Figure 1: Overall study design. In part one, semen of normozoospermic patient was treated with GTE at different concentrations before the incubation with oxidative stress inducer (H2O2) for 15 min. The concentration that provided a significant protective effect on sperm motility was tested on protecting sperm DNA integrity. In part two, the effective GTE concentration, based on results of part one, was added to sperm freezing media, and the cryoprotective effect of GTE was evaluated based on sperm motility, DNA integrity, and reactive oxygen species level. GTE: green tea extract; DGC: density gradient centrifugation; ROS: reactive oxygen species.