Glutathione (reduced glutathione) bulk powder for formulators

Glutathione is the INCI name of the tripeptide γ-L-glutamyl-L-cysteinyl-glycine, listed in CosIng and supplied here in its reduced form, GSH. It is a peptide by structure but unusual in two ways that matter at the bench: the first bond is a γ-glutamyl linkage rather than an ordinary peptide bond, and the central cysteine carries a free thiol. That thiol is why formulators buy the material and why it needs more care than the other peptides here: in air it oxidises to the disulfide-linked dimer GSSG.

Pepti, Guangzhou manufactures the material and supplies it as bulk powder from 5 g, shipped cold-chain, with a lot certificate of analysis reporting HPLC purity and mass-spectrometry identity and a safety data sheet on request. No public batch record for glutathione is listed in the Pepti COA library yet, so the lot COA issued with the shipment is the purity document for this compound.

Identity: reduced glutathione, not the disulfide

PubChem lists the compound under CID 124886 with the title Glutathione, the formula C10H17N3O6S, a molecular weight of about 307.3 g/mol and CAS 70-18-8 (PubChem CID 124886). GSH, L-glutathione reduced and γ-Glu-Cys-Gly are synonyms for the same molecule. Two other materials travel under similar names.

• Glutathione disulfide, GSSG, CAS 27025-41-8. Two GSH units joined through a disulfide bond: PubChem CID 65359, C20H32N6O12S2, about 612.6 g/mol (PubChem CID 65359). It is the oxidation product of the reduced form and the form used in the topical study cited below.
• Derivatives. S-acetyl glutathione, glutathione esters and glutathione salts are separate materials and are not what this page describes.

The mass-spectrometry line on the COA shows the protonated molecule near 308.3 m/z. Ask on the RFQ if you want the disulfide reported as a named impurity.

Appearance, solubility and handling

The material is a white crystalline powder with the faint sulfur note characteristic of a thiol; the smell is stronger in solution and grows as the material ages. It is freely soluble in water, giving a clear, colourless and distinctly acidic solution, sparingly soluble in ethanol and insoluble in oils. Dry powder in a closed container oxidises slowly, a solution open to air much faster, so dissolve the peptide shortly before use and do not keep stock solutions.

Open the container at room temperature, weigh quickly and close it with as little headspace as possible; splitting a large pack into smaller containers helps. Storage is 2–8 °C, protected from light and air, with −20 °C for the long term, as stated on the lot COA together with a retest date.

What the published literature reports

Topical cosmetic data are thin, and the most cited study used the oxidised form. Watanabe, Hashizume, Chan and Kamimura ran a double-blind, placebo-controlled, split-face study in thirty adult women in the Philippines, who applied a lotion containing 2% oxidised glutathione (GSSG) to one side of the face and a placebo lotion to the other, twice daily for ten weeks. The authors report lower melanin index values on the GSSG side, with changes in moisture, wrinkles and smoothness, and they note that the mechanism is unclear and that longer-term safety needs further study (Watanabe F et al. Clin Cosmet Investig Dermatol, 2014).

That study concerns the disulfide form, not the reduced thiol, and is not a substantiation file for a product made with this material. Claims for a finished cosmetic are made and supported by the brand in each market; Pepti supplies identity and purity documents.

Formulation notes for the bench

Everything on this list is chemistry, and nearly all of it is about keeping the thiol reduced: dissolved oxygen oxidises it to the disulfide, traces of copper and iron catalyse the reaction, and it runs faster as the pH rises.

• Chelate the metals. A chelator in the water phase helps here; EDTA, phytate or GLDA are the usual choices. This is the opposite of the copper-peptide advice, and it is why GSH and GHK-Cu do not belong in the same water phase: the thiol strips and reduces the copper.
• Keep the pH at 4 to 6. The reactive species is the thiolate anion, which becomes more abundant as pH rises, so oxidation accelerates in neutral and alkaline bases.
• Exclude air. Blanket the batch with nitrogen during compounding, fill with minimal headspace and prefer airless packaging. Degassed water for the premix removes most of the dissolved oxygen.
• Keep oxidisers out. Peroxides, hypochlorite and oxidising preservative chemistry consume the thiol directly. Ascorbic acid is itself a reducer and is often paired with GSH, but the pair still has to be shown stable in the buyer's base.
• Heat, light, odour and colour. Add during cool-down below 40 °C and protect from light. A faint sulfur note is normal for fresh material; a stronger smell, or a yellow tint developing in solution, signals oxidation and is a reason to check the batch.

Preservation is confirmed by challenge test in the buyer's base; the formulator sets the use level.

Specification and documents for this material

The lot certificate of analysis gives reverse-phase HPLC purity as area per cent, mass-spectrometry identity against the expected molecular weight, appearance, and the storage and retest statements; water content and disulfide content can be added as named items where the buyer's specification calls for them. A sixteen-section safety data sheet is available, and both documents name the Pepti site in Guangzhou as manufacturer.

No public batch record for this compound is listed in the Pepti COA library yet. The lot COA is issued with each shipment; if a public glutathione record is published later it will appear in the library at peptioem.com/coa.

Public batch records

No public batch record is listed for this compound in the manufacturer's library yet. The lot you receive carries its own COA with HPLC purity, MS identity and lot number; ask for the current lot's COA with your quote. The library itself is at peptioem.com/coa.