Protective effects of Nigella sativa extract against H O -induced cell death through the inhibition of DNA damage and cell cycle arrest in human umbilical vein endothelial cells (HUVECs).

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 H O -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 μg/ml) and H O (25-1000 μM) for 24 h. Then, the HUVECs were pretreated with noncytotoxic doses (10-50 μg/ml) of NSE for 24 h before administration of 200 μM H O 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 μg/ml) of NSE were found to protect HUVECs against H O (200 μM)-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 H O . Furthermore, NSE inhibited H O -induced cell cycle arrest and cellular DNA damage in HUVECs. Altogether, these results suggest that NSE can prevent H O -induced cell death, and NSE could be a potential candidate that can prevent HUVECs against toxicants.