Mitochondrial and Redox Mechanisms of Leflunomide-Induced Hepatotoxicity Following Repeated Exposure

Arjmand, Abdollah; Golabi, Sara; Maghami, Sepideh; Yousefipour, Kiana; Jamshidzadeh, Akram; Hossein, Hossein; Heidari, Reza

doi:10.30476/tips.2026.110550.1350

Mitochondrial and Redox Mechanisms of Leflunomide-Induced Hepatotoxicity Following Repeated Exposure

Document Type : Research(Original) Article

Authors

¹ Medicinal Plants Research Center, Yasuj University of Medical Sciences, Yasuj, Iran

² Students Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran

³ Department of Pharmacology and Toxicology, School of Pharmacy

⁴ Shiraz University of Medical Sciences, Pharmaceutical Sciences Research Center

10.30476/tips.2026.110550.1350

Abstract

Leflunomide is a disease-modifying antirheumatic drug widely used for inflammatory arthritis. Although leflunomide or its active metabolite has shown antioxidant or protective effects in some acute and extrahepatic models, whether repeated hepatic exposure produces a coordinated redox–mitochondrial injury phenotype remains insufficiently defined. This study investigated the effects of repeated oral leflunomide administration on hepatic injury markers, oxidative stress, and mitochondrial function in male BALB/c mice. Animals received leflunomide at 5, 10, or 20 mg/kg by gavage for 28 consecutive days. Plasma ALT, AST, and LDH were measured as biochemical indices of tissue injury. Hepatic oxidative status was assessed by reactive oxygen species formation, lipid peroxidation, reduced glutathione content, ferric-reducing antioxidant power, and the activities of superoxide dismutase and catalase. Liver mitochondria were isolated to evaluate dehydrogenase activity, membrane potential, and calcium-triggered swelling. Repeated leflunomide exposure reduced body weight gain at 10 and 20 mg/kg without significantly altering the liver weight index. ALT and AST were increased in treated animals, whereas LDH remained unchanged. Leflunomide also shifted the hepatic redox profile toward oxidative stress, as evidenced by increased ROS formation and lipid peroxidation, GSH depletion, reduced antioxidant capacity, and lower SOD and CAT activities. These alterations were accompanied by mitochondrial dysfunction, including reduced dehydrogenase activity, loss of mitochondrial membrane potential, and enhanced mitochondrial swelling. These findings indicate that repeated leflunomide exposure induces a hepatic injury phenotype characterized by oxidative stress and mitochondrial impairment.

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