Quercetin and Naringenin Provide Functional and Antioxidant Protection to Stored Boar Semen

SIMPLE SUMMARY: A significant effort has been devoted to the enhancement of boar sperm preservation media and techniques, which have become a critical pillar of modern swine production. Despite the availability of numerous semen extenders, a higher antioxidant protection of male gametes is highly required, which may be achieved by the supplementation of natural biomolecules such as quercetin and naringenin. In this regard, we have performed a number of experiments in order to define the optimal concentration range of both biomolecules that could ensure a higher structural integrity, functional activity, and antioxidant profile of boar spermatozoa subjected to short-term storage. The beneficial outcomes achieved in this study shall be tested in vivo at our collaborating pig farm, with their potential contribution to the optimization of the use of stored boar semen in the porcine breeding industry. ABSTRACT: In this study, we evaluated the impact of 5–50 μM quercetin (QUE) and naringenin (NAR) on extended boar spermatozoa in the BTS (Beltsville Thawing Solution) medium for 72 h. Spermatozoa motion, membrane, acrosome, and DNA integrity were investigated immediately after sample dilution (0 h) as well as after 24 h, 48 h, and 72 h of semen storage. Furthermore, reactive oxygen species (ROS) and superoxide production, as well as the extent of oxidative damage to the sperm proteins and lipids, were assessed to determine the potential of QUE and NAR to prevent a potential loss of sperm vitality due to oxidative stress development. Our results indicate that the most notable parameter influenced by QUE was the mitochondrial activity, which remained significantly higher throughout the experiment (p < 0.001 and p < 0.0001; 10 μM), and which correlated with the most prominent maintenance of sperm motility (p < 0.01, 48 h; p < 0.05, 72 h). A significant membrane stabilization (p < 0.01, 24 h and 48 h; p < 0.0001, 72 h) and prevention of lipid peroxidation (p < 0.05, 24 h and 48 h; p < 0.01, 72 h) was primarily observed following administration of 10 and 25 μM NAR; respectively. Administration of 10 μM QUE led to a significant decrease of superoxide (p < 0.0001, 48 h and 72 h) while the most notable decline of ROS generation was recorded in the case of 10 and 25 μM NAR (p < 0.001). This study may provide new information on the specific mechanisms of action involved in the favorable effects of natural biomolecules on spermatozoa.