Olive (Olea europaea L.) Biophenols: A Nutriceutical against Oxidative Stress in SH-SY5Y Cells

Syed Omar,Christopher Scott,Hassan Obied,Adam Hamlin,Philip Kerr

doi:10.3390/molecules22111858

Syed Omar, Christopher Scott + Show 3 more

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https://doi.org/10.3390/molecules22111858

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Abstract

Plant biophenols have been shown to be effective in the modulation of Alzheimer’s disease (AD) pathology resulting from free radical-induced oxidative stress and imbalance of the redox chemistry of transition metal ions (e.g., iron and copper). On the basis of earlier reported pharmacological activities, olive biophenols would also be expected to have anti-Alzheimer’s activity. In the present study, the antioxidant activity of individual olive biophenols (viz. caffeic acid, hydroxytyrosol, oleuropein, verbascoside, quercetin, rutin and luteolin) were evaluated using superoxide radical scavenging activity (SOR), hydrogen peroxide (H2O2) scavenging activity, and ferric reducing ability of plasma (FRAP) assays. The identification and antioxidant activities in four commercial olive extracts—Olive leaf extractTM (OLE), Olive fruit extractTM (OFE), Hydroxytyrosol ExtremeTM (HTE), and Olivenol plusTM (OLP)—were evaluated using an on-line HPLC-ABTS•+ assay, and HPLC-DAD-MS analysis. Oleuropein and hydroxytyrosol were the predominant biophenols in all the extracts. Among the single compounds examined, quercetin (EC50: 93.97 μM) and verbascoside (EC50: 0.66 mM) were the most potent SOR and H2O2 scavengers respectively. However, OLE and HTE were the highest SOR (EC50: 1.89 μg/mL) and H2O2 (EC50: 115.8 μg/mL) scavengers among the biophenol extracts. The neuroprotection of the biophenols was evaluated against H2O2-induced oxidative stress and copper (Cu)-induced toxicity in neuroblastoma (SH-SY5Y) cells. The highest neuroprotection values (98% and 92%) against H2O2-induced and Cu-induced toxicities were shown by the commercial extract HTETM. These were followed by the individual biophenols, caffeic acid (77% and 64%) and verbascoside (71% and 72%). Our results suggest that olive biophenols potentially serve as agents for the prevention of neurodegenerative diseases such as AD, and other neurodegenerative ailments that are caused by oxidative stress.

Highlights

Alzheimer’s disease (AD), is one of the most frequent forms of neurodegenerative disorder associated with dementia in the elderly, and is believed to be caused by an abnormal deposition of amyloid-β peptide (Aβ) [1]
Our results suggest that olive biophenols potentially serve as agents for the prevention of neurodegenerative diseases such as AD, and other neurodegenerative ailments that are caused by oxidative stress
The present study is the first report of the phenolic composition and antioxidant activity comparison of four commercial olive extracts with the individual biophenols in the SH-SY5Y cells

Summary

Introduction

Alzheimer’s disease (AD), is one of the most frequent forms of neurodegenerative disorder associated with dementia in the elderly, and is believed to be caused by an abnormal deposition of amyloid-β peptide (Aβ) [1]. Metal ions induce the Aβ itself to produce the ROS, in turn causing oxidative stress-induced neurotoxicity [4]. Metal ions, such as iron and copper, that promote the formation of free radicals via the Fenton reaction, were observed to increase neurotoxicity in AD [5]. These elevated markers for oxidative stress precede Aβ deposition and neurofibrillary tangles, suggesting that oxidative stress is an “early event” in AD pathogenesis

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