(-)-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 μM 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 μM group exhibited significantly increased (p< 0.05) nuclear maturation (89.8%) compared with the control group (86.1%). However, the 25 μM group observed significantly decreased (p< 0.05) nuclear maturation (83.5%). In intracellular maturation assessment the 5-, 15-, and 25 μM groups had significantly increased (p< 0.05) GSH levels and decreased ROS levels compared with the controls. The 5- and 15 μM 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 μM group observed significantly lower blastocyst formation rates after PA (27.6% vs. 23.2%) than control group, the 5 μM group showed significantly increased blastocyst formation rates after PA (37.2% vs. 23.2%) compared to the control group. Furthermore, the 5 μM group measured significantly increased blastocyst formation rates (20.7% vs. 8.6%) and total cell number after IVF (88.3±1.5 vs. 58.0±3.6) compared to the control group.
The treatment of 5 μM ECG during IVM affectively improved the porcine embryonic developmental competence by regulating intracellular oxidative stress during IVM.

INTRODUCTION
 MATERIALS AND METHODS
  1. Chemicals
  2. Oocyte collection and in vitro maturation
  3. Evaluation of nuclear maturation
  4. Measurement of intracellular GSH and ROS levels
  5. Parthenogenetic activation of oocytes
  6. In vitro fertilization and culture
  7. Embryo evaluation and total cell count of blastocysts
  8. Statistical analysis
 RESULTS
  1. Effect of ECG on nuclear maturation during IVM
  2. Effect of EGC on intracellular GSH and ROS levels during IVM
  3. Effect of ECG added to IVM media on subsequent embryonicdevelopment after PA and IVF
 DISCUSSION
 REFERENCES

• Min-Su Seo(Laboratory of Veterinary Embryology and Biotechnology, Veterinary Medical Center and College of Veterinary, Institute of Stem Cell & Regenerative Medicine, Chungbuk National University, 1 Chungdae-ro, Seowon-gu, Cheongju 28644, Republic of Korea)
• Kyoung-Ha So(Laboratory of Veterinary Embryology and Biotechnology, Veterinary Medical Center and College of Veterinary, Institute of Stem Cell & Regenerative Medicine, Chungbuk National University, 1 Chungdae-ro, Seowon-gu, Cheongju 28644, Republic of Korea) Correspondence
• Sang-Hwan Hyun(Laboratory of Veterinary Embryology and Biotechnology, Veterinary Medical Center and College of Veterinary, Institute of Stem Cell & Regenerative Medicine, Chungbuk National University, 1 Chungdae-ro, Seowon-gu, Cheongju 28644, Republic of Korea) Correspondence