Procyanidin B1 promotes in vitro maturation of pig oocytes by reducing oxidative stress.

Oxidative stress negatively affects the in vitro maturation (IVM) of oocytes. Procyanidin B1 (PB1) is a natural polyphenolic compound that has antioxidant properties. In this study, we investigated the effect of PB1 supplementation during IVM of porcine oocytes. Treatment with 100 μM PB1 significantly increased the MII oocytes rate (p <0.05), the parthenogenetic (PA) blastocyst rate (p <0.01) and the total cell number in the PA blastocyst (p < 0.01) which were cultured in regular in vitro culture (IVC) medium. The PA blastocyst rate of regular MII oocytes activated and cultured in IVC medium supplemented with 100 and 150 μM PB1 significantly increased compared with control (p < 0.01 and p < 0.05). We also evaluated the reactive oxygen species (ROS) levels, mitochondrial membrane potential (Δψm) levels, glutathione (GSH) levels, and apoptotic levels in MII oocytes and cumulus cells following 100 μM PB1 treatment. The results showed that the PB1 supplementation decreased ROS production and apoptotic levels. In addition, PB1 was found to increase Δψm levels and GSH levels. In conclusion, PB1 inhibited apoptosis of oocytes and cumulus cells by reducing oxidative stress. Moreover, PB1 improved the quality of oocytes and promoted PA embryo development. Taken together, our results suggest that PB1 is a promising antioxidant additive for IVM of oocytes.