Effect of Quercetin Supplementation in Extender on Sperm Kinematics, Extracellular Enzymes Release, and Oxidative Stress of Egyptian Buffalo Bulls Frozen-Thawed Semen.

Buffalo spermatozoa are more sensitive for cryopreservation compared to other species. This study aimed to evaluate the consequences of quercetin against cryodamage of buffalo frozen-thawed spermatozoa characteristics. Semen of Egyptian bulls (n = 4) was extended in OptiXcell extender incorporated with quercetin at 0 (control), 2.5, 5.0, 10.0, 20.0, 40.0, and 80.0 μM before cryopreservation. Frozen-thawed semen was evaluated for sperm motility by computer-assisted sperm analyzer (CASA), viability, morphology, membrane, and acrosome integrities. The kinematics parameters including average path velocity (VAP; μm/s), straight linear velocity (VSL; μm/s), curvilinear velocity (VCL; μm/s), amplitude of lateral head displacement (ALH; μm), beat cross frequency (BCF; Hz), linearity [LIN, (VSL/VCL) × 100], and straightness [STR, (VSL/VAP) × 100] were assessed. The sperm-free extender was evaluated for aspartate aminotransferase (AST), alanine aminotransferase (ALT), and H2O2. Homogenized sperm cells were evaluated for oxidative stress biomarkers [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX)], and lipid peroxidation [malondialdehyde (MDA)]. The highest values of total motility, progressive motility, viability, intact acrosome, and membrane integrity substantially improved with 10 μM of quercetin. STR (%) was substantially low (P < 0.01), and VCL (μm/s) and ALH (μm) were markedly high (P < 0.05) in 10 μM of quercetin. The outflow of ALT enzyme to extracellular fluid was lower with 10 μM of quercetin (P < 0.001) and higher at 2.5 μM of quercetin. The spermatozoa leaked AST was markedly lower at 5.0, 10 (P < 0.001) and 20 μM (P < 0.05) of quercetin. The activity of antioxidant enzymes was eminently low at all quercetin concentrations, and this was accompanied by the decrease in H2O2 in the media. SOD activity at 10-80 μM, CAT at 5.0-40 μM, and GPX at 2.5-80.0 μM of quercetin in spermatozoa were substantially low. MDA level significantly (P < 0.001) decreased at all quercetin concentrations. In conclusion, the incorporation of quercetin at the level of 10 μM is promising in improving buffalo semen characteristics and lower the freezing-thawing oxidative stress.