The Effect of Tetramethylpyrazine on Hydrogen Peroxide-Induced Oxidative Damage in Human Umbilical Vein Endothelial Cells

Tetramethylpyrazine has been widely used in traditional Chinese medicine to treat cardiovascular diseases such as atherosclerosis and hypertension. The underlying mechanism of cardioprotective effects, however, remains to be elucidated. Here, using human umbilical vein endothelial cells (HUVECs), we have assessed the protective effect of tetramethylpyrazine on H2O2-induced oxidative damage. After pre-incubation with tetramethylpyrazine (50, 100 and 150 mu g/ml) for 24 hr., viability loss in H2O2-induced HUVECs (76.5% of the control level, p < 0.05, at 400 mu M of H2O2 for 12 hr.) was restored in a concentration-dependent manner, and the maximal recovery (88.7% of the control level, p < 0.05) was achieved with tetramethylpyrazine at 150 mu g/ml. The production of reactive oxygen species was suppressed by measuring fluorescent intensity of 2',7'-dichorofluorescein (83.1% of the H2O2-treated group, p < 0.05, at 150 mu g/ml of tetramethylpyrazine). Tetramethylpyrazine also increased activities of superoxide dismutase and glutathione peroxidase (144.1% and 118.3% of the H2O2-treated group, respectively, p < 0.05 at 150 mu g/ml of tetramethylpyrazine). In addition, tetramethylpyrazine reduced levels of malonaldehyde, intracellular nitric oxide and nitric oxide synthase (83.8%. 91.2% and 78.7% of the H2O2-treated group, respectively, p < 0.05, at 150 mu g/ml of tetramethylpyrazine). Furthermore, pre-incubation of tetramethylpyrazine with HUVECs for 24 hr. resulted in reduction of apoptosis and removal of cell cycle arrest in the S phase (56.6% and 59.7% of the H2O2-treated group, respectively, p < 0.01, at 150 mu g/ml of tetramethylpyrazine). Altogether, these results suggest that tetramethylpyrazine has it protective effect oil H2O2-induced oxidative damage in HUVECs due to its antioxidant and antiapoptotic properties.