Thymoquinone as a natural spermostatic substance in reproductive medicine: An experimental study

Background: Nonoxynol-9 a nonionic surfactant is widely used for its spermicidal effects. Finding new sperm immobilizing agents is necessary because Nonoxynol-9 damages the tissues of female reproductive system.
Objective: The aim of this study was to evaluate the effects of Thymoquinone (TQ) as a potential spermostatic compound on the motility and viability of human spermatozoa.
Materials and Methods: In this experimental study, the effects of 5, 10, 20, 50, 100 μg/ml, 1 and 10 mg/ml of TQ on normozoospermic semen samples were investigated. Sperm motility and viability were compared between untreated and TQ-treated aliquots of each semen sample. To evaluate the effects of TQ on the alteration of mitochondrial membrane potential (MMP), 32 semen samples were examined using 50 μg/ml of TQ. Flow cytometric analysis was performed after staining of spermatozoa with JC-1.
Results: Doses above 20 μg/ml of TQ could eventually immobilize all spermatozoa in culture medium. Adding 50 μg/ml of TQ did not significantly diminish the percentage of viable spermatozoa and flow cytometry results revealed that this amount of TQ could decrease sperm MMP.
Conclusion: TQ could discontinue the movement of sperm cells in medium without reducing the population of live spermatozoa. It is more likely that TQ exerts its spermostatic action by mitigating the MMP of spermatozoa. Therefore, TQ could be considered as a potential new natural spermostatic chemical.

Keywords
Nigella sativa; Sperm immobilizing agents; Sperm motility; Thymoquinone.