Glutathione Research Guide: Master Antioxidant, Redox & Dosing Math
Glutathione is the master endogenous antioxidant — a tripeptide central to cellular redox balance, detoxification, and immune function research.
What is Glutathione?
Glutathione (GSH) is a tripeptide — gamma-glutamyl-cysteinyl-glycine — synthesized in every cell of the body. It is the principal endogenous low-molecular-weight antioxidant and one of the most-studied molecules in redox biology.
Intracellular concentrations are typically in the millimolar range, vastly higher than circulating plasma levels, which underscores its role as an intracellular rather than extracellular antioxidant.
Mechanism of action
GSH donates an electron from the thiol (-SH) group of its cysteine residue to neutralize reactive oxygen species (ROS), peroxides, and electrophiles. In the process two GSH molecules become a disulfide-linked GSSG.
Glutathione reductase, using NADPH as the electron source, recycles GSSG back to GSH — the GSH/GSSG cycle is one of the cell's central redox regulators.
GSH is also a cofactor for glutathione peroxidases (neutralizing H2O2 and lipid peroxides) and glutathione S-transferases (Phase II conjugation of xenobiotics in hepatic detoxification studies).
Half-life and bioavailability
Plasma half-life of exogenous reduced glutathione is short — roughly 10–30 minutes — because circulating GSH is rapidly broken down by gamma-glutamyl transferase on endothelial surfaces. This is why oral glutathione is largely ineffective for raising intracellular levels and why parenteral routes are used in research.
Compliance reminder
Glutathione is sold for laboratory research use only. Not for human consumption, diagnosis, treatment, or cure of any disease.
Frequently asked questions
What is Glutathione?
Glutathione (GSH) is a tripeptide composed of glutamate, cysteine, and glycine. It is the most abundant intracellular antioxidant in mammalian cells.
Mechanism?
GSH neutralizes reactive oxygen species (ROS) by donating an electron from its cysteine thiol group, becoming oxidized GSSG, which is then recycled back to GSH by glutathione reductase using NADPH.
Why does the literature use parenteral preparations?
Oral glutathione is largely degraded in the gastrointestinal tract, which is why the published mechanistic literature is based on parenteral research preparations rather than oral formulations.