Scavenging effect of N-acetyl-L-cysteine against reactive oxygen species in human semen: a possible therapeutic modality for male factor infertility?

A new approach to reduce the level of reactive oxygen species (ROS) in human semen by using N-acetyl-L-cysteine (NAC) was evaluated. Semen samples were incubated with or without NAC (1.0 mg ml-1) at room temperature. The chemiluminescent signal of the oxidation of luminol was detected by means of an MTP reader after 0, 20, 40, 60 and 120 min, respectively, using 200 microM luminol. In addition, the dose-dependent action of NAC (0.1, 1.0 and 5.0 mg ml-1) and the influence of NAC on functional sperm parameters (motility and acrosome reaction) were studied. ROS levels decreased significantly after 20 min incubation with NAC. This reduction was greater in the high ROS group (> 30000 counts/10(7) viable sperm at t = 0) than in the low ROS group (< 30000). In addition, a marked dose-dependence of NAC was observed. Concerning sperm function, total sperm motility improved after incubation with NAC, but no significant change was observed with respect to the acrosome reaction. NAC (at concentrations of 1.0 mg ml-1) significantly reduced ROS in human semen and showed the possibility of improving impaired sperm function. After further testing NAC might be useful for the treatment of male infertility patients.