Evaluation of Oxidative Stress and Its Impact on Sperm DNA Fragmentation and Semen Parameters in Infertile Men

Oxidative stress, defined as an imbalance between reactive oxygen species (ROS) production and antioxidant defenses, plays a central role in the pathophysiology of male infertility and has been reported in approximately 30%-80% of infertile men. Excessive ROS production promotes lipid peroxidation, DNA damage, and mitochondrial dysfunction, ultimately compromising sperm quality. The aim of our study was to evaluate oxidative stress biomarkers in seminal plasma, including malondialdehyde (MDA) as a marker of lipid peroxidation and key enzymatic antioxidants superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), and to assess their impact on sperm DNA fragmentation, semen parameters, and serum total testosterone levels. Semen samples were collected from a total of 150 participants, including 120 infertile men (30 oligozoospermic, 30 teratozoospermic, 30 asthenozoospermic, and 30 necrozoospermic) and 30 fertile controls. Semen analysis was performed according to WHO 2021 criteria. Sperm DNA fragmentation index (DFI) was assessed using the TUNEL assay. Seminal antioxidant enzyme activities (SOD, CAT, and GPx) and lipid peroxidation levels were measured in seminal plasma using spectrophotometric methods. Serum total testosterone levels were measured using an electrochemiluminescence immunoassay. The results showed that DFI and MDA levels were significantly higher in infertile men compared with controls. Conversely, seminal antioxidant enzyme activities and serum testosterone levels were significantly lower in the infertile groups (p < 0.05). DFI was positively correlated with MDA (r = 0.63, p < 0.001). In contrast, reduced seminal antioxidant enzyme activities and lower testosterone levels were negatively associated with higher DFI and MDA (p < 0.001). Additionally, both DFI and MDA showed negative correlations with semen parameters. Our findings highlight the potential value of oxidative stress biomarkers and sperm DNA fragmentation assessment in the evaluation of male infertility, emphasizing the central role of oxidative stress in sperm dysfunction.