Portulaca oleracea Linn seed extract ameliorates hydrogen peroxide-induced cell death in human liver cells by inhibiting reactive oxygen species generation and oxidative stress.

Purpose: To investigate the protective effects of Portulaca oleracea seed extract (POA) against cytotoxicity, oxidative stress and reactive oxygen species (ROS) generation induced by hydrogen peroxide (H2O2) in human liver cells (HepG2). Methods: The extract (POA) was obtained by ethanol extraction of P. oleracea seeds. Cytotoxicity in HepG2 cells was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, neutral red uptake (NRU) assay and morphological changes. The cells were pre-exposed to noncytotoxic concentrations (5 - 25 μg/mL) of POA for 24 h, and then cytotoxic (0.25 mM) concentration of H2O2. After 24 h of exposure, MTT and NRU assays were used to evaluate cell viability, while morphological changes were assessed using phase contrast inverted microscopy. The effect of POA on reduced glutathione (GSH) level, lipid peroxidation (LPO), and ROS generation induced by H2O2 was also studied. Results: The results showed that pre-exposure to POA (25 μg/mL) significantly (p <0.01) attenuated the loss of cell viability by up to 38 % against H2O2-induced oxidative stress and ROS generation. In addition, POA (25 μg/mL) significantly (p <0.01) increased GSH level (31 %), but decreased the levels of LPO (37 %) and ROS generation (49 %). Conclusion: This study demonstrates that POA has the capacity to protect HepG2 cells against H2O2- induced cell death by inhibiting oxidative stress and ROS generation. [ABSTRACT FROM AUTHOR]