{"id":"3e1b9a2a-d599-58f8-9791-6c4a4209a613","stable_key":"cb568d28-484a-5c2e-9fcc-2d780358e514:vc-transport-selenium-liver-ascorbate","predicate":"deficiency-reduces","statement":"Selenium-deficient rats had 33% less liver ascorbate together with an 88% fall in thioredoxin-reductase activity; liver GSH content was unchanged.","claim_class":"observational","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"f6d9a634-4226-57d5-a636-13c30c6020a2","mechanism_event_label":"Selenium shortage reduced a vitamin C recycling pathway and liver vitamin C in rats.","subject":{"id":"dc89d7e2-8f89-577b-838f-42bf5d8ec7c8","slug":"selenium","display_name":"Selenium","entity_type_key":"nutrient_element"},"object":{"id":"da256879-996c-5b86-b26c-41a64a00ab95","slug":"liver-ascorbate-content","display_name":"Liver ascorbate content","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"f6d9a634-4226-57d5-a636-13c30c6020a2","stable_key":"cb568d28-484a-5c2e-9fcc-2d780358e514:vc-transport-selenium-liver-ascorbate-event","event_type":"observed_intervention","label":"Selenium shortage reduced a vitamin C recycling pathway and liver vitamin C in rats.","description":"Selenium-deficient rats had 33% less liver ascorbate together with an 88% fall in thioredoxin-reductase activity; liver GSH content was unchanged.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"44c93642-76cb-5254-9edb-14a3020a5ae6","slug":"rat-txnrd1","display_name":"Rat thioredoxin reductase 1 / Txnrd1","entity_type_key":"protein"},"role":"selenium-dependent machinery","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"38d0c4d9-53d1-5239-bfe3-c1b5e9b79085","slug":"ascorbate","display_name":"L-Ascorbate","entity_type_key":"small_molecule"},"role":"measured metabolite","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"b44c9e27-4bbb-52d3-a022-14cddded5073","slug":"glutathione","display_name":"GSH","entity_type_key":"small_molecule"},"role":"unchanged pool","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"dc89d7e2-8f89-577b-838f-42bf5d8ec7c8","slug":"selenium","display_name":"Selenium","entity_type_key":"nutrient_element"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"da256879-996c-5b86-b26c-41a64a00ab95","slug":"liver-ascorbate-content","display_name":"Liver ascorbate content","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""}]},"contexts":[{"dimension":"availability_state","value_text":"nutrient_deficiency","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null},{"dimension":"cross_nutrient","value_text":"true","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Purified rat liver thioredoxin reductase/thioredoxin and selenium-deficient rat liver","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Dietary selenium deficiency","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Several selenoenzymes were affected, including glutathione peroxidase; cannot attribute the entire ascorbate decrease solely to thioredoxin reductase.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Vitamin C research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"vitamin-c","display_name":"Vitamin C","entity_type_key":"chemical_species"}},{"dimension":"organism","value_text":"Rattus norvegicus","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Selenium shortage reduced a vitamin C recycling pathway and liver vitamin C in rats.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[may1997] Reduction of dehydroascorbate to ascorbate by the selenoenzyme thioredoxin reductase. (1997). https://pubmed.ncbi.nlm.nih.gov/9278416/ DOI: 10.1074/jbc.272.36.22607","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Liver","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"trigger_kind","value_text":"nutrient_deficiency","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null}],"evidence":[{"id":"595440cc-417d-5608-b387-b3a1aa9e2718","evidence_kind":"source_excerpt","locator":"Lines 403-414","start_line":403,"end_line":414,"excerpt":"### vc-transport-selenium-liver-ascorbate\nSelenium-deficient rats had 33% less liver ascorbate together with an 88% fall in thioredoxin-reductase activity; liver GSH content was unchanged.\nCondition category: nutrient_deficiency\nnutrient_topic: Vitamin C research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Selenium shortage reduced a vitamin C recycling pathway and liver vitamin C in rats.\norganism: Rattus norvegicus\ntissue_or_cell_type: Liver\nexperimental_model: Purified rat liver thioredoxin reductase/thioredoxin and selenium-deficient rat liver\nlimitations: Several selenoenzymes were affected, including glutathione peroxidase; cannot attribute the entire ascorbate decrease solely to thioredoxin reductase.\nexposure: Dietary selenium deficiency\ncross_nutrient: true\n[may1997] Reduction of dehydroascorbate to ascorbate by the selenoenzyme thioredoxin reductase. (1997). https://pubmed.ncbi.nlm.nih.gov/9278416/ DOI: 10.1074/jbc.272.36.22607","model_system":"Purified rat liver thioredoxin reductase/thioredoxin and selenium-deficient rat liver","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [may1997] Reduction of dehydroascorbate to ascorbate by the selenoenzyme thioredoxin reductase. (1997). https://pubmed.ncbi.nlm.nih.gov/9278416/ DOI: 10.1074/jbc.272.36.22607","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"fa811221-13bd-5c10-adc1-eaf097c7703c","stable_key":"import-cb568d28-484a-5c2e-9fcc-2d780358e514","title":"Vitamin C: 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. 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