Cytoprotective Effect of Hydroalcoholic Extract of Pinus eldarica Bark against H2O2-Induced Oxidative Stress in Human Endothelial Cells

Background: Pinus eldarica is a widely growing pine in Iran consisting of biologically active constituents with antioxidant properties. This study investigates the effect of hydroalcoholic extract of P. eldarica bark against oxidative damage induced by hydrogen peroxide (H₂O₂) in human umbilical vein endothelial cells (HUVECs). Methods: The total phenolic content of p. eldarica extract was determined using Folin-Ciocalteu method. The cytotoxicity of P. eldarica extract (25-1000 µg/ml) on HUVECs was assessed using 3-(4,5- Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) method. Cytoprotective effect of P. eldarica extract (25-500 µg/ml) on H₂O₂-induced oxidative stress was also evaluated by MTT assay. The intra- and extra-cellular hydroperoxides concentration and ferric reducing antioxidant power (FRAP) were measured in pretreated cells. Results: The total phenolic content of P. eldarica extract was estimated as 37.04±1.8% gallic acid equivalent. P. eldarica extract (25-1000 µg/ml) had no cytotoxic effect on HUVECs viability. The pretreatment of HUVECs with P. eldarica extract at the concentrations of 50-500 µg/ml significantly reduced the cytotoxicity of H₂O₂. P. eldarica extract decreased hydroperoxides concentration and increased FRAP value in intra-cellular fluid at the concentration range of 100-500 µg/ml and in extra-cellular fluid at the concentration range of 25-500 µg/ml. Conclusions: This study revealed the antioxidant and cytoprotective effects of P. eldarica extract against H₂O₂-induced oxidative stress in HUVECs. Concerning the high content of phenolic compounds in P. eldarica, more research is needed to evaluate its clinical value in endothelial dysfunction and in other oxidative conditions.