Neuroprotective effect of different virgin olive oil extracts in SH-SY5Y cells

Neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease are the largest growing area of neurological research still in search of an effective therapy. Virgin olive oil is a rich source of phenolic compounds that have been demonstrated to interfere with different mechanisms involved in neurodegenerative disorders1. Olive oil polyphenols can be divided into three categories: secoiridoids such as oleocanthal, simple phenols such as hydroxytyrosol and lignanes. Here, we evaluated the neuroprotective effect of four different virgin olive oil extracts against neurodegeneration by determining their effect in modulating oxidative stress and pro-survival pathways. The different olive oil extracts were characterized for their content in tyrosol, hydroxytyrosol, oleacein and oleocanthal by HPLC. SH-SY5Y cells were treated with different concentrations (1-10 µg/mL) of the extracts. Cell viability was evaluated by MTT assay and the results showed that three of the tested extracts significantly increased cell viability. Furthermore, two of these extracts decreased basal reactive oxygen species level measured by dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay. Interestingly all the extracts increased reduced GSH level measured by monochlorobimane (MCB) assay. These extracts were also able to modulate phase II antioxidant enzymes and MAPK signalling pathways as measured by RT-PCR and immunoblotting. Our findings support the idea that virgin olive oil has a beneficial health effect in counteracting neurodegeneration and these effects are strongly related to the specific pattern of olive oil phenols.