Protective Effects of Astaxanthin on Post‐Thaw Sperm Quality in Normozoospermic Men

Fighting against free radical accumulation during the cryopreservation process with the help of exogenous antioxidants has become an effective strategy to augment post‐thaw sperm quality. The present study explored the effects of various concentrations of astaxanthin, as a potent antioxidant, on human sperm parameters during the freeze–thaw process. Twenty‐five normozoospermic specimens were included in this prospective study. Each sample was divided into five equal parts: fresh group, and frozen–thawed groups including 0, 1, 10, and 50 μM of astaxanthin. The prepared spermatozoa were cryopreserved by rapid freezing technique. Precryopreservation and post‐thaw sperm motility parameters, sperm morphology, vitality, DNA fragmentation, reactive oxygen species (ROS) levels, and mitochondrial membrane potential (MMP) were investigated. All sperm parameters after thawing significantly decreased compared to before freezing. Treatment of spermatozoa with 50 μM of astaxanthin significantly increased their total and progressive motility, viability, DNA integrity, and MMP and decreased their intracellular ROS levels compared with the control group. In total, 10 μM of astaxanthin significantly improved total and progressive motility, DNA integrity, MMP, and decreased ROS levels, whereas, in the 1 µM group, there were significant differences only in ROS levels. As a result, we found that astaxanthin can improve sperm quality after freezing/thawing and decrease the detrimental effects of this process on sperm parameters.