Supplementation of lupeol during in vitro maturation improves preimplantation embryonic development in pigs

Lupeol is a triterpene with several pharmacological properties, including antioxidant activity. This study investigated the antioxidant effects of lupeol supplementation during in vitro maturation (IVM) of porcine oocytes. Oocytes were divided into six groups and matured for 44 h in medium supplemented with lupeol at concentrations of 0, 1, 2, 4, and 8 µM. As a control, oocytes were cultured without lupeol or its dilution solution (dimethyl sulfoxide). After IVM, in vitro fertilization and embryo culture were performed to evaluate fertilization rate and developmental competence. Nuclear maturation, DNA integrity, intracellular glutathione (GSH) levels, reactive oxygen species (ROS) levels, fertilization, embryo development, and embryo quality were assessed. Lupeol at 4 and 8 µM increased metaphase II rates compared with the control group; however, the DNA integrity of the oocyte nucleus did not differ between groups. GSH levels increased, and ROS levels decreased at all concentrations compared with the control group. Monospermic fertilization rate of oocytes matured with 4 µM lupeol was higher than that of the 0 µM and control groups. Among the lupeol concentrations tested in IVM medium, only 4 µM significantly enhanced blastocyst formation. Moreover, 4 µM lupeol reduced DNA fragmentation in blastocysts compared with the 0 and 1 µM groups but did not affect the total cell number of blastocysts. In conclusion, the addition of 4 µM lupeol diluted in DMSO to the culture medium during IVM enhanced blastocyst formation by increasing intracellular GSH and reducing ROS in matured oocytes.