Component
Human quinone reductase 2 / NQO2
Human quinone reductase 2 / NQO2. Species, exposure and limitations are retained in each linked claim.
4 recorded relationships. Experimental role, claim status and evidence remain attached to each record.
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.
Other things that act on it
Enzymes, hormones, genes, and other components with a recorded effect. These are not nutrients, so they do not count toward the arrows above. Each finding names the chapter that recorded it.
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.
What it acts on
NQO2 RNAi in human K562 cells increased quinone resistance and antioxidant/detoxification enzyme expression, resembling resveratrol treatment.
Experimental context and source evidence
- availability_state
- machinery_impairment Imported condition classification; unverified.
- evidence_access
- Primary abstract
- experimental_model
- Human leukemia cell culture.
- limitations
- Phenocopy does not establish that all resveratrol effects are mediated by NQO2.
- nutrient_topic
- Resveratrol collection; molecular form, preparation, species, exposure and manipulation remain explicit. · Resveratrol
- plain_language
- Genetic reduction of a shared melatonin target reproduced part of the response.
- primary_references
- Crystal structure of quinone reductase 2 in complex with resveratrol. · 2004 · https://pubmed.ncbi.nlm.nih.gov/15350128/ · DOI 10.1021/bi049162o
- trigger_kind
- machinery_impairment Imported condition classification; unverified.
Resveratrol: metabolites, target selectivity and cross-nutrient mechanisms (2026-09-19) · lines 118–124
AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Human leukemia cell culture. · source_derived_draft · unverified_draft
## resveratrol-nqo2-loss Genetic reduction of a shared melatonin target reproduced part of the response. NQO2 RNAi in human K562 cells increased quinone resistance and antioxidant/detoxification enzyme expression, resembling resveratrol treatment. Model: Human leukemia cell culture. Limitations: Phenocopy does not establish that all resveratrol effects are mediated by NQO2. Evidence access: Primary abstract Crystal structure of quinone reductase 2 in complex with resveratrol. · 2004 · https://pubmed.ncbi.nlm.nih.gov/15350128/ · DOI 10.1021/bi049162o
Complete structured claim and evidence
What acts on it
Melatonin competitively inhibited NQO2 with respect to N-methyldihydronicotinamide, with Ki about 7.2 micromolar.
Experimental context and source evidence
- evidence_span
- {"source_cache": "artifacts/melatonin-research/18254726.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "4b99428e7457cd7b67c75ef01b056609dcdf6d5d36cf1c0e933607e2be485c18", "start_char": 0, "end_char": 1724, "text_sha256": "4b99428e7457cd7b67c75ef01b056609dcdf6d5d36cf1c0e933607e2be485c18"}
- experimental_model
- Kinetics, calorimetry and crystal structures
- exposure
- Melatonin versus N-methyldihydronicotinamide or menadione in enzyme assays
- limitations
- NQO2 is the historically named MT3 binding site, not a third MT1/MT2-like GPCR. Micromolar inhibition does not establish the dominant effect at physiological blood concentrations.
- nutrient_topic
- Melatonin research collection; topical membership is not evidence of a direct dietary effect. · Melatonin
- organism
- Purified human NQO2/QR2
- plain_language
- A redox enzyme is a distinct target from the high-affinity membrane receptors.
- primary_references
- [melatonin-p18254726] Kinetic, thermodynamic and X-ray structural insights into the interaction of melatonin and analogues with quinone reductase 2. (2008). https://pubmed.ncbi.nlm.nih.gov/18254726/ DOI: 10.1042/bj20071373
- tissue_or_cell_type
- Cytosolic quinone-reductase active site
Melatonin: synthesis, receptors, circadian timing and nutrient interactions (2026-09-17) · lines 487–498
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Kinetics, calorimetry and crystal structures · source_derived_draft · unverified_draft
### melatonin-nqo2-cosubstrate-competition Melatonin competitively inhibited NQO2 with respect to N-methyldihydronicotinamide, with Ki about 7.2 micromolar. Condition category: normal nutrient_topic: Melatonin research collection; topical membership is not evidence of a direct dietary effect. plain_language: A redox enzyme is a distinct target from the high-affinity membrane receptors. organism: Purified human NQO2/QR2 tissue_or_cell_type: Cytosolic quinone-reductase active site experimental_model: Kinetics, calorimetry and crystal structures limitations: NQO2 is the historically named MT3 binding site, not a third MT1/MT2-like GPCR. Micromolar inhibition does not establish the dominant effect at physiological blood concentrations. exposure: Melatonin versus N-methyldihydronicotinamide or menadione in enzyme assays evidence_span: {"source_cache": "artifacts/melatonin-research/18254726.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "4b99428e7457cd7b67c75ef01b056609dcdf6d5d36cf1c0e933607e2be485c18", "start_char": 0, "end_char": 1724, "text_sha256": "4b99428e7457cd7b67c75ef01b056609dcdf6d5d36cf1c0e933607e2be485c18"} [melatonin-p18254726] Kinetic, thermodynamic and X-ray structural insights into the interaction of melatonin and analogues with quinone reductase 2. (2008). https://pubmed.ncbi.nlm.nih.gov/18254726/ DOI: 10.1042/bj20071373
Complete structured claim and evidenceAgainst menadione, melatonin showed uncompetitive NQO2 inhibition with Ki about 92 micromolar.
Experimental context and source evidence
- evidence_span
- {"source_cache": "artifacts/melatonin-research/18254726.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "4b99428e7457cd7b67c75ef01b056609dcdf6d5d36cf1c0e933607e2be485c18", "start_char": 0, "end_char": 1724, "text_sha256": "4b99428e7457cd7b67c75ef01b056609dcdf6d5d36cf1c0e933607e2be485c18"}
- experimental_model
- Kinetics, calorimetry and crystal structures
- exposure
- Melatonin versus N-methyldihydronicotinamide or menadione in enzyme assays
- limitations
- NQO2 is the historically named MT3 binding site, not a third MT1/MT2-like GPCR. Micromolar inhibition does not establish the dominant effect at physiological blood concentrations.
- nutrient_topic
- Melatonin research collection; topical membership is not evidence of a direct dietary effect. · Melatonin
- organism
- Purified human NQO2/QR2
- plain_language
- The inhibition pattern depends on which reaction participant is varied.
- primary_references
- [melatonin-p18254726] Kinetic, thermodynamic and X-ray structural insights into the interaction of melatonin and analogues with quinone reductase 2. (2008). https://pubmed.ncbi.nlm.nih.gov/18254726/ DOI: 10.1042/bj20071373
- tissue_or_cell_type
- Cytosolic quinone-reductase active site
Melatonin: synthesis, receptors, circadian timing and nutrient interactions (2026-09-17) · lines 500–511
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Kinetics, calorimetry and crystal structures · source_derived_draft · unverified_draft
### melatonin-nqo2-menadione-kinetics Against menadione, melatonin showed uncompetitive NQO2 inhibition with Ki about 92 micromolar. Condition category: normal nutrient_topic: Melatonin research collection; topical membership is not evidence of a direct dietary effect. plain_language: The inhibition pattern depends on which reaction participant is varied. organism: Purified human NQO2/QR2 tissue_or_cell_type: Cytosolic quinone-reductase active site experimental_model: Kinetics, calorimetry and crystal structures limitations: NQO2 is the historically named MT3 binding site, not a third MT1/MT2-like GPCR. Micromolar inhibition does not establish the dominant effect at physiological blood concentrations. exposure: Melatonin versus N-methyldihydronicotinamide or menadione in enzyme assays evidence_span: {"source_cache": "artifacts/melatonin-research/18254726.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "4b99428e7457cd7b67c75ef01b056609dcdf6d5d36cf1c0e933607e2be485c18", "start_char": 0, "end_char": 1724, "text_sha256": "4b99428e7457cd7b67c75ef01b056609dcdf6d5d36cf1c0e933607e2be485c18"} [melatonin-p18254726] Kinetic, thermodynamic and X-ray structural insights into the interaction of melatonin and analogues with quinone reductase 2. (2008). https://pubmed.ncbi.nlm.nih.gov/18254726/ DOI: 10.1042/bj20071373
Complete structured claim and evidenceResveratrol bound the active-site cleft of human NQO2 beside FAD, with reported dissociation constant 35 nM, and inhibited activity in vitro.
Experimental context and source evidence
- evidence_access
- Primary abstract
- experimental_model
- Purified enzyme crystal structure and biochemical assays.
- limitations
- Binding beside FAD does not mean resveratrol depletes riboflavin or displaces FAD.
- nutrient_topic
- Resveratrol collection; molecular form, preparation, species, exposure and manipulation remain explicit. · Resveratrol
- plain_language
- A riboflavin-derived cofactor sits beside a directly observed binding site.
- primary_references
- Crystal structure of quinone reductase 2 in complex with resveratrol. · 2004 · https://pubmed.ncbi.nlm.nih.gov/15350128/ · DOI 10.1021/bi049162o
Resveratrol: metabolites, target selectivity and cross-nutrient mechanisms (2026-09-19) · lines 110–116
AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Purified enzyme crystal structure and biochemical assays. · source_derived_draft · unverified_draft
## resveratrol-nqo2-binding A riboflavin-derived cofactor sits beside a directly observed binding site. Resveratrol bound the active-site cleft of human NQO2 beside FAD, with reported dissociation constant 35 nM, and inhibited activity in vitro. Model: Purified enzyme crystal structure and biochemical assays. Limitations: Binding beside FAD does not mean resveratrol depletes riboflavin or displaces FAD. Evidence access: Primary abstract Crystal structure of quinone reductase 2 in complex with resveratrol. · 2004 · https://pubmed.ncbi.nlm.nih.gov/15350128/ · DOI 10.1021/bi049162o
Complete structured claim and evidence
The events it takes part in
A mechanism often involves more than two components. These are the full events, with every participant and its role.
Situations it appears in
Low-supply and faulty-machinery situations recorded in the chapters where this component plays a part.
In the sources
Preserved passages that mention this component, quoted exactly. Open one to read it in context.
Open hypotheses
Proposed ideas that involve this component. They are labeled as hypotheses and do not change any recorded statement.
This is a research prototype built from draft material. It is not medical advice, and its statements still await verification against the original studies.