Effect of α-tocopherol and tocopherol succinate on lipid peroxidation in equine spermatozoa

The objective of this study was to compare the effect of α-tocopherol and its ester, α tocopherol succinate, on lipid peroxidation and motility of equine spermatozoa. In experiment one, spermatozoa were incubated with dl-α-tocopherol (5, 25, 100 or 500 μM), dl-α tocopherol succinate (5, 25, 100 or 500 μM) or vehicle (0.5% ethanol) at 38°C, and sperm motility was determined at 30, 60 and 120 min. In experiment two, spermatozoa loaded with the lipophilic probe, C₁₁BODIPY^581/591, were incubated with dl-α-tocopherol (50 and 100 μM), dl-α-tocopherol succinate (50 and 100 μM) or ethanol (0.5%) and with the promoters cumene hydroperoxide, Fe₂SO₄, and ascorbate at 38°C in 5% CO₂. Lipid peroxidation was determined by changes in fluorescence of C₁₁BODIPY^581/591, and motility was determined by CASA at 0, 15, 30 and 60 min. In experiment three, spermatozoa loaded with C ₁₁BODIPY^581/591 were incubated with dl-α-tocopherol (5, 25, 100 or 500 μM), dl-α-tocopherol succinate (5, 25, 100 or 500 μM) or ethanol (0.5%) at 38°C and then submitted to a 4-hour incubation at room temperature. Motility and lipid peroxidation were determined at 1 and 4 h. In experiment four, the effect of DL α tocopherol (5, 25 or 500 μM), dl-α-tocopherol succinate (5, 25 or 500 μM) or ethanol (0.5%) on lipid peroxidation and motility were evaluated during storage at 5°C in a skim-milk based extender. Although dl-α-tocopherol succinate appeared more effective than dl-α-tocopherol in preventing lipid peroxidation during short-term incubations, the succinate ester suppressed sperm motility compared to dl-α-tocopherol alone.