Objective: To investigate the effects of syringic acid on HEK 293 and HepG2 cells in the absence and presence of exogenous Cu (II) and Fe (II) ions. Methods: The antiproliferative effects of syringic acid on HEK 293 and HepG2 cells in the absence and presence of exogenous Cu (II) and Fe (II) ions were examined by MTT assay. Additionally, colony-forming, reactive oxidative species (ROS) generation, apoptosis induction, autophagy, mitochondrial membrane potential, and mitochondrial mass were investigated. Results: At 24 and 72 h, no significant differences were observed in the viability of HepG2 cells between the control and syringic acid + Fe (II) groups. However, exposure of HepG2 cells to syringic acid + Cu (II) for 72 h reduced the cell viability significantly. Furthermore, ROS formation, induction of apoptosis, and autophagic vacuoles were significantly increased in HepG2 cells without marked changes in mitochondrial membrane potential and mitochondrial mass. Moreover, syringic acid + Cu (II) reduced the plating efficiency and surviving fraction significantly. Conclusions: The combination of syringic acid with Cu (II) was toxic to cancer cells and showed pro-oxidant activity. In addition, this combination induced autophagy in cancer cells with less cytotoxic effects on normal cells, which is a potential candidate for the development of novel therapeutics towards cancer.

Background and aim The liver is the primary organ affected by cholestasis, and complications such as renal injury, renal failure, and the need for renal transplantation are associated with cholestatic liver disease. There is substantial evidence indicating that reactive oxygen species (ROS) and mitochondrial impairment are fundamental mechanisms underlying cholestasis-induced hepatic and renal injury. Edaravone (EDV) is a potent radical scavenger and antioxidant that may prevent oxidative stress and improve impaired mitochondrial function in various diseases. This study was performed to evaluate the effects and mechanisms of action of EDV on hepatic and renal injury in an animal model of cholestasis. Methods Rats subjected to bile duct ligation (BDL) were treated with EDV 1 or 10 mg/kg/day intraperitoneally for 14 consecutive days. Biomarkers of oxidative stress and mitochondrial impairment in the liver and kidney were assessed in EDV-treated and untreated rats with cholestasis. Results Significant increases in tissue ROS level, lipid peroxidation, protein carbonylation, and oxidized glutathione level were detected in rats subjected to BDL. Additionally, significant decreases in tissue glutathione level and antioxidant capacity were observed in the hepatic and renal tissues of rats with cholestasis. Markers of mitochondrial impairment, including mitochondrial depolarization, lipid peroxidation, mitochondrial permeabilization, depleted adenosine triphosphate content, and decreased dehydrogenase activity, were also detected in rats subjected to BDL. Furthermore, portal inflammation, necrosis, and tissue fibrosis were detected in the liver and significant tubular atrophy and interstitial inflammation, as well as fibrotic lesions, were detected in the kidneys of rats with cholestasis. EDV treatment significantly mitigated cholestasis-associated hepatic and renal injury. Conclusions The antioxidative properties of EDV and its positive effects on the indices of mitochondrial function may be critical factors contributing to protection against cholestasis-associated hepatic and renal injury.