S-Methyl glutathione
Also known as: GSMe, S-Me-GSH, S-Methylglutathione, S‑Methyl‑GSH, S‑Methylglutathione, γ-L-Glutamyl-S-methyl-L-cysteinylglycine
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Summary
S‑Methyl glutathione (GSMe) is a chemically modified analogue of the tripeptide glutathione in which the cysteine thiol is methylated. It can arise from chemical alkylation or enzymatic methylation in bacteria and has been detected in human plasma, where its concentration rises in acute myocardial infarction. Research use is limited to in‑vitro, ex‑vivo and analytical applications; it is not an approved therapeutic agent.
Mechanism of Action
GSMe retains the γ‑glutamyl‑cysteinylglycine backbone of glutathione but the sulfhydryl group is blocked by a methyl group. This modification prevents disulfide formation while preserving the ability of the molecule to bind glutathione‑dependent enzymes such as glutathione S‑transferases (GSTs) and to serve as a substrate for multidrug‑resistance protein 1 (MRP1) transport. In vitro, S‑methyl glutathione can enhance MRP1‑mediated efflux of glutathione‑conjugated toxins and can substitute for oxidized glutathione in corneal endothelial fluid transport.
What the Research Shows
Early biochemical work demonstrated that strong alkylating agents (N‑methyl‑N‑nitrosourea, methyl methanesulfonate) rapidly methylate glutathione in vitro, producing S‑methyl glutathione, and that the sulfide anion is the preferred methyl acceptor (Environ Res 1987). In Escherichia coli, the cheR methyltransferase catalyzes the transfer of a methyl group from S‑adenosyl‑methionine to glutathione, generating S‑methyl glutathione, although the compound is not required for chemotaxis (J Bacteriol 1986). In human plasma, metabolomic profiling identified elevated S‑methyl glutathione as one of three metabolites that together predict acute myocardial infarction with high accuracy (MedComm 2025). Cellular detoxification studies showed that S‑methyl glutathione enhances MRP1‑mediated export of glutathione‑conjugated carcinogen metabolites, suggesting a role in xenobiotic clearance (Biochemistry 2005). Ophthalmic perfusion experiments revealed that S‑methyl glutathione can replicate the stromal‑thinning effect of oxidized glutathione in rabbit corneas, indicating functional activity in fluid transport (Invest Ophthalmol Vis Sci 1980). Finally, affinity chromatography experiments found that S‑methyl glutathione elutes glutathione‑S‑transferases as efficiently as reduced glutathione, confirming its binding affinity (Biochim Biophys Acta 1981).
Reported Benefits
Evidence suggests S‑methyl glutathione may serve as a biomarker for acute myocardial infarction, contributing to diagnostic panels with high predictive value. In vitro, it can enhance the export of toxic glutathione‑conjugates via MRP1, potentially supporting cellular detoxification. It also mimics oxidized glutathione in promoting corneal endothelial fluid transport, offering a tool for ocular physiology studies. Additionally, its ability to bind glutathione‑S‑transferases makes it useful in enzyme purification protocols.
Limitations of the Evidence
All reported findings are confined to laboratory models, bacterial systems, or metabolomic associations; no clinical trials have evaluated therapeutic effects. The relevance of S‑methyl glutathione levels in human disease beyond biomarker correlation remains unclear. Its synthesis in vivo appears limited and non‑essential in bacteria, and the compound’s biological role in mammals is not established. Consequently, functional claims are speculative, and safety or efficacy data in humans are absent.
Safety Considerations
To date, no human safety data have been published for S‑methyl glutathione. In vitro studies indicate it can react with strong alkylating agents, suggesting potential chemical reactivity. Because the compound is used only in controlled laboratory settings (e.g., cell culture, perfusion chambers, chromatography buffers), standard laboratory safety precautions apply. Without pharmacokinetic or toxicity studies, any extrapolation to clinical use would be premature.
How It Is Administered
S‑methyl glutathione is supplied for research purposes only. It is typically added to aqueous solutions such as cell culture media, perfusion buffers, or chromatography buffers at micromolar concentrations. No formulation for human administration exists, and the compound is not approved for therapeutic use.
Routes of Administration
Goals & Uses
- Glutathione metabolism tracerMetabolic ResearchModerate
- Glutathione S-transferase substrate/inhibitor researchEnzymologyModerate
- Antioxidant defense modulationBiochemical ResearchLow
Contraindications
- Human therapeutic useRegulatory/safetyHigh
Adverse Effects
- Unknown systemic effectsGeneralUnknown
Drug Interactions
No drug interactions recorded yet.
Population Constraints
- All clinical populationsRegulatory / SafetyAbsolute
Regulatory Status
- European UnionUnapprovedNot approved by EMA.
- United StatesUnapprovedNot approved by FDA; available only as a research chemical.
- United KingdomUnapprovedNot approved by MHRA.
No approved therapeutic indication in any major jurisdiction. Used as a research/reference compound. Not listed as an approved drug by FDA, EMA, or MHRA.
Evidence & Sources
- Journal ArticleLowTrézl L, et al.1987-01-01T00:00:00.000000Z
- Journal ArticleLowTerwilliger TC, et al.1986-01-01T00:00:00.000000Z
- Journal ArticleLowLiu J, et al.2025-01-01T00:00:00.000000Z
- Journal ArticleLowPeklak-Scott C, Townsend AJ, Morrow CS2005-01-01T00:00:00.000000Z
- Journal ArticleLowAnderson EI, Wright DD1980-01-01T00:00:00.000000Z
- Journal ArticleLowInoue M, et al.1981-01-01T00:00:00.000000Z
Frequently Asked Questions
What is S‑methyl glutathione?
S‑Methyl glutathione is a derivative of the antioxidant tripeptide glutathione in which the cysteine sulfhydryl group is methylated, creating a molecule that cannot form disulfide bonds but still interacts with glutathione‑dependent enzymes.
How is S‑methyl glutathione produced?
In the laboratory it can be generated by exposing glutathione to strong methylating agents such as N‑methyl‑N‑nitrosourea. In bacteria, the cheR methyltransferase transfers a methyl group from S‑adenosyl‑methionine to glutathione, forming the S‑methyl analogue.
Does S‑methyl glutathione have any medical use?
No. The compound is currently used only in research settings—cell culture, perfusion experiments, and analytical methods. It has not been evaluated in clinical trials and is not an approved drug for any indication.
Why is S‑methyl glutathione studied as a heart‑attack biomarker?
Metabolomic profiling of plasma from patients with acute myocardial infarction identified elevated S‑methyl glutathione alongside two other metabolites. Together they formed a diagnostic model that distinguished heart‑attack cases with high accuracy, suggesting the molecule reflects disease‑related metabolic changes.
What is S-Methyl glutathione used for?
S-Methyl glutathione is educationally associated with: Glutathione metabolism tracer, Glutathione S-transferase substrate/inhibitor research, Antioxidant defense modulation. Educational only — not medical advice.
How is S-Methyl glutathione administered?
Recorded routes of administration: Research Use Only (in Vitro / Ex Vivo).
What are the potential side effects of S-Methyl glutathione?
Reported adverse effects include: Unknown systemic effects. This list is not exhaustive — consult a qualified clinician.
Who should avoid S-Methyl glutathione?
Recorded contraindications: Human therapeutic use. Consult a qualified clinician before use.