Objective: Oxidative stress plays a key role in the pathogenesis of male infertility. But, the adverse effects of oxidative biomarkers on sperm quality remain unclear. This study aimed to investigate the levels of nitric oxide (NO), 8-hydroxydesoxyguanosine (8-OHdG), and total antioxidant capacity (TAC) oxidative biomarkers in seminal plasma and their relationship with sperm parameters.Methods: A total of 77 volunteers participated in the study, including fertile (n=40) and infertile men (n=37). NO, 8-OHdG, and TAC levels were measured using the ferric reducing ability of plasma, Griess reagent method and an enzyme-linked immunosorbent assay kit, respectively.Results: The mean values of sperm parameters in the infertile group were significantly lower than those in the fertile group (<i>p</i><0.001). The mean 8-OHdG in the seminal plasma of infertile men was significantly higher (<i>p</i>=0.013) than those of controls, while the mean TAC was significantly lower (<i>p</i>=0.046). There was no significant difference in NO level between the two groups. The elevated seminal 8-OHdG levels were negatively correlated with semen volume, total sperm counts and morphology (<i>p</i><0.001, <i>p</i>=0.001 and <i>p</i>=0.052, respectively). NO levels were negatively correlated with semen volume, total sperm counts and morphology (<i>p</i>=0.014, <i>p</i>=0.020 and <i>p</i>=0.060, respectively). Positive correlations between TAC and both sperm count and morphology (<i>p</i>=0.043 and <i>p</i>=0.025, respectively) were also found.Conclusion: These results suggested that increased levels of NO and 8-OHdG in seminal plasma could have a negative effect on sperm function by inducing damage to the sperm DNA hence their fertility potentials. Therefore, these biomarkers can be useful in the diagnosis and treatment of male infertility.

Our findings suggested that these large-scale deletions of mtDNA may be genetic risk factors for poor sperm quality in asthenoteratozoospermia-induced male infertility. Thus, it is necessary to understand the mechanisms behind the generation of these deletions.

Background: Varicocele is the leading cause of male infertility throughout the world. Objectives: This study aimed to identify the effects of varicocele on oxidative stress, total antioxidant capacity (TAC), and semen parameters.