Protective effect of Punica granatum L. (pomegranate) fruit extracts and ellagic acid against cytotoxicity induced by methyl tertiary butyl ether in isolated rat hepatocytes

Abstract

Methyl tertiary butyl ether (MTBE) is the most widely used motor vehicle fuel oxygenate since it reduces automobile emissions of carbon monoxide and compounds involved in photochemical smog formation. Although recently banned in some developed countries, the increasing use of MTBE in Iran and many developing countries raised concern over its health safety. The protective effects of different concentrations (100, 150, 200 or 300 μg/ml) of aqueous and ethanolic extracts of Punica granatum L. fruit and also ellagic acid (120 μM) as one of its main components were examined against oxidative stress toxicity induced by MTBE in isolated rat hepatocytes. Addition of MTBE to isolated rat hepatocytes results in reactive oxygen species (ROS) formation, rapid glutathione (GSH) depletion, mitochondrial membrane potential collapse and lysosomal membrane rupture before hepatocyte lysis ensues. All Punica extracts and ellagic acid protected the hepatocyte against all cytotoxicity markers, including cell lysis, ROS generation, lipid peroxidation, GSH depletion, mitochondrial membrane potential decrease and lysosomal membrane oxidative damage. Punica aqueous extract (100, 150, 200 or 300 μg/ml) was more effective than its ethanolic extract (100, 150, 200 or 300 μg/ml) but similar to ellagic acid (120 μM) at protecting hepatocytes against MTBE-induced cytotoxicity, ROS generation, lipid peroxidation, GSH depletion, mitochondrial membrane potential reduction and lysosomal membrane damage. However, there were no significant differences between both Punica granatum L. fruit extracts and ellagic acid at hydrogen peroxide (H2O2) scavenging activity. These results suggest a hepatoprotective role for Punica extracts against liver injury resulting from MTBE-induced oxidative stress.