Fig. 1.

Cell viability detected by MTT assay. PC12 cells were treated with curcumin (0.5–10 μg/mL), boiled curcumin mixture Cur-B1 (360 μg/mL), boiled curcumin mixture Cur-B2 (360 μg/mL), ferulic acid (2–400 μg/mL), vanillic acid (2–400 μg/mL) and vanillin (2–400 μg/mL) for 0.5 h prior to exposure to 500 μM H₂O₂. The cytotoxic doses of H₂O₂ (a), curcumin, Cur-B1, Cur-B2 (b), and the selected degradation products of curcumin (c) were determined. The protective effect of curcumin, Cur-B1, and Cur-B2 (d) and the selected degradation products of curcumin (e) on H₂O₂ induced cytotoxicity in PC12 cells. Data were displayed as mean ± SD value from three separate experiments. Bars with different features manifested statistical difference at p < 0.05. *p < 0.05, different from H₂O₂-only group; **p < 0.01, significantly different from H₂O₂-only group.