Effects of (-)-Epicatechin Gallate on porcine oocyte in vitro maturation and subsequent embryonic development after parthenogenetic activation and in vitro fertilization

(-)-Epicatechin gallate (ECG) is a polyphenol compound of green tea exhibiting biological activities, such as antioxidant and anticancer effects. To examine the effect of ECG on porcine oocytes during in vitro maturation (IVM), oocytes were treated with 0-, 5-, 15-, and $25{\mu}M$ ECG. After maturation, we investigated nuclear maturation, intracellular glutathione (GSH) and reactive oxygen species (ROS) levels and subsequent embryonic development after parthenogenetic activation (PA) and in vitro fertilization (IVF). After 42 hours of IVM, the $5{\mu}M$ group exhibited significantly increased (p< 0.05) nuclear maturation (89.8%) compared with the control group (86.1%). However, the $25{\mu}M$ group observed significantly decreased (p< 0.05) nuclear maturation (83.5%). In intracellular maturation assessment the 5-, 15-, and $25{\mu}M$ groups had significantly increased (p< 0.05) GSH levels and decreased ROS levels compared with the controls. The 5- and $15{\mu}M$ group showed significantly increased (p< 0.05) embryo formation rates and total cell number of blastocysts after PA (18% and 68.9, 15% and 85.1 vs. 12% and 59.5, respectively) compared with controls. Although the $25{\mu}M$ group observed significantly lower blastocyst formation rates after PA (27.6% vs. 23.2%) than control group, the $5{\mu}M$ group showed significantly increased blastocyst formation rates after PA (37.2% vs. 23.2%) compared to the control group. Furthermore, the $5{\mu}M$ group measured significantly increased blastocyst formation rates (20.7% vs. 8.6%) and total cell number after IVF ($88.3{\pm}1.5$ vs. $58.0{\pm}3.6$) compared to the control group. The treatment of $5{\mu}M$ ECG during IVM affectively improved the porcine embryonic developmental competence by regulating intracellular oxidative stress during IVM.