Anotace:
The presence of bacterial contamination in bovine insemination doses may lead to unexpected economic loss. Currently used antimicrobial supplements are often ineffective due to antibiotic resistance of the common bacterial contaminants. Staphylococcus aureus belongs to the frequent inhabitant of bovine semen with a deleterious effect on spermatozoa quality. Bioactive substances including naringenin, curcumin and isoquercitrin were previously studied with various beneficial effects on spermatozoa. Therefore, the study aimed to simulate bacteriospermia in vitro using S. aureus, which was previously isolated from the bovine ejaculate, and to test if the bioactive substances mentioned above would bring some protective properties against the bacterial damage. Density gradient centrifugation was used to avoid contamination by naturally present bacteria. S. aureus was inoculated in BGM-3 medium, and co-incubated with pre-washed spermatozoa and bioactive substances. At times of 0, 2, and 4 h, progressive motility, the membrane potential of mitochondria, reactive oxygen species (ROS) formation, and sperm DNA damage were evaluated. The results showed that S. aureus significantly increased ROS production, sperm cells with damaged mitochondrial membrane potential, and sperm DNA integrity which led to a decrease in the progressive movement of spermatozoa. On the other hand, all three bioactive substances significantly scavenged elevated ROS. Especially, the groups treated with naringenin and isoquercitrin showed preserved mitochondrial membrane, DNA integrity inside the sperm head, and improved sperm progressive movement under bacteriospermia in vitro.