摘要Background:Aristolochic acid Ⅱ(AAⅡ),a major nephrotoxic and carcinogenic component of aristolochic acids(AAs),has been less studied compared with its well-characterized analog,aristolochic acid Ⅰ(AAⅠ).Although AAs are known to induce carcinogenesis via DNA adduct formation,the toxicity mechanisms,environmental prevalence,and long-term health impacts of AAⅡ remain poorly understood.Objective:This study aimed to systematically evaluate AAⅡ's acute and chronic toxicity,carcinogenic mechanisms,and environ-mental exposure patterns using integrated murine models and phytochemical analyses to clarify its toxicological profile and associ-ated health risks.Methods:C57BL/6J mice were used in the following experiments:(1)determination of AAⅡ content in 3 commonly used Aristolochia medicinal materials via liquid chromatography-mass spectrometry/mass spectrometry;(2)acute toxicity testing with single doses of 10,20,or 40mg/kg;and(3)chronic exposure with 1 or 10mg/kg administered every other day for 24 weeks,followed by 21 to 40 weeks of postexposure monitoring.Histopathological examination,whole-exome sequencing,biochemical assays,and micronu-cleus tests were performed to assess multi-organ damage,tumorigenesis,genomic mutation signatures,and direct clastogenicity.Phytochemical analyses were used to evaluate environmental distribution.Results:(1)A single 40mg/kg dose of AAⅡ induced dose-dependent renal tubular degeneration without hepatotoxicity;(2)the 10 mg/kg group showed significant mortality(20％),tumor incidence(33.3％,primarily forestomach and bladder transitional cell car-cinomas),persistent renal interstitial fibrosis,and subclinical hepatic injury.Chronic exposure to 1 mg/kg still induced 13.3％mortality and 15.5％tumor incidence over a 64-week period;(3)whole-exome sequencing revealed a predominance of C＞T mutations and pathway enrichment in chemical carcinogenesis and cytochrome P450-mediated metabolism,indicating reactive metabolite-driven mechanisms distinct from classical AA-DNA adducts;and(4)no histopathological changes were observed in nontarget organs(brain,heart,and testes),and micronucleus assays confirmed the absence of direct clastogenicity.Conclusion:This study highlights the delayed carcinogenic risks of low-dose chronic AAⅡ exposure and emphasizes the need to update regulatory frameworks to ensure the safe use of aristolochiaceae-containing herbal products.