Two herbal medicines, daio-kanzo-to and choi-joki-to, identified as neuroprotective agents in the course of screening.

(A) NGF-differentiated PC12D cells were treated with 0.3 µM rotenone and herbal medicine extract for 48 h. Cell viability was evaluated by trypan blue dye exclusion assay. (B) NGF-differentiated PC12D cells were treated with various concentrations of choi-joki-to or daio-kanzo-to in the presence of 0.3 mM MPP⁺ for 48 h. Cell viability was evaluated by trypan blue dye exclusion assay. Values are the means of triplicate samples; bars, s.d. ^**p<0.01 compared with MPP⁺ group cells.