Beneficial effect of AntiOxBEN2, a mitochondria-directed antioxidant, on maturation of bovine oocytes: Analysis of bioenergetics pathways and embryo production.

Oxidative stress during in vitro maturation of oocytes impairs mitochondrial function and reduces developmental competence. We evaluated the potential of AntiOxBEN2, a novel triphenylphosphonium-conjugated antioxidant, to enhance bovine oocyte maturation and early embryo development. Cumulus-oocyte complexes were matured for 22h in medium supplemented with 0, 10, 20, 50, or 100 μM AntiOxBEN2. Nuclear maturation rates, cleavage and blastocyst formation were assessed after in vitro fertilization, while bioenergetic parameters (lactate production, oxygen consumption rate, intracellular ATP, and reactive oxygen species (ROS), transcripts for antioxidant defense-related genes (Nfe2l2/Nqo1), and mtND5 gene copy number, as an indirect measure of mitochondrial DNA copy number, were measured in mature oocytes. AntiOxBEN2 improved nuclear maturation in a dose-dependent manner (p < 0.05) and maximized cleavage rate at 10 μM (79.4 ± 2.5 % versus 67.7 ± 2.7 % in control; p ≤ 0.01). At this concentration, mtND5 copy number also increased significantly (p < 0.05), whereas higher doses (50-100 μM) delayed meiosis and elevated lactate without affecting ATP, ROS, or oxygen consumption. No treatment altered Nfe2l2 or Nqo1 transcript levels. These findings indicate that 10 μM AntiOxBEN2 optimizes mitochondrial biogenesis and enhances early embryo cleavage, supporting its inclusion in maturation media as a strategy to improve assisted reproductive technologies (ART).