Anti-oxidative Effects of Ethanol Extract of <i>Origanum vulgare</i> on Kinetics, Microscopic and Oxidative Parameters of Cryopreserved Holstein Bull Spermatozoa

Abstract

<em>Origanum vulgare</em> contains high levels of phenolic compounds such as gallic acid and polyphenols such as rosmarinic acid and quercetin. The purpose of this study was to investigate the effects of <em>Origanum vulgare</em> extract, as a natural antioxidant, on freezing-thawing semen quality in Holstein bulls. Three Holstein bulls (5-6 years old, mean live weight 800 kg) were used for semen collection twice a week for two months. Ethanol extract of <em>Origanum vulgare</em> (2, 4, 8, 12, 16 and 20 mL/dL extender) was added to a citrate-yolk-base extender. After freezing-thawing sperm motility parameters, viability and membrane integrity were determined using a CASA system, eosin-nigrosin staining, and hypo-osmotic swelling test, respectively; malondialdehyde concentration and activity of superoxide dismutase and catalase were also measured. The percentages of motility were higher (P<0.05) in the freezing extender containing 4 mL/dL <em>Origanum vulgare </em>extract (72.34±7.98). Addition of 2 and 4 mL/dL extract of <em>Origanum vulgare</em> significantly improved the motility, viability and plasma membrane integrity of the spermatozoa following freezing-thawing process compared to the control group. Addition of 4 mL/dL extract significantly reduced the concentration of malondialdehyde compared to the control group (P<0.05). The activity of superoxide dismutase and catalase increased significantly by inclusion of 4 and 8 mL/dL extract of <em>Origanum vulgare</em> to the extender (1.86±0.18 and 1.92±0.28 U/mg protein; 4.54±0.13 and 4.28±0.28 U/mg protein, respectively). The activity of superoxide dismutase and catalase was significantly increased by inclusion of 4 and 8 mL/dL extract to the extender. In conclusion, addition of 2 and 4 mL/dL extract of <em>Origanum vulgare</em> to the semen extender improved the post-thawed quality of semen, which may be due to increasing in antioxidant enzyme activity and reduction in lipid peroxidation.