OBJECTIVETo investigate the protective effects and related mechanisms of soybean isoflavone (SI) on human umbilical vein endothelial cells (HUVECs) injury induced by H₂O₂ and lipopolysaccharide (LPS).

METHODSH₂O₂ and LPS were used to induce HUVECs injury in vitro. Nine experimental groups were examined: control group, H₂O₂ (2 mmol/L for 4 h), LPS (2 mmol/L for 4 h), H₂O₂+low dose SI (1 mg/ml), H₂O₂+moderate dose SI (2.5 mg/ml), H₂O₂+high dose SI (5 mg/ml), LPS+low dose SI (1 mg/ml), LPS+moderate dose SI (2.5 mg/ml), LPS+high dose SI (5 mg/ml). The survival ratio of HUVECs was detected with MTT assay. The cultured cells were loaded by Fura-2/AM and the change of [Ca²⁺] in HUVECs was measured by fluorospectrophotometry. The contents of malondialdehyde (MDA), superoxide dismutase (SOD), reduced glutathione (GSH-Px) were measured by the commercial kits. The levels of tissue plasminogen activator IL-6 in the supematant were measured by enzyme linked immunosorbent assay (ELISA) kits. Apoptosis rate of the HUVECs was analyzed by flow cytometry.

RESULTSH₂O₂ and LPS significantly decreased HUVECs viability, increased the contents of MDA, IL-6 and decreased the contents of SOD and GSH-Px, and increased the apoptosis rate [(37.8 ± 1.8)% and (38.9 ± 1.1)%]. Co-treatment with SI could reduce MDA and IL-6 while increase SOD and GSH-Px and reduce apoptosis in a dose-dependent manner.

CONCLUSIONThe findings demonstrate that soybean isoflavone could attenuate H₂O₂ and LPS induced injury in human umbilical vein endothelial cells through protecting mitochondrial function, improving antioxygenic activity, and suppressing the mobilization of cytosolic calcium.