Abstract: BACKGROUND AND AIM: To investigate oxidative damage of mitochondria induced by olaquindox in human hepatoma G2 (HepG2) cells. MATERIALS AND METHODS: HepG2 cells were treated with 0，200，400 and 800 μg/ml olaquindox for 24 h. The value of IC50 of olaquindox in HepG2 cells was determined by MTT assay. The levels of reactive oxygen species (ROS) were detected by 2, 7-dichlorodihydrofluorescein diacetate (DCFDA) and Dihydroethidium (DHE). The level of mitochondrial membrane potential(△Ψm) and calcium concentration were measured by Rhodamine123(Rh-123) and Fluo-3AM, respectively. Finally, the damage ratio of mtDNA and nDNA was assessed by quantitative PCR. RESULTS: MTT assay revealed that the HepG2 cells viabilities were significantly inhibited by olaquindox in dose- and time- dependent manners. Olaquindox induced increased levels of ROS and calcium in HepG2 cells, and reduced the level of △Ψm . Quantitative PCR assay showed that olaquindox led to a dose-dependent decrease in the amplification of both mtDNA and nDNA. These data also suggested that the olaquindox-induced damage to mtDNA was more extensive than its damage to nDNA. CONCLUSION: Olaquindox could cause oxidative damage of mitochondria in HepG2 cells.

Key words: olaquindox, mitochondria, reactive oxygen species, mitochondrial membrane potential, calcium