Protective effects of Phellinus linteus extract against iron overload-mediated oxidative stress in cultured rat hepatocytes

Phellinus linteus (PL) mushroom has been reported to possess antioxidant activity. The present study was designed to investigate whether an ethanol extract obtained from PL might ameliorate oxidative stress and enhance antioxidant enzyme activities in primary rat hepatocytes, which were overloaded with iron using ferric nitrilotriacetate (FeNTA) complex. FeNTA enables hepatocytes to accumulate substantially redox-active iron and stimulates the production of injurious hydroxyl radicals, which in turn, initiate oxidative stress-mediated cytotoxicity. The results showed that pretreatment of hepatocytes with PL extract (50, 100 and 200 mu g/mL) for 24 h significantly reversed FeNTA-induced cell viability loss, lactate dehydrogenase leakage (LDH), lipid peroxidation (LPO) and protein carbonyl formation in a dose-dependent manner. It was further observed that PL extract produced an inhibitory effect on intracellular reactive oxygen species (ROS) formation caused by FeNTA. Concomitantly, the amount of GSH content and the activities of glutathione reductase (GSH Rd) and glutathione peroxidase (GSH Px) in hepatocytes pretreated with PL extract increased substantially compared with those treated with FeNTA alone. These results suggest that PL may be useful in protecting against FeNTA-induced oxidative damage and also be capable of attenuating cytotoxicity of other oxidants. Copyright (c) 2007 John Wiley & Sons, Ltd