Effectiveness of Curcumin on Oxidative Stress in Goat Semen: Explorations Regarding Semen Quality, Sperm Apoptosis, Ultrastructure, and Markers of Oxidative Stress

Oxidative stress induces reactive oxygen species (ROS) accumulation, which compromises sperm DNA integrity, cellular homeostasis, and semen quality in Hainan black goats. This study aimed to mitigate ROS-mediated sperm damage by examining the protective effects of curcumin on metabolic regulation and sperm structural integrity. Semen samples were treated in vitro with varying concentrations of curcumin (5, 25, 50 μmol/L) under oxidative stress conditions. The intermediate concentration (25 μmol/L) was most effective at enhancing sperm quality. Following treatment, sperm motility, membrane integrity, and acrosome stability were significantly improved (<i>p</i> < 0.05), while ROS levels and apoptosis rates decreased. Antioxidant enzyme activities-glutathione peroxidase (GPX, <i>p</i> < 0.05), catalase (CAT, <i>p</i> < 0.05), and superoxide dismutase (SOD, <i>p</i> < 0.05)-were markedly elevated. Metabolomic analysis identified 48 differential metabolites (<i>p</i> < 0.05), including gluconic acid, 3-hydroxybutyric acid, and argininosuccinic acid, which were mainly involved in antioxidant defense, energy metabolism (e.g., the citrate cycle), and osmoregulatory pathways. Lipidomics revealed reduced lipid peroxidation and increased polyunsaturated fatty acid content, correlating with enhanced membrane stability. Transmission and scanning electron microscopy revealed preservation of sperm ultrastructure, with reduced mitochondrial and chromatin damage. Quantitative PCR further indicated curcumin-mediated downregulation of pro-apoptotic genes (<i>BAX</i>, <i>Caspase3</i>, and <i>FAS</i>) and upregulation of the anti-apoptotic gene <i>BCL2</i> (<i>p</i> < 0.05). These findings demonstrate that Curcumin at 25 μM mitigated menadione-induced oxidative stress in goat sperm in vitro, improving antioxidant status, mitochondrial function and membrane integrity while reducing apoptosis. Multi-omic profiling supported redox and lipid homeostasis restoration. These findings establish proof-of-principle in an acute oxidative model.