RESUMO
BACKGROUND: Grape extracts of the Greek species Vitis vinifera possess potent antioxidant properties in vitro. The freeze/thaw process and the preparation of semen during assisted reproductive techniques can adversely affect the functional integrity of spermatozoa. The objective was to assess the effect of three different concentrations (1 µg ml(-1), 2 µg ml(-1) and 5 µg ml(-1)) of a polyphenol-rich grape pomace extract on motility, viability, acrosomal and lipid peroxidation status of thawed bovine spermatozoa after 2 and 4 hrs of incubation. RESULTS: The results indicate that the percentage of "Rapid" spermatozoa remained significantly increased (p <0.05) in the presence of 5 µg ml(-1) of the extract, compared to the control after 2 hrs of incubation. Additionally, the incubation of spermatozoa with 2 µg ml(-1) and 5 µg ml(-1) of the extract for 2 hrs resulted in a significantly better maintenance of viable spermatozoa with intact acrosome (p <0.05). The other parameters did not show statistically significant changes. Moreover, the presence of 2 µg ml(-1) and 5 µg ml(-1) of the extract kept the levels of Malondialdehyde (MDA) production in significantly lower level, compared to the other groups, after 2 hrs and 4 hrs of incubation (p <0.05). Particularly, a dose-dependent effect was noticed after 2 hrs of incubation. CONCLUSIONS: Our results suggest that the grape pomace extract exerts a powerful antioxidant role, by suppressing lipid peroxidation, and provides protection in terms of motility and acrosomal integrity, which are correlated with in vivo fertility. The optimal extract concentration is 5 µg ml(-1).