Glutathione (L-Glutathione)

1 Identity

Endogenous gamma-glutamyl tripeptide; a genuine tripeptide, sold throughout the peptide market, distinguished from every other tripeptide in this catalog by an isopeptide backbone bond and a free thiol. The oxidized disulfide-linked dimer is a different article: GSSG, oxidized glutathione, L-glutathione oxidized, CAS 27025-41-8. Marketing terms that are not identity statements and are not used on any document in this catalog: "the master antioxidant".

Sequence

Gamma-L-Glu-L-Cys-Gly. Three residues, all proteinogenic, both chiral centers L. The structural point that determines every release test on this record: the glutamate is joined through its side-chain (gamma) carboxyl, not through the alpha-carboxyl, so the first backbone bond is an ISOPEPTIDE bond and not an ordinary peptide bond. Free N-terminal alpha-amine and free alpha-carboxyl on the glutamate, free thiol on the cysteine, free C-terminal carboxylic acid on the glycine. No amidation, no acetylation, no acylation, no lipidation, no PEGylation, no metal center, no glycosylation. There is one cysteine and therefore no intramolecular disulfide is possible; the disulfide that matters is INTERmolecular and gives the dimer GSSG, a separate article. No D-residue and no non-proteinogenic residue — stated explicitly so that P3 is not applied by reflex — but note that the gamma linkage is itself a non-standard connectivity, and its alpha-linked isomer is exactly isobaric, which is why this P1 record carries mandatory additions that an ordinary P1 article does not.

Molecular formula

C10H17N3O6S (free acid, reduced). Oxidized dimer GSSG C20H32N6O12S2. Monosodium salt C10H16N3O6SNa.

Average mass

307.321 Da for C10H17N3O6S, from the formula on IUPAC 2021 abridged conventional atomic weights. Listings commonly print 307.32; the formula gives 307.321. GSSG 612.63 Da (C20H32N6O12S2). Monosodium salt 329.30 Da.

Monoisotopic mass

307.0838 Da neutral. [M+H]+ 308.0911; [M-H]- 306.0765; [M+Na]+ 330.0730. GSSG 612.1520 neutral, [M+H]+ 613.1593, [M+2H]2+ 307.0833 — and that last figure is the trap on this molecule: the doubly charged dimer sits at 307.0833 against the singly charged monomer's neutral mass of 307.0838, a separation of 1.6 ppm, so a spectrum reported without its charge state named does not distinguish reduced from oxidized glutathione at all, and a certificate that omits the charge state has failed to distinguish two articles carrying two different CAS numbers.

Salt / variant note

(1) the isomer that no mass measurement will ever see. Alpha-Glutathione, the ordinary alpha-linked Glu-Cys-Gly, has formula C10H17N3O6S and a mass identical to the target to every decimal place — 307.32 average, 307.0838 monoisotopic. It is what routine solid-phase synthesis produces if the glutamate side-chain protection strategy is wrong, and it is separated only by chromatographic retention against a qualified gamma-linked standard, by MS/MS fragment pattern, or by NMR. A qualified gamma-linked reference standard is therefore a release requirement on this article rather than good practice. (2) D-glutathione and the two single-center epimers: likewise exactly isobaric and co-eluting on achiral columns. (3) GSSG, oxidized glutathione, C20H32N6O12S2, 612.63 / 612.1520, CAS 27025-41-8 — a different article with its own literature, and the routine degradation product of this one; its [M+2H]2+ at 307.0833 collides with the monomer's neutral monoisotopic mass. (4) Monosodium salt C10H16N3O6SNa, 329.30 / 329.0658, +21.98 Da — the common injectable-grade presentation, so a quoted 329 is a salt mass and not a heavier peptide. (5) S-acetylglutathione C12H19N3O7S, 349.36 / 349.0944, +42.04 Da. (6) Glutathione monoethyl ester C12H21N3O6S, 335.38 / 335.1151, +28.05 Da. (7) S-nitrosoglutathione (GSNO) C10H16N4O7S, 336.32 / 336.0740, +29.00 Da. (8) Glutathione sulfonic acid C10H17N3O9S, 355.32 / 355.0686, +48.00 Da — the terminal thiol-oxidation product and the marker of an air-exposed lot. (9) Degradation fragments from gamma-glutamyl transpeptidase or from hydrolysis: gamma-glutamylcysteine C8H14N2O5S, 250.27 / 250.0623, and cysteinylglycine C5H10N2O3S, 178.21 / 178.0412. (10) Ophthalmic acid, gamma-Glu-2-aminobutyryl-Gly, C11H19N3O6, 289.29 / 289.1274 — the natural thiol-free analog, 18.03 Da lighter, which passes every test that does not specifically look for sulfur.

2 Class & testing panel

Form

Single article

Testing panel

P1 — panel definition

3 Primary sources & evidence

The index reports the design and provenance of the literature, not a conclusion about effect.

Published literature exists and the index grades it C: small or preliminary human data only. What follows is study design and identifier only; no outcome, direction, magnitude or tolerability finding is reproduced on this record. Human randomized controlled trials. Arjinpathana N, Asawanonda P, 2012, PMID 20524875: randomized, double-blind, placebo-controlled; n=60 healthy subjects; oral route; 4 weeks; six measurement sites. Weschawalit S et al., 2017, PMID 28490897: three-arm randomized trial, oral reduced glutathione 250 mg/day versus oral oxidized glutathione 250 mg/day versus placebo; 12 weeks; healthy female subjects. Watanabe F et al., 2014, PMID 25378941: randomized split-face design; n=30; topical 2 percent w/w oxidized-glutathione lotion versus placebo; 10 weeks; the most methodologically clean design among the trials cited here. Wahab et al., 2021, PMID 33871071: double-blind randomized controlled trial; n=46; 8 weeks; combined topical plus oral versus monotherapy. Regulatory and safety-communication document: Philippine FDA public warning, PMID 27088927. The route fact that governs every citation on this record, and it is a fact about the literature rather than about the substance: every randomized controlled trial cited here tested the oral or topical route, and not one tested the intravenous route — so the route with the most clinics, the highest cost and the loudest marketing is the route with zero randomized evidence, and an intravenous citation offered on this article is a citation to something that was not studied. The trials cited here ran 4 to 12 weeks in modest numbers of healthy volunteers, mostly in Thai and Indonesian populations, and none of them included a post-cessation durability arm.

4 Storage & specification

Storage

White crystalline or lyophilized powder in a Type I amber glass vial with a nitrogen-flushed headspace and a PTFE-lined closure; a laboratory-chemical presentation, not a stoppered and crimped injection vial, with no sterility claim. The nitrogen headspace is a specification and not a courtesy: the free thiol oxidizes in air to the disulfide dimer, which is a different article, so an air-filled vial converts the product into its own principal impurity on the shelf. Store at -20 degrees C plus or minus 5 degrees C, desiccated, tightly closed, protected from light. Hygroscopic. Equilibrate the sealed vial to ambient temperature before opening, and where a lot is subdivided the operation is performed under nitrogen or argon with the atmosphere recorded on the batch record. Avoid contact with transition-metal ions, which catalyze thiol oxidation — so no copper-containing article is weighed in the same area, which is a second reason this record and the GHK-Cu record are physically segregated. Reconstituted solution is prepared fresh, is not stored, and is aliquoted single-use at -80 degrees C only where storage is unavoidable, with the free-thiol assay repeated on any stored solution before use. Ships ambient with a labeled cumulative excursion allowance and a single-use temperature logger in every export carton.

Shelf life

Provisional 24 months at -20 degrees C plus or minus 5 degrees C, desiccated, protected from light, under nitrogen, from the date of QA release, stated as provisional pending the company's own stability data. Stability-indicating attributes are chosen for a thiol rather than for a generic peptide: free thiol content by Ellman titration, GSSG content, glutathione sulfonic acid content, total related substances and Karl Fischer water. Real-time pulls at 3, 6, 9, 12, 18 and 24 months at the labeled condition plus 6 months accelerated at 40 degrees C and 75 percent relative humidity, and a headspace-integrity check at each pull because the nitrogen blanket is part of the specification and a failed seal is the likeliest single cause of an out-of-trend thiol result. Extension beyond 24 months only on real-time data from three commercial lots. Printed retest date on every vial and first-expiry-first-out enforced against that date rather than against receipt date; material passing retest is re-dated for a further 12 months, material failing is destroyed and the destruction is recorded.