Antioxidant activity in the semen of fertile and infertile men

OBJECTIVES: To evaluate catalase- and superoxide dismutase (SOD)-like activities in the seminal plasma of fertile and infertile men. METHODS: Semen samples were obtained from consecutive men presenting for vasectomy (n = 12) and infertility evaluation (n = 105) at our institution. Catalase-like activity was measured by the decrease in hydrogen peroxide after incubation with seminal plasma. SOD-like activity was measured as the inhibition of nitroblue tetrazolium reduction due to superoxide anion generation by xanthine plus xanthine oxidase. RESULTS: Mean seminal catalase-like activity (+/-SEM) in fertile men was not significantly different from that of infertile men (369 +/- 49 versus 326 +/- 17 U/mL, respectively). Mean SOD-like activity in the semen of infertile men was significantly greater than in the semen of fertile controls (46.7 +/- 1.5 versus 37.0 +/- 2.8 U/mL, respectively, P <0.05). CONCLUSIONS: Our data show that infertile men do not have deficient seminal plasma SOD- and/or catalase-like activity (two key antioxidants). These findings suggest that the high semen ROS levels in some infertile men are likely due to excessive generation of ROS rather than deficient ROS scavenging activity in semen.