Evaluation of the mutagenicity of a traditional Chinese medicine Radix isatidis root by modified Ames tests, SOS/umu and SOS/rec tests

Radix isatidis root (RIR), the root of plant Isatis indigotica Fort., is a traditional Chinese medicine (TCM) that has been commonly used in China to control upper respiratory tract infections. However, the genetic toxicity of RIR has not been well studied and is the focus of this paper. RIR gave positive results in the Ames test at some doses; and gave positive results in modified Ames tests at a few doses. RIR gave negative results in SOS/umu-lacZ tests. In addition, RIR gave negative results in the mammalian bone marrow chromosomal aberration test and TK gene mutation test. Because the concentrations of RIR in the above tests were all greatly higher than the commonly clinical dose, it could be summarized that at the commonly used clinical dose, RIR showed a negative response in the Ames test, the umu/lacZ test, the TK gene mutation test and the mammalian bone marrow cell chromosomal aberration test. Moreover, different tests sometimes gave conflicting results which may be due to their different sensitivities. This suggests that it is important to choose the appropriate test method when assessing the mutagenicity of traditional Chinese medicine samples.