Background: Defective sperm function is now recognized as one of the most important causes of male infertility. Seminal plasma possesses a rich source of different enzymatic and non-enzymatic antioxidants such as vitamin C (ascorbic acid) that protect spermatozoa against oxidative stress as one of the mediators of infertility causing sperm dysfunction and low sperm quality. The aim of this study was investigation of seminal total antioxidant capacity and determination of vitamin C effects on sperm motility.

Methods: We designed a case-control study with a total subject of 62 males. Sperm parameters were analyzed according to World Health Organization guidelines (WHO, 1999). Total antioxidant capacity and vitamin C level of seminal plasma were measured in the 32 normozoospermic as the control group and 32 asthenospermic men as the case group using FRAP (Ferric Reducing of Antioxidants Powers) and RP-HPLC (Reverse Phase High Performance Liquid Chromatography) methods, respectively.

Results: Our results indicated that total antioxidant capacity levels in the seminal plasma of asthenospermic men were significantly lower than healthy men (p=0.002). In addition, we found a positive correlation between reduced total antioxidant capacity levels and low sperm motility. Vitamin C levels of seminal plasma in asthenospermic men were statistically lower than control men (p=0.01).

Conclusions: It is suggested that asthenospermia could be related to an antioxidant deficiency or it's reduction.