L-2-oxothiazolidine-4-carboxylate and N-acetylcysteine as precursors of intracellular glutathione in human peritoneal mesothelial cells

L-2-Oxothiazolidine-4-carboxylate and N-acetylcysteine as substrates for intracellular glutathione in human peritoneal mesothelial cells were tested. Both substances at concentrations of 0.01 mM and higher augmented the level of glutathione in mesothelial cells. L-2-Oxothiazolidine-4-carboxylate had a milder but more stable effect than N-acetylcysteine. Cells with increased concentrations of the intracellular glutathione were more resistant to injury by free radicals. When used at higher concentrations (>1 mM), both substances became cytostatic to mesothelial cells as evidenced by growth inhibition.