Combined Phloretin and Idebenone Supplementation Improves Ovine Oocyte Quality and Early Embryonic Development by Attenuating Oxidative Stress and Mitochondrial Dysfunction

Abstract Objective Phloretin (PHL), a natural dihydrochalcone flavonoid, possesses significant antioxidant, anti-apoptotic, and anti-inflammatory activities. Idebenone (IDE), a structural analog of coenzyme Q10, protects mitochondrial function and enhances antioxidant capacity. This study investigated the combined effects of PHL and IDE on the in vitro maturation (IVM) of ovine oocytes and subsequent embryonic development, aiming to identify their optimal synergistic concentration. Methods We used a base medium supplemented with 5 µM PHL as the control to evaluate the effects of different IDE concentrations. Results Results demonstrated that the combination of PHL with 10 µM IDE significantly enhanced the rates of oocyte maturation, cleavage, and blastocyst formation compared to the control. This co-treatment also significantly increased intracellular glutathione (GSH) levels and mitochondrial membrane potential (ΔΨm), while reducing reactive oxygen species (ROS) levels in oocytes. Furthermore, it up-regulated the expression of antioxidant genes (CAT, SOD-2, GPX-3) and the follicular development-related gene GDF-9. During early embryo culture, the 10 µM IDE co-treatment similarly elevated GSH levels and ΔΨm in morulae, reduced ROS levels, and up-regulated the antioxidant genes CAT and GPX-3. Concurrently, it up-regulated the embryonic development-related gene SOX-2, suppressed the apoptosis-related gene Caspase-3 and decreased the Bax/Bcl-2 ratio. Conclusion In conclusion, the combination of PHL and IDE significantly improves the efficiency of ovine oocyte IVM and early embryonic development by enhancing antioxidant capacity, inhibiting apoptosis, and promoting developmental competence. Collectively, these findings provide a valuable foundation for optimizing in vitro embryo production systems in sheep.