Figure 1: Protective effect of honokiol on H2O2-induced cytotoxicity in HaCaT cells. HaCaT cells were stimulated with various concentrations of honokiol (A) for 24 h or pre-treated with or without honokiol (10 μM) or NAC (10 μM) for 1 h and then cultured in the presence or absence of H2O2 (500 μM) for 24 h (B) . The cell viability was determined by MTT assay. The results are expressed as mean ± SD of three independent experiments (*P < 0.05 compared with the control group; *P < 0.05 compared with the H2O2-treated group). NAC: N-acetyl-L-cysteine.