{"id":"d90932f5-daec-5995-91d0-92c4559f40a5","stable_key":"ae1ed35d-8ce7-5936-9067-a641374bbf79:carnosine-histidine-metal","predicate":"increases","statement":"Histidine increased DNA damage in the tested iron/peroxide/ascorbate system and weakened carnosine protection when combined with it.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"1cad3073-376c-5354-8abd-320a33627b8c","mechanism_event_label":"The breakdown product did not behave like the intact peptide.","subject":{"id":"44374451-3436-5136-a8ae-5dcc6d8c353b","slug":"histidine","display_name":"L-Histidine","entity_type_key":"small_molecule"},"object":{"id":"7e4b517d-0a1a-531e-ab71-35b5f4d4fdbc","slug":"cell-free-metal-induced-dna-damage","display_name":"Cell-free metal/peroxide/ascorbate-induced DNA damage","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"1cad3073-376c-5354-8abd-320a33627b8c","stable_key":"ae1ed35d-8ce7-5936-9067-a641374bbf79:carnosine-histidine-metal-event","event_type":"observed_relationship","label":"The breakdown product did not behave like the intact peptide.","description":"Histidine increased DNA damage in the tested iron/peroxide/ascorbate system and weakened carnosine protection when combined with it.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"44374451-3436-5136-a8ae-5dcc6d8c353b","slug":"histidine","display_name":"L-Histidine","entity_type_key":"small_molecule"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"7e4b517d-0a1a-531e-ab71-35b5f4d4fdbc","slug":"cell-free-metal-induced-dna-damage","display_name":"Cell-free metal/peroxide/ascorbate-induced DNA damage","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"9998eb9b-0d09-58c9-885b-a442477dec8d","slug":"carnosine","display_name":"L-Carnosine / beta-alanyl-L-histidine","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"59d6d1cd-df32-5b58-b950-3188bc7b95d6","slug":"iron-ii","display_name":"Ferrous iron","entity_type_key":"ion"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"38d0c4d9-53d1-5239-bfe3-c1b5e9b79085","slug":"ascorbate","display_name":"L-Ascorbate","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""}]},"contexts":[{"dimension":"evidence_access","value_text":"Primary abstract","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Cell-free 10 mM amino-acid comparison.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Not evidence that dietary histidine damages human DNA.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Carnosine collection; isomer, preparation, species, exposure and manipulation remain explicit.","comparator":null,"unit":null,"notes":"","entity":{"slug":"carnosine","display_name":"L-Carnosine / beta-alanyl-L-histidine","entity_type_key":"small_molecule"}},{"dimension":"plain_language","value_text":"The breakdown product did not behave like the intact peptide.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"Antioxidant properties of carnosine re-evaluated with oxidizing systems involving iron and copper ions. · 2005 · https://pubmed.ncbi.nlm.nih.gov/15853927/ · DOI 10.1111/j.1742-7843.2005.pto_03.x","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"029b8b28-c267-5e1b-9696-1d0d006450f2","evidence_kind":"source_excerpt","locator":"Lines 316-322","start_line":316,"end_line":322,"excerpt":"## carnosine-histidine-metal\nThe breakdown product did not behave like the intact peptide.\nHistidine increased DNA damage in the tested iron/peroxide/ascorbate system and weakened carnosine protection when combined with it.\nModel: Cell-free 10 mM amino-acid comparison.\nLimitations: Not evidence that dietary histidine damages human DNA.\nEvidence access: Primary abstract\nAntioxidant properties of carnosine re-evaluated with oxidizing systems involving iron and copper ions. · 2005 · https://pubmed.ncbi.nlm.nih.gov/15853927/ · DOI 10.1111/j.1742-7843.2005.pto_03.x","model_system":"Cell-free 10 mM amino-acid comparison.","directness":"reported_statement","verification_status":"source_derived_draft","notes":"Original curation paraphrase; evidence access and experimental limitations specified.","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"87dc5af2-4eb6-5980-b7e0-bf3697b1156e","stable_key":"import-ae1ed35d-8ce7-5936-9067-a641374bbf79","title":"Carnosine: synthesis, transport, carbonyl chemistry and nutrient interactions (2026-09-19)","document_type":"imported_text","citation_label":"AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text.","file_path":"","sha256":"469cbc38203db56bd031f9d8a2dd2bfa387713950ca30199511cd137e927aa7a","revision_id":"cc409a15-8b04-50ee-a7ff-d1bf32f686bb","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}