Inhibitory effect of glycoprotein isolated from Ulmus davidiana Nakai on caspase 3 activity in 12-O-tetradecanoylphorbol 13-acetate–treated liver cells through the reduction of intracellular reactive oxygen species

Ulmus davidiana Nakai (UDN) has traditionally been used for healing of inflammation, ulcers, and cancers as a folk medicine. This experiment was carried out to evaluate the hepatoprotective activity of UDN glycoprotein (molecular weight, 116 kd) in 12-O-tetradecanoylphorbol 13-acetate (TPA)–treated BNL CL.2 (murine embryonic liver) cells. We evaluated the changes of activity in apoptosis-related signals (cytochrome c, caspase 9, and caspase 3), cleavage of poly(adenosine diphosphate-ribose) polymerase (PARP), and nuclei staining for apoptosis after cotreatment with UDN glycoprotein in the presence of TPA (200 nmol/L). The results showed that UDN glycoprotein (200 μg/mL) does not have any cytotoxic effect and decreases intracellular reactive oxygen species (ROS) in a dose-dependent manner. When cells were treated with TPA (200 nmol/L) alone, the activities of the apoptotic-related signals (cytochrome c, caspase 9, and caspase 3) were activated. However, their activities were inhibited through the reduction of intracellular ROS after treatment with UDN glycoprotein (200 μg/mL) in the presence of TPA (200 nmol/L). Also, the results indicate that UDN glycoprotein prevents PARP cleavage and DNA fragmentation. These findings suggest that UDN glycoprotein protects from TPA-induced apoptosis through modulating intracellular ROS in BNL CL.2 cells, and UDN may be a nutraceutical supplement for liver health.