266 ANTIOXIDANT CAPACITY OF BOAR SEMINAL PLASMA

Abstract

It has been established that antioxidants in seminal plasma play an important role in protecting the spermatozoa against oxidative stress-induced damage. This study was conducted to measure the total antioxidant capacity (TAC) of boar seminal plasma. Fifty-four ejaculates were collected from 17 mature boars of proven fertility by the gloved-hand technique. Ejaculates were collected separately in different fractions (pre-sperm, sperm-rich, and post-sperm) according to their macroscopic (color) characteristics. After centrifugation (2400g for 3 min), the sperm pellet was discarded; the supernatant was recentrifuged and filtered through a 10-μm nylon mesh filter to remove debris or clumped spermatozoa. The seminal plasma was frozen at -20°C until further use. After thawing at room temperature, seminal plasma aliquots of 5 μL were immediately assessed for total antioxidant capacity. TAC was measured using the ABTS/H2O2/HRP decoloration method (Cano A et al. 2000 Redox Report 5, 365–370) which allows differentiation between hydrophilic and lipophilic antioxidant activity capacity. TAC units were expressed as micromolar (μM) Trolox equivalents. Data were analyzed using ANOVA. Only the hydrophilic activity was measurable, with the lipophilic activity being undetected. The overall TAC of seminal samples (mean ± SEM) was 1623.7 ± 56.28 μM, ranging from 674 to 2428 μM. Different TACs were observed among males (P < 0.05) and between ejaculates of the same male (P < 0.05). Ejaculate fraction had a significant effect (P < 0.001) on the TAC levels. The post-sperm fraction had a significantly lower TAC level (1104.09 ± 57.66 μM) than the pre-sperm and sperm-rich fractions (1611.95 ± 153.68 μM and 1356.136 ± 72.47 μM, respectively, P < 0.001). In conclusion, hydrophilic antioxidant activity represented the main contribution to the TAC in boar seminal plasma, showing differences among males, between ejaculates of the same male, and also between the different ejaculate fractions. This work was supported by CICYT (AGF98-0533; AGL01-0471) and INIA (RZ01-019).