Glutathione and glutathione-dependent antioxidant system (GSH system)

The glutathione and glutathione-dependent antioxidant system is a critical cellular defense mechanism responsible for maintaining redox homeostasis and detoxifying reactive oxygen species (ROS) and electrophilic xenobiotics. The system centers on the tripeptide glutathione (GSH), which acts as a potent antioxidant and a cofactor for enzymes such as glutathione peroxidase (GPX), glutathione S-transferase (GST), and glutathione reductase (GR). In healthy cells, this system prevents oxidative damage to DNA, proteins, and lipids, while also modulating immune responses and cell signaling pathways like ferroptosis. In disease states, the glutathione system plays a dual role; its depletion is a hallmark of neurodegenerative disorders like Parkinson's and Alzheimer's, whereas its upregulation in many cancers contributes to chemoresistance and tumor survival. Pharmacological interventions target this system through various approaches, including the use of N-acetylcysteine to replenish GSH levels in cases of toxicity or chronic inflammation, and the use of inhibitors like buthionine sulfoximine to sensitize tumors to oxidative stress-inducing therapies. Understanding the balance of this system is vital for developing targeted therapies that can either protect vulnerable tissues or overcome adaptive resistance in malignant cells.

Other names

Glutathione redox systemGSH-dependent antioxidant systemGamma-glutamylcysteinylglycine systemGlutathione metabolic pathway

Therapeutic strategies involve either supplementing glutathione levels to combat oxidative stress or depleting them to sensitize cancer cells to treatment. N-acetylcysteine acts as a precursor to increase GSH synthesis, while buthionine sulfoximine inhibits glutamate-cysteine ligase to deplete GSH. Other agents like erastin and sulfasalazine inhibit the cystine/glutamate antiporter (System Xc-), reducing the availability of the rate-limiting precursor cysteine. Additionally, Nrf2 activators like dimethyl fumarate induce the expression of multiple glutathione-dependent enzymes to enhance antioxidant capacity.