Untargeted LC–MS/MS Metabolomics Reveals Nrf2-Mediated Antioxidant Activation and Metabolic Reprogramming by IAA-Based Hydrazone Derivatives in Subchronic Cadmium Toxicity

BACKGROUND: Indole-3-acetic acid (IAA)-based hydrazone derivatives, exemplified by specifically (E)-2-(1H-indol-3-yl)-N'-(3-methoxybenzylidene) acetohydrazide acetohydrazide (MBIH) and (E)-N'-(4-fluorobenzylidene)-2-(1H-indol-3-yl) acetohydrazide (FBIH), have garnered significant attention in the field of heavy metal toxicity for their potent antioxidant and cytoprotective properties. METHODS: This study evaluated their efficacy, alongside ascorbic acid (AA), in mitigating sub-chronic cadmium (Cd) toxicity in a rat model. Sixty Swiss albino rats were randomized into five groups: control, Cd-exposed, Cd + AA (100 mg/kg), Cd + MBIH (10 mg/kg), and Cd + FBIH (10 mg/kg). Following 28 days of treatment, we assessed body weight trajectories, fasting blood glucose, and HbA1c. Serum biomarkers of hepatic, renal, inflammatory, and lipid function were quantified. Antioxidant capacity was measured via glutathione (GSH) assays and qRT-PCR analysis of SOD2, CAT, Nrf2, and Hmox 1 expression. Untargeted LC-MS/MS metabolomic profiling of serum identified disturbances in amino acids and lipid species, while histopathology of brain, liver, and pancreas documented structural injury. RESULTS: Cd exposure induced significant weight loss, hyperglycemia, and elevated HbA1c, alongside dyslipidemia and heightened inflammatory markers. Hepatic and renal dysfunction, GSH depletion, and downregulation of antioxidant genes confirmed oxidative stress. Metabolomics revealed a Cd-specific fingerprint characterized by altered sulfur amino acid and phospholipid metabolism. Histologically, Cd caused liquefactive necrosis in the brain, inflammatory infiltrates in the liver, and acinar cell vacuolization with islet distortion in the pancreas. In contrast, MBIH and FBIH restored glycemic control, lipid profiles, inflammatory and hepatic renal markers, replenished GSH, and upregulated antioxidant genes via robust Nrf2 activation. CONCLUSIONS: These findings demonstrate that IAA-based hydrazone derivatives MBIH and FBIH afford superior protection against Cd-induced multi organ injury compared to ascorbic acid.