survival at 0.94, with the interaction between aspirin and PIK3CA yielding a p value of 0.009. Condition category: biomarker_context nutrient_topic: Aspirin research collection; topical membership is not evidence of a direct clinical effect, and aspirin is recorded separately from salicylate, the metabolite it becomes. plain_language: Aspirin after diagnosis tracked with much better survival, but only in tumours carrying one particular mutation. organism: Human tissue_or_cell_type: Colorectal tumour experimental_model: Molecular pathological epidemiology in 964 colorectal cancer patients from the Nurses’ Health Study and the Health Professionals Follow-up Study limitations: Observational cohorts with tumour genotyping, not a randomised trial, so aspirin use after diagnosis is chosen rather than assigned and may travel with other differences between patients. exposure: Regular aspirin use after diagnosis, stratified by tumour PIK3CA mutation status evidence_span: {"source_cache": "artifacts/aspirin-research/23094721.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "0fab66fe6fa87b7288d31cfbda54b13b3a1d81fd32302054aa4c791b9d6ede43", "start_char": 0, "end_char": 2456, "text_sha256": "0fab66fe6fa87b7288d31cfbda54b13b3a1d81fd32302054aa4c791b9d6ede43"} [asa-p23094721] Aspirin use, tumor PIK3CA mutation, and colorectal-cancer survival. (2012). https://pubmed.ncbi.nlm.nih.gov/23094721/ DOI: 10.1056/nejmoa1207756

evidence_span

{"source_cache": "artifacts/aspirin-research/7872783.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "f7e8a07a2704cb600938505ec51355671355769c01868ed0966731382901425b", "start_char": 0, "end_char": 1756, "text_sha256": "f7e8a07a2704cb600938505ec51355671355769c01868ed0966731382901425b"}

experimental_model

Eight acyl salicylates tested against human cyclooxygenase-1 and -2 expressed transiently in cos-1 cells, with the S530A mutant as a control

exposure

Valeryl salicylate and related esters compared with acetylsalicylate

limitations

Uses the acetylation chemistry as a design principle and confirms the serine requirement with a mutant. Recombinant enzyme and a murine fibroblast line, not human tissue.

nutrient_topic

Aspirin research collection; topical membership is not evidence of a direct clinical effect, and aspirin is recorded separately from salicylate, the metabolite it becomes. · Aspirin / acetylsalicylic acid

organism

Human and sheep enzyme

plain_language

Swap aspirin’s acetyl group for a bigger one and you get a drug that hits only the first enzyme.

primary_references

[asa-p7872783] Selective inhibition of prostaglandin endoperoxide synthase-1 (cyclooxygenase-1) by valerylsalicylic acid. (1995). https://pubmed.ncbi.nlm.nih.gov/7872783/ DOI: 10.1006/abbi.1995.1130

tissue_or_cell_type

Recombinant cyclooxygenase

Aspirin: the serine it acetylates, the enzyme that acetylation creates, the dose that separates platelet from vessel wall, and the metabolite that is a different drug (2026-09-22) · lines 182–193

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Eight acyl salicylates tested against human cyclooxygenase-1 and -2 expressed transiently in cos-1 cells, with the S530A mutant as a control · source_derived_draft · unverified_draft

### asa-bigger-acyl-group-selective Valeryl (pentanoyl) salicylate was the only compound of eight acyl salicylates to show isozyme selectivity and inhibited human cyclooxygenase-1 much more effectively than cyclooxygenase-2 in a time-dependent manner, inhibited ovine cyclooxygenase-1 but did not inhibit the S530A mutant of ovine cyclooxygenase-1 which is also refractory to acetylsalicylate, so valeryl salicylate acylates the active site serine. Condition category: normal nutrient_topic: Aspirin research collection; topical membership is not evidence of a direct clinical effect, and aspirin is recorded separately from salicylate, the metabolite it becomes. plain_language: Swap aspirin’s acetyl group for a bigger one and you get a drug that hits only the first enzyme. organism: Human and sheep enzyme tissue_or_cell_type: Recombinant cyclooxygenase experimental_model: Eight acyl salicylates tested against human cyclooxygenase-1 and -2 expressed transiently in cos-1 cells, with the S530A mutant as a control limitations: Uses the acetylation chemistry as a design principle and confirms the serine requirement with a mutant. Recombinant enzyme and a murine fibroblast line, not human tissue. exposure: Valeryl salicylate and related esters compared with acetylsalicylate evidence_span: {"source_cache": "artifacts/aspirin-research/7872783.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "f7e8a07a2704cb600938505ec51355671355769c01868ed0966731382901425b", "start_char": 0, "end_char": 1756, "text_sha256": "f7e8a07a2704cb600938505ec51355671355769c01868ed0966731382901425b"} [asa-p7872783] Selective inhibition of prostaglandin endoperoxide synthase-1 (cyclooxygenase-1) by valerylsalicylic acid. (1995). https://pubmed.ncbi.nlm.nih.gov/7872783/ DOI: 10.1006/abbi.1995.1130

evidence_span

{"source_cache": "artifacts/aspirin-research/41265381.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "88710110438cddd108a51822aeb63c5f0a8125192eecc85eeeaf1edf3c3d85cc", "start_char": 0, "end_char": 2110, "text_sha256": "88710110438cddd108a51822aeb63c5f0a8125192eecc85eeeaf1edf3c3d85cc"}

experimental_model

Aspirin pharmacodynamics in MEG-01 and CHRF-288-11 human megakaryocytic cell lines with selective isoform inhibitors

exposure

Single and repeated aspirin exposures from 0.1 to 10 micromolar, with SC-560 and NS-398 as isoform probes

limitations

A surrogate for a tissue that cannot ethically be sampled repeatedly. Cell lines rather than primary megakaryocytes, which the authors state.

nutrient_topic

Aspirin research collection; topical membership is not evidence of a direct clinical effect, and aspirin is recorded separately from salicylate, the metabolite it becomes. · Aspirin / acetylsalicylic acid

organism

Human cells

plain_language

The precursor cell makes its thromboxane with the first enzyme, and has to build new enzyme to recover.

primary_references

[asa-p41265381] Aspirin inhibition and recovery of cyclooxygenase activity and thromboxane biosynthesis in human megakaryocytes: a translational surrogate model. (2025). https://pubmed.ncbi.nlm.nih.gov/41265381/ DOI: 10.1016/j.jpet.2025.103762

tissue_or_cell_type

Megakaryocytic cell lines

Aspirin: the serine it acetylates, the enzyme that acetylation creates, the dose that separates platelet from vessel wall, and the metabolite that is a different drug (2026-09-22) · lines 429–440

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Aspirin pharmacodynamics in MEG-01 and CHRF-288-11 human megakaryocytic cell lines with selective isoform inhibitors · source_derived_draft · unverified_draft

### asa-megakaryocyte-cox1 In human megakaryocytic cell lines a single 10 micromolar aspirin exposure suppressed thromboxane B2 by 90% and 85% respectively with full recovery within 48 to 72 hours, selective cyclooxygenase-1 inhibition by SC-560 reduced thromboxane B2 by more than 75% whereas cyclooxygenase-2 inhibition by NS-398 had minimal effect, and repeated exposure every 24 hours produced concentration- and time-dependent suppression reaching 89% by day 2 at 1 micromolar and 73% by day 4 at 0.1 micromolar, with delayed recovery likely reflecting de novo synthesis of cyclooxygenase-1 protein. Condition category: normal nutrient_topic: Aspirin research collection; topical membership is not evidence of a direct clinical effect, and aspirin is recorded separately from salicylate, the metabolite it becomes. plain_language: The precursor cell makes its thromboxane with the first enzyme, and has to build new enzyme to recover. organism: Human cells tissue_or_cell_type: Megakaryocytic cell lines experimental_model: Aspirin pharmacodynamics in MEG-01 and CHRF-288-11 human megakaryocytic cell lines with selective isoform inhibitors limitations: A surrogate for a tissue that cannot ethically be sampled repeatedly. Cell lines rather than primary megakaryocytes, which the authors state. exposure: Single and repeated aspirin exposures from 0.1 to 10 micromolar, with SC-560 and NS-398 as isoform probes evidence_span: {"source_cache": "artifacts/aspirin-research/41265381.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "88710110438cddd108a51822aeb63c5f0a8125192eecc85eeeaf1edf3c3d85cc", "start_char": 0, "end_char": 2110, "text_sha256": "88710110438cddd108a51822aeb63c5f0a8125192eecc85eeeaf1edf3c3d85cc"} [asa-p41265381] Aspirin inhibition and recovery of cyclooxygenase activity and thromboxane biosynthesis in human megakaryocytes: a translational surrogate model. (2025). https://pubmed.ncbi.nlm.nih.gov/41265381/ DOI: 10.1016/j.jpet.2025.103762

evidence_span

{"source_cache": "artifacts/aspirin-research/12925531.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "732e941e7f912ae2495715634eabdef176dae39e32359609f15b05a230d5f6e0", "start_char": 0, "end_char": 1473, "text_sha256": "732e941e7f912ae2495715634eabdef176dae39e32359609f15b05a230d5f6e0"}

experimental_model

Site-directed mutants of COX-2 at Arg-120, Tyr-355, Tyr-348 and Ser-530 tested against a series of inhibitors, with a diclofenac co-crystal structure

exposure

Diclofenac, nimesulide and piroxicam against the mutant panel

limitations

Shows the acetylation serine is also a general binding determinant for other drugs. The structural work is on murine rather than human enzyme.

nutrient_topic

Aspirin research collection; topical membership is not evidence of a direct clinical effect, and aspirin is recorded separately from salicylate, the metabolite it becomes. · Aspirin / acetylsalicylic acid

organism

Mouse enzyme

plain_language

The same serine aspirin attacks is where several other anti-inflammatories anchor themselves.

primary_references

[asa-p12925531] A novel mechanism of cyclooxygenase-2 inhibition involving interactions with Ser-530 and Tyr-385. (2003). https://pubmed.ncbi.nlm.nih.gov/12925531/ DOI: 10.1074/jbc.m305481200

tissue_or_cell_type

Cyclooxygenase-2

Aspirin: the serine it acetylates, the enzyme that acetylation creates, the dose that separates platelet from vessel wall, and the metabolite that is a different drug (2026-09-22) · lines 169–180

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Site-directed mutants of COX-2 at Arg-120, Tyr-355, Tyr-348 and Ser-530 tested against a series of inhibitors, with a diclofenac co-crystal structure · source_derived_draft · unverified_draft

### asa-ser530-binds-other-drugs Diclofenac inhibition was unaffected by mutation of Arg-120 to alanine but was dramatically attenuated by the S530A mutation, and the crystal structure of diclofenac with murine COX-2 shows it bound in an inverted conformation with its carboxylate hydrogen-bonded to Tyr-385 and Ser-530, the first experimental demonstration that an acidic non-steroidal anti-inflammatory drug can bind in an orientation that precludes a salt bridge with Arg-120; Ser-530 is also important in time-dependent inhibition by nimesulide and piroxicam. Condition category: normal nutrient_topic: Aspirin research collection; topical membership is not evidence of a direct clinical effect, and aspirin is recorded separately from salicylate, the metabolite it becomes. plain_language: The same serine aspirin attacks is where several other anti-inflammatories anchor themselves. organism: Mouse enzyme tissue_or_cell_type: Cyclooxygenase-2 experimental_model: Site-directed mutants of COX-2 at Arg-120, Tyr-355, Tyr-348 and Ser-530 tested against a series of inhibitors, with a diclofenac co-crystal structure limitations: Shows the acetylation serine is also a general binding determinant for other drugs. The structural work is on murine rather than human enzyme. exposure: Diclofenac, nimesulide and piroxicam against the mutant panel evidence_span: {"source_cache": "artifacts/aspirin-research/12925531.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "732e941e7f912ae2495715634eabdef176dae39e32359609f15b05a230d5f6e0", "start_char": 0, "end_char": 1473, "text_sha256": "732e941e7f912ae2495715634eabdef176dae39e32359609f15b05a230d5f6e0"} [asa-p12925531] A novel mechanism of cyclooxygenase-2 inhibition involving interactions with Ser-530 and Tyr-385. (2003). https://pubmed.ncbi.nlm.nih.gov/12925531/ DOI: 10.1074/jbc.m305481200

evidence_span

{"source_cache": "artifacts/aspirin-research/7552725.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "dd61431f20eb312313942bc8a89f970d5d2e33600b32abe692f20d9d5c57d7b1", "start_char": 0, "end_char": 751, "text_sha256": "dd61431f20eb312313942bc8a89f970d5d2e33600b32abe692f20d9d5c57d7b1"}

experimental_model

X-ray crystal structure at 3.4 angstrom of prostaglandin H2 synthase-1 inactivated by a potent aspirin analogue

exposure

2-bromoacetoxy-benzoic acid acetylation, with salicylic acid soaked into the structure

limitations

Direct structural evidence rather than inference from mutants, though at modest resolution and using an analogue rather than aspirin itself.

nutrient_topic

Aspirin research collection; topical membership is not evidence of a direct clinical effect, and aspirin is recorded separately from salicylate, the metabolite it becomes. · Aspirin / acetylsalicylic acid

organism

Enzyme

plain_language

The picture confirms it: the acetyl group simply plugs the tunnel the fatty acid has to travel down.

primary_references

[asa-p7552725] The structural basis of aspirin activity inferred from the crystal structure of inactivated prostaglandin H2 synthase. (1995). https://pubmed.ncbi.nlm.nih.gov/7552725/ DOI: 10.1038/nsb0895-637

tissue_or_cell_type

Crystallised prostaglandin H2 synthase-1

Aspirin: the serine it acetylates, the enzyme that acetylation creates, the dose that separates platelet from vessel wall, and the metabolite that is a different drug (2026-09-22) · lines 130–141

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · X-ray crystal structure at 3.4 angstrom of prostaglandin H2 synthase-1 inactivated by a potent aspirin analogue · source_derived_draft · unverified_draft

### asa-structure-shows-blockage The 3.4 angstrom X-ray crystal structure of prostaglandin H2 synthase isoform-1 inactivated by the potent aspirin analogue 2-bromoacetoxy-benzoic acid shows that acetylation abolishes cyclooxygenase activity by steric blockage of the active-site channel and not through a large conformational change, with two rotameric states of the acetyl-serine side chain blocking the channel to different extents, a result which may explain the dissimilar effects of aspirin on the two isoforms. Condition category: normal nutrient_topic: Aspirin research collection; topical membership is not evidence of a direct clinical effect, and aspirin is recorded separately from salicylate, the metabolite it becomes. plain_language: The picture confirms it: the acetyl group simply plugs the tunnel the fatty acid has to travel down. organism: Enzyme tissue_or_cell_type: Crystallised prostaglandin H2 synthase-1 experimental_model: X-ray crystal structure at 3.4 angstrom of prostaglandin H2 synthase-1 inactivated by a potent aspirin analogue limitations: Direct structural evidence rather than inference from mutants, though at modest resolution and using an analogue rather than aspirin itself. exposure: 2-bromoacetoxy-benzoic acid acetylation, with salicylic acid soaked into the structure evidence_span: {"source_cache": "artifacts/aspirin-research/7552725.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "dd61431f20eb312313942bc8a89f970d5d2e33600b32abe692f20d9d5c57d7b1", "start_char": 0, "end_char": 751, "text_sha256": "dd61431f20eb312313942bc8a89f970d5d2e33600b32abe692f20d9d5c57d7b1"} [asa-p7552725] The structural basis of aspirin activity inferred from the crystal structure of inactivated prostaglandin H2 synthase. (1995). https://pubmed.ncbi.nlm.nih.gov/7552725/ DOI: 10.1038/nsb0895-637

evidence_span

{"source_cache": "artifacts/aspirin-research/10692466.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "9da1ede1fbf95d6f42d4bb15dc08b5d1869549a7cd94cbfa9da9f9865fd780ff", "start_char": 0, "end_char": 2055, "text_sha256": "9da1ede1fbf95d6f42d4bb15dc08b5d1869549a7cd94cbfa9da9f9865fd780ff"}

experimental_model

Site-directed mutagenesis of mouse COX-2 residues predicted from comparison of the two isoform crystal structures

exposure

Val-434, Arg-513, Val-523, Val-228 and Gly-533 mutated towards their cyclooxygenase-1 equivalents, then acetylated

limitations

Explains the isoform difference residue by residue. Murine enzyme, and the L-shaped substrate configuration is an inference from the mutant product profiles.

nutrient_topic

Aspirin research collection; topical membership is not evidence of a direct clinical effect, and aspirin is recorded separately from salicylate, the metabolite it becomes. · Aspirin / acetylsalicylic acid

organism

Mouse enzyme

plain_language

Three amino acids are the whole difference between an enzyme aspirin kills and one aspirin repurposes.

primary_references

[asa-p10692466] Spatial requirements for 15-(R)-hydroxy-5Z,8Z,11Z, 13E-eicosatetraenoic acid synthesis within the cyclooxygenase active site of murine COX-2. Why acetylated COX-1 does not synthesize 15-(R)-hete. (2000). https://pubmed.ncbi.nlm.nih.gov/10692466/ DOI: 10.1074/jbc.275.9.6586

tissue_or_cell_type

Cyclooxygenase-2

Aspirin: the serine it acetylates, the enzyme that acetylation creates, the dose that separates platelet from vessel wall, and the metabolite that is a different drug (2026-09-22) · lines 247–258

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Site-directed mutagenesis of mouse COX-2 residues predicted from comparison of the two isoform crystal structures · source_derived_draft · unverified_draft

### asa-three-residues-decide Acetylated cyclooxygenase-2 is essentially a lipoxygenase making 15(R)- and 11(R)-hydroxyeicosatetraenoic acid whereas acetylated cyclooxygenase-1 is unable to oxidise arachidonic acid to any products, and site-directed mutagenesis of Val-434, Arg-513 and Val-523 in mouse cyclooxygenase-2 to their cyclooxygenase-1 equivalents abrogated 11- and 15-HETE production after aspirin treatment, confirming these residues as the major isoform selectivity determinants; V228F and G533A produced wild-type-like profiles but on acetylation neither could make HETE products, suggesting arachidonic acid orientates in an L-shaped binding configuration. Condition category: normal nutrient_topic: Aspirin research collection; topical membership is not evidence of a direct clinical effect, and aspirin is recorded separately from salicylate, the metabolite it becomes. plain_language: Three amino acids are the whole difference between an enzyme aspirin kills and one aspirin repurposes. organism: Mouse enzyme tissue_or_cell_type: Cyclooxygenase-2 experimental_model: Site-directed mutagenesis of mouse COX-2 residues predicted from comparison of the two isoform crystal structures limitations: Explains the isoform difference residue by residue. Murine enzyme, and the L-shaped substrate configuration is an inference from the mutant product profiles. exposure: Val-434, Arg-513, Val-523, Val-228 and Gly-533 mutated towards their cyclooxygenase-1 equivalents, then acetylated evidence_span: {"source_cache": "artifacts/aspirin-research/10692466.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "9da1ede1fbf95d6f42d4bb15dc08b5d1869549a7cd94cbfa9da9f9865fd780ff", "start_char": 0, "end_char": 2055, "text_sha256": "9da1ede1fbf95d6f42d4bb15dc08b5d1869549a7cd94cbfa9da9f9865fd780ff"} [asa-p10692466] Spatial requirements for 15-(R)-hydroxy-5Z,8Z,11Z, 13E-eicosatetraenoic acid synthesis within the cyclooxygenase active site of murine COX-2. Why acetylated COX-1 does not synthesize 15-(R)-hete. (2000). https://pubmed.ncbi.nlm.nih.gov/10692466/ DOI: 10.1074/jbc.275.9.6586