Combined Extract of L. and Synergistically Attenuates Oxidative Damage Induced by Hydrogen Peroxide in Human Umbilical Vein Endothelial Cells.

Endothelial cell injury caused by oxidative stress is a critical factor in the initial stage of vascular diseases. Thus, identification of more effective antioxidants is a promising strategy to protect against endothelial cell injury. Recently, synergistic effects between phytochemicals have received renewed attention for their role in the treatment of various diseases. L. and are well-known medicinal plants with various biological effects. However, the combination of the two has not previously been studied. Here, we investigated the effects of L. leaf and extract combination (VCEC), a standardized herbal blend comprising L. leaf extract (VE) and extract (CE), for its antioxidant activity and for the protection of endothelial cells against hydrogen peroxide (HO)-mediated oxidative damage in human umbilical vein endothelial cells (HUVECs). VCEC showed higher antioxidant activity than VE or CE in oxygen radical antioxidant capacity assays. In HUVECs, VCEC significantly suppressed increases in the production of intracellular reactive oxygen species, decreased levels of nitric oxide and vascular endothelial-cadherin, and increased endothelial hyperpermeability triggered by HO. Treatment with VE or CE alone ameliorated HUVEC injury in a pattern similar to VCEC, although their effects were significantly weaker than VCEC. Overall, VCEC exhibited a substantial synergistic effect on protecting endothelial cells against oxidative damage through its antioxidant activity. Therefore, VCEC could be developed as a potential agent for reducing the risk of vascular diseases related to oxidative stress.