Hypoxia is related to the etiology of numerous pathological disease states, such as the formation of tumors or diverse retinopathies. Epigallocatechin-3-gallate (EGCG), a potent polyphenolic antioxidant and antiangiogenic compound found in green tea, has been shown to suppress the growth of blood vessels necessary for the growth of tumors and the induction of retinopathies. However, only a few studies have been carried focusing on the protective effects of EGCG on hypoxia-induced injury of cultured endothelial cells. The present study investigated the effects of EGCG on Na(2)S(2)O(4)-induced hypoxic injury in three types of cultured endothelial cells, primary isolates of normal human umbilical vein endothelial cells (HUVECs), and two transformed endothelial cells lines, RF/6A and ECV304. Our results indicated that Na(2)S(2)O(4) inhibited the growth of HUVE, RF/6A, and ECV304 cells in a dose-dependent manner; EGCG also exerted inhibitory effects on the growth of the three cell types, but the toxicity of EGCG to HUVECs was less than to RF/6A and ECV304 cells. The viability of HUVE, RF/6A, and ECV304 cells treated with EGGC were the lowest at 24, 24, and 36 h, respectively, and the IC(50) of EGCG were 420 +/- 8.0, 125 +/- 7.1, and 75 +/- 5.1 microM, respectively. Furthermore, EGCG, an efficient nontoxic agent, protected all three cell types from Na(2)S(2)O(4)-induced hypoxia injury, providing partial protection from hypoxia-induced injury in normal endothelial cells at 100, 30, and 10 microM for HUVE, RF/6A, and ECV304 cells, respectively.