BACKGROUND: Antioxidants have gained significant attention for improving sperm parameters. Green tea and catechin, known for their potent antioxidant properties, are particularly interesting in this context. OBJECTIVE: This study investigated the in vitro effects of green tea extract (GTE) and (+)-catechin on semen quality parameters of Arabi rams during chilled storage. METHODS: The pooled and diluted semen was divided and supplemented with GTE and (+)-catechin (50, 100, 150 and 200 µg/mL levels). The control group did not receive any supplements. Sperm quality and semen pH were evaluated at 1, 24, 48 and 72 h after storage. Seminal plasma MDA level was measured at 72 h of semen storage. RESULTS: Supplementation with GTE and (+)-catechin improved sperm motility more than control (p < 0.05). Specifically, GTE at 50 and 100 µg/mL enhanced motility, while higher concentrations were detrimental. Catechin at 600 and 800 µg/mL maintained motility better than the control at 72 h. Sperm viability and membrane integrity were significantly improved at 50 and 100 µg/mL GTE and all catechin concentrations (p < 0.05) compared to the control. However, higher GTE concentrations (150-200 µg/mL) decreased sperm viability and membrane integrity at 72 h. Additionally, morphological abnormalities were reduced by 100 µg/mL GTE and the higher catechin concentrations in comparison to the control. Seminal plasma pH varied over the 72-h storage period, but no significant differences were observed between the experimental and control. MDA levels were significantly lower (p < 0.05) in the GTE (50-200 µg/mL) and catechin (200-800 µg/mL) treatment groups, compared to the control at 72 h. CONCLUSIONS: GTE and catechin enhance semen parameters during chilled storage, with optimal effects at specific concentrations. High levels of GTE may negatively impact sperm quality, underscoring the importance of precise dosing in semen preservation.
Nabhani et al. (Tue,) studied this question.