Glutathione exists in both reduced (GSH) and oxidized (GSSG) states. In the reduced state, the thiol group of cysteine is able to donate a reducing equivalent (H++ e−) to other molecules, such as reactive oxygen species to neutralize them, or to protein cysteines to maintain their reduced forms. With donating an electron, glutathione itself becomes reactive and readily reacts with another reactive glutathione to form glutathione disulfide (GSSG). Such a reaction is probable due to the relatively high concentration of glutathione in cells (up to 7 mM in the liver).
Generally, interactions between GSH and other molecules with higher relative electrophilicity deplete GSH levels within the cell. An exception to this case involves the sensitivity of GSH to the electrophilic compound’s relative concentration. In high concentrations, the organic molecule Diethyl maleate fully depleted GSH levels in cells. However, in low concentrations, a minor decrease in cellular GSH levels was followed by a two-fold increase. It is used for the prevention and treatment of tissue and cell damage caused by drugs (such as chemotherapy drugs, antituberculosis drugs, psychiatric drugs, paracetamol, etc.), radiotherapy, alcohol, organic phosphorus, etc. It has a protective effect on liver damage caused by various reasons.