Oleuropein protects L-02 cells against H2O2-induced oxidative stress by increasing SOD1, GPx1 and CAT expression.

Oleuropein (OL), a natural phenolic compound, comprises the major constituent of Olea europea leaves and unprocessed olives, and OL is considered to be the principal components that confer the characteristic taste and stability of olive oil. Oxidative damage induced by H2O2 treatment can irreversibly damage the L-02 cells, resulting in cell death and apoptosis. Whether the effects of oxidative stress could be attenuated in cultured human L-02 cells by incubation with OL is still unknown. In this research, the function of OL in protecting human L-02 cells against H2O2 induced cell death and cell apoptosis was investigated, and the mechanism by which OL underlies the effect was also examed. L-02 cells were exposed to 100µM H2O2 with or without OL pretreatment at different concentrations. Cell viabilities were monitored by WST-1 assay. ALT, AST and LDH production in culture medium were also determined. ROS levels were detected by L-012 chemiluminescence, and OL increased SOD1, CAT and GPx1 expression in a concentration-dependent manner. Further studies showed that OL also inhibited H2O2-induced P38 and JNK phosphorylation but enhanced ERK1/2 phosphorylation in a dose-dependent manner. These findings suggested that OL as a potent antioxidant agent and a natural compound found in several plants, may be exploited as a potentially useful method for hepatopathy prevention.