Carvacrol Protects Neuroblastoma SH-SY5Y Cells Against Fe2+-induced Apoptosis by Suppressing Activation of MAPK/JNK-NF-κB Signaling Pathway

Aim: Carvacrol (2-methyl-5-isopropylphenol), a phenolic monoterpene in the essential oils of the genera Origanum and Thymus , has been shown to exert a variety of therapeutic effects. Here we examined whether carvacrol protected neuroblastoma SH-SY5Y cells against Fe 2+ -induced apoptosis and explored the underlying mechanisms. Methods: Neuroblastoma SH-SY5Y cells were incubated with Fe 2+ for 24 h, and the cell viability was assessed with CCK-8 assay. TUNEL assay and flow cytometric analysis were performed to evaluate cell apoptosis. The mRNA levels of pro-inflammatory cytokines and NF-κB p65 were determined using qPCR. The expression of relevant proteins was determined using Western blot analysis or immunofluorescence staining. Results: Treatment of SH-SY5Y cells with Fe 2+ (50–200 μmol/L) dose-dependently decreased the cell viability, which was significantly attenuated by pretreatment with carvacrol (164 and 333 μmol/L). Treatment with Fe 2+ increased the Bax level and caspase-3 activity, and decreased the Bcl-2 level, resulting in cell apoptosis. Furthermore, treatment with Fe 2+ significantly increased the gene expression of IL-1β, IL-6 and TNF-α, and induced the nuclear translocation of NF-κB. Treatment with Fe 2+ also significantly increased the phosphorylation of p38, ERK, JNK and IKK in the cells. Pretreatment with carvacrol significantly inhibited Fe 2+ -induced activation of NF-κB, expression of the pro-inflammatory cytokines, and cell apoptosis. Moreover, pretreatment with carvacrol inhibited Fe 2+ -induced phosphorylation of JNK and IKK, but not p38 and ERK in the cells. Conclusion: Carvacrol protects neuroblastoma SH-SY5Y cells against Fe 2+ -induced apoptosis, which may result from suppressing the MAPK/JNK-NF-κB signaling pathways.