Hydroxytyrosol,a dietary phenolic compound forestalls the toxic effects of methylmercury‐induced toxicity in IMR‐32 human neuroblastoma cells

This study demonstrates the protective potential of hydroxytyrosol (HT), an olive oil phenol, against methylmercury (MeHg)‐induced neurotoxicity using IMR‐32 human neuroblastoma cell line. HT inhibited MeHg‐induced cytotoxicity and genotoxicity as confirmed by MTT, micronucleus, and comet assays. Cells preconditioned with HT showed reduction of MeHg‐induced cellular oxidative stress along with the maintenance of glutathione, superoxide dismutase, glutathione‐S‐tranferase, and catalase. Fluorescence microscopy and DNA ladder assays indicated the inhibitory effect of HT against MeHg‐induced apoptosis, which was further established by Western blotting. An effective concentration of 5 µM HT caused downregulation of p53, bax, cytochrome c, and caspase 3 and upregulation of prosurvival proteins including nuclear factor erythroid 2‐related factor 2 (Nrf2) and metallothionein. This work indicates the cytoprotective potential of HT against MeHg‐induced toxicity primarily by the lowering of oxidative stress, which may be endorsed to its antigenotoxic and antiapoptotic potential, in addition to its free radical scavenging ability. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1264–1275, 2016.