Improvement of ram semen quality by luteolin enrichment during cold preservation

The present experiment aimed to investigate the probable protective role of luteolin (Lut) in ram spermatozoa kinematics and the oxidative/anti-oxidative/nitrosative status of semen during cold storage. Ejaculates were collected from five Qezel rams twice a week. Ejaculates were pooled, diluted with Tris-egg yolk extender (negative control) or supplemented with 0 (control; received the solvent of luteolin), 4, 8 and 16  $\mu$ m Lut. Kinematics parameters, viability and membrane functionality of spermatozoa were assessed. Furthermore, amounts of malondialdehyde (MDA) and anti-oxidant activity (AOA), superoxide dismutase activity (SOD) and total nitrate nitrite (TNN) were evaluated in the medium (diluent) and spermatozoa, separately, at 0, 24, 48 and 72 h after storage at 4 °C. Percentages of forward progressive motility and membrane integrity were significantly higher in 8 and 16  $\mu$ m groups compared to control groups at 72 h ( $P<0.05$ ). No significant differences were observed in viability among groups during the study ( $P>0.05$ ). Lower MDA contents were observed in medium and spermatozoa of 8 and 16  $\mu$ m treated groups compared to controls at 72 h ( $P<0.05$ ). In addition, higher AOA levels were observed in the medium of Lut-treated groups compared to controls at 48 and 72 h ( $P<0.05$ ). The activity of SOD was improved by luteolin addition. Luteolin enrichment did not affect TNN amounts. It seems that luteolin (at 8 and 16  $\mu$ m) as a flavonoid protects the ram semen by its anti-oxidative properties and by reduction of lipid peroxidation following 48 and 72 h storage.