Evaluation of the Antioxidant Properties and Bioactivity of Koroneiki and Athinolia Olive Varieties Using In Vitro Cell-Free and Cell-Based Assays

Olive oil and table olives are considered staples of the Mediterranean diet and have been associated with various health benefits. Literature reports that the final composition of the olive drupe is greatly affected by varietal and agronomic factors, each contributing to a different degree. To that end, the objective of the study was the evaluation of the contribution of different agronomic conditions applied to two Greek olive varieties (Koroneiki, Mastoidis) using a holistic approach of in vitro methods. The findings highlight the importance of the application of a combination of agronomic techniques for each variety, as marked by the differences found in the antioxidant radical-scavenging and reducing power assays. Furthermore, the results obtained from the measurement of redox biomarkers (GSH, ROS, TBARS) in cell lines (EA.hy926, HepG2, MKN45) treated with olive samples demonstrate the capacity of the samples to induce redox imbalance, either by protecting normal cells from damage, or by inducing oxidative damage in cancer cell lines, with the Athinolia samples exhibiting greater antioxidant potential at lower concentrations. This particular finding could have further applications in possible chemo-preventive approaches facilitated by antioxidant compounds of natural origins.