Purity >95%. Glutathione (GSH) serves as a nucleophilic co-substrate to glutathione transferase in the detoxification of xenobiotics and is an essential electron donor to glutathione peroxidases in the reduction of hydroperoxides. GSH ethyl ester is a cell permeable derivative of GSH that undergoes hydrolysis by intracellular esterases to release GSH. Effective transport of GSH ethyl ester has been used to protect cells against damage from radiation, oxidants, and various toxic compounds including heavy metals.