Figure 2. Cytoprotective effects of NK-4 against neurotoxins in PC12 cells.

(A) Effect of NK-4 on H₂O₂-induced cytotoxicity. PC12 cells were treated with 200 µM H₂O₂ for 2 hr in the absence or presence of the indicated concentrations of NK-4. Control cells were incubated under the same conditions, but without H₂O₂. (B) Effect of NK-4 against 6-OHDA-induced toxicity. PC12 cells were treated with 100 µM 6-OHDA for 24 hr in the absence or presence of the indicated concentrations of NK-4. Control cells were incubated under the same conditions, but without 6-OHDA. All results were obtained by alamarBlue assay and are expressed as the percentage fluorescence of control cells. Values are means ± SD obtained in triplicate. *P<0.05, **P<0.01 for comparison of wells with and without NK-4.