Cytoprotective Potential of Annurca Apple Polyphenols on Mercury-Induced Oxidative Stress in Human Erythrocytes

Abstract Mercury (Hg) exposure is a major environmental risk factor, closely linked to oxidative stress and cardiovascular disease. Red blood cells (RBC), due to their high oxygen exposure and lack of repair mechanisms, are particularly sensitive to oxidative injury and are key indicators of systemic redox imbalance. This study evaluates the protective effects of polyphenolic extracts from Annurca apple, specifically flesh and peel, from both ripe and unripe fruit, on HgCl2-exposed human RBCs. Key oxidative stress markers were measured, including ROS production, GSH levels, lipid peroxidation (TBARS), MetHb formation, SH group content, microvesicle (MV) generation, and morphological changes. Peel extracts, particularly those from ripe apples, consistently exhibited stronger antioxidant and cytoprotective effects than flesh extracts, effectively reversing Hginduced oxidative damage and preserving RBC integrity. Notably, these extracts restored redox homeostasis and GSH levels, reduced ROS and TBARS accumulation, prevented MetHb formation, and mitigated MV release and morphological alterations. These protective effects appear to involve multifactorial mechanisms. These findings highlight the nutraceutical potential of Annurca apple extracts in counteracting heavy metalinduced oxidative stress and support their possible relevance for future studies aimed at health protection and waste valorization.