Component
Human dihydrofolate reductase / DHFR
Human dihydrofolate reductase / DHFR; species and subcellular isoforms retained separately.
3 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
Human liver DHFR converted 7,8-dihydrofolate to tetrahydrofolate in NADPH-containing assays.
Experimental context and source evidence
- experimental_model
- Fresh human liver extracts from six donors and rat comparison
- exposure
- DHF substrate; THF quantified by HPLC
- limitations
- Assay chemistry, not an outcome study.
- nutrient_topic
- Folate and folic acid research collection; topical membership is not evidence of a direct dietary effect. · Folate (vitamin B9)
- organism
- Homo sapiens
- plain_language
- DHFR regenerates reduced folate from DHF.
- primary_references
- [bailey2009] The extremely slow and variable activity of dihydrofolate reductase in human liver and its implications for high folic acid intake (2009). https://pubmed.ncbi.nlm.nih.gov/19706381/ DOI: 10.1073/pnas.0902072106
- tissue_or_cell_type
- Liver extracts
Folate and folic acid: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 363–373
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Fresh human liver extracts from six donors and rat comparison · source_derived_draft · unverified_draft
### folate-dhfr-dhf-recycling Human liver DHFR converted 7,8-dihydrofolate to tetrahydrofolate in NADPH-containing assays. Condition category: normal nutrient_topic: Folate and folic acid research collection; topical membership is not evidence of a direct dietary effect. plain_language: DHFR regenerates reduced folate from DHF. organism: Homo sapiens tissue_or_cell_type: Liver extracts experimental_model: Fresh human liver extracts from six donors and rat comparison limitations: Assay chemistry, not an outcome study. exposure: DHF substrate; THF quantified by HPLC [bailey2009] The extremely slow and variable activity of dihydrofolate reductase in human liver and its implications for high folic acid intake (2009). https://pubmed.ncbi.nlm.nih.gov/19706381/ DOI: 10.1073/pnas.0902072106
Complete structured claim and evidenceDHFR reduces folic acid to dihydrofolate before further reduction to tetrahydrofolate.
Experimental context and source evidence
- experimental_model
- Fresh human liver extracts from six donors and rat comparison
- exposure
- Folic acid substrate with NADPH
- limitations
- Reaction identity; liver rates cannot define a universal intake ceiling.
- nutrient_topic
- Folate and folic acid research collection; topical membership is not evidence of a direct dietary effect. · Folate (vitamin B9)
- organism
- Homo sapiens
- plain_language
- Folic acid needs a reduction step before it becomes usable folate.
- primary_references
- [bailey2009] The extremely slow and variable activity of dihydrofolate reductase in human liver and its implications for high folic acid intake (2009). https://pubmed.ncbi.nlm.nih.gov/19706381/ DOI: 10.1073/pnas.0902072106
- tissue_or_cell_type
- Liver enzyme preparations
Folate and folic acid: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 351–361
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Fresh human liver extracts from six donors and rat comparison · source_derived_draft · unverified_draft
### folate-dhfr-folic-acid-first-reduction DHFR reduces folic acid to dihydrofolate before further reduction to tetrahydrofolate. Condition category: normal nutrient_topic: Folate and folic acid research collection; topical membership is not evidence of a direct dietary effect. plain_language: Folic acid needs a reduction step before it becomes usable folate. organism: Homo sapiens tissue_or_cell_type: Liver enzyme preparations experimental_model: Fresh human liver extracts from six donors and rat comparison limitations: Reaction identity; liver rates cannot define a universal intake ceiling. exposure: Folic acid substrate with NADPH [bailey2009] The extremely slow and variable activity of dihydrofolate reductase in human liver and its implications for high folic acid intake (2009). https://pubmed.ncbi.nlm.nih.gov/19706381/ DOI: 10.1073/pnas.0902072106
Complete structured claim and evidenceFolic-acid reduction per gram of six human livers averaged less than 2% of rat liver activity at physiological pH, with nearly fivefold human variation.
Experimental context and source evidence
- experimental_model
- Fresh human liver extracts from six donors and rat comparison
- exposure
- Matched ex-vivo activity assay
- limitations
- Small tissue series; neither whole-body clearance nor harm was measured.
- nutrient_topic
- Folate and folic acid research collection; topical membership is not evidence of a direct dietary effect. · Folate (vitamin B9)
- organism
- Homo sapiens and Rattus norvegicus comparison
- plain_language
- Human liver processing was slow and varied between samples.
- primary_references
- [bailey2009] The extremely slow and variable activity of dihydrofolate reductase in human liver and its implications for high folic acid intake (2009). https://pubmed.ncbi.nlm.nih.gov/19706381/ DOI: 10.1073/pnas.0902072106
- tissue_or_cell_type
- Fresh liver extracts
Folate and folic acid: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 375–385
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Fresh human liver extracts from six donors and rat comparison · source_derived_draft · unverified_draft
### folate-human-liver-folic-acid-slow-processing Folic-acid reduction per gram of six human livers averaged less than 2% of rat liver activity at physiological pH, with nearly fivefold human variation. Condition category: normal nutrient_topic: Folate and folic acid research collection; topical membership is not evidence of a direct dietary effect. plain_language: Human liver processing was slow and varied between samples. organism: Homo sapiens and Rattus norvegicus comparison tissue_or_cell_type: Fresh liver extracts experimental_model: Fresh human liver extracts from six donors and rat comparison limitations: Small tissue series; neither whole-body clearance nor harm was measured. exposure: Matched ex-vivo activity assay [bailey2009] The extremely slow and variable activity of dihydrofolate reductase in human liver and its implications for high folic acid intake (2009). https://pubmed.ncbi.nlm.nih.gov/19706381/ DOI: 10.1073/pnas.0902072106
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.