Component

Pyridoxal

Unphosphorylated aldehyde vitamer of vitamin B6.

22 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 it acts on

  1. Pyridoxal and 4-pyridoxic acid inhibited PLP binding to human serum albumin in vitro.

    Pyridoxal → PLP source_derived_draftungraded
    Experimental context and source evidence
    evidence_location
    Indexed abstract: equilibrium dialysis and competition
    experimental_model
    Purified human serum albumin binding assays.
    exposure
    In-vitro binding-inhibition experiments.
    limitations
    Physiological competition magnitude and consequences were not established.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    Related B6 molecules can compete in albumin-binding assays.
    primary_references
    [fonda1991] The binding of pyridoxal 5'-phosphate to human serum albumin. (1991). https://pubmed.ncbi.nlm.nih.gov/1898027/ DOI: 10.1016/0003-9861(91)90167-h
    tissue_or_cell_type
    Purified serum albumin

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 348–359

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified human serum albumin binding assays. · source_derived_draft · unverified_draft

    ### b6-transport-albumin-competition Pyridoxal and 4-pyridoxic acid inhibited PLP binding to human serum albumin in vitro. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Related B6 molecules can compete in albumin-binding assays. organism: Homo sapiens tissue_or_cell_type: Purified serum albumin experimental_model: Purified human serum albumin binding assays. limitations: Physiological competition magnitude and consequences were not established. exposure: In-vitro binding-inhibition experiments. evidence_location: Indexed abstract: equilibrium dialysis and competition [fonda1991] The binding of pyridoxal 5'-phosphate to human serum albumin. (1991). https://pubmed.ncbi.nlm.nih.gov/1898027/ DOI: 10.1016/0003-9861(91)90167-h
    Complete structured claim and evidence

  2. During apical PL incubation, basolateral PL appearance approximately matched apical disappearance, without detectable medium PLP or PMP.

    Pyridoxal → Intestinal pyridoxal translocation source_derived_draftungraded
    Experimental context and source evidence
    evidence_location
    Results: Incubation with pyridoxal; Table 1
    experimental_model
    Polarized human Caco-2 monolayers; human intestinal lysates.
    exposure
    100 or 1000 nM PL; 6-48 h.
    limitations
    Cell monolayer model; PL and PN transport mechanisms need not be identical.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    Pyridoxal crossed the cell layer largely as pyridoxal.
    primary_references
    [albersen2013] The intestine plays a substantial role in human vitamin B6 metabolism: a Caco-2 cell model. (2013). https://pubmed.ncbi.nlm.nih.gov/23342087/ DOI: 10.1371/journal.pone.0054113
    tissue_or_cell_type
    Polarized Caco-2 monolayers

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 150–161

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Polarized human Caco-2 monolayers; human intestinal lysates. · source_derived_draft · unverified_draft

    ### b6-transport-enterocyte-pl-translocation During apical PL incubation, basolateral PL appearance approximately matched apical disappearance, without detectable medium PLP or PMP. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Pyridoxal crossed the cell layer largely as pyridoxal. organism: Homo sapiens tissue_or_cell_type: Polarized Caco-2 monolayers experimental_model: Polarized human Caco-2 monolayers; human intestinal lysates. limitations: Cell monolayer model; PL and PN transport mechanisms need not be identical. exposure: 100 or 1000 nM PL; 6-48 h. evidence_location: Results: Incubation with pyridoxal; Table 1 [albersen2013] The intestine plays a substantial role in human vitamin B6 metabolism: a Caco-2 cell model. (2013). https://pubmed.ncbi.nlm.nih.gov/23342087/ DOI: 10.1371/journal.pone.0054113
    Complete structured claim and evidence

What acts on it

  1. In 150 affected children/adolescents, mean plasma pyridoxal was 66.7 versus 37.1 nM in controls; mean 4-pyridoxic acid did not differ.

    Tissue-nonspecific alkaline phosphatase ALPL / TNAP → Pyridoxal source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    biomarker_context Imported condition classification; unverified.
    experimental_model
    Primary measurement study in 150 children/adolescents with hypophosphatasia and healthy pediatric comparators; adult observations separately discussed.
    exposure
    ALPL-related hypophosphatasia, variable clinical severity; plasma vitamers, not direct all-tissue cofactor measurement.
    limitations
    Cohort result cannot be transferred to every severe neonatal case; does not establish all-tissue sufficiency.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    ALPL impairment did not make circulating pyridoxal universally low in this pediatric cohort.
    primary_references
    [b6-whyte2022] Hypophosphatasia: Vitamin B6 status of affected children and adults (2022). https://pubmed.ncbi.nlm.nih.gov/34547524/ DOI: 10.1016/j.bone.2021.116204
    tissue_or_cell_type
    Human blood and whole-body measurements
    trigger_kind
    biomarker_context Imported condition classification; unverified.

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1633–1643

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Primary measurement study in 150 children/adolescents with hypophosphatasia and healthy pediatric comparators; adult observations separately discussed. · source_derived_draft · unverified_draft

    ### b6-hpp-pediatric-pyridoxal In 150 affected children/adolescents, mean plasma pyridoxal was 66.7 versus 37.1 nM in controls; mean 4-pyridoxic acid did not differ. Condition category: biomarker_context nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: ALPL impairment did not make circulating pyridoxal universally low in this pediatric cohort. organism: Homo sapiens tissue_or_cell_type: Human blood and whole-body measurements experimental_model: Primary measurement study in 150 children/adolescents with hypophosphatasia and healthy pediatric comparators; adult observations separately discussed. limitations: Cohort result cannot be transferred to every severe neonatal case; does not establish all-tissue sufficiency. exposure: ALPL-related hypophosphatasia, variable clinical severity; plasma vitamers, not direct all-tissue cofactor measurement. [b6-whyte2022] Hypophosphatasia: Vitamin B6 status of affected children and adults (2022). https://pubmed.ncbi.nlm.nih.gov/34547524/ DOI: 10.1016/j.bone.2021.116204
    Complete structured claim and evidence

  2. Isoniazid and pyridoxal formed PIH without cells or enzymes.

    Isoniazid → Pyridoxal source_derived_draftungraded
    Experimental context and source evidence
    experimental_model
    Cell-free chemistry, primary human hepatocytes and HepG2/C3A cells
    exposure
    1 mM reactants in PBS; timed incubations at 4 or 37 C.
    limitations
    High-concentration cell-free chemistry; not proof of neuronal depletion.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Not applicable; chemical reaction
    plain_language
    A drug can chemically capture a B6 vitamer.
    primary_references
    [brewer-2019-isoniazid] The Isoniazid Metabolites Hydrazine and Pyridoxal Isonicotinoyl Hydrazone Modulate Heme Biosynthesis (2019). https://pmc.ncbi.nlm.nih.gov/articles/PMC6390808/ DOI: 10.1093/toxsci/kfy294
    tissue_or_cell_type
    Cell-free PBS

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1271–1281

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Cell-free chemistry, primary human hepatocytes and HepG2/C3A cells · source_derived_draft · unverified_draft

    ### b6-neuro-isoniazid-pl-conjugation Isoniazid and pyridoxal formed PIH without cells or enzymes. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: A drug can chemically capture a B6 vitamer. organism: Not applicable; chemical reaction tissue_or_cell_type: Cell-free PBS experimental_model: Cell-free chemistry, primary human hepatocytes and HepG2/C3A cells limitations: High-concentration cell-free chemistry; not proof of neuronal depletion. exposure: 1 mM reactants in PBS; timed incubations at 4 or 37 C. [brewer-2019-isoniazid] The Isoniazid Metabolites Hydrazine and Pyridoxal Isonicotinoyl Hydrazone Modulate Heme Biosynthesis (2019). https://pmc.ncbi.nlm.nih.gov/articles/PMC6390808/ DOI: 10.1093/toxsci/kfy294
    Complete structured claim and evidence

  3. Polarized Caco-2 cells supplied apically with PM generated PL and released more PL basolaterally than apically.

    Pyridoxamine → Pyridoxal source_derived_draftungraded
    Experimental context and source evidence
    evidence_location
    Results: Incubation with pyridoxamine; Figure 4
    experimental_model
    Polarized human Caco-2 monolayers; human intestinal lysates.
    exposure
    100 or 1000 nM PM; 6-48 h.
    limitations
    Vitamer measurements establish net conversion; individual enzyme fluxes were not separately perturbed.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    Enterocytes can process a precursor before releasing pyridoxal.
    primary_references
    [albersen2013] The intestine plays a substantial role in human vitamin B6 metabolism: a Caco-2 cell model. (2013). https://pubmed.ncbi.nlm.nih.gov/23342087/ DOI: 10.1371/journal.pone.0054113
    tissue_or_cell_type
    Polarized Caco-2 monolayers

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 137–148

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Polarized human Caco-2 monolayers; human intestinal lysates. · source_derived_draft · unverified_draft

    ### b6-transport-enterocyte-pm-to-pl Polarized Caco-2 cells supplied apically with PM generated PL and released more PL basolaterally than apically. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Enterocytes can process a precursor before releasing pyridoxal. organism: Homo sapiens tissue_or_cell_type: Polarized Caco-2 monolayers experimental_model: Polarized human Caco-2 monolayers; human intestinal lysates. limitations: Vitamer measurements establish net conversion; individual enzyme fluxes were not separately perturbed. exposure: 100 or 1000 nM PM; 6-48 h. evidence_location: Results: Incubation with pyridoxamine; Figure 4 [albersen2013] The intestine plays a substantial role in human vitamin B6 metabolism: a Caco-2 cell model. (2013). https://pubmed.ncbi.nlm.nih.gov/23342087/ DOI: 10.1371/journal.pone.0054113
    Complete structured claim and evidence

  4. Polarized Caco-2 cells supplied apically with PN generated PL and released more PL basolaterally than apically.

    Pyridoxine → Pyridoxal source_derived_draftungraded
    Experimental context and source evidence
    evidence_location
    Results: Incubation with pyridoxine; Figure 4
    experimental_model
    Polarized human Caco-2 monolayers; human intestinal lysates.
    exposure
    100 or 1000 nM PN; 6-48 h.
    limitations
    Vitamer measurements establish net conversion; individual enzyme fluxes were not separately perturbed.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    Enterocytes can process a precursor before releasing pyridoxal.
    primary_references
    [albersen2013] The intestine plays a substantial role in human vitamin B6 metabolism: a Caco-2 cell model. (2013). https://pubmed.ncbi.nlm.nih.gov/23342087/ DOI: 10.1371/journal.pone.0054113
    tissue_or_cell_type
    Polarized Caco-2 monolayers

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 124–135

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Polarized human Caco-2 monolayers; human intestinal lysates. · source_derived_draft · unverified_draft

    ### b6-transport-enterocyte-pn-to-pl Polarized Caco-2 cells supplied apically with PN generated PL and released more PL basolaterally than apically. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Enterocytes can process a precursor before releasing pyridoxal. organism: Homo sapiens tissue_or_cell_type: Polarized Caco-2 monolayers experimental_model: Polarized human Caco-2 monolayers; human intestinal lysates. limitations: Vitamer measurements establish net conversion; individual enzyme fluxes were not separately perturbed. exposure: 100 or 1000 nM PN; 6-48 h. evidence_location: Results: Incubation with pyridoxine; Figure 4 [albersen2013] The intestine plays a substantial role in human vitamin B6 metabolism: a Caco-2 cell model. (2013). https://pubmed.ncbi.nlm.nih.gov/23342087/ DOI: 10.1371/journal.pone.0054113
    Complete structured claim and evidence

  5. Rat jejunal perfusion and in-vitro assays demonstrated phosphatase-mediated hydrolysis of luminal PLP.

    Intestinal PLP hydrolysis → Pyridoxal source_derived_draftungraded
    Experimental context and source evidence
    evidence_location
    Indexed abstract: hydrolysis, albumin and pH experiments
    experimental_model
    Rat jejunal perfusion and in-vitro phosphatase assays.
    exposure
    PLP hydrolysis tested across luminal pH and albumin concentrations.
    limitations
    Luminal disappearance is not a complete absorption balance; no specific human phosphatase is assigned.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Rattus norvegicus
    plain_language
    Intestinal phosphatases remove PLP phosphate.
    primary_references
    [middleton1986] Intestinal hydrolysis of pyridoxal 5'-phosphate in vitro and in vivo in the rat. Effect of protein binding and pH. (1986). https://pubmed.ncbi.nlm.nih.gov/3721120/ DOI: 10.1016/0016-5085(86)90567-6
    tissue_or_cell_type
    Jejunum

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 72–83

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Rat jejunal perfusion and in-vitro phosphatase assays. · source_derived_draft · unverified_draft

    ### b6-transport-gut-plp-hydrolysis Rat jejunal perfusion and in-vitro assays demonstrated phosphatase-mediated hydrolysis of luminal PLP. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Intestinal phosphatases remove PLP phosphate. organism: Rattus norvegicus tissue_or_cell_type: Jejunum experimental_model: Rat jejunal perfusion and in-vitro phosphatase assays. limitations: Luminal disappearance is not a complete absorption balance; no specific human phosphatase is assigned. exposure: PLP hydrolysis tested across luminal pH and albumin concentrations. evidence_location: Indexed abstract: hydrolysis, albumin and pH experiments [middleton1986] Intestinal hydrolysis of pyridoxal 5'-phosphate in vitro and in vivo in the rat. Effect of protein binding and pH. (1986). https://pubmed.ncbi.nlm.nih.gov/3721120/ DOI: 10.1016/0016-5085(86)90567-6
    Complete structured claim and evidence

  6. Human PDXK assays directly measured ATP-dependent conversion of pyridoxal to PLP, a reaction distinct from PNPO oxidation.

    Pyridoxal kinase / PDXK → Pyridoxal source_derived_draftungraded
    Experimental context and source evidence
    cross_nutrient
    Separates the B6 phosphorylation step from the B2-dependent oxidation step.
    evidence_location
    Abstract
    experimental_model
    Recombinant human PDXK expressed in E. coli; PL-to-PLP kinetics and unliganded/MgATP-bound structures.
    exposure
    Purified-enzyme assay
    limitations
    This biochemical route does not establish that dietary pyridoxal bypasses all consequences of PNPO disease.
    nutrient_topic
    Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)
    organism
    Homo sapiens
    plain_language
    Not every route to active B6 passes through PNPO.
    primary_references
    [safo2007] Crystal Structure of human pyridoxal kinase: structural basis of M(+) and M(2+) activation. (2007). https://pubmed.ncbi.nlm.nih.gov/17766369/ DOI: 10.1110/ps.073022107
    tissue_or_cell_type
    Purified recombinant enzyme; no intact tissue

    Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1192–1204

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human PDXK expressed in E. coli; PL-to-PLP kinetics and unliganded/MgATP-bound structures. · source_derived_draft · unverified_draft

    ### b2-pdxk-pyridoxal-route Human PDXK assays directly measured ATP-dependent conversion of pyridoxal to PLP, a reaction distinct from PNPO oxidation. Condition category: normal nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: Not every route to active B6 passes through PNPO. organism: Homo sapiens tissue_or_cell_type: Purified recombinant enzyme; no intact tissue experimental_model: Recombinant human PDXK expressed in E. coli; PL-to-PLP kinetics and unliganded/MgATP-bound structures. limitations: This biochemical route does not establish that dietary pyridoxal bypasses all consequences of PNPO disease. exposure: Purified-enzyme assay cross_nutrient: Separates the B6 phosphorylation step from the B2-dependent oxidation step. evidence_location: Abstract [safo2007] Crystal Structure of human pyridoxal kinase: structural basis of M(+) and M(2+) activation. (2007). https://pubmed.ncbi.nlm.nih.gov/17766369/ DOI: 10.1110/ps.073022107
    Complete structured claim and evidence

Where it participates (unsigned role)

  1. Enzyme replacement was associated with lower serum PLP: PL ratios; CSF PL was higher in treated than untreated cases.

    Tissue-nonspecific alkaline phosphatase ALPL / TNAP → Serum PLP to pyridoxal ratio source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    machinery_impairment Imported condition classification; unverified.
    experimental_model
    Over 100 hypophosphatasia cases, serum vitamers and available CSF; supplementation/enzyme-replacement subgroups.
    exposure
    Observational clinical sampling by subtype and treatment; no randomized B6 efficacy comparison.
    limitations
    Nonrandomized treatment comparisons; does not directly measure transport flux or establish neurological benefit.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    Restoring enzyme activity changed B6 handling markers, including the sampled fluid around the brain.
    primary_references
    [b6-akitomo2025] Vitamin B6 Status in Hypophosphatasia: Association With Clinical Severity, Diagnostic Utility, and Effects on Vitamin B6 Metabolism by Supplementation and Enzyme Replacement Therapy (2025). https://pubmed.ncbi.nlm.nih.gov/40387451/ DOI: 10.1002/jimd.70036
    tissue_or_cell_type
    Serum and cerebrospinal fluid
    trigger_kind
    machinery_impairment Imported condition classification; unverified.

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1657–1667

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Over 100 hypophosphatasia cases, serum vitamers and available CSF; supplementation/enzyme-replacement subgroups. · source_derived_draft · unverified_draft

    ### b6-hpp-enzyme-replacement-ratio Enzyme replacement was associated with lower serum PLP: PL ratios; CSF PL was higher in treated than untreated cases. Condition category: machinery_impairment nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Restoring enzyme activity changed B6 handling markers, including the sampled fluid around the brain. organism: Homo sapiens tissue_or_cell_type: Serum and cerebrospinal fluid experimental_model: Over 100 hypophosphatasia cases, serum vitamers and available CSF; supplementation/enzyme-replacement subgroups. limitations: Nonrandomized treatment comparisons; does not directly measure transport flux or establish neurological benefit. exposure: Observational clinical sampling by subtype and treatment; no randomized B6 efficacy comparison. [b6-akitomo2025] Vitamin B6 Status in Hypophosphatasia: Association With Clinical Severity, Diagnostic Utility, and Effects on Vitamin B6 Metabolism by Supplementation and Enzyme Replacement Therapy (2025). https://pubmed.ncbi.nlm.nih.gov/40387451/ DOI: 10.1002/jimd.70036
    Complete structured claim and evidence

  2. In the 2025 cohort, untreated HPP had higher serum PLP and PLP: PL ratios; severe perinatal disease had lower PL than benign perinatal disease and the lowest PA across subtypes.

    Tissue-nonspecific alkaline phosphatase ALPL / TNAP → Serum PLP to pyridoxal ratio source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    biomarker_context Imported condition classification; unverified.
    experimental_model
    Over 100 hypophosphatasia cases, serum vitamers and available CSF; supplementation/enzyme-replacement subgroups.
    exposure
    Observational clinical sampling by subtype and treatment; no randomized B6 efficacy comparison.
    limitations
    Observational subtype comparison; contextual difference from broader pediatric cohorts, not an editorial conflict.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    Disease severity changes which B6 forms accumulate or become low.
    primary_references
    [b6-akitomo2025] Vitamin B6 Status in Hypophosphatasia: Association With Clinical Severity, Diagnostic Utility, and Effects on Vitamin B6 Metabolism by Supplementation and Enzyme Replacement Therapy (2025). https://pubmed.ncbi.nlm.nih.gov/40387451/ DOI: 10.1002/jimd.70036
    tissue_or_cell_type
    Human blood and whole-body measurements
    trigger_kind
    biomarker_context Imported condition classification; unverified.

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1645–1655

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Over 100 hypophosphatasia cases, serum vitamers and available CSF; supplementation/enzyme-replacement subgroups. · source_derived_draft · unverified_draft

    ### b6-hpp-severity-vitamer-pattern In the 2025 cohort, untreated HPP had higher serum PLP and PLP: PL ratios; severe perinatal disease had lower PL than benign perinatal disease and the lowest PA across subtypes. Condition category: biomarker_context nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Disease severity changes which B6 forms accumulate or become low. organism: Homo sapiens tissue_or_cell_type: Human blood and whole-body measurements experimental_model: Over 100 hypophosphatasia cases, serum vitamers and available CSF; supplementation/enzyme-replacement subgroups. limitations: Observational subtype comparison; contextual difference from broader pediatric cohorts, not an editorial conflict. exposure: Observational clinical sampling by subtype and treatment; no randomized B6 efficacy comparison. [b6-akitomo2025] Vitamin B6 Status in Hypophosphatasia: Association With Clinical Severity, Diagnostic Utility, and Effects on Vitamin B6 Metabolism by Supplementation and Enzyme Replacement Therapy (2025). https://pubmed.ncbi.nlm.nih.gov/40387451/ DOI: 10.1002/jimd.70036
    Complete structured claim and evidence

  3. Ginkgotoxin competed with pyridoxal and delayed PLP formation by human PDXK; increasing pyridoxal alleviated inhibition.

    Ginkgotoxin / 4-prime-O-methylpyridoxine → Pyridoxal kinase / PDXK source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    machinery_impairment Imported condition classification; unverified.
    experimental_model
    Purified recombinant human PDXK; HPLC and kinetic competition assays
    exposure
    25 micromolar pyridoxal with 12.5-25 micromolar ginkgotoxin in illustrative co-incubations.
    limitations
    Reported Ki was assay-specific; not a clinical exposure limit.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    The toxin competes for the enzyme that activates B6.
    primary_references
    [kastner-2007-ginkgotoxin] The human pyridoxal kinase, a plausible target for ginkgotoxin from Ginkgo biloba (2007). https://doi.org/10.1111/j.1742-4658.2007.05654.x DOI: 10.1111/j.1742-4658.2007.05654.x
    tissue_or_cell_type
    Purified recombinant protein; no intact tissue
    trigger_kind
    machinery_impairment Imported condition classification; unverified.

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1196–1206

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified recombinant human PDXK; HPLC and kinetic competition assays · source_derived_draft · unverified_draft

    ### b6-neuro-ginkgotoxin-plp-competition Ginkgotoxin competed with pyridoxal and delayed PLP formation by human PDXK; increasing pyridoxal alleviated inhibition. Condition category: machinery_impairment nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: The toxin competes for the enzyme that activates B6. organism: Homo sapiens tissue_or_cell_type: Purified recombinant protein; no intact tissue experimental_model: Purified recombinant human PDXK; HPLC and kinetic competition assays limitations: Reported Ki was assay-specific; not a clinical exposure limit. exposure: 25 micromolar pyridoxal with 12.5-25 micromolar ginkgotoxin in illustrative co-incubations. [kastner-2007-ginkgotoxin] The human pyridoxal kinase, a plausible target for ginkgotoxin from Ginkgo biloba (2007). https://doi.org/10.1111/j.1742-4658.2007.05654.x DOI: 10.1111/j.1742-4658.2007.05654.x
    Complete structured claim and evidence

  4. Pyridoxal, pyridoxamine, PLP and PMP did not reduce viability in the tested 24-hour cell assay.

    PLP → SH-SY5Y cell viability by MTT source_derived_draftungraded
    Experimental context and source evidence
    experimental_model
    Differentiated human SH-SY5Y and CaCo-2 cells; isolated enzyme assays
    exposure
    Comparators 0-500 micromolar for 24 hours.
    exposure-class
    Experimental excess pyridoxine; not dietary B6 deficiency · Pyridoxine
    limitations
    A negative short-term cell assay proves neither universal safety nor equivalent toxicity.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    The tested B6 forms behaved differently in this assay.
    primary_references
    [vrolijk-2017-pn] The vitamin B6 paradox: Supplementation with high concentrations of pyridoxine leads to decreased vitamin B6 function (2017). https://doi.org/10.1016/j.tiv.2017.07.009 DOI: 10.1016/j.tiv.2017.07.009
    tissue_or_cell_type
    SH-SY5Y and CaCo-2 cells

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1245–1256

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Differentiated human SH-SY5Y and CaCo-2 cells; isolated enzyme assays · source_derived_draft · unverified_draft

    ### b6-neuro-pn-vitamer-specificity Pyridoxal, pyridoxamine, PLP and PMP did not reduce viability in the tested 24-hour cell assay. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: The tested B6 forms behaved differently in this assay. organism: Homo sapiens tissue_or_cell_type: SH-SY5Y and CaCo-2 cells experimental_model: Differentiated human SH-SY5Y and CaCo-2 cells; isolated enzyme assays limitations: A negative short-term cell assay proves neither universal safety nor equivalent toxicity. exposure: Comparators 0-500 micromolar for 24 hours. exposure-class: Experimental excess pyridoxine; not dietary B6 deficiency [vrolijk-2017-pn] The vitamin B6 paradox: Supplementation with high concentrations of pyridoxine leads to decreased vitamin B6 function (2017). https://doi.org/10.1016/j.tiv.2017.07.009 DOI: 10.1016/j.tiv.2017.07.009
    Complete structured claim and evidence

  5. Theophylline inhibited purified human PDXK, with Ki 50 micromolar, and occupied its vitamin-substrate site.

    Theophylline → Pyridoxal kinase / PDXK source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    machinery_impairment Imported condition classification; unverified.
    experimental_model
    Purified human PDXK; crystallography and inhibition kinetics
    exposure
    Purified-enzyme inhibition series; 2.1 angstrom crystal structure.
    limitations
    Other preparations yielded different Ki values; this is assay context, not a nutritional threshold.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    This drug can interfere with B6 activation in an enzyme assay.
    primary_references
    [gandhi-2012-pdxk-inhibitors] Crystal Structures of Human Pyridoxal Kinase in Complex with the Neurotoxins, Ginkgotoxin and Theophylline: Insights into Pyridoxal Kinase Inhibition (2012). https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0040954 DOI: 10.1371/journal.pone.0040954
    tissue_or_cell_type
    Purified recombinant protein; no intact tissue
    trigger_kind
    machinery_impairment Imported condition classification; unverified.

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1220–1230

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified human PDXK; crystallography and inhibition kinetics · source_derived_draft · unverified_draft

    ### b6-neuro-theophylline-pdxk Theophylline inhibited purified human PDXK, with Ki 50 micromolar, and occupied its vitamin-substrate site. Condition category: machinery_impairment nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: This drug can interfere with B6 activation in an enzyme assay. organism: Homo sapiens tissue_or_cell_type: Purified recombinant protein; no intact tissue experimental_model: Purified human PDXK; crystallography and inhibition kinetics limitations: Other preparations yielded different Ki values; this is assay context, not a nutritional threshold. exposure: Purified-enzyme inhibition series; 2.1 angstrom crystal structure. [gandhi-2012-pdxk-inhibitors] Crystal Structures of Human Pyridoxal Kinase in Complex with the Neurotoxins, Ginkgotoxin and Theophylline: Insights into Pyridoxal Kinase Inhibition (2012). https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0040954 DOI: 10.1371/journal.pone.0040954
    Complete structured claim and evidence

  6. Human fibroblast ALPL hydrolyzed extracellular micromolar PLP at physiological pH; intact-cell and PI-PLC experiments supported lipid-anchored ecto-orientation.

    Tissue-nonspecific alkaline phosphatase ALPL / TNAP → PLP source_derived_draftungraded
    Experimental context and source evidence
    evidence_location
    Indexed abstract: intact/disrupted cells, PI-PLC and patient enzyme activity
    experimental_model
    Normal and hypophosphatasia human skin fibroblasts.
    exposure
    Extracellular PLP; intact versus disrupted cells; PI-PLC release.
    limitations
    Directly demonstrated in fibroblasts; does not itself measure brain entry.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    Cell-surface ALPL processes PLP outside the cell.
    primary_references
    [fedde1990] Alkaline phosphatase (tissue-nonspecific isoenzyme) is a phosphoethanolamine and pyridoxal-5'-phosphate ectophosphatase: normal and hypophosphatasia fibroblast study. (1990). https://pubmed.ncbi.nlm.nih.gov/2220817/
    tissue_or_cell_type
    Skin fibroblasts

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 309–320

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Normal and hypophosphatasia human skin fibroblasts. · source_derived_draft · unverified_draft

    ### b6-transport-alpl-ecto Human fibroblast ALPL hydrolyzed extracellular micromolar PLP at physiological pH; intact-cell and PI-PLC experiments supported lipid-anchored ecto-orientation. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Cell-surface ALPL processes PLP outside the cell. organism: Homo sapiens tissue_or_cell_type: Skin fibroblasts experimental_model: Normal and hypophosphatasia human skin fibroblasts. limitations: Directly demonstrated in fibroblasts; does not itself measure brain entry. exposure: Extracellular PLP; intact versus disrupted cells; PI-PLC release. evidence_location: Indexed abstract: intact/disrupted cells, PI-PLC and patient enzyme activity [fedde1990] Alkaline phosphatase (tissue-nonspecific isoenzyme) is a phosphoethanolamine and pyridoxal-5'-phosphate ectophosphatase: normal and hypophosphatasia fibroblast study. (1990). https://pubmed.ncbi.nlm.nih.gov/2220817/
    Complete structured claim and evidence

  7. Human PDXK showed lower substrate Km with potassium than sodium, whereas sodium supported over twice the maximal activity.

    Potassium ion → Pyridoxal kinase / PDXK source_derived_draftungraded
    Experimental context and source evidence
    cross_nutrient
    Potassium/sodium-B6 enzyme kinetics.
    evidence_location
    Full text: Metal binding and enzyme activity; Figure 1
    experimental_model
    Purified recombinant human PDXK kinetics and crystallography.
    exposure
    Kinetic assays at pH 7.3.
    limitations
    Lower Km is not a direct binding constant; results do not define dietary sodium/potassium effects.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    Potassium and sodium affect different kinetic properties.
    primary_references
    [safo2007] Crystal Structure of human pyridoxal kinase: structural basis of M(+) and M(2+) activation. (2007). https://pubmed.ncbi.nlm.nih.gov/17766369/ DOI: 10.1110/ps.073022107
    tissue_or_cell_type
    Purified human enzyme

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 203–215

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified recombinant human PDXK kinetics and crystallography. · source_derived_draft · unverified_draft

    ### b6-transport-pdxk-k-na Human PDXK showed lower substrate Km with potassium than sodium, whereas sodium supported over twice the maximal activity. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Potassium and sodium affect different kinetic properties. organism: Homo sapiens tissue_or_cell_type: Purified human enzyme experimental_model: Purified recombinant human PDXK kinetics and crystallography. limitations: Lower Km is not a direct binding constant; results do not define dietary sodium/potassium effects. exposure: Kinetic assays at pH 7.3. evidence_location: Full text: Metal binding and enzyme activity; Figure 1 cross_nutrient: Potassium/sodium-B6 enzyme kinetics. [safo2007] Crystal Structure of human pyridoxal kinase: structural basis of M(+) and M(2+) activation. (2007). https://pubmed.ncbi.nlm.nih.gov/17766369/ DOI: 10.1110/ps.073022107
    Complete structured claim and evidence

  8. Kinase kinetic experiments identified MgATP as the preferred phosphate-donor complex under the reported physiological assay conditions.

    Magnesium-ATP complex → Pyridoxal kinase / PDXK source_derived_draftungraded
    Experimental context and source evidence
    cross_nutrient
    Magnesium-B6 activation chemistry.
    evidence_location
    Indexed abstract and publisher abstract; human enzyme findings only
    experimental_model
    Purified recombinant human and E. coli pyridoxal kinases.
    exposure
    MgATP versus ZnATP kinetic comparisons.
    limitations
    Metal preference depends on assay conditions and does not prove magnesium supplementation improves B6 status.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    Magnesium helps supply ATP to B6 activation.
    primary_references
    [disalvo2004] Expression, purification, and kinetic constants for human and Escherichia coli pyridoxal kinases. (2004). https://pubmed.ncbi.nlm.nih.gov/15249053/ DOI: 10.1016/j.pep.2004.04.021
    tissue_or_cell_type
    Purified human enzyme

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 189–201

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified recombinant human and E. coli pyridoxal kinases. · source_derived_draft · unverified_draft

    ### b6-transport-pdxk-mgatp Kinase kinetic experiments identified MgATP as the preferred phosphate-donor complex under the reported physiological assay conditions. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Magnesium helps supply ATP to B6 activation. organism: Homo sapiens tissue_or_cell_type: Purified human enzyme experimental_model: Purified recombinant human and E. coli pyridoxal kinases. limitations: Metal preference depends on assay conditions and does not prove magnesium supplementation improves B6 status. exposure: MgATP versus ZnATP kinetic comparisons. evidence_location: Indexed abstract and publisher abstract; human enzyme findings only cross_nutrient: Magnesium-B6 activation chemistry. [disalvo2004] Expression, purification, and kinetic constants for human and Escherichia coli pyridoxal kinases. (2004). https://pubmed.ncbi.nlm.nih.gov/15249053/ DOI: 10.1016/j.pep.2004.04.021
    Complete structured claim and evidence

  9. Homozygous A228T cases had PDXK activities of 0.8 and 1.1 pmol per dried-blood-spot punch per hour; controls ranged 2.6-14.7.

    Human PDXK Ala228Thr homozygous genotype → Pyridoxal kinase / PDXK source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    machinery_impairment Imported condition classification; unverified.
    evidence_location
    Figure 3F; Results
    experimental_model
    Human families, dried blood spots, recombinant PDXK variants.
    exposure
    Patient blood-spot assay.
    limitations
    Assay-specific values.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    Inherited activation defects reduced enzyme output.
    primary_references
    [chelban2019] PDXK mutations cause polyneuropathy responsive to pyridoxal 5'-phosphate supplementation. (2019). https://pubmed.ncbi.nlm.nih.gov/31187503/ DOI: 10.1002/ana.25524
    tissue_or_cell_type
    Erythrocytes
    trigger_kind
    machinery_impairment Imported condition classification; unverified.

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 230–241

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human families, dried blood spots, recombinant PDXK variants. · source_derived_draft · unverified_draft

    ### b6-transport-pdxk-patient-a228t Homozygous A228T cases had PDXK activities of 0.8 and 1.1 pmol per dried-blood-spot punch per hour; controls ranged 2.6-14.7. Condition category: machinery_impairment nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Inherited activation defects reduced enzyme output. organism: Homo sapiens tissue_or_cell_type: Erythrocytes experimental_model: Human families, dried blood spots, recombinant PDXK variants. limitations: Assay-specific values. exposure: Patient blood-spot assay. evidence_location: Figure 3F; Results [chelban2019] PDXK mutations cause polyneuropathy responsive to pyridoxal 5'-phosphate supplementation. (2019). https://pubmed.ncbi.nlm.nih.gov/31187503/ DOI: 10.1002/ana.25524
    Complete structured claim and evidence

  10. Homozygous R220Q cases had PDXK activities of 0.5 and 1.19 pmol per dried-blood-spot punch per hour; controls ranged 2.6-14.7.

    Human PDXK Arg220Gln homozygous genotype → Pyridoxal kinase / PDXK source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    machinery_impairment Imported condition classification; unverified.
    evidence_location
    Figure 3F; Results
    experimental_model
    Human families, dried blood spots, recombinant PDXK variants.
    exposure
    Patient blood-spot assay.
    limitations
    Assay-specific values.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    Inherited activation defects reduced enzyme output.
    primary_references
    [chelban2019] PDXK mutations cause polyneuropathy responsive to pyridoxal 5'-phosphate supplementation. (2019). https://pubmed.ncbi.nlm.nih.gov/31187503/ DOI: 10.1002/ana.25524
    tissue_or_cell_type
    Erythrocytes
    trigger_kind
    machinery_impairment Imported condition classification; unverified.

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 243–254

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human families, dried blood spots, recombinant PDXK variants. · source_derived_draft · unverified_draft

    ### b6-transport-pdxk-patient-r220q Homozygous R220Q cases had PDXK activities of 0.5 and 1.19 pmol per dried-blood-spot punch per hour; controls ranged 2.6-14.7. Condition category: machinery_impairment nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Inherited activation defects reduced enzyme output. organism: Homo sapiens tissue_or_cell_type: Erythrocytes experimental_model: Human families, dried blood spots, recombinant PDXK variants. limitations: Assay-specific values. exposure: Patient blood-spot assay. evidence_location: Figure 3F; Results [chelban2019] PDXK mutations cause polyneuropathy responsive to pyridoxal 5'-phosphate supplementation. (2019). https://pubmed.ncbi.nlm.nih.gov/31187503/ DOI: 10.1002/ana.25524
    Complete structured claim and evidence

  11. Human erythrocyte pyridoxal phosphatase required divalent cations; magnesium activated PLP hydrolysis with Michaelis-Menten behavior.

    Mg2+ → Human pyridoxal phosphatase / PDXP source_derived_draftungraded
    Experimental context and source evidence
    cross_nutrient
    Magnesium participates in both sides of B6 phosphate cycling.
    evidence_location
    Indexed abstract: divalent-cation kinetics at pH 7.4, 37 C
    experimental_model
    Purified human erythrocyte pyridoxal phosphatase kinetics.
    exposure
    pH 7.4, 37 C; Mg2+ titration.
    limitations
    Other metals also activated in vitro; does not establish net PLP response to changing dietary magnesium.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    Magnesium supports B6 dephosphorylation as well as activation.
    primary_references
    [fonda1995] Kinetic mechanism and divalent metal activation of human erythrocyte pyridoxal phosphatase. (1995). https://pubmed.ncbi.nlm.nih.gov/7625842/ DOI: 10.1016/0003-9861(95)90018-7
    tissue_or_cell_type
    Erythrocyte enzyme

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 282–294

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified human erythrocyte pyridoxal phosphatase kinetics. · source_derived_draft · unverified_draft

    ### b6-transport-pdxp-magnesium Human erythrocyte pyridoxal phosphatase required divalent cations; magnesium activated PLP hydrolysis with Michaelis-Menten behavior. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Magnesium supports B6 dephosphorylation as well as activation. organism: Homo sapiens tissue_or_cell_type: Erythrocyte enzyme experimental_model: Purified human erythrocyte pyridoxal phosphatase kinetics. limitations: Other metals also activated in vitro; does not establish net PLP response to changing dietary magnesium. exposure: pH 7.4, 37 C; Mg2+ titration. evidence_location: Indexed abstract: divalent-cation kinetics at pH 7.4, 37 C cross_nutrient: Magnesium participates in both sides of B6 phosphate cycling. [fonda1995] Kinetic mechanism and divalent metal activation of human erythrocyte pyridoxal phosphatase. (1995). https://pubmed.ncbi.nlm.nih.gov/7625842/ DOI: 10.1016/0003-9861(95)90018-7
    Complete structured claim and evidence

  12. Catalytically active recombinant human pyridoxal phosphatase hydrolyzed pyridoxal-phosphate.

    Human pyridoxal phosphatase / PDXP → PLP source_derived_draftungraded
    Experimental context and source evidence
    evidence_location
    Indexed abstract: cloning and substrate hydrolysis
    experimental_model
    Recombinant human pyridoxal phosphatase expressed in E. coli.
    exposure
    Recombinant-enzyme characterization.
    limitations
    Model-specific evidence; no dietary threshold or treatment benefit established.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    PDXP removes phosphate from a B6 vitamer.
    primary_references
    [jang2003] Human pyridoxal phosphatase. Molecular cloning, functional expression, and tissue distribution. (2003). https://pubmed.ncbi.nlm.nih.gov/14522954/ DOI: 10.1074/jbc.m309619200
    tissue_or_cell_type
    Purified recombinant human enzyme

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 256–267

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human pyridoxal phosphatase expressed in E. coli. · source_derived_draft · unverified_draft

    ### b6-transport-pdxp-plp Catalytically active recombinant human pyridoxal phosphatase hydrolyzed pyridoxal-phosphate. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: PDXP removes phosphate from a B6 vitamer. organism: Homo sapiens tissue_or_cell_type: Purified recombinant human enzyme experimental_model: Recombinant human pyridoxal phosphatase expressed in E. coli. limitations: Model-specific evidence; no dietary threshold or treatment benefit established. exposure: Recombinant-enzyme characterization. evidence_location: Indexed abstract: cloning and substrate hydrolysis [jang2003] Human pyridoxal phosphatase. Molecular cloning, functional expression, and tissue distribution. (2003). https://pubmed.ncbi.nlm.nih.gov/14522954/ DOI: 10.1074/jbc.m309619200
    Complete structured claim and evidence

  13. Forty-eight-hour PDXP siRNA restored PLP toward control concentrations in PLPBP-deficient HEK293 cells and decreased PL.

    Human PDXP knockdown → PLP source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    machinery_impairment Imported condition classification; unverified.
    evidence_location
    Figure 6B-C
    experimental_model
    Human patient skin fibroblasts and CRISPR PLPBP-null HEK293 cells.
    exposure
    15 nM siRNA; 48 h; standard PN-containing medium.
    limitations
    Cell experiment; does not prove a direct PLPBP-PDXP interaction.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Homo sapiens
    plain_language
    Reducing breakdown restored the cellular PLP pool.
    primary_references
    [ciapaite2023] Maintenance of cellular vitamin B6 levels and mitochondrial oxidative function depend on pyridoxal 5'-phosphate homeostasis protein. (2023). https://pubmed.ncbi.nlm.nih.gov/37451483/ DOI: 10.1016/j.jbc.2023.105047
    tissue_or_cell_type
    HEK293 cells
    trigger_kind
    machinery_impairment Imported condition classification; unverified.

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 439–450

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human patient skin fibroblasts and CRISPR PLPBP-null HEK293 cells. · source_derived_draft · unverified_draft

    ### b6-transport-pdxp-silencing-plpbp-null Forty-eight-hour PDXP siRNA restored PLP toward control concentrations in PLPBP-deficient HEK293 cells and decreased PL. Condition category: machinery_impairment nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Reducing breakdown restored the cellular PLP pool. organism: Homo sapiens tissue_or_cell_type: HEK293 cells experimental_model: Human patient skin fibroblasts and CRISPR PLPBP-null HEK293 cells. limitations: Cell experiment; does not prove a direct PLPBP-PDXP interaction. exposure: 15 nM siRNA; 48 h; standard PN-containing medium. evidence_location: Figure 6B-C [ciapaite2023] Maintenance of cellular vitamin B6 levels and mitochondrial oxidative function depend on pyridoxal 5'-phosphate homeostasis protein. (2023). https://pubmed.ncbi.nlm.nih.gov/37451483/ DOI: 10.1016/j.jbc.2023.105047
    Complete structured claim and evidence

  14. Partially purified rat tissue NAD-dependent aldehyde-dehydrogenase activity oxidized PL to 4-pyridoxic acid; oxidase-null rats still excreted the acid.

    Rat NAD-dependent pyridoxal dehydrogenase activity → 4-Pyridoxic acid source_derived_draftungraded
    Experimental context and source evidence
    cross_nutrient
    NAD links niacin-derived redox chemistry to B6 catabolism in this rat assay.
    evidence_location
    Indexed abstract: partially purified rat enzyme and urinary metabolites
    experimental_model
    Rat tissue enzyme fractions and aldehyde-oxidase activity variants.
    exposure
    Partially purified activity; kinetic assays at pH 9.6.
    limitations
    Molecular isoenzyme and quantitative contribution in humans not established.
    nutrient_topic
    Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B6
    organism
    Rattus norvegicus
    plain_language
    Rat B6 breakdown had an alternative to aldehyde oxidase.
    primary_references
    [stanulovic1976] New pathway of conversion of pyridoxal to 4-pyridoxic acid. (1976). https://pubmed.ncbi.nlm.nih.gov/939227/ DOI: 10.1159/000458879
    tissue_or_cell_type
    Rat tissue enzyme fractions and urine

    Vitamin B6: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 491–503

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Rat tissue enzyme fractions and aldehyde-oxidase activity variants. · source_derived_draft · unverified_draft

    ### b6-transport-rat-pl-catabolism Partially purified rat tissue NAD-dependent aldehyde-dehydrogenase activity oxidized PL to 4-pyridoxic acid; oxidase-null rats still excreted the acid. Condition category: normal nutrient_topic: Vitamin B6 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Rat B6 breakdown had an alternative to aldehyde oxidase. organism: Rattus norvegicus tissue_or_cell_type: Rat tissue enzyme fractions and urine experimental_model: Rat tissue enzyme fractions and aldehyde-oxidase activity variants. limitations: Molecular isoenzyme and quantitative contribution in humans not established. exposure: Partially purified activity; kinetic assays at pH 9.6. evidence_location: Indexed abstract: partially purified rat enzyme and urinary metabolites cross_nutrient: NAD links niacin-derived redox chemistry to B6 catabolism in this rat assay. [stanulovic1976] New pathway of conversion of pyridoxal to 4-pyridoxic acid. (1976). https://pubmed.ncbi.nlm.nih.gov/939227/ DOI: 10.1159/000458879
    Complete structured claim and evidence

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