Human xanthine oxidoreductase / XDH

evidence_span

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experimental_model

Recombinant human XDH variants with urate, superoxide and NO assays

exposure

Xanthine, oxygen and inorganic nitrite assays

limitations

Established reaction summarized in the primary article background; this paper directly assayed xanthine-based activity rather than newly establishing the hypoxanthine step.

nutrient_topic

Molybdenum research collection; topical membership is not evidence of a direct dietary effect. · Molybdenum

organism

Homo sapiens protein

plain_language

Hypoxanthine enters the same two-step purine pathway.

primary_references

[mo-p37713777] Natural mutations of human XDH promote the nitrite (NO2-)-reductase capacity of xanthine oxidoreductase: A novel mechanism to promote redox health? (2023). https://pubmed.ncbi.nlm.nih.gov/37713777/ DOI: 10.1016/j.redox.2023.102864

tissue_or_cell_type

Purified human enzyme

Molybdenum: cofactor assembly, sulfur metabolism and nutrient interactions (2026-09-17) · lines 755–766

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human XDH variants with urate, superoxide and NO assays · source_derived_draft · unverified_draft

### mo-xdh-hypoxanthine The primary article describes sequential XOR hydroxylation of hypoxanthine to xanthine and xanthine to urate. Condition category: normal nutrient_topic: Molybdenum research collection; topical membership is not evidence of a direct dietary effect. plain_language: Hypoxanthine enters the same two-step purine pathway. organism: Homo sapiens protein tissue_or_cell_type: Purified human enzyme experimental_model: Recombinant human XDH variants with urate, superoxide and NO assays limitations: Established reaction summarized in the primary article background; this paper directly assayed xanthine-based activity rather than newly establishing the hypoxanthine step. exposure: Xanthine, oxygen and inorganic nitrite assays evidence_span: {"source_cache": "artifacts/molybdenum-research/37713777.fulltext.txt", "locator": "Exact primary full-text span; zero-based, end-exclusive Unicode character offsets", "file_sha256": "a8092b2aa7328b59f0275dd8a37d2a2dbb5abb2a32236d0cab5fffcc1ddc671d", "start_char": 1061, "end_char": 1244, "text_sha256": "45575621674b6b2e232b2e7b9605ad8e6acde4977d3f22e20abebfcbfa0b4dcb"} [mo-p37713777] Natural mutations of human XDH promote the nitrite (NO2-)-reductase capacity of xanthine oxidoreductase: A novel mechanism to promote redox health? (2023). https://pubmed.ncbi.nlm.nih.gov/37713777/ DOI: 10.1016/j.redox.2023.102864

evidence_span

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experimental_model

Recombinant human XDH variants with urate, superoxide and NO assays

exposure

Xanthine, oxygen and inorganic nitrite assays

limitations

Canonical electron-transfer mechanism stated in this primary article; not an experiment on dietary B2 or niacin depletion.

nutrient_topic

Molybdenum research collection; topical membership is not evidence of a direct dietary effect. · Molybdenum

organism

Homo sapiens protein

plain_language

Riboflavin-derived FAD, iron-sulfur centers and niacin-derived NAD work alongside molybdenum.

primary_references

[mo-p37713777] Natural mutations of human XDH promote the nitrite (NO2-)-reductase capacity of xanthine oxidoreductase: A novel mechanism to promote redox health? (2023). https://pubmed.ncbi.nlm.nih.gov/37713777/ DOI: 10.1016/j.redox.2023.102864

tissue_or_cell_type

Purified human enzyme

Molybdenum: cofactor assembly, sulfur metabolism and nutrient interactions (2026-09-17) · lines 768–779

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human XDH variants with urate, superoxide and NO assays · source_derived_draft · unverified_draft

### mo-xdh-nad The XDH form transfers purine-derived electrons through its iron-sulfur centers and FAD to NAD+, producing NADH. Condition category: normal nutrient_topic: Molybdenum research collection; topical membership is not evidence of a direct dietary effect. plain_language: Riboflavin-derived FAD, iron-sulfur centers and niacin-derived NAD work alongside molybdenum. organism: Homo sapiens protein tissue_or_cell_type: Purified human enzyme experimental_model: Recombinant human XDH variants with urate, superoxide and NO assays limitations: Canonical electron-transfer mechanism stated in this primary article; not an experiment on dietary B2 or niacin depletion. exposure: Xanthine, oxygen and inorganic nitrite assays evidence_span: {"source_cache": "artifacts/molybdenum-research/37713777.fulltext.txt", "locator": "Exact primary full-text span; zero-based, end-exclusive Unicode character offsets", "file_sha256": "a8092b2aa7328b59f0275dd8a37d2a2dbb5abb2a32236d0cab5fffcc1ddc671d", "start_char": 0, "end_char": 1579, "text_sha256": "18325172be489f8f4beae16c04dbc4f49f94c87186321e32aede61f27089c7c4"} [mo-p37713777] Natural mutations of human XDH promote the nitrite (NO2-)-reductase capacity of xanthine oxidoreductase: A novel mechanism to promote redox health? (2023). https://pubmed.ncbi.nlm.nih.gov/37713777/ DOI: 10.1016/j.redox.2023.102864

availability_state

machinery_impairment Imported condition classification; unverified.

evidence_span

{"source_cache": "artifacts/molybdenum-research/9153281.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "736b96f30570738a8aa1f55f33d1839eef8ce5911ce2c51b221db2e325517a0e", "start_char": 0, "end_char": 1243, "text_sha256": "736b96f30570738a8aa1f55f33d1839eef8ce5911ce2c51b221db2e325517a0e"}

experimental_model

Genetic analysis of four classical-xanthinuria subjects

exposure

XDH nonsense and frameshift variants

limitations

Specific XDH deficiency, distinct from loss of all Moco synthesis or the combined XDH/AOX1 deficiency of MOCOS defects.

nutrient_topic

Molybdenum research collection; topical membership is not evidence of a direct dietary effect. · Molybdenum

organism

Homo sapiens

plain_language

An enzyme-specific genetic defect should not be labeled a shortage of the mineral.

primary_references

[mo-p9153281] Identification of two mutations in human xanthine dehydrogenase gene responsible for classical type I xanthinuria. (1997). https://pubmed.ncbi.nlm.nih.gov/9153281/ DOI: 10.1172/jci119421

tissue_or_cell_type

Duodenal mucosa and genetics

trigger_kind

machinery_impairment Imported condition classification; unverified.

Molybdenum: cofactor assembly, sulfur metabolism and nutrient interactions (2026-09-17) · lines 1223–1234

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Genetic analysis of four classical-xanthinuria subjects · source_derived_draft · unverified_draft

### mo-xdh-type-i Three type I xanthinuria subjects had confirmed XDH gene defects; one tested nonsense variant lacked duodenal XDH protein despite preserved mRNA. Condition category: machinery_impairment nutrient_topic: Molybdenum research collection; topical membership is not evidence of a direct dietary effect. plain_language: An enzyme-specific genetic defect should not be labeled a shortage of the mineral. organism: Homo sapiens tissue_or_cell_type: Duodenal mucosa and genetics experimental_model: Genetic analysis of four classical-xanthinuria subjects limitations: Specific XDH deficiency, distinct from loss of all Moco synthesis or the combined XDH/AOX1 deficiency of MOCOS defects. exposure: XDH nonsense and frameshift variants evidence_span: {"source_cache": "artifacts/molybdenum-research/9153281.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "736b96f30570738a8aa1f55f33d1839eef8ce5911ce2c51b221db2e325517a0e", "start_char": 0, "end_char": 1243, "text_sha256": "736b96f30570738a8aa1f55f33d1839eef8ce5911ce2c51b221db2e325517a0e"} [mo-p9153281] Identification of two mutations in human xanthine dehydrogenase gene responsible for classical type I xanthinuria. (1997). https://pubmed.ncbi.nlm.nih.gov/9153281/ DOI: 10.1172/jci119421

evidence_span

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experimental_model

Recombinant human XDH variants with urate, superoxide and NO assays

exposure

Xanthine, oxygen and inorganic nitrite assays

limitations

The 2023 Fig. 6E corrigendum corrects a displayed panel; authors state data and conclusions are unchanged. Enzyme activity is not a clinical benefit or dietary response.

nutrient_topic

Molybdenum research collection; topical membership is not evidence of a direct dietary effect. · Molybdenum

organism

Homo sapiens protein

plain_language

The purine-breakdown pathway uses a molybdenum enzyme to make urate.

primary_references

[mo-p37713777] Natural mutations of human XDH promote the nitrite (NO2-)-reductase capacity of xanthine oxidoreductase: A novel mechanism to promote redox health? (2023). https://pubmed.ncbi.nlm.nih.gov/37713777/ DOI: 10.1016/j.redox.2023.102864

tissue_or_cell_type

Purified human enzyme

Molybdenum: cofactor assembly, sulfur metabolism and nutrient interactions (2026-09-17) · lines 742–753

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human XDH variants with urate, superoxide and NO assays · source_derived_draft · unverified_draft

### mo-xdh-xanthine Recombinant human XDH/XOR catalyzed conversion of xanthine to urate. Condition category: normal nutrient_topic: Molybdenum research collection; topical membership is not evidence of a direct dietary effect. plain_language: The purine-breakdown pathway uses a molybdenum enzyme to make urate. organism: Homo sapiens protein tissue_or_cell_type: Purified human enzyme experimental_model: Recombinant human XDH variants with urate, superoxide and NO assays limitations: The 2023 Fig. 6E corrigendum corrects a displayed panel; authors state data and conclusions are unchanged. Enzyme activity is not a clinical benefit or dietary response. exposure: Xanthine, oxygen and inorganic nitrite assays evidence_span: {"source_cache": "artifacts/molybdenum-research/37713777.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "30e93ea24784120403bef1dfe72cf46411f1af88946b9cc1cba3d4c45a367bf9", "start_char": 0, "end_char": 1655, "text_sha256": "30e93ea24784120403bef1dfe72cf46411f1af88946b9cc1cba3d4c45a367bf9"} [mo-p37713777] Natural mutations of human XDH promote the nitrite (NO2-)-reductase capacity of xanthine oxidoreductase: A novel mechanism to promote redox health? (2023). https://pubmed.ncbi.nlm.nih.gov/37713777/ DOI: 10.1016/j.redox.2023.102864

evidence_span

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experimental_model

Recombinant human XDH variants with urate, superoxide and NO assays

exposure

Xanthine, oxygen and inorganic nitrite assays

limitations

The 2023 Fig. 6E corrigendum corrects a displayed panel; authors state data and conclusions are unchanged. Enzyme activity is not a clinical benefit or dietary response.

nutrient_topic

Molybdenum research collection; topical membership is not evidence of a direct dietary effect. · Molybdenum

organism

Homo sapiens protein

plain_language

Changing the available electron acceptor changed the products.

primary_references

[mo-p37713777] Natural mutations of human XDH promote the nitrite (NO2-)-reductase capacity of xanthine oxidoreductase: A novel mechanism to promote redox health? (2023). https://pubmed.ncbi.nlm.nih.gov/37713777/ DOI: 10.1016/j.redox.2023.102864

tissue_or_cell_type

Purified human enzyme

Molybdenum: cofactor assembly, sulfur metabolism and nutrient interactions (2026-09-17) · lines 794–805

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human XDH variants with urate, superoxide and NO assays · source_derived_draft · unverified_draft

### mo-xor-nitrite Human XOR reduced nitrite to NO under the tested reducing conditions, and nitrite decreased XOR-driven superoxide production. Condition category: normal nutrient_topic: Molybdenum research collection; topical membership is not evidence of a direct dietary effect. plain_language: Changing the available electron acceptor changed the products. organism: Homo sapiens protein tissue_or_cell_type: Purified human enzyme experimental_model: Recombinant human XDH variants with urate, superoxide and NO assays limitations: The 2023 Fig. 6E corrigendum corrects a displayed panel; authors state data and conclusions are unchanged. Enzyme activity is not a clinical benefit or dietary response. exposure: Xanthine, oxygen and inorganic nitrite assays evidence_span: {"source_cache": "artifacts/molybdenum-research/37713777.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "30e93ea24784120403bef1dfe72cf46411f1af88946b9cc1cba3d4c45a367bf9", "start_char": 0, "end_char": 1655, "text_sha256": "30e93ea24784120403bef1dfe72cf46411f1af88946b9cc1cba3d4c45a367bf9"} [mo-p37713777] Natural mutations of human XDH promote the nitrite (NO2-)-reductase capacity of xanthine oxidoreductase: A novel mechanism to promote redox health? (2023). https://pubmed.ncbi.nlm.nih.gov/37713777/ DOI: 10.1016/j.redox.2023.102864

evidence_span

{"source_cache": "artifacts/molybdenum-research/37713777.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "30e93ea24784120403bef1dfe72cf46411f1af88946b9cc1cba3d4c45a367bf9", "start_char": 0, "end_char": 1655, "text_sha256": "30e93ea24784120403bef1dfe72cf46411f1af88946b9cc1cba3d4c45a367bf9"}

experimental_model

Recombinant human XDH variants with urate, superoxide and NO assays

exposure

Xanthine, oxygen and inorganic nitrite assays

limitations

The 2023 Fig. 6E corrigendum corrects a displayed panel; authors state data and conclusions are unchanged. Enzyme activity is not a clinical benefit or dietary response.

nutrient_topic

Molybdenum research collection; topical membership is not evidence of a direct dietary effect. · Molybdenum

organism

Homo sapiens protein

plain_language

The enzyme can generate oxidants as well as carry out purine breakdown.

primary_references

[mo-p37713777] Natural mutations of human XDH promote the nitrite (NO2-)-reductase capacity of xanthine oxidoreductase: A novel mechanism to promote redox health? (2023). https://pubmed.ncbi.nlm.nih.gov/37713777/ DOI: 10.1016/j.redox.2023.102864

tissue_or_cell_type

Purified human enzyme

Molybdenum: cofactor assembly, sulfur metabolism and nutrient interactions (2026-09-17) · lines 781–792

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human XDH variants with urate, superoxide and NO assays · source_derived_draft · unverified_draft

### mo-xor-oxygen In its oxidase activity, XOR can generate superoxide and hydrogen peroxide rather than exclusively transferring electrons to NAD+. Condition category: normal nutrient_topic: Molybdenum research collection; topical membership is not evidence of a direct dietary effect. plain_language: The enzyme can generate oxidants as well as carry out purine breakdown. organism: Homo sapiens protein tissue_or_cell_type: Purified human enzyme experimental_model: Recombinant human XDH variants with urate, superoxide and NO assays limitations: The 2023 Fig. 6E corrigendum corrects a displayed panel; authors state data and conclusions are unchanged. Enzyme activity is not a clinical benefit or dietary response. exposure: Xanthine, oxygen and inorganic nitrite assays evidence_span: {"source_cache": "artifacts/molybdenum-research/37713777.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "30e93ea24784120403bef1dfe72cf46411f1af88946b9cc1cba3d4c45a367bf9", "start_char": 0, "end_char": 1655, "text_sha256": "30e93ea24784120403bef1dfe72cf46411f1af88946b9cc1cba3d4c45a367bf9"} [mo-p37713777] Natural mutations of human XDH promote the nitrite (NO2-)-reductase capacity of xanthine oxidoreductase: A novel mechanism to promote redox health? (2023). https://pubmed.ncbi.nlm.nih.gov/37713777/ DOI: 10.1016/j.redox.2023.102864

evidence_span

{"source_cache": "artifacts/molybdenum-research/11302742.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "8f595c96d16b055cd6b9611c4d036626222ffb084ec778f840255cac57ecdfb3", "start_char": 0, "end_char": 1011, "text_sha256": "8f595c96d16b055cd6b9611c4d036626222ffb084ec778f840255cac57ecdfb3"}

experimental_model

Gene identification in two type II xanthinuria patients and comparison subjects

exposure

MOCOS Arg419 stop mutation

limitations

Genetic evidence for terminal sulfuration; type II xanthinuria is different from loss of all Moco synthesis.

nutrient_topic

Molybdenum research collection; topical membership is not evidence of a direct dietary effect. · Molybdenum

organism

Homo sapiens

plain_language

Two molybdenum enzymes need an additional sulfur-activation step.

primary_references

[mo-p11302742] Mutation of human molybdenum cofactor sulfurase gene is responsible for classical xanthinuria type II. (2001). https://pubmed.ncbi.nlm.nih.gov/11302742/ DOI: 10.1006/bbrc.2001.4719

tissue_or_cell_type

Liver cDNA and patient genetics

Molybdenum: cofactor assembly, sulfur metabolism and nutrient interactions (2026-09-17) · lines 521–532

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Gene identification in two type II xanthinuria patients and comparison subjects · source_derived_draft · unverified_draft

### mo-mocos-sulfuration MOCOS defects in type II xanthinuria support its role in supplying the terminal sulfur required by XDH and AOX1. Condition category: normal nutrient_topic: Molybdenum research collection; topical membership is not evidence of a direct dietary effect. plain_language: Two molybdenum enzymes need an additional sulfur-activation step. organism: Homo sapiens tissue_or_cell_type: Liver cDNA and patient genetics experimental_model: Gene identification in two type II xanthinuria patients and comparison subjects limitations: Genetic evidence for terminal sulfuration; type II xanthinuria is different from loss of all Moco synthesis. exposure: MOCOS Arg419 stop mutation evidence_span: {"source_cache": "artifacts/molybdenum-research/11302742.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "8f595c96d16b055cd6b9611c4d036626222ffb084ec778f840255cac57ecdfb3", "start_char": 0, "end_char": 1011, "text_sha256": "8f595c96d16b055cd6b9611c4d036626222ffb084ec778f840255cac57ecdfb3"} [mo-p11302742] Mutation of human molybdenum cofactor sulfurase gene is responsible for classical xanthinuria type II. (2001). https://pubmed.ncbi.nlm.nih.gov/11302742/ DOI: 10.1006/bbrc.2001.4719

evidence_span

{"source_cache": "artifacts/hbot-research/8248932.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "54ab057eb31320490d893896d8ab5b0c856a8b59489424b14b81409f01a78f7f", "start_char": 0, "end_char": 1870, "text_sha256": "54ab057eb31320490d893896d8ab5b0c856a8b59489424b14b81409f01a78f7f"}

experimental_model

Rats poisoned with carbon monoxide, with leukocyte function assays

exposure

3 atmospheres absolute for 45 minutes, given 24 hours before or up to 45 minutes after poisoning; 3 ATA pressure without oxygen as a control

limitations

The pressure-only control separates oxygen from pressure. The integrin defect is functional: surface expression was normal, which is the informative detail.

nutrient_topic

Hyperbaric oxygen research collection; topical membership is not evidence of a direct clinical effect, and a therapeutic exposure is not a dietary intake. · Hyperbaric oxygen therapy

organism

Rat

plain_language

Stopping the white cells sticking stops the enzyme switch that generates the damage.

primary_references

[hbot-p8248932] Functional inhibition of leukocyte B2 integrins by hyperbaric oxygen in carbon monoxide-mediated brain injury in rats. (1993). https://pubmed.ncbi.nlm.nih.gov/8248932/ DOI: 10.1006/taap.1993.1243

tissue_or_cell_type

Brain microvasculature and polymorphonuclear leukocytes

Hyperbaric oxygen: the exposure, its reactive species, the signals they carry, and the nutrient-dependent enzymes that handle them (2026-09-19) · lines 764–775

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Rats poisoned with carbon monoxide, with leukocyte function assays · source_derived_draft · unverified_draft

### hbot-xanthine-oxidase-prevention Exposure inhibited carbon monoxide-mediated brain lipid peroxidation by preventing the conversion of xanthine dehydrogenase to oxidase, a conversion known to be due to the action of leukocytes. Condition category: normal nutrient_topic: Hyperbaric oxygen research collection; topical membership is not evidence of a direct clinical effect, and a therapeutic exposure is not a dietary intake. plain_language: Stopping the white cells sticking stops the enzyme switch that generates the damage. organism: Rat tissue_or_cell_type: Brain microvasculature and polymorphonuclear leukocytes experimental_model: Rats poisoned with carbon monoxide, with leukocyte function assays limitations: The pressure-only control separates oxygen from pressure. The integrin defect is functional: surface expression was normal, which is the informative detail. exposure: 3 atmospheres absolute for 45 minutes, given 24 hours before or up to 45 minutes after poisoning; 3 ATA pressure without oxygen as a control evidence_span: {"source_cache": "artifacts/hbot-research/8248932.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "54ab057eb31320490d893896d8ab5b0c856a8b59489424b14b81409f01a78f7f", "start_char": 0, "end_char": 1870, "text_sha256": "54ab057eb31320490d893896d8ab5b0c856a8b59489424b14b81409f01a78f7f"} [hbot-p8248932] Functional inhibition of leukocyte B2 integrins by hyperbaric oxygen in carbon monoxide-mediated brain injury in rats. (1993). https://pubmed.ncbi.nlm.nih.gov/8248932/ DOI: 10.1006/taap.1993.1243

evidence_span

{"source_cache": "artifacts/molybdenum-research/25845827.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "8f5a9632067829ecae57508a9127fb042a6467165c3fc494fdd44be975dadf40", "start_char": 0, "end_char": 1619, "text_sha256": "8f5a9632067829ecae57508a9127fb042a6467165c3fc494fdd44be975dadf40"}

experimental_model

Human liver cytosolic fractionation, proteomics, inhibitors and docking

exposure

GDC-0834 amide-hydrolysis assays

limitations

AO and carboxylesterase both implicated; docking proposes a mechanism but does not prove every catalytic step.

nutrient_topic

Molybdenum research collection; topical membership is not evidence of a direct dietary effect. · Molybdenum

organism

Homo sapiens

plain_language

AOX1 can participate in drug breakdown beyond simple aldehyde oxidation.

primary_references

[mo-p25845827] A novel reaction mediated by human aldehyde oxidase: amide hydrolysis of GDC-0834. (2015). https://pubmed.ncbi.nlm.nih.gov/25845827/ DOI: 10.1124/dmd.114.061804

tissue_or_cell_type

Liver cytosol

Molybdenum: cofactor assembly, sulfur metabolism and nutrient interactions (2026-09-17) · lines 924–935

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human liver cytosolic fractionation, proteomics, inhibitors and docking · source_derived_draft · unverified_draft

### mo-aox-amide Inhibitor and fractionation experiments implicated AO and carboxylesterase, but not XOR, in GDC-0834 amide hydrolysis. Condition category: normal nutrient_topic: Molybdenum research collection; topical membership is not evidence of a direct dietary effect. plain_language: AOX1 can participate in drug breakdown beyond simple aldehyde oxidation. organism: Homo sapiens tissue_or_cell_type: Liver cytosol experimental_model: Human liver cytosolic fractionation, proteomics, inhibitors and docking limitations: AO and carboxylesterase both implicated; docking proposes a mechanism but does not prove every catalytic step. exposure: GDC-0834 amide-hydrolysis assays evidence_span: {"source_cache": "artifacts/molybdenum-research/25845827.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "8f5a9632067829ecae57508a9127fb042a6467165c3fc494fdd44be975dadf40", "start_char": 0, "end_char": 1619, "text_sha256": "8f5a9632067829ecae57508a9127fb042a6467165c3fc494fdd44be975dadf40"} [mo-p25845827] A novel reaction mediated by human aldehyde oxidase: amide hydrolysis of GDC-0834. (2015). https://pubmed.ncbi.nlm.nih.gov/25845827/ DOI: 10.1124/dmd.114.061804

availability_state

nutrient_deficiency Imported condition classification; unverified.

evidence_span

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experimental_model

Single case during prolonged total parenteral nutrition

exposure

Prolonged parenteral nutrition followed by ammonium molybdate

limitations

Rare single case. The paper reports 300 micrograms/day ammonium molybdate, not 300 micrograms elemental molybdenum. Historical observation, not a general regimen.

nutrient_topic

Molybdenum research collection; topical membership is not evidence of a direct dietary effect. · Molybdenum

organism

Homo sapiens

plain_language

A second molybdenum-dependent pathway was also impaired.

primary_references

[mo-p6795919] Amino acid intolerance during prolonged total parenteral nutrition reversed by molybdate therapy. (1981). https://pubmed.ncbi.nlm.nih.gov/6795919/ DOI: 10.1093/ajcn/34.11.2551

tissue_or_cell_type

Systemic symptoms; plasma and urine

trigger_kind

nutrient_deficiency Imported condition classification; unverified.

Molybdenum: cofactor assembly, sulfur metabolism and nutrient interactions (2026-09-17) · lines 1132–1143

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Single case during prolonged total parenteral nutrition · source_derived_draft · unverified_draft

### mo-tpn-purines The same patient had low serum urate with increased urinary hypoxanthine and xanthine. Condition category: nutrient_deficiency nutrient_topic: Molybdenum research collection; topical membership is not evidence of a direct dietary effect. plain_language: A second molybdenum-dependent pathway was also impaired. organism: Homo sapiens tissue_or_cell_type: Systemic symptoms; plasma and urine experimental_model: Single case during prolonged total parenteral nutrition limitations: Rare single case. The paper reports 300 micrograms/day ammonium molybdate, not 300 micrograms elemental molybdenum. Historical observation, not a general regimen. exposure: Prolonged parenteral nutrition followed by ammonium molybdate evidence_span: {"source_cache": "artifacts/molybdenum-research/6795919.publisher-abstract.txt", "locator": "Exact primary publisher abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "d2838a46a598539818059c1a1f8295e283334afced15326a6b5ba1a6104cbfd7", "start_char": 0, "end_char": 1820, "text_sha256": "d2838a46a598539818059c1a1f8295e283334afced15326a6b5ba1a6104cbfd7"} [mo-p6795919] Amino acid intolerance during prolonged total parenteral nutrition reversed by molybdate therapy. (1981). https://pubmed.ncbi.nlm.nih.gov/6795919/ DOI: 10.1093/ajcn/34.11.2551

evidence_access

Primary abstract

experimental_model

Same 21-person caffeine-phenotyping study.

limitations

Changed ratios do not prove corresponding changes in NAT2 or CYP1A2 catalytic activity.

nutrient_topic

Caffeine collection; salts, coffee, species and coexposure contexts retain their identities. · Caffeine

plain_language

A downstream block can make another enzyme’s probe result misleading.

primary_references

Xanthine oxidase inhibition by allopurinol affects the reliability of urinary caffeine metabolic ratios as markers for N-acetyltransferase 2 and CYP1A2 activities. · 1999 · https://pubmed.ncbi.nlm.nih.gov/10027663/ · DOI 10.1007/s002280050569

Caffeine: receptors, metabolism, nutrient interactions, adaptation and discovery questions (2026-09-18) · lines 244–250

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Same 21-person caffeine-phenotyping study. · source_derived_draft · unverified_draft

## caf-probe-confounding A downstream block can make another enzyme’s probe result misleading. The NAT2 ratio AFMU/1MX fell to 56.7%, an alternative combined-metabolite NAT2 ratio stayed constant, and a CYP1A2 ratio transiently rose to 167%. Model: Same 21-person caffeine-phenotyping study. Limitations: Changed ratios do not prove corresponding changes in NAT2 or CYP1A2 catalytic activity. Evidence access: Primary abstract Xanthine oxidase inhibition by allopurinol affects the reliability of urinary caffeine metabolic ratios as markers for N-acetyltransferase 2 and CYP1A2 activities. · 1999 · https://pubmed.ncbi.nlm.nih.gov/10027663/ · DOI 10.1007/s002280050569

evidence_access

Primary abstract

experimental_model

Two healthy nonsmokers; caffeine 5 mg/kg before/during allopurinol 300 or 600 mg/day.

limitations

Very small human mechanistic study; not proof that dietary molybdenum controls parent-caffeine clearance.

nutrient_topic

Caffeine collection; salts, coffee, species and coexposure contexts retain their identities. · Caffeine

plain_language

A later caffeine metabolite uses the xanthine-oxidoreductase pathway.

primary_references

Effect of allopurinol on caffeine disposition in man. · 1986 · https://pubmed.ncbi.nlm.nih.gov/3754760/ · DOI 10.1111/j.1365-2125.1986.tb05222.x

Caffeine: receptors, metabolism, nutrient interactions, adaptation and discovery questions (2026-09-18) · lines 228–234

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Two healthy nonsmokers; caffeine 5 mg/kg before/during allopurinol 300 or 600 mg/day. · source_derived_draft · unverified_draft

## caf-xor-product A later caffeine metabolite uses the xanthine-oxidoreductase pathway. Allopurinol specifically and dose-dependently inhibited conversion of caffeine-derived 1-methylxanthine to 1-methyluric acid. Model: Two healthy nonsmokers; caffeine 5 mg/kg before/during allopurinol 300 or 600 mg/day. Limitations: Very small human mechanistic study; not proof that dietary molybdenum controls parent-caffeine clearance. Evidence access: Primary abstract Effect of allopurinol on caffeine disposition in man. · 1986 · https://pubmed.ncbi.nlm.nih.gov/3754760/ · DOI 10.1111/j.1365-2125.1986.tb05222.x

evidence_access

Primary abstract

experimental_model

200 mg caffeine tests during allopurinol 300 mg/day for eight days.

limitations

The ratio is a context-dependent probe, not a direct measurement of dietary molybdenum.

nutrient_topic

Caffeine collection; salts, coffee, species and coexposure contexts retain their identities. · Caffeine

plain_language

Blocking a downstream enzyme changed the metabolite pattern.

primary_references

Xanthine oxidase inhibition by allopurinol affects the reliability of urinary caffeine metabolic ratios as markers for N-acetyltransferase 2 and CYP1A2 activities. · 1999 · https://pubmed.ncbi.nlm.nih.gov/10027663/ · DOI 10.1007/s002280050569

Caffeine: receptors, metabolism, nutrient interactions, adaptation and discovery questions (2026-09-18) · lines 236–242

AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · 200 mg caffeine tests during allopurinol 300 mg/day for eight days. · source_derived_draft · unverified_draft

## caf-xor-ratio Blocking a downstream enzyme changed the metabolite pattern. In 21 participants, allopurinol reduced urinary 1-methyluric-acid/1-methylxanthine to 15.9% of baseline. Model: 200 mg caffeine tests during allopurinol 300 mg/day for eight days. Limitations: The ratio is a context-dependent probe, not a direct measurement of dietary molybdenum. Evidence access: Primary abstract Xanthine oxidase inhibition by allopurinol affects the reliability of urinary caffeine metabolic ratios as markers for N-acetyltransferase 2 and CYP1A2 activities. · 1999 · https://pubmed.ncbi.nlm.nih.gov/10027663/ · DOI 10.1007/s002280050569