Effect of reactive oxygen species and the activity of antioxidant systems on human semen; association with male infertility.

A range of compounds with a role in oxidative stress were measured in ejaculates from 40 normozoospermic individuals and 93 infertile males. Ejaculates were classified according to WHO criteria. Seminal plasma and the sperm cell fraction were assessed separately for superoxide dismutase (SOD), catalase, xanthine oxidase, capability for singlet oxygen trapping and content of thiobarbituric acid-reactive substances (TBARS). Pathological cases defined as oligozoospermia, asthenozoospermia, or teratozoospermia revealed different backgrounds of oxidative stress as reflected by different levels of tested substances in every type of sperm pathology. In the majority of abnormal ejaculates, a significant increase in intracellular activity of SOD, decreased intracellular levels of catalase, elevated levels of xanthine oxidase and TBARS, and severely impaired singlet oxygen trapping were observed when compared to normozoospermic ejaculates. Interrelationships between SOD and TBARS, and between xanthine oxidase and catalase, appeared to be of key importance when analysed separately in seminal plasma and in spermatozoa or in a combination of both. Elevated xanthine oxidase levels and low capacity for singlet oxygen trapping are statistically significant factors for the evaluation of male infertility which can develop as a result of persistent oxidative stress.