Cytotoxicity of aristolochic acid I in HepG2 cells: comparison of different cell viability assays

Application of herbal preparations in the context of Traditional Chinese Medicine for example becomes more and more popular. The focus of research is on the one hand the pharmacological activity of such herbal preparations and on the other hand whose potential toxicological risk for the human organism. A number of methods have been developed to determine cytotoxicity, each of them using specific approach to detect different aspects of cell viability, such as proliferation and metabolic functions. In this study the natural product aristolochic acid I (AAI), a component of Aristolochia species, was analyzed for its toxic effects on the human hepatoma cell line HepG2. Four methods (cell counter, MTT assay, BrdU assay, colony forming ability) were compared. HepG2 were exposed to AAI for 24h. BrdU assay and colony forming ability were more sensitive than MTT assay and the determination of cell viability using a cell counter. Especially for risk assessment of natural products as well as herbal preparations the results point out the importance of the deliberate selection of cytotoxicity assay.