Glutathione
Endogenous antioxidant tripeptide
A tripeptide antioxidant studied extensively in oxidative-stress and recovery research.
Also referenced as: GSH
Overview
Glutathione is a naturally occurring tripeptide synthesized in virtually all human cells from glutamate, cysteine and glycine. It is one of the body's principal intracellular antioxidants and is not a synthetic research peptide.
At a glance
What Glutathione does
Glutathione (GSH) is a tripeptide of glutamate, cysteine, and glycine that serves as the cell's master intracellular antioxidant and a central regulator of redox balance. Its power comes from the reactive sulfhydryl (-SH) group on its cysteine residue, which donates electrons to neutralize reactive oxygen species (ROS) and reactive nitrogen species. As it does so, two glutathione molecules become oxidized to glutathione disulfide (GSSG); the ratio of reduced GSH to GSSG is one of the body's key measures of oxidative stress, and glutathione reductase continually regenerates GSH to keep that ratio high.
Functionally, glutathione does several distinct jobs. It acts as the essential cofactor for glutathione peroxidase enzymes, which reduce hydrogen peroxide and toxic lipid hydroperoxides, protecting cell membranes, DNA, and proteins from oxidative damage. Through glutathione S-transferase enzymes it conjugates to xenobiotics, drugs, and electrophilic toxins, tagging them for detoxification and excretion (a major Phase II liver detox pathway). It also recycles other antioxidants such as vitamins C and E, and participates in redox signaling that influences immune function and cell survival.
As a supplement, glutathione is well established in basic biochemistry, but its behavior when administered is a practical caveat: oral GSH is largely broken down in the gut, so bioavailability is limited, and much research focuses on precursors (such as N-acetylcysteine) or on IV/nebulized delivery. Human clinical evidence for exogenous glutathione is mixed and condition-dependent, stronger for raising blood glutathione and for certain oxidative-stress and neurological contexts than as a broad cure-all.
Effects reported in research
- Directly neutralizes reactive oxygen and nitrogen species via its cysteine sulfhydryl group, protecting lipids, DNA, and proteins from oxidative damage (established biochemistry).
- Serves as the essential cofactor for glutathione peroxidase enzymes that reduce hydrogen peroxide and lipid hydroperoxides.
- Detoxifies electrophilic xenobiotics, drugs, and toxins through glutathione S-transferase conjugation, a major liver Phase II pathway.
- Maintains cellular redox homeostasis, with the GSH/GSSG ratio acting as a core marker of oxidative-stress status.
- Regenerates other antioxidants including vitamin C and vitamin E, extending the antioxidant network.
- Nebulized and IV delivery raised tissue/blood glutathione and reduced oxidative-stress markers in some studies, including neurodegenerative-condition research (human, mixed results).
- Oral glutathione is largely degraded in the gut, limiting bioavailability, so precursor strategies (e.g., NAC) are often used instead.
- Human clinical benefit beyond raising glutathione levels is condition-dependent and not uniformly established.
Effects listed reflect findings reported in the research literature — many in animal or in-vitro models. Listing an effect is not a claim of efficacy or a therapeutic indication in humans.
Mechanism of action
Glutathione acts as a major intracellular antioxidant and redox buffer, neutralizing reactive oxygen species and participating in the glutathione peroxidase and glutathione-S-transferase systems. It supports detoxification of certain xenobiotics and helps maintain the redox state of protein thiols. It cycles between reduced (GSH) and oxidized (GSSG) forms as part of cellular redox homeostasis.
Mechanistic description reflects published research-literature understanding. Much peptide research is preclinical (in-vitro or animal-model); mechanism in humans may differ and is not established for many compounds.
What it's studied for
Research contexts in which Glutathione appears in the literature. Listing a research area is not a claim of efficacy or a therapeutic indication.
Key characteristics
- A naturally occurring tripeptide made in the body from three amino acids
- Contains an unusual gamma-peptide bond between glutamate and cysteine
- Functions as a central intracellular antioxidant and redox regulator
- Widely available as a dietary supplement in oral and other forms
- Distinct from synthetic research peptides in this category due to its endogenous, well-characterized biology
Reported research dosing reference only
Educational reference, not dosing guidance. The figures below summarize amounts reported in published research and research-community protocols, provided for educational and research context only. They are not medical advice, not a recommendation, and not instructions for human use. Glutathione is a research compound.
Intravenous glutathione protocols reported in the literature typically use gram-range doses per infusion given intermittently over several weeks. These are reference figures for research/clinical context only, not dosing guidance for humans.
- IV infusion protocols: commonly ~1500-2500 mg per session (some protocols up to ~3000 mg)
- Frequency in protocols: ~1-3 times per week for ~4-8 weeks
Plasma half-life ~15 minutes after IV; oral bioavailability of intact GSH is debated. Endogenous antioxidant rather than a synthetic peptide drug.
How it compares
Unlike the synthetic research peptides in this group, glutathione is an endogenous, well-studied antioxidant tripeptide available as a supplement rather than a research-only compound.
Commonly studied alongside
Compounds frequently researched together with Glutathione in the literature. Cross-referenced for research context — not a usage or combination recommendation.
Compare and calculate
Side-by-side pages for the pairings the literature already documents for Glutathione, plus the unit-conversion reference for a reconstituted vial. Factual comparisons of documented characteristics — not a recommendation to combine or use any compound.
Glutathione reconstitution calculator → Concentration, volume per measured amount and syringe units for a stated vial mass and diluent volume. A unit-conversion reference, not a dosing recommendation.
Handling & Stability
Lyophilized peptides are stored cold, protected from light, and reconstituted only at the time of intended in-vitro work.
- Avoid repeated freeze-thaw cycles
- Verify supplier lot and Certificate of Analysis
- Follow institutional lab-safety protocols
Analytical & COA Concepts
Reputable research suppliers publish a third-party Certificate of Analysis per batch. Key analytical concepts referenced in COAs include:
Category Context
Glutathione sits in the Healing & Recovery area of the PeptiDex library.
- Entry type: Research compound reference
- Healing & Recovery category hub →
- Browse the full library →
- Glossary of terms →
Where researchers source Glutathione
For researchers studying Glutathione, third-party suppliers such as Practically Natty Peptides offer research-grade material, third-party tests every batch and provides Certificates of Analysis on request, and ship from the US.
View research-supplier listing →
Outbound link to a third-party research supplier. Inclusion does not constitute endorsement; all editorial content is developed independently.
Frequently asked questions
What is glutathione?
Glutathione (GSH) is a tripeptide, L-gamma-glutamyl-L-cysteinyl-glycine, found in virtually all cells and functioning as a major intracellular antioxidant. It is notable for an unusual gamma peptide bond between the glutamate side chain and cysteine, and for the reactive thiol on its cysteine residue that carries out its redox chemistry. It is an endogenous molecule rather than a synthetic research peptide.
What is glutathione studied for?
It is researched for its roles in antioxidant defense, detoxification, and redox homeostasis, neutralizing reactive oxygen species, free radicals, peroxides, and heavy metals. In applied research it is examined in the context of oxidative-stress conditions and, popularly, skin-related outcomes. As a supplement or IV agent its systemic efficacy remains debated.
Why does the gamma peptide bond in glutathione matter?
The gamma linkage between glutamate and cysteine is not the standard alpha peptide bond, which makes glutathione resistant to cleavage by ordinary peptidases and contributes to its intracellular stability. Only the enzyme gamma-glutamyl transpeptidase can break this bond, which is central to how glutathione is recycled and transported.
What is glutathione's half-life and what does that imply?
Circulating glutathione is cleared quickly, with a plasma half-life reported around 15 minutes after IV administration, distributing into the extracellular compartment. This rapid clearance is one reason IV protocols use repeated sessions rather than a single dose, and why oral bioavailability of intact GSH is often questioned.
How is glutathione administered in research and clinical settings?
It is used intravenously (as a reduced-glutathione solution), by intramuscular or subcutaneous injection, and orally or as liposomal formulations. IV protocols in the literature commonly describe gram-range infusions given one to three times weekly. These are reference figures, not dosing guidance.
Answers are educational summaries of research-literature context and do not constitute medical advice. See the Research Library, COA guide, and Storage & Handling guide for more.
References
Primary literature indexed in PubMed for Glutathione. Listing a study records that it exists and is indexed — it is not a claim of efficacy, a therapeutic indication, or an endorsement of its conclusions. Much of this literature is preclinical (in-vitro or animal-model).
- Glutathione and glutathione-dependent enzymes: From biochemistry to gerontology and successful aging
- Mitochondrial Glutathione in Cellular Redox Homeostasis and Disease Manifestation
Each reference was checked against its PubMed record on 2026-07-28: the PMID resolves and the title, journal and year match. Where no indexed literature exists for a compound, PeptiDex says so rather than substituting a citation about a different molecule. See the editorial policy.