Comparative assessment of the antioxidant potency of aqueous maca (lepidium meyenii) extract versus ascorbic acid, cysteamine, and glycine in the cryopreservation of caprine semen

Abstract

Goat sperm cryopreservation is a fundamental tool for the advancement of reproductive biotechnologies. However, the freeze–thaw cycle generates oxidative stress, which compromises sperm functionality. Consequently, this study aimed to evaluate the effect of aqueous maca extract (Lepidium meyenii) as a natural antioxidant alternative, in comparison with ascorbic acid, cysteamine, and glycine. Semen was collected from five male goats (Alpine and Murciano-Granadina breeds), diluted with Optixcell, centrifuged, and the supernatant discarded. The resulting pellet was adjusted to a final concentration of 100 × 10⁶ sperm/mL and divided into the following experimental groups: Control (no antioxidants), AA (ascorbic acid at 2.5, 5, and 10 mg/mL), CIS (cysteamine at 50, 100, and 200 nM), GLI (glycine at 5, 10, and 20 mM), and MACA (aqueous maca extract at 1:50, 1:25, and 1:12.5 dilutions). The semen was then loaded into straws and cryopreserved using an automated freezer. Post-thaw sperm motility was assessed using a Computer-Assisted Sperm Analysis (CASA) system. Additionally, a thermal resistance test (TRT) was conducted after a 2-hour incubation, evaluating motility parameters. Results showed that maca extract had a superior effect on post-thaw motility, with the 1:25 dilution reaching a total motility of 62.66 ± 1.54—significantly higher than AA (53.91 ± 1.34), CIS (53.67 ± 1.17), and GLI (54.24 ± 1.42). In the TRT, maca at 1:25 also yielded the highest progressive motility (54.79 ± 1.45), outperforming AA (44.45 ± 2.36), CIS (52.02 ± 2.75), and GLI (49.72 ± 1.88). At 1:12.5, maca maintained a progressive motility of 44.80 ± 2.47, higher than AA (26.04 ± 2.05) and comparable to CIS and GLI. Notably, the lowest percentage of immotile sperm was recorded in the maca 1:25 group (44.83 ± 1.46). In conclusion, maca extract demonstrates strong potential in goat semen cryopreservation, improving post-thaw sperm motility and resistance to thermal stress.