Benzalkonium chlorides compromise oocyte maturation and developmental competence by disrupting mitochondrial function...

Benzalkonium chlorides (BACs), a class of quaternary ammonium compounds (QACs) widely used as disinfectants and preservatives, have increasingly replaced triclosan and triclocarban in personal care products following their global restriction. However, the potential reproductive toxicity of BACs remains largely unexplored. Notably, we investigated the effects of BACs exposure on porcine oocyte maturation and fertilization competence, as well as the underlying mitochondrial mechanisms. COCs were cultured under in vitro maturation (IVM) conditions for 44 h with 0.2-50.0 μg/mL BACs. BACs exposure markedly inhibited cumulus expansion, reduced first polar body extrusion, and impaired fertilization and early embryonic development in a dose-dependent manner. Cytological analysis revealed disrupted spindle assembly, decreased microtubule stability, and disorganized F-actin structures. BACs also caused abnormal cortical granule distribution, diminished Ovastacin expression, and reduced sperm-binding capacity. Mechanistically, BACs induced mitochondrial depolarization, reduced mitochondrial abundance, elevated mitochondrial ROS, and disrupted Ca²⁺ homeostasis, leading to oxidative stress, DNA damage, apoptosis, and autophagy-lysosomal imbalance. Further, BACs exposure suppressed the mitochondrial SIRT3-SOD2 antioxidant axis, while pharmacological activation of SIRT3 by UBCS039 or ROS scavenging with Mito-TEMPO partially rescued mitochondrial dysfunction and oocyte maturation defects. Collectively, these findings demonstrate that BACs exposure compromises oocyte quality and developmental competence via mitochondrial oxidative stress and SIRT3-SOD2 axis inhibition, providing new insights into the reproductive risks associated with emerging disinfectant contaminants.