Protective Molecular Mechanisms of Olive Oil Phenolic Compounds: Bioactivity and Pathway Profiling of Isolated Compounds Versus Their Mixture

Introduction: The Mediterranean diet is consistently associated with a reduced risk of chronic diseases, including cancer, cardiovascular disorders, and neurodegenerative conditions. These protective effects are largely attributed to its high intake of plant-derived bioactive compounds, with extra virgin olive oil serving as the principal source of dietary fat. Olive oil phenolic compounds are recognized as key mediators of the Mediterranean diet’s antioxidant, anti-inflammatory, and cytoprotective properties. Since oxidative stress and immune dysregulation are central mechanisms in the development and progression of chronic diseases, understanding the cellular and molecular actions of Mediterranean diet-derived bioactives is of significant relevance. This study aimed to assess the bioactivity and molecular effects of selected olive oil phenolic compounds in comparison to a Custom Mixture formulation in order to correlate the modulation of specific pathways with crucial cellular decisions of pharmacological relevance. Methods: The effects of olive oil phenolic compounds were evaluated in HepG2 hepatocellular carcinoma cells and peripheral blood mononuclear cells (PBMCs). Cell viability and proliferation assays were performed, along with targeted molecular profile analysis related to cellular pathways involved in DNA repair, lipid metabolism, oxidative stress, inflammation, and neurotrophic signaling. Results: Overall, distinct molecular and bioactivity profiles were observed in HepG2 cells among individual phenolic compounds as well as in comparison to their mixture, referring mainly to DNA damage gene response activation (API 1), enhanced antioxidant gene expression (API 7), and apoptosis induction (APIs 5 and 6). Interestingly in PBMCs, combined effects on immune-related and neuroprotective signaling pathways were revealed, alongside the modulation of inflammation-associated gene biomarkers. Discussion: As a matter of fact, by affecting proliferation-related and immune response-associated molecular pathways in a cell-specific manner, olive oil phenolic data may represent a mechanistic link between olive oil consumption and chronic disease risk prevention and management in populations.