AIM: To investigate the role of reactive oxygen species( ROS)-mediated mitochondrial oxidative injury in isonicotinyl hydrazide( INH)-induced DNA damage and the protective effect of quercetin on L-02 cells. METHODS: The injury model of hepatocyte L-02 cells in vitro induced by INH was established. The cells were divided into control group,INH group,low-dose quercetin group and high-dose quercetin group. The DNA damage of L-02 cells was evaluated by the comet test. The mitochondrion was prepared,and the leve...