{"id":"e5dad03e-866f-5b2a-b817-44d870f270ae","stable_key":"ec174d5a-4903-5745-8646-df0e9d4265e8:folate-human-liver-folic-acid-slow-processing","predicate":"processes","statement":"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.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"3a32e4a6-974e-5d3d-955d-28c501399f8b","mechanism_event_label":"Human liver processing was slow and varied between samples.","subject":{"id":"3e8c5745-4f15-5fde-865e-82529344a044","slug":"dhfr","display_name":"Human dihydrofolate reductase / DHFR","entity_type_key":"protein"},"object":{"id":"d322bfef-5135-599f-82e6-0aa58748dc8b","slug":"folic-acid","display_name":"Folic acid","entity_type_key":"small_molecule"},"evidence_count":1,"mechanism_event":{"id":"3a32e4a6-974e-5d3d-955d-28c501399f8b","stable_key":"ec174d5a-4903-5745-8646-df0e9d4265e8:folate-human-liver-folic-acid-slow-processing-event","event_type":"biochemical_relationship","label":"Human liver processing was slow and varied between samples.","description":"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.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"3e8c5745-4f15-5fde-865e-82529344a044","slug":"dhfr","display_name":"Human dihydrofolate reductase / DHFR","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"d322bfef-5135-599f-82e6-0aa58748dc8b","slug":"folic-acid","display_name":"Folic acid","entity_type_key":"small_molecule"},"role":"object","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""}]},"contexts":[{"dimension":"experimental_model","value_text":"Fresh human liver extracts from six donors and rat comparison","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Matched ex-vivo activity assay","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Small tissue series; neither whole-body clearance nor harm was measured.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Folate and folic acid research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"folate","display_name":"Folate (vitamin B9)","entity_type_key":"chemical_species"}},{"dimension":"organism","value_text":"Homo sapiens and Rattus norvegicus comparison","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Human liver processing was slow and varied between samples.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[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","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Fresh liver extracts","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"2a58b01c-95f1-55fe-a3aa-4650cf475eea","evidence_kind":"source_excerpt","locator":"Lines 375-385","start_line":375,"end_line":385,"excerpt":"### folate-human-liver-folic-acid-slow-processing\nFolic-acid reduction per gram of six human livers averaged less than 2% of rat liver activity at physiological pH, with nearly fivefold human variation.\nCondition category: normal\nnutrient_topic: Folate and folic acid research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Human liver processing was slow and varied between samples.\norganism: Homo sapiens and Rattus norvegicus comparison\ntissue_or_cell_type: Fresh liver extracts\nexperimental_model: Fresh human liver extracts from six donors and rat comparison\nlimitations: Small tissue series; neither whole-body clearance nor harm was measured.\nexposure: Matched ex-vivo activity assay\n[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","model_system":"Fresh human liver extracts from six donors and rat comparison","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study 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","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"f4ce1a62-9582-5f7a-84f5-a23d0e1bfc68","stable_key":"import-ec174d5a-4903-5745-8646-df0e9d4265e8","title":"Folate and folic acid: mechanisms, deficiency and nutrient interactions (2026-09-17)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text.","file_path":"","sha256":"e564d43989ece1006c95cd0748e9af6fe369074599a2eebba0a99ebff864b0dd","revision_id":"76674a33-b2a1-5e41-b71b-44399038ff7c","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}