Rhizoma Coptidis （RC）, a widely used traditional Chinese medicine, is commonly believed to be non-toxic. However, little is known about its cytotoxicity and relevant mechanisms at cellular and genetic levels. The present study aimed to explore the cytotoxicity of RC and its possible mechanisms related to cell cycle arrest, DNA damage and reactive oxygen species （ROS） level in L929 murine fibroblast cells. The cells were cultured in vitro and treated with different RC concentrations for 24 h. Cell viability was determined by CCK-8 method, morphological changes were observed with an inverted microscope, cell cycle and ROS level were examined by flow cytometry, and DNA damages were detected by comet assay. Our results showed that cell viability was significantly decreased in a dose-dependent manner when the RC concentration was higher than 1 mg/mL. ARC concentration above 1 mg/mL altered the morphology of L929 cells. Both cells at G2/M phase and the ROS level increased in the 2 mg/mL group. Each DNA damage indicator score increased in the groups with the RC concentration of above 0.05 mg/mL. Taken together, our study suggested that RC at a high dosage exhibited cytotoxicity on L929 cells, which was likely to be the consequences of cell cycle arrest, DNA damage and accumulation of intracellular ROS.
