Tacrine-induced reactive oxygen species in a human liver cell line: The role of anethole dithiolethione as a scavenger

The mechanisms leading to tacrine (THA) hepatotoxic effects are not yet fully understood. Reactive oxygen species (ROS) overproduction and intracellular reduced glutathione (GSH) depletion are common mechanisms involved in drug toxicity. The aim of this study was to investigate, on the human liver cell line HepG2. whether THA at human blood concentrations induces ROS production stimulation and/or GSH depletion. A possible effect of a free radical scavenger, anethole dithiolethione (ADT), was also assessed. ROS production was measured with a fluorogen probe 2',7'-dichlorofluorescin diacetate (DCFH-DA). Reduced GSH and cell viability were measured with, respectively, monochlorobimane (mBCl) and neutral red probes. Assays were performed directly on living adherent cells in 96-well microplates, and sensitive fluorescent detection used microplate cytofluorimetry with cold light fluorimetry technology. The results showed that THA induced a concentration-dependent increase in ROS production and a decrease in GSH. Furthermore, for THA concentrations between 10 and 100 mu M ADT protected cells from ROS production stimulation and GSH depletion induced by THA. In conclusion, our in vitro study demonstrates that oxidative stress. evidenced by enhanced ROS production and GSH depletion, is a mechanism involved in THA cytotoxicity. Moreover, ADT is effective in preventing THA-induced injury. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.