Oxiglutathione, also known as oxidized glutathione, glutathione disulfide, or GSSG, is the oxidized disulfide form of L-glutathione. It is produced when two reduced glutathione molecules undergo oxidation and form a disulfide bond between their cysteine sulfur atoms. Oxiglutathione is an important biochemical compound associated with cellular redox balance, antioxidant systems and glutathione metabolism.
Oxiglutathione has the CAS Number 27025-41-8, molecular formula C20H32N6O12S2, and molecular weight 612.63 g/mol. Commercial analytical references identify it as a white to off-white crystalline powder or solid and characterize it using chromatographic, spectroscopic and optical-rotation techniques.
TCI describes oxidized glutathione as a white to almost white powder to crystal with minimum 98.0 area% HPLC purity and a specific rotation of −102° to −109° under its stated analytical conditions.
Oxiglutathione is the oxidized form of reduced glutathione. The GSH/GSSG redox couple is an important biochemical system involved in maintaining cellular redox conditions.
During oxidative reactions, reduced glutathione can be converted into GSSG. Glutathione reductase subsequently converts GSSG back to reduced glutathione using NADPH. Because of this reversible relationship, GSSG is widely used in biochemical research involving oxidative stress and glutathione metabolism.
HPLC is an important analytical technique for determining the purity of oxidized glutathione. Current commercial specifications demonstrate HPLC purity requirements ranging from ≥97.5% to ≥98.0%, depending on the grade and manufacturer.
Infrared spectroscopy provides an additional identity test. Thermo Fisher specifies that the infrared spectrum conforms for its oxidized glutathione reference material.
Specific optical rotation is particularly useful for confirming the stereochemical characteristics of the material. Thermo Fisher specifies −92° to −106° at 20°C using its stated concentration and solvent conditions, while TCI specifies −102° to −109° under its own analytical conditions. The difference demonstrates why optical-rotation values must always be associated with the analytical conditions used.
Quality evaluation of Oxiglutathione should include identity, chromatographic purity, moisture or loss on drying, inorganic residue and stereochemical characterization.
The oxidation state is particularly important because Oxiglutathione is chemically different from reduced glutathione. Where applicable, reduced glutathione may be monitored as a related substance or process-related component.
Commercial reference specifications demonstrate that moisture-related limits can be relatively broad. Thermo Fisher specifies loss on drying not more than 8.0% at 105°C for 3 hours, while residue after ignition is specified at not more than 0.5%.
Oxiglutathione and reduced glutathione are two chemically related forms of glutathione.
Oxiglutathione is water-soluble. FUJIFILM Wako reports a preparation of 0.2 g in 20 mL water, equivalent to approximately 10 mg/mL, while Cayman Chemical reports approximately 10 mg/mL solubility in PBS at pH 7.2.
FUJIFILM Wako describes the material as white to nearly white crystals, powder or granules and reports a melting point of approximately 178°C with decomposition.
Oxiglutathione should be protected from unsuitable environmental conditions and stored according to the validated specification for the intended grade.
Commercial references use refrigerated or cool-storage conditions. FUJIFILM Wako recommends 2–10°C, while Sigma-Aldrich lists 2–8°C for its BioXtra oxidized glutathione material.
For pharmaceutical API applications, the final storage condition and retest period should be established from stability data for the specific manufacturing process and material form.
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Loss on Drying | NMT 8.0% |
| Residue on Ignition | NMT 0.5% |
| Individual Impurity | NMT 0.1% |
| Specific Rotation | −92° to −106° at 20°C, 589 nm, c=4, wa |