Component

Selectivity of a drug between cell types rather than between enzyme isoforms

Selectivity of a drug between cell types rather than between enzyme isoforms. Species, exposure and limitations are retained in each linked claim.

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

Read recorded mechanisms Open recursive mind map

How nutrients influence it

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

How nutrients reach it in more than one step

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

Tracing routes…

What it does

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

Recorded relationships

What acts on it

  1. 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.

    Paracetamol → Selectivity of a drug between cell types rather than between enzyme isoforms source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    biomarker_context Imported condition classification; unverified.
    evidence_span
    {"source_cache": "artifacts/paracetamol-research/12011469.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "7e599890f658a63c52471fbc7e6853d7db6a5ecbe892241a39c8a633b3ab2d0d", "start_char": 0, "end_char": 1561, "text_sha256": "7e599890f658a63c52471fbc7e6853d7db6a5ecbe892241a39c8a633b3ab2d0d"}
    experimental_model
    Interleukin-1-alpha-stimulated human endothelial cells and human platelets compared, with hydroperoxide addition
    exposure
    Acetaminophen with 2 micromolar arachidonic acid, and with prostaglandin G2, 12-hydroperoxyeicosatetraenoic acid or tert-butyl hydroperoxide added back
    limitations
    The decisive record of the chapter: it measures a 435-fold difference between two human cell types, shows it is not isoform selectivity, and reverses it by adding the peroxide back.
    nutrient_topic
    Paracetamol research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from the metabolites NAPQI and AM404. · Paracetamol
    organism
    Human
    plain_language
    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
    Complete structured claim and evidence

Where it participates (unsigned role)

  1. 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.

    Paracetamol → Platelet thromboxane A2 production in vitro source_derived_draftungraded
    Experimental context and source evidence
    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"}
    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
    Complete structured claim and evidence

In the sources

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

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

    Evidence, AI assistance and curation standards