Propyl gallate inhibits the growth of endothelial cells, especially calf pulmonary arterial endothelial cells via caspase-independent apoptosis.

Propyl gallate (PG) as a synthetic antioxidant exerting a variety of effects on tissue and cell functions. We evaluated the effects of PG on the growth of endothelial cells, especially calf pulmonary artery endothelial cells (CPAEC) in relation to apoptosis. PG dose-dependently inhibited the growth of CPAEC and human umbilical vein endothelial cells (HUVEC) at 24 h. The susceptibility of CPAEC to PG was higher than that of HUVEC. PG induced apoptosis in CPAEC, which was accompanied by the loss of mitochondrial membrane potential (MMP; DeltaPsim). The tested caspase inhibitors (pan-caspase, caspase-3, -8 or -9 inhibitor) did not rescue CPAEC from PG-induced cell death but instead slightly enhanced the cell death. PG increased reactive oxygen species (ROS) level in CPAEC. The caspase inhibitors did not significantly change the ROS level. Furthermore, PG increased the GSH depleted cell number and decreased GSH level in CPAEC. The tested caspase inhibitors did not significantly change the number in PG-treated CPAEC. Each caspase inhibitor differently alters GSH levels in CPAEC. In conclusion, PG inhibited the growth of endothelial cells, especially CPAEC via caspase-independent apoptosis. PG-induced CPAEC death was accompanied by ROS increase and GSH depletion.