Glutation

Glutation, also known as glutathione (GSH), is a tripeptide composed of the amino acids glutamate, cysteine, and glycine. It is the most abundant intracellular thiol and serves as a key antioxidant in nearly all cells, helping to protect against oxidative stress and to maintain the redox state of the cell. In its reduced form (GSH) it donates electrons to neutralize reactive oxygen species, becoming oxidized to glutathione disulfide (GSSG) in the process; the GSH/GSSG ratio is a common indicator of cellular health.

Biosynthesis of glutathione occurs in two ATP-dependent steps in the cytosol. First, gamma-glutamylcysteine synthetase (GCL) couples glutamate and cysteine to form gamma-glutamylcysteine, a rate-limiting step. Then glutathione synthetase adds glycine to produce GSH. Cysteine availability often limits synthesis, and production is regulated by cellular redox status and nutrient supply. Glutathione participates in the gamma-glutamyl cycle and also functions as a substrate for detoxification reactions mediated by glutathione S-transferases.

Functions extend beyond direct antioxidant activity. Glutathione participates in detoxification by conjugating electrophilic compounds, helps maintain thiol groups on proteins, and supports regeneration of other antioxidants through enzymes such as glutathione reductase, which converts GSSG back to GSH using NADPH.

Dietary intake and endogenous synthesis influence glutathione levels. Foods rich in cysteine and related precursors, as well as supplements such as N-acetylcysteine, can affect availability. Oral bioavailability of glutathione itself is variable, and therapeutic use is most established in specific settings (for example, acetaminophen toxicity) rather than as a general treatment for disease.