In vitro effects of green tea (Camellia sinensis) aqueous extract on sperm quality: Mitigating oxidative stress and sperm DNA fragmentation in freeze-dried human spermatozoa.

OBJECTIVE

Freeze-drying is a promising method for the long-term preservation of sperm; however, it often leads to increased oxidative stress. Green tea (Camellia sinensis [L.] Kuntze) contains polyphenols known for their antioxidant properties. This study aimed to evaluate the in vitro effects of green tea aqueous extract (GTE) on oxidative stress markers and sperm DNA fragmentation (SDF) in freeze-dried human sperm.

METHODS

Ten normal semen samples were collected from men aged 20 to 45 years and divided into three groups: conventionally cryopreserved (A), freeze-dried (B), and freeze-dried with pre-incubation in GTE (C). In group C, samples were incubated with 1 mL of GTE at a concentration of 40 μg/mL for 30 minutes prior to freeze-drying. Oxidative stress markers and SDF were assessed 1 month post-preservation, following thawing in group A and rehydration in groups B and C.

RESULTS

Freeze-drying resulted in less DNA damage to sperm compared to cryopreservation (p=0.005). Relative to cryopreservation, incubation with GTE significantly reduced intracellular reactive oxygen species levels (p<0.0001), DNA fragmentation index (p=0.005), and malondialdehyde concentration (p<0.0001) while increasing the percentage of sperm with high mitochondrial membrane potential (p<0.0001) and glutathione concentration (p<0.0001).

CONCLUSION

Treating normal human sperm with GTE before freeze-drying significantly reduces markers of oxidative stress and promotes indicators of sperm health compared to conventional cryopreservation. These findings suggest that natural antioxidants like GTE may offer a promising therapeutic approach to preserving male fertility with regard to oxidative stress and improving the effectiveness of freeze-drying as an alternative to cryopreservation.