Glutathione (Reduced GSH) – Tripeptide Antioxidant for Skin Brightening and Detox
INCI: Glutathione | CAS: 70-18-8 | MW: 307.32 g/mol | Composition: L-glutamate, L-cysteine, glycine tripeptide
Glutathione (GSH) is the primary intracellular antioxidant in human tissue. It is a linear tripeptide of L-glutamate, L-cysteine and glycine, linked by a gamma-peptide bond between glutamate and cysteine. Every nucleated cell synthesises it, but plasma levels decline roughly 10-15% per decade after age 30. That age-related drop correlates with increased oxidative damage, slower detoxification and visible skin changes including uneven pigmentation.
TCS NEXUS S.L. supplies reduced Glutathione at over 99% purity from our EU warehouse in Valencia, Spain. Standard delivery across the European Union is 5-7 working days. Samples are available on request.
Mechanism of Action: Brightening and Antioxidant Defence
GSH affects skin pigmentation through two parallel routes. First, it directly inhibits tyrosinase, the rate-limiting enzyme in melanin production. Second, it shifts melanogenesis away from eumelanin (brown-black pigment) toward pheomelanin (yellow-red pigment), resulting in a lighter overall complexion. A 12-week randomised controlled trial (n=60) demonstrated that 500 mg/day oral GSH combined with 2% topical GSH reduced the melanin index by 15% compared to placebo.
Beyond brightening, GSH neutralises reactive oxygen species (ROS), regenerates oxidised vitamin C back to its active ascorbic acid form, and conjugates electrophilic xenobiotics via glutathione S-transferase in phase II liver detoxification. This regeneration cycle with vitamin C is why the two ingredients work well together in topical formulations.
Formulation Guidelines for Topical GSH
Reduced glutathione is not a forgiving raw material. The free thiol group on cysteine oxidises rapidly in the presence of dissolved oxygen, metal ions or alkaline pH. A serum that starts water-white can turn yellow within days if these variables are not controlled.
| Parameter | Recommendation |
|---|---|
| Use level | 0.1-2% (typical serum range 0.5-1%) |
| pH | 4.0-5.0 (thiol stability window) |
| Addition temperature | Cool-down phase, below 40 C |
| Packaging | Airless pump, opaque container mandatory |
| Incompatibilities | Strong oxidisers, copper ions (catalyse GSH oxidation), pH above 6 |
| Synergy | Vitamin C (ascorbic acid) – GSH regenerates oxidised vitamin C |
| Storage (raw material) | 2-8 C, nitrogen-flushed packaging preferred |
Practical note: If your GSH serum turns yellow, that colour comes from the formation of glutathione disulphide (GSSG) and mixed disulphides. Check your water quality for dissolved metals, verify pH is below 5.0, and confirm your filling line purges headspace with nitrogen. Switching to airless packaging alone often resolves the issue.
Related Ingredients from TCS NEXUS
- Glutathione Oxidized (GSSG) – The oxidised disulphide form. Used as a redox standard and in formulations studying or leveraging the GSH/GSSG ratio.
- Ergothioneine – A diet-derived thione antioxidant that accumulates in high-stress tissues. Pairs with GSH in multi-layer antioxidant strategies.
- Ectoin – An extremolyte osmolyte for barrier repair and sensitive skin. Complements GSH in urban-defence and anti-pollution product concepts.
Frequently Asked Questions
Where can I buy reduced Glutathione in the EU?
TCS NEXUS S.L. holds stock in Valencia, Spain. We ship across the European Union within 5-7 working days. Request a sample or quote through our contact form and specify the quantity and purity grade you need.
What is the difference between GSH and GSSG?
GSH is the reduced (active) form with a free thiol group. GSSG is the oxidised disulphide dimer formed when two GSH molecules donate electrons to neutralise a free radical. In healthy cells the GSH:GSSG ratio sits around 100:1. A falling ratio signals oxidative stress. For topical brightening you want reduced GSH; GSSG has no direct tyrosinase-inhibiting activity.
Why does my Glutathione serum turn yellow?
Yellow discolouration indicates oxidation of the thiol group, forming GSSG and mixed disulphides. Common causes: pH above 5, dissolved copper or iron in your water, oxygen headspace in the bottle, or addition temperature above 40 C. Fix the root cause – adjust pH to 4.0-5.0, use deionised water tested for metals, switch to airless packaging, and add GSH only in the cool-down phase.
Can I combine Glutathione with vitamin C in the same formula?
Yes, and there is a good biochemical reason to do so. GSH regenerates oxidised vitamin C (dehydroascorbic acid) back to ascorbic acid. In practice, keep the combined pH in the 3.5-4.5 window, add both actives in the cool-down phase, and use airless packaging. The two together provide a broader antioxidant effect than either alone.
What is your minimum order quantity and do you offer samples?
We supply from small R and D sample quantities up to multi-kilogram production lots. Contact us with your project details and we will confirm pricing, lead time and any documentation (CoA, MSDS) you require.