Protective Effect of Protocatechuic Acid on Human Umbilical Vein Endothelial Cells (HUVECs) and Underlying Mechanisms

The purpose of this study was to investigate the protective effect of protocatechuic acid (PCA) on human umbilical vein endothelial cells (HUVECs) and the underlying mechanisms. The cell viability and apoptosis in HUVECs were investigated by methyl thiazolyl tetrazolium (MTT) cell viability assay and Annexin V-FITC/PI double stain method. The intracellular reactive oxygen species (ROS) level was determined by the oxidant-sensing fluorescent probe 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA). Silent information regulator 1 (SIRT1) protein expression was analysed by western blotting assay. As a result, the cell viability was increased to 120.42 +/- 0.08% after HUVECs were incubated with 150 mu M PCA. However, the cell viability was decreased to 51.54 +/- 0.20% after treated with H2O2. PCA protected HUVECs against H2O2-induced oxidative damage and the cell viabilities were respectively enhanced to 69.91 +/- 0.16 and 64.03 +/- 0.30% at 200 and 300 mu M. The apoptosis rates were reduced to 6.07 +/- 0.32% (p < 0.01) and 3.83 +/- 0.21% (p < 0.05) in with and without H2O2-treated cells. PCA inhibited the generation of ROS induced by H2O2 and the fluorescent intensity was abated to 9.69 +/- 0.78. Moreover, the SIRT1 protein level was enhanced. The protective effect of PCA on HUVECs might be due to the inhibition of ROS generation and cell apoptosis, and the upregulation of SIRT1 expression. These findings provide us a new perspective on the biological potential of PCA.