Chemical Characterization of Phenol-Rich Olive Leaf Extract (Olea europaea L. cv. Ogliarola) and Its Neuro-Protective Effects on SH-SY5Y Cells from Oxidative Stress, Lipid Peroxidation, and Glycation

Olive leaf phenols are recognized for their antioxidant and anti-inflammatory properties. A hydroalcoholic extract of Olea europaea L. cv. Ogliarola leaves was recovered with an ultrasound-assisted extraction using green solvents. Phenol content was investigated by means of liquid chromatography coupled with photodiode array and mass spectrometer detectors. Extract cytotoxicity was determined in SH-SY5Y neuroblastoma cells by the MTT assay to establish non-cytotoxic concentrations. The effects of the extract under lipopolysaccharide-induced conditions were investigated by assessing oxidative stress and lipid peroxidation through malondialdehyde quantification using the thiobarbituric acid assay. Antiglycation capacity was examined with a BSA methylglyoxal model. In parallel, quantitative real-time PCR was employed to assess the modulation of inflammation- and oxidative stress-related genes (TLR4, NF-κB, IL-6, IL-8, Nrf2, and HO-1), providing molecular insights into the extract’s bioactivity. The extract did not exert cytotoxic effects at the selected concentrations and with modulated oxidative stress, lipid peroxidation, protein glycation, and gene expression profiles associated with inflammatory and redox pathways in neuronal cells. These data demonstrated that olive leaf extract, rich in phenols, influenced multiple biochemical and molecular endpoints relevant to neuronal physiology, supporting its potential application as a nutraceutical ingredient for the modulation of oxidative and glycation-related processes.