Abstract
Oxidative stress is known to induce cytotoxicity and apoptosis in endothelial cells and indorse development of atherosclerosis. The aim of this research was to assess the cytoprotective effects of ethanolic extract of Nigella sativa (NSE) against H2O2-induced cell death in human umbilical vein endothelial cells (HUVECs) and also study the probable mechanisms through which NSE exhibited cyto-protection. The cytotoxicity was measured by exposing the HUVECs with NSE (10-200 mu g/ml) and H2O2 (25-1000 mu M) for 24 h. Then, the HUVECs were pretreated with noncytotoxic doses (10-50 mu g/ml) of NSE for 24 h before administration of 200 mu M H2O2 for 24 h. The MTT, NRU, and morphological assays were performed to assess the cytotoxicity and cyto-protection. Potential antioxidant activity of NSE on oxidative stress marker (glutathione [GSH] and lipid peroxidation [LPO]) was also evaluated. The fluorescence probe, DCF-DA, and Rh123 were applied to measure the reactive oxygen species (ROS) level and mitochondrial membrane potential. Moreover, flow cytometric analysis and comet assay were used to study the cell cycle arrest and DNA damage, respectively. The concentrations (10, 30, and 50 mu g/ml) of NSE were found to protect HUVECs against H2O2 (200 mu M)-induced cytotoxicity in HUVECs. Pretreatment of HUVECs with NSE significantly reduced the LPO and ROS levels and restored the GSH and loss of MMP induced by H2O2. Furthermore, NSE inhibited H2O2-induced cell cycle arrest and cellular DNA damage in HUVECs. Altogether, these results suggest that NSE can prevent H2O2-induced cell death, and NSE could be a potential candidate that can prevent HUVECs against toxicants.