Sperm DNA damage, excessive oxidative stress and decrease in motility ‎may lead to low fertilisation or poor‎ assisted reproductive techniques outcomes in asthenoteratozoospermic ‎men. Selenium was considered as essential element for male reproductive functions. Selenium has important role in enzymatic process for elimination of excessive reactive oxygen species and helps to maintain membrane integrity. The aim of this study was to determine the effect of selenium supplementation on sperm quality, DNA fragmentation, mitochondrial membrane potential and membrane lipid peroxidation during sperm sampling in vitro at different times. In this experimental study, semen samples were collected from 50 asthenoteratozoospermic men. Samples were divided into two groups as control group and test group (incubated with 2 μg/ml selenium at 37°C for 2, 4 and 6 hr). Motility and viability were assessed based on WHO 2010 criteria. Mitochondrial membrane potential, sperm DNA fragmentation and malondialdehyde levels were evaluated in each group. Results revealed that motility, viability and mitochondrial membrane potential were significantly higher in the test group (p < .05). Also malondialdehyde levels were significantly lower in the test group (p < .03). DNA fragmentation significantly decreased in the test group after 6 hr of incubation (p < .02). In conclusion, in vitro selenium supplementation may protect spermatozoa from maltreatment effect of reactive oxygen species (ROS) during sperm sampling via keeping enzymatic and antioxidant process in optimum condition.

Oxidative stress‐induced apoptosis in spermatozoa may lead to male infertility. Environmental pollutants and heavy metals such as cadmium cause harmful effects on the reproductive system and sperm parameters through the induction of oxidative stress. Silymarin, as a potent antioxidant, is able to inhibit oxidative stress. This study was performed to investigate the protective effects of silymarin on cadmium‐induced toxicity in human spermatozoa. Sperm samples were divided into the following five groups: (a) spermatozoa at 0 min, (b) spermatozoa in the control group, (c) spermatozoa treated with cadmium chloride (20 μM), (d) spermatozoa treated with silymarin (2 μM)+ cadmium chloride (20 μM) and (e) spermatozoa treated with silymarin (2 μM). Sperm parameters related to apoptosis, such as DNA fragmentation, nucleus diameter, mitochondrial membrane potential (MMP) and expression of caspase‐3, were evaluated in all groups. After 180 min, spermatozoa treated with cadmium chloride showed a significant decrease in nucleus diameter and MMP but a significant increase in DNA fragmentation; however, caspase‐3 expression remained unchanged. At this time point, silymarin in the silymarin + cadmium chloride group could significantly reverse the adverse effects of cadmium chloride on these parameters.Silymarn could partly compensate for the caspase‐independent apoptosis in the spermatozoa. Therefore, oxidative stress could be a consequence for cadmium toxicity.

Infertility is one of the problems of today's society which has created psychological and therapeutic difficulties for couples (Makker et al., 2009). According to global statistics, about 10-15 per cent of couples are infertile (Fanaei et al., 2014). Asthenoteratozoospermia is one of the reasons for infertility in men (WHO, 2010). Sperm parameters of these patients have motility less than 40% and abnormal morphology more than 96% (WHO, 2010). Previous studies have shown that semen of asthenoteratozoospermic men compared to normal men produces high levels of ROS (Ghafarizadeh et al., 2018). This extra ROS can be caused by a decrease of semen antioxidants levels and mitochondrial dysfunction that was created during incomplete spermatogenesis and also originated from the NADPH oxidase system (Fanaei et al., 2014; WHO, 2010). Fatty acid peroxidation in the plasma membrane is the most important cause hurt to spermatozoa by oxidative stress induction (Lenzi et al., 1996), and it is worth mentioning that polyunsaturated fatty acids (PUFA) are one of the significant factors in the risk of ROS attack (Lenzi et al., 1996). In addition to the semen of asthenoteratozoospermic men that has sperm abnormality, preparing and maintaining of sampling also in these patients in the laboratory for ART may take several hours (Nabi et al., 2014; WHO, 2010). During this stage, due to the imbalance between antioxidant capacity and ROS production, spermatozoa are damaged and their function is reduced (Jeulin et al., 1982; Nabi et al., 2014). Cause the inherent property of antioxidants to ROS scavenging, VE can be recommended as a potent antioxidant to asthenoteratozoospermia in sperm preparation.

Sperm cryopreservation may lead to adverse effects on sperm structure and function. Cyanocobalamin (vitamin B12) has antioxidant potential and can protect DNA from free radical‐induced damages. Recent studies have shown that vitamin B12 preserves glutathione that leads to modulate oxidative stress responses. Also, vitamin B12 might act directly as a scavenger of ROS. The aim of this study was to investigate the effects of vitamin B12 supplementation on human sperm parameters during the cryopreservation process. Thirty semen samples were obtained from normozoospermic men. Using cryopreservation medium supplemented with different concentrations of vitamin B12 (0, 0.5, 1, 2, 2.5 mg/ml), the semen samples were cryopreserved. After thawing, all samples were evaluated for motility and viability. Based on results, 2 mg/ml was considered as the optimal concentration of vitamin B12 for evaluating sperm DNA fragmentation. The results showed that 1 and 2 mg/ml vitamin B12 significantly increased post‐thawing motility and viability compared with the 0 mg/ml vitamin B12 (p < .05). Also, by supplementing with 2 mg/ml vitamin B12, DNA fragmentation decreased when compared to the control. The present study showed that cryopreservation medium supplemented with vitamin B12 at 2 mg/ml could improve sperm quality after freeze–thaw process.