{"id":"aae2aa4c-56f3-5417-bce5-6703955323f4","stable_key":"3238e4f0-8d45-5c72-8624-6e9a8b20527c:ibu-both-hands-block-nfkb","predicate":"inhibits","statement":"R(-)-ibuprofen with a half-maximal inhibitory concentration of 121.8 micromolar and S(+)-ibuprofen at 61.7 micromolar both inhibited activation of nuclear factor kappa B in response to T-cell stimulation, the effect was specific in that ibuprofen up to 10 millimolar did not affect heat shock transcription factor or activation by prostaglandin E2, concentrations of 20 millimolar did not prevent binding to DNA in vitro, and immunofluorescence and nuclear import experiments indicate the site of action is upstream of dissociation of the nuclear factor kappa B-I-kappa-B complex; only the S(+) enantiomer is an effective cyclooxygenase inhibitor, so the mechanism by which R(-) exerts anti-inflammatory and antinociceptive effects remains unknown.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"1b13e591-e1f1-5ad8-a4be-909debf6b226","mechanism_event_label":"On this target the two hands are only twofold apart, not thirty, which is a route by which the so-called inactive one could work.","subject":{"id":"07a563b8-3005-5217-9cc9-b76365f062c7","slug":"r-ibuprofen","display_name":"R(-)-ibuprofen","entity_type_key":"small_molecule"},"object":{"id":"9dfed6db-cb71-5fe1-9e18-d96fe47d4134","slug":"nfkb-activation-ibu","display_name":"Activation of nuclear factor kappa B in response to T-cell stimulation","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"1b13e591-e1f1-5ad8-a4be-909debf6b226","stable_key":"3238e4f0-8d45-5c72-8624-6e9a8b20527c:ibu-both-hands-block-nfkb-event","event_type":"biochemical_relationship","label":"On this target the two hands are only twofold apart, not thirty, which is a route by which the so-called inactive one could work.","description":"R(-)-ibuprofen with a half-maximal inhibitory concentration of 121.8 micromolar and S(+)-ibuprofen at 61.7 micromolar both inhibited activation of nuclear factor kappa B in response to T-cell stimulation, the effect was specific in that ibuprofen up to 10 millimolar did not affect heat shock transcription factor or activation by prostaglandin E2, concentrations of 20 millimolar did not prevent binding to DNA in vitro, and immunofluorescence and nuclear import experiments indicate the site of action is upstream of dissociation of the nuclear factor kappa B-I-kappa-B complex; only the S(+) enantiomer is an effective cyclooxygenase inhibitor, so the mechanism by which R(-) exerts anti-inflammatory and antinociceptive effects remains unknown.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"04282f17-56c4-54a9-aa33-37bc4c537c87","slug":"s-ibuprofen","display_name":"S(+)-ibuprofen","entity_type_key":"small_molecule"},"role":"co_active_enantiomer","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"4b7e6069-53d4-58cf-be3c-d63e362025bf","slug":"nfkbia","display_name":"Human I-kappa-B alpha / NFKBIA","entity_type_key":"protein"},"role":"upstream_complex","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"ecf9653e-8710-540d-953a-78ef96bf4752","slug":"rela","display_name":"Human NF-kappa-B p65 / RELA","entity_type_key":"protein"},"role":"retained_subunit","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"22df9702-5510-59d6-90e2-c23ec314a47f","slug":"heat-shock-factor","display_name":"Heat shock transcription factor","entity_type_key":"protein"},"role":"unaffected_control","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"07a563b8-3005-5217-9cc9-b76365f062c7","slug":"r-ibuprofen","display_name":"R(-)-ibuprofen","entity_type_key":"small_molecule"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""},{"entity":{"id":"9dfed6db-cb71-5fe1-9e18-d96fe47d4134","slug":"nfkb-activation-ibu","display_name":"Activation of nuclear factor kappa B in response to T-cell stimulation","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":5,"notes":""}]},"contexts":[{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/ibuprofen-research/9517383.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"7a3938a95448a472769fdce1c05ac55d853bfdbdbcda7554ec5b79dcb423db35\", \"start_char\": 0, \"end_char\": 1478, \"text_sha256\": \"7a3938a95448a472769fdce1c05ac55d853bfdbdbcda7554ec5b79dcb423db35\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Electrophoretic mobility-shift assays, transient transfection, confocal immunofluorescence and nuclear import experiments","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"R(-)- and S(+)-ibuprofen compared as inhibitors of nuclear factor kappa B activation","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Compares the enantiomers on a target where the cyclooxygenase argument does not apply. The concentrations are high, in the tens to hundreds of micromolar.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"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.","comparator":null,"unit":null,"notes":"","entity":{"slug":"ibuprofen","display_name":"Ibuprofen","entity_type_key":"drug"}},{"dimension":"organism","value_text":"Human cells","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"On this target the two hands are only twofold apart, not thirty, which is a route by which the so-called inactive one could work.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[ibu-p9517383] Modulation of transcription factor NF-kappaB by enantiomers of the nonsteroidal drug ibuprofen. (1998). https://pubmed.ncbi.nlm.nih.gov/9517383/ DOI: 10.1038/sj.bjp.0701652","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"T lymphocytes","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"85f8da10-7d95-56e9-99a0-858fd057af65","evidence_kind":"source_excerpt","locator":"Lines 370-381","start_line":370,"end_line":381,"excerpt":"### ibu-both-hands-block-nfkb\nR(-)-ibuprofen with a half-maximal inhibitory concentration of 121.8 micromolar and S(+)-ibuprofen at 61.7 micromolar both inhibited activation of nuclear factor kappa B in response to T-cell stimulation, the effect was specific in that ibuprofen up to 10 millimolar did not affect heat shock transcription factor or activation by prostaglandin E2, concentrations of 20 millimolar did not prevent binding to DNA in vitro, and immunofluorescence and nuclear import experiments indicate the site of action is upstream of dissociation of the nuclear factor kappa B-I-kappa-B complex; only the S(+) enantiomer is an effective cyclooxygenase inhibitor, so the mechanism by which R(-) exerts anti-inflammatory and antinociceptive effects remains unknown.\nCondition category: normal\nnutrient_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.\nplain_language: On this target the two hands are only twofold apart, not thirty, which is a route by which the so-called inactive one could work.\norganism: Human cells\ntissue_or_cell_type: T lymphocytes\nexperimental_model: Electrophoretic mobility-shift assays, transient transfection, confocal immunofluorescence and nuclear import experiments\nlimitations: Compares the enantiomers on a target where the cyclooxygenase argument does not apply. The concentrations are high, in the tens to hundreds of micromolar.\nexposure: R(-)- and S(+)-ibuprofen compared as inhibitors of nuclear factor kappa B activation\nevidence_span: {\"source_cache\": \"artifacts/ibuprofen-research/9517383.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"7a3938a95448a472769fdce1c05ac55d853bfdbdbcda7554ec5b79dcb423db35\", \"start_char\": 0, \"end_char\": 1478, \"text_sha256\": \"7a3938a95448a472769fdce1c05ac55d853bfdbdbcda7554ec5b79dcb423db35\"}\n[ibu-p9517383] Modulation of transcription factor NF-kappaB by enantiomers of the nonsteroidal drug ibuprofen. (1998). https://pubmed.ncbi.nlm.nih.gov/9517383/ DOI: 10.1038/sj.bjp.0701652","model_system":"Electrophoretic mobility-shift assays, transient transfection, confocal immunofluorescence and nuclear import experiments","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [ibu-p9517383] Modulation of transcription factor NF-kappaB by enantiomers of the nonsteroidal drug ibuprofen. (1998). https://pubmed.ncbi.nlm.nih.gov/9517383/ DOI: 10.1038/sj.bjp.0701652","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"31c4939d-f520-55c0-973b-224743caf245","stable_key":"import-3238e4f0-8d45-5c72-8624-6e9a8b20527c","title":"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)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text.","file_path":"","sha256":"cc2b388178f97f5906b66ecbe441fc5c86d51fd645947c5260fb0b4bdb4bcd21","revision_id":"0b4e5c65-05d3-5430-a4cd-8d6a03647dcb","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[{"id":"8d81c36e-8817-5916-ab3e-91de380a25d4","title":"Is R-ibuprofen the inactive enantiomer?","kind":"context_difference","status":"open","why":"It is routinely called that, and at cyclooxygenase the description is accurate: S is 32-, 41- and 96-fold more potent for inhibition of cyclooxygenase-1, platelet aggregation and serotonin release, and a 1997 cloning paper states plainly that the R enantiomer is inactive in terms of cyclooxygenase inhibition. On three other measures it is not inactive at all. It inhibits nuclear factor kappa B with a half-maximal concentration of 121.8 micromolar against 61.7 for S, a twofold gap rather than a thirtyfold one. It lowers amyloid-beta 42 production despite that poor cyclooxygenase activity, and by a route that is not nuclear factor kappa B. And it is the only enantiomer that acyl-CoA synthetase will activate, which is what drives the inversion to S and what gets it built into triacylglycerol. At cyclooxygenase-2 the two enantiomers are indistinguishable. The word inactive is a statement about one target that has been generalised to the molecule, and this chapter keeps the two enantiomers as separate entities so that the generalisation cannot be made silently.","resolution":"Unresolved; needs review.","created_at":"2026-09-22 14:28:23","record_type":"conflict","display_label":"Recorded conflict","record_url":"/conflicts/8d81c36e-8817-5916-ab3e-91de380a25d4","sides":[{"conflict_id":"8d81c36e-8817-5916-ab3e-91de380a25d4","ordinal":0,"label":"At the first enzyme one hand is thirty to ninety times stronger; at the second enzyme the two hands are indistinguishable.","revision_id":"0b4e5c65-05d3-5430-a4cd-8d6a03647dcb","start_line":318,"end_line":329,"quote":"### ibu-thirty-two-fold-at-cox1\nThe 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.\nCondition category: normal\nnutrient_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.\nplain_language: At the first enzyme one hand is thirty to ninety times stronger; at the second enzyme the two hands are indistinguishable.\norganism: Rat, human and sheep systems\ntissue_or_cell_type: Transfected cells, hepatoma cells, platelets and purified enzyme\nexperimental_model: Reporter and enzyme assays comparing ibuprofen isomers against naproxen and indomethacin across four readouts\nlimitations: 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.\nexposure: S(+)- and R(-)-ibuprofen compared directly on cyclooxygenase-1 and -2, platelet function and nuclear receptor activation\nevidence_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\"}\n[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","source_key":"import-3238e4f0-8d45-5c72-8624-6e9a8b20527c","source_title":"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)","claim_ids":["a7c4dd5c-b0e4-5366-8bd3-e6283469bc27"]},{"conflict_id":"8d81c36e-8817-5916-ab3e-91de380a25d4","ordinal":1,"label":"On this target the two hands are only twofold apart, not thirty, which is a route by which the so-called inactive one could work.","revision_id":"0b4e5c65-05d3-5430-a4cd-8d6a03647dcb","start_line":370,"end_line":381,"quote":"### ibu-both-hands-block-nfkb\nR(-)-ibuprofen with a half-maximal inhibitory concentration of 121.8 micromolar and S(+)-ibuprofen at 61.7 micromolar both inhibited activation of nuclear factor kappa B in response to T-cell stimulation, the effect was specific in that ibuprofen up to 10 millimolar did not affect heat shock transcription factor or activation by prostaglandin E2, concentrations of 20 millimolar did not prevent binding to DNA in vitro, and immunofluorescence and nuclear import experiments indicate the site of action is upstream of dissociation of the nuclear factor kappa B-I-kappa-B complex; only the S(+) enantiomer is an effective cyclooxygenase inhibitor, so the mechanism by which R(-) exerts anti-inflammatory and antinociceptive effects remains unknown.\nCondition category: normal\nnutrient_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.\nplain_language: On this target the two hands are only twofold apart, not thirty, which is a route by which the so-called inactive one could work.\norganism: Human cells\ntissue_or_cell_type: T lymphocytes\nexperimental_model: Electrophoretic mobility-shift assays, transient transfection, confocal immunofluorescence and nuclear import experiments\nlimitations: Compares the enantiomers on a target where the cyclooxygenase argument does not apply. The concentrations are high, in the tens to hundreds of micromolar.\nexposure: R(-)- and S(+)-ibuprofen compared as inhibitors of nuclear factor kappa B activation\nevidence_span: {\"source_cache\": \"artifacts/ibuprofen-research/9517383.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"7a3938a95448a472769fdce1c05ac55d853bfdbdbcda7554ec5b79dcb423db35\", \"start_char\": 0, \"end_char\": 1478, \"text_sha256\": \"7a3938a95448a472769fdce1c05ac55d853bfdbdbcda7554ec5b79dcb423db35\"}\n[ibu-p9517383] Modulation of transcription factor NF-kappaB by enantiomers of the nonsteroidal drug ibuprofen. (1998). https://pubmed.ncbi.nlm.nih.gov/9517383/ DOI: 10.1038/sj.bjp.0701652","source_key":"import-3238e4f0-8d45-5c72-8624-6e9a8b20527c","source_title":"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)","claim_ids":["aae2aa4c-56f3-5417-bce5-6703955323f4"]},{"conflict_id":"8d81c36e-8817-5916-ab3e-91de380a25d4","ordinal":2,"label":"The half of the molecule that cannot block cyclooxygenase is the half that lowers the Alzheimer peptide.","revision_id":"0b4e5c65-05d3-5430-a4cd-8d6a03647dcb","start_line":396,"end_line":407,"quote":"### ibu-r-enantiomer-lowers-abeta42\nR-ibuprofen and R-flurbiprofen, with poor cyclooxygenase-inhibiting activity, reduce amyloid-beta 42 production by human cells, and although these R enantiomers inhibit nuclear factor kappa B activation and that factor can selectively regulate amyloid-beta 42, the reduction is not mediated by inhibition of nuclear factor kappa B activation; clinical use of these drugs for Alzheimer’s disease has been hampered by dose-limiting toxicity believed to be due to cyclooxygenase inhibition, which is reportedly not essential for selective amyloid-beta 42 reduction.\nCondition category: biomarker_context\nnutrient_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.\nplain_language: The half of the molecule that cannot block cyclooxygenase is the half that lowers the Alzheimer peptide.\norganism: Human cells\ntissue_or_cell_type: Cultured cells\nexperimental_model: Human cells treated with single enantiomers of ibuprofen and flurbiprofen\nlimitations: Uses the enantiomer as the control for cyclooxygenase involvement, which is cleaner than comparing different drugs. It also rules out the nuclear factor kappa B route explicitly.\nexposure: R-ibuprofen and R-flurbiprofen, chosen for their poor cyclooxygenase-inhibiting activity\nevidence_span: {\"source_cache\": \"artifacts/ibuprofen-research/12421374.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"bb022923aad1deb90ae4c540e3e8aab4080a3b78aa9c4a9356447385c31e9c8b\", \"start_char\": 0, \"end_char\": 1003, \"text_sha256\": \"bb022923aad1deb90ae4c540e3e8aab4080a3b78aa9c4a9356447385c31e9c8b\"}\n[ibu-p12421374] Selective inhibition of Abeta42 production by NSAID R-enantiomers. (2002). https://pubmed.ncbi.nlm.nih.gov/12421374/ DOI: 10.1046/j.1471-4159.2002.01195.x","source_key":"import-3238e4f0-8d45-5c72-8624-6e9a8b20527c","source_title":"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)","claim_ids":["64d96cfb-c288-5a83-9f4c-ec4f73b757fe"]}]}],"corrections":[],"research":null}