Glutathione

What is Glutathione?

Glutathione (GSH) is a tripeptide consisting of glutamate, cysteine, and glycine joined by an unusual γ-glutamyl bond that resists most peptidases. It is the most abundant intracellular non-protein thiol in mammalian cells (millimolar concentrations) and serves as the primary cellular antioxidant and substrate for Phase II xenobiotic conjugation. Research-grade GSH is used as a reference substrate and supplement in cell-free and cell-based redox assays.

Mechanism of action (preclinical evidence)

GSH neutralizes reactive oxygen species (ROS) directly via its cysteine thiol and indirectly as a cofactor for glutathione peroxidases (GPx) and glutathione S-transferases (GST). The oxidized dimer (GSSG) is regenerated to GSH by glutathione reductase using NADPH. The GSH/GSSG ratio is a key indicator of cellular redox status. GSH is also conjugated to electrophilic xenobiotics in Phase II detoxification, contributing to drug metabolism research.

Research applications

• Oxidative stress models (hydrogen peroxide, superoxide, peroxynitrite)
• Cellular redox status measurement (GSH/GSSG ratio)
• Glutathione peroxidase and S-transferase enzyme assays
• Phase II drug metabolism and xenobiotic conjugation studies
• Mitochondrial function and apoptosis research

Storage and handling

Store lyophilised GSH at -20 °C in a sealed, light-protected vial — the cysteine thiol is highly susceptible to oxidation. Reconstitute in degassed buffer (often slightly acidic) and minimize air exposure. Adding chelators like EDTA can reduce metal-catalyzed oxidation in solution.

Regulatory status

Glutathione is sold as a dietary supplement in some jurisdictions but is not an approved therapeutic for any specific indication. Research-grade material is supplied by Peptra Labs for laboratory use only.