Use of glycosaminoglycans from Oreochromis niloticus skin as an antioxidant supplement for milt cryopreservation of Brazilian bocachico

Abstract

The study aimed to evaluate the in vitro antioxidant action of glycosaminoglycans (GAGs) from the skin of Oreochromis niloticus, and to determine their ideal concentration to supplement the sperm freezing medium of Prochilodus brevis. In experiment 1, the in vitro antioxidant properties of GAGs were verified through the analysis of DPPH, chelating ferrous ability, and total antioxidant capacity. In experiment 2, milt pools were formed, which were frozen in solution supplemented or not with different GAGs concentrations: 0 (control), 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 mg mL-1 (total of 10 treatments). The samples were evaluated for membrane integrity, DNA integrity, sperm morphology, and sperm kinetics. The results of experiment 1 showed that the GAGs exhibited, with the increase of the concentration, significant antioxidant action, for all the evaluated tests, mainly in the chelating ferrous ability. In experiment 2, it was observed that the increase of GAGs concentration decreased kinetic parameters (P < 0.05), however, the control and 0.5 mg mL-1 GAGs concentration showed similar results. For the other parameters (membrane integrity, DNA integrity, and sperm morphology), there was no decrease in results with the increase of GAGs concentration. In conclusion, GAGs extracted from O. niloticus skin have antioxidant action, and the concentration of 0.5 mg mL-1 was the most adequate to supplement the P. brevis sperm-freezing medium.